Haefely Test AG TTR 2796 Operating Instructions Manual

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Operating Instructions

HAEFELY TEST AG

TTR 2796

Transformer Turns

Ratio Meter

Version 0.7

Title Operating Instructions

TTR 2796 Transformer Turns Ratio Meter Date 10-2010 Authors RSch Layout LWA

Revision History

V0.7 22/10/10 RSch Initial release of the document

WARNING Before operating the instrument, be sure to read and understand fully

the operating instructions. This instrument produces hazardous voltages. It is the responsibility of the user to ensure that the system is operated in a safe manner.

This equipment contains exposed terminals carrying hazardous voltages. There are no user serviceable components in the unit. All repairs and upgrades that require the unit to be opened must be referred to HAEFELY TEST AG or one of their nominated agents.

Unauthorized opening of the unit may damage the EMI protection of the system and will reduce its resistance to interference and transients. It may also cause the individual unit to be no longer compliant with the relevant EMC emission and susceptibility requirements. If the unit has been opened, the calibration will be rendered invalid.

In all correspondence, please quote the exact type number and serial number of the instrument and the version of software that is currently installed on it. The software version is reported at power-up.

Note

HAEFELY TEST AG has a policy of continuing improvement on all their products. The design of this instrument will be subject to review and modification over its life. There may be small discrepancies between the manual and the operation of the instrument, particularly where software has been upgraded in the field.

HAEFELY TEST AG retain the right to modify the functionality, specification or operation of the instrument without prior notice.

2005, HAEFELY TEST AG, Switzerland

Manual Conventions

In the manual, the following conventions are used:

Indicates a matter of note - if it refers to a sequence of operations, failure to follow the instructions could result in errors in measurement.

Indicates hazards. There is a risk of equipment damage or personal injury or death. Carefully read and follow the instructions. Be sure to follow any safety instructions given in addition to those for the site at which tests are being performed.

Text in “Courier New“ font denotes text shown on the display of the unit and on-screen buttons when described in the text of the operating instructions.

Introduction I

Contents

1 Introduction 3

1.1 Introduction .................................................................................................. 3

1.2 Scope of Supply........................................................................................... 3

1.3 Technical Data ............................................................................................. 4

1.3.1 Standard Features........................................................................... 4

1.3.2 Physical and Environmental Specifications ..................................... 4

1.3.3 Measuring System........................................................................... 5

1.3.4 User Interface System..................................................................... 5

1.3.5 Tap Changer Interface .................................................................... 5

1.3.6 Printer paper Specification .............................................................. 6

2 Safety 7

2.1 Safety........................................................................................................... 7

2.2 Grounding .................................................................................................... 7

2.3 Essential Safety Recommendations ............................................................ 7

3 Operation Elements 9

3.1 Front panel................................................................................................... 9

3.2 Printer ........................................................................................................ 10

4 Connection and Setup 11

4.1 Connection and Setup ............................................................................... 11

4.2 Cable Color Indication................................................................................ 11

4.3 General Notes On Cable Routing .............................................................. 11

4.4 Cable fixing ................................................................................................ 12

4.5 Single Phase Transformers........................................................................ 13

4.6 Three Phase Transformers ........................................................................ 14

4.7 Current Transformers................................................................................. 14

4.8 Bushing Current Transformers................................................................... 16

4.9 Transformer Look Up Tables ..................................................................... 18

4.9.1 Definitions ..................................................................................... 18

4.9.2 Tables ........................................................................................... 19

5 Control Knob 22

5.1 Control Knob .............................................................................................. 22

5.2 Editing Parameters .................................................................................... 22

6 Startup 24

6.1 Startup ....................................................................................................... 24

7 Setting Up Tests 25

7.1 Setting Up Tests ........................................................................................ 25

7.2 Setting Up Transformer Configuration ....................................................... 27

7.3 Setting Test Voltage................................................................................... 28

7.4 Setting up an Untapped Transformer......................................................... 28

7.5 Setting Up a transformer with irregularly spaced taps................................ 31

7.6 Loading A Stored Setup For Use ............................................................... 32

7.7 Saving a Setup........................................................................................... 32

8 Running A Test 34

II Introduction

8.1 Running A Test .......................................................................................... 34

8.2 Errors & Warnings While Testing ............................................................... 35

8.3 Testing Stage 1 - Pretest stage.................................................................. 36

8.4 Testing an Untapped Transformer ............................................................. 37

8.5 Testing A Tapped Transformer using the Tap Changer Button.................. 38

8.6 Options When the Test has Completed ..................................................... 38

8.7 Saving the Test Results ............................................................................. 39

8.8 Printing the Test Results............................................................................ 39

8.9 Graphing the Test Results ......................................................................... 40

9 Memory Functions 41

9.1 Memory Functions ..................................................................................... 41

9.2 Printing the Memory Information ................................................................ 41

9.3 Showing Memory Info On The Screen ....................................................... 42

10 Options 45

10.1 Options ...................................................................................................... 45

10.2 Editable Options......................................................................................... 45

10.3 Fixed Options & Information....................................................................... 46

11 Remote Control 47

11.1 RemoteControl........................................................................................... 47

11.2 Transfer Protocol ....................................................................................... 47

11.3 Remote Control System Error Codes......................................................... 48

11.4 Communications Functions........................................................................ 48

11.5 Test Control Functions............................................................................... 50

11.6 Memory Control Functions......................................................................... 57

11.7 System Setup and Calibration.................................................................... 61

12 Application Software APSW 2796 69

12.1 Application Software APSW 2796.............................................................. 69

12.2 Start-up ...................................................................................................... 69

12.3 Structure .................................................................................................... 71

12.4 Tab Sheet SETUP ..................................................................................... 73

12.5 Tab Sheet MEASURE................................................................................ 79

12.6 Tab Sheet ANALYSIS................................................................................ 81

12.6.1 More Analysis................................................................................ 82

12.7 Data transfer .............................................................................................. 84

12.8 Arbitrary Phase Shift .................................................................................. 85

13 Accessories 90

13.1 Accessories................................................................................................ 90

13.2 Verification Box 2796V............................................................................... 90

13.3 External Tap Switch 279XTAP................................................................... 90

14 Miscellaneous 91

14.1 Miscellaneous ............................................................................................ 91

14.2 Care and Maintenance............................................................................... 91

14.3 Instrument Storage .................................................................................... 91

14.4 Packing and Transport............................................................................... 92

14.5 Recycling ................................................................................................... 92

14.6 Customer Support...................................................................................... 92

14.7 Conformity.................................................................................................. 93

Introduction 3

1 Introduction

1.1 Introduction

The Tettex TTR 2796 Transformer Turns Ratio Measurement system provides simple testing of both single phase and three phase transformers with up to 125 taps. It is a self-contained portable unit that allows gathering, printing and storage of results. The TTR2796 comes with a user-friendly remote software and can be directly controlled by a laptop by using the RS-232 to USB communications link delivered with the instrument. Measurement data stored in the unit can also be downloaded at a later moment to a computer using this RS-232-to-USB communications link.

The TTR 2796 uses a simple and intuitive user interface to make the process of testing as easy as possible. It guides the user through the measurement of turns ratio, phase angles and phase displacement. To further simplify the operation of the unit, it includes a system to automatically determine the configuration and phase displacements of three phase transformers “Automatic Winding Connection Identification AWCI” (patent pending) and “Automatic Vector Group detection”.

The unit offers precise measurement of turns ratio for both on-site and laboratory applications. It uses modern microprocessor and gate array technologies to optimize the performance of the system. The need for recalibration is kept to a minimum through the use of high-quality precision components and self-calibration systems.

1.2 Scope of Supply

The following items are supplied with the standard instrument:

Qty Description

1 TTR 2796 Turns Ratio Meter

1 High voltage side (H) measuring cable (spider), 5m

1 Low voltage side (X) measuring cable (spider), 5m

1 High voltage side (H) extension cable with Velcro strap, 20m

1 Low voltage side (X) extension cable with Velcro strap, 20m

10 Measuring clips, black

4 Measuring clamps, black

4 Measuring clamps, red

1 Mains cable

1 Operating Instructions

1 Remote control software CD “APSW 2796”

1 Remote control cable (RS 232 to USB communications link, pin 6+7 removed)

1 Programming connector (between RS-232 and instrument)

1 Cable and accessory carrying bag

1 Spare kit (Printer paper roll, Fuses)

4 Introduction

On receipt of the unit check that all items have been delivered. Also check that the correct power cord for your location has been supplied. In the event of missing or damaged parts please contact you local sales representative stating the serial number and type of the instrument and the sales order number.

1.3 Technical Data

1.3.1 Standard Features

 Automatic measurement of Voltage

 Automatic measurement of Turns Ratio

 Automatic measurement of Phase Displacement

 Automatic measurement of Current

 Automatic determination of three-phase configuration

 Selectable testing standard

 Measurement of up to 125 taps

 Graphical display of ratio for a tapped transformer

 Internal memory for up to 100 tests

 Checking of measured ratio against nominal

 Minimal load on test object (<0.05VA)

 Test circuit protection system

 RS-232 to USB interface for data download

 Tap changer interface

 Suitable for operation indoor and outdoors

1.3.2 Physical and Environmental Specifications

Size: 406mm x 330mm x 174mm (16” x 13” x 7”)

Weight: 8.8 kg (19 lbs) excluding cables

Case Material: High Impact, high visibility resin

Environmental protection: IP66 (case lid closed), IP51 (case lid open)

Operating Temperature:

-10C to +55C (-10°C typical, -5°C guaranteed)

Storage Temperature:

-20C to 70C

Humidity: 0 to 90% non-condensing

Supply Voltage: 95 to 240VAC, Auto-sensing

Supply Current: < 3.15A

Supply Frequency: 50Hz or 60Hz, Auto-sensing

Compliance: CE marked

Introduction 5

1.3.3 Measuring System

Test Voltages: 2.5VRMS, 25VRMS, 100VRMS, 250VRMS Nominal

Maximum Input Voltage: 1000V for 5 secs

Energizing Frequency: 50Hz or 60Hz depending on local mains

Turns Ratio Measuring Range:

0.8 to 20,000

Turns Ratio Resolution: 5 digits

Ratio Accuracy @ 25V @ 100V @ 250V

0.8 .. 100 ± 0.05% ± 0.05% ± 0.03%

101 .. 1000 ± 0.05% ± 0.05% ± 0.05%

1001 .. 1500 ± 0.05% ± 0.05% ± 0.05%

1501 .. 2000 ± 0.10% ± 0.05% ± 0.05%

2001 .. 4000 ± 0.20% ± 0.05% ± 0.05%

4001 .. 13000 n/a ± 0.25% ± 0.15%

13001 .. 20000 n/a n/a ± 0.20%

Excitation Current Range Resolution Accuracy

Range and Accuracy 0 to 1A 0.1mA ± 1mA

Phase Angle Range Resolution Accuracy

Range and Accuracy ± 180° 0.01° ± 0.05°

1.3.4 User Interface System

Display: 5.2”, dot matrix LCD 240x128, LED Backlight

User Controls: 4 off Soft keys

1 off Rotary Encoder (Control knob)

1 off Emergency Stop

Memory: 100 locations, either settings or data

Communications: RS-232-to-USB, 19200baud

Printer: 58mm wide Thermal Roll, 32 characters

1.3.5 Tap Changer Interface

Tap Changer Sense: Volt Free Contact

Tap Changer Output: Open Collector

Output Voltage: 12V

Max Current: 500mA, Suitable for driving a relay contact or lamp

6 Introduction

1.3.6 Printer paper Specification

Paper Type: Thermal Roll

Paper Width: 58mm +/- 1mm

Maximum Roll Diameter: Outer : 50mm, Inner : 10mm

Safety 7

2 Safety

2.1 Safety

Safety is the responsibility of the user. Always operate the equipment in accordance with the instructions, always paying full attention to local safety practices and procedures

This equipment must be operated only by trained and competent personnel who are aware of the dangers and hazards involved in testing transformers. HAEFELY TEST AG accepts no liability for loss, damage, injury or death caused by the incorrect or unsafe operation of this instrument

Do not operate the TTR 2796 from a variable power supply. The TTR 2796 adjusts to the local line voltage at start-up. Changing the line voltage while the unit is in operation may cause damage to the unit and to the test object

Hazardous voltages exist on the terminals of the instrument when the “Active” lamps are lit. Never assume that the connections are safe if these lamps are extinguished. Switch off and unplug the unit before touching the connections, particularly if a fault is suspected

Use only the supplied Remote Control Cable (RS-232, 1:1, pin 6+7 removed). Do NOT use a normal RS-232 or RS-232-to-USB-cable without removed pins 6&7. This will damage the unit!

2.2 Grounding

The instrument must always be connected to a grounded power outlet (i.e. a safety earth) It must never be operated

in a non-grounded configuration as this may result in electrical shock to the user or damage to the instrument.

Where possible the outer casing of the transformer under test should also be connected to a safety earth to prevent the risk of shock. Where this cannot be achieved, adequate precautions should be taken to prevent access to the transformer, such as barriers.

2.3 Essential Safety Recommendations

Before connecting the instrument ensure that the transformer to be tested is completely deenergized and isolated from both line and load. Every terminal should be checked and verified before connection of the instrument. Ground connections may be left in place

Never exchange connections to the HV and LV sides of the transformer. The “H” connections must always be connected to the High Voltage side of the transformer. The “X” connections must always be connected to the Low Voltage side of the transformer. Interchanging any or all of the connections may result in damage to the transformer or the

8 Safety

instrument and represents a significant safety hazard for personnel

Never operate the equipment in an explosive environment or where there are flammable gases or fumes

Operation Elements 9

3 Operation Elements

3.1 Front panel

Figure 1 : Instrument frontpanel

1 Printer

2 HV cable “H” connection - when the Active lamp is lit, voltage is present on the output

LV cable “X” connection - when the Active lamp is lit, voltage may be present on the terminals

4 Tap changer interface connector

RS-232 communications port. (For use with the supplied RS-232 to USB communications link ONLY!)

6 Soft-keys - these are used to select options to control the system.

7 Control knob - used to set up values, the knob can also be clicked for data entry.

Emergency Stop - this shuts down the output of the system instantly. Once activated the button locks. Turn it clockwise to release it and allow operation to continue.

Power Inlet - Connect only to an earthed power outlet. The unit can be switched on or off using the integrated mains switch. The main fuse holder is also integrated.

Grounding Post - used to provide earth continuity to the test object to minimize interference

11 Display contrast control *

12 Output voltage indication. The LEDs are lit to indicate the applied voltage.

13 Main display

* To the top right of the LCD is the display contrast control (11). This can be used to set the contrast of the display to the optimum value for the environment in which the system is being used. Press and hold the button until the desired contrast is achieved - if the screen is too dark, keep the button pressed until it lightens again. While the button is held down, the system increases the contrast to darken the display until it reached the upper limit of the control, it will then switch to minimum contrast, so the display will go blank (light) and the contrast will increase again from minimum. It then starts adjusting the contrast from minimum again.

10 Operation Elements

3.2 Printer

The printer on the system is a thermal roll type printer and will only operate with thermal paper. See the specifications for details or the required paper. The supplied paper has a paper low warning indication on it. When the paper is getting towards the end of the roll, there are colored streaks (usually pink or red) on the paper. This indicates the user should be ready to replace the paper. When the paper is actually empty, the printer will cease to print and the lamp o the front of the printer unit will flash.

The instrument should be switched on to change the paper. To change the paper, swing open the front of the printer by pressing the release button on the right hand side of the printer and pulling gently. Remove the core of the spent roll from the printer and insert the new roll over the spindle. Ensure that the paper is inserted as indicated below - the “tail” of the paper should be towards the rear of the door. Insert the end of the paper into the feed slot at the top edge of the printer, which should then be fed into the mechanism automatically. Once the paper is loaded, the automatic feed process will stop. Swing the door closed and latch it shut.

Figure 2 : Loading the Printer Paper Figure 3 : Correct paper path

In the event of a paper jam, the paper can be released from the system. Open the paper loading door and then press on the side of the door, behind the release button. This allows the mechanism cover to be opened up. Move the paper release lever (gray or green depending on the printer type) 90 to the vertical position. The paper can then be pulled free. Return the paper release lever to the operating position and snap closed the mechanism door. The paper can now be reloaded; making sure any creased or torn paper is removed from the roll before reloading.

Figure 4 : Clearing Paper Jams

Connection and Setup 11

4 Connection and Setup

4.1 Connection and Setup

Before attempting to connect to the test transformer make sure that it is fully disconnected and de-energized.

4.2 Cable Color Indication

For easy recognition of the different cable leads a clear and definite color indication is used in addition to the

description labels:

to HV side “H”, Phase 1

to HV side “H”, Phase 2

to HV side “H”, Phase 3

to HV side “H”, Neutral

to LV side “X” , Phase 1

to LV side “X”, Phase 2

to LV side “X”, Phase 3

to LV side “X”, Neutral

So it’s possible to check the correct cable connection to the test object from far even if the description labels are not

readable.

4.3 General Notes On Cable Routing

The measurement of turns ratio requires sensitive voltage measurements to be made. It is necessary to minimize the pick-up and cross-coupling on the cables if the most accurate result possible is to be achieved. The following guidelines should be followed. The TTR 2796 has circuitry to minimize the effects of common-mode and high-

12 Connection and Setup

2796

UUT

Bad Layout Practice

"H" & "X"

Cables

Together

"X" Cables Separated

"H" Cables

Separated

2796

UUT

Good Layout Practice

"X" Cables

Together

"H" Cables

Together

"H" & "X" Cables

from each other

frequency interference, however good practice in the setting up of the test systems will aid the quality of the measurements made.

Ensure, as far as is feasible, that any sources of interference are eliminated from the test area. Equipment such as

welding sets and phase-angle furnace controllers should be switched off if at all possible.

Keep the “H” and the “X” cables physically separate. This will minimize the effects of any capacitive coupling between

them.

Keep the “H” cables physically close to each other as far as possible.

Keep the “X” cables physically close to each other as far as possible.

Figure 5 : Cable Routing Practice

Care has to be taken to minimize the possible effects of common mode interference. Particularly when testing transformers with high turns ratios, it is recommended that a grounding lead be run between the case of the transformer under test and the grounding post on the front of the unit.

4.4 Cable fixing

The “H” and “X” extension cables are used for connecting power transformers where the single bushings have bigger spacing between each other and the ground Therefore the extension cables are equipped with a long Velcro strap to fix them e.g. on a bushing’s isolator as a strain-relief. From the fixing point the single test cables can then be connected easily.

Figure 6 : Cable fixing on bushing

Connection and Setup 13

4.5 Single Phase Transformers

To connect to a single-phase transformer using the standard three-phase cable set, the cables must be connected to the unit, using the extension leads if required. Ensure that the connectors are locked fully home. The connections should be made as follows:

Transformer Terminal TTR Connection

ANSI, IEEE IEC, VDE AS (Australian) “H” (Green Plugs) “X” (White plugs)

H1 U A Brown Lead

H0 N N Blue Lead

X1 u a Brown Lead

X0 n n Blue Lead

Figure 7 : Connecting To Single Phase Transformer

If an autotransformer is being tested, then the H0 and X0 terminals are common. The plugs supplied with the test cables are stacking types. The Blue “X” cable (White plug) should be stacked onto the Blue “H” cable (Green Plug).

When connecting to an autotransformer, great care should be taken to ensure that the “H” connection is connected to the top of the winding, especially if the transformer has an overwind on it. Failure to do this may result in damage to the transformer and the instrument.

14 Connection and Setup

4.6 Three Phase Transformers

Connecting to three phase transformers depends on whether the transformer is equipped with neutral connections on

primary or secondary.

If there is no primary neutral connection, the H0 lead (Blue lead, Green Plug) is left unconnected. It must be placed in such a way that it is isolated from earth and from any other connection, and that there is no possibility of it being touched by any personnel during the test.

If there is no secondary neutral connection the X0 lead (Blue Lead, White plug) should be plugged into the X1 lead (Brown lead, White plug).

The connections should be made as follows:

Transformer Terminal TTR Connection

ANSI, IEEE IEC, VDE AS

(Australian)

“H” (Green Plugs) “X” (White plugs)

H1 U A Brown

H2 V B Black

H3 W C Grey

H0 N N Blue

X1 u a Brown

X2 v b Black

X3 w c Grey

X0 n n Blue

If the three-phase transformer is equipped with a tertiary winding this should be tested in the same manner as the secondary. The transformer is energized using the high voltage windings (H0 to H3) with X0 to X3 connected to the tertiary.

4.7 Current Transformers

Care has to be take to ensure that the current transformer is connected correctly otherwise there is a risk of damage to the CT and Instrument. There is also the risk of injury.

When testing CT’s not using the CT setting of the TTR, care has to be taken to ensure that the energization voltage does not cause saturation of the transformer core. It is recommended that the test voltage is limited to 25VAC unless it is certain that the CT can tolerate a higher voltage.

If the CT saturates at 25VAC try using either the CT measurement mode or use 2.5V energization. This is a problem that is more likely to be encountered with smaller transformers with a ratio of 20:1 or less, or with small cores such as “wedding ring” CTs.

Connection and Setup 15

Note the CT measurement mode is an indication only mode, for checking if saturation is the problem. It must not be used for measurement.

CTs are measured by energizing the secondary and measuring on the primary. For “ring” type current transformers

connect the system as follows:

Figure 8 : Connecting to a Ring CT

For core type current transformers, the “H” connections should be made to the secondary (Low current side) and the “X” connections made to the primary (High current side). The transformer can then be tested using either single phase or CT operation.

If the CT has multiple taps, these must be tested individually. Each tap on the secondary is tested in turn, by connecting the “H” connections to each tap in turn. How this is handled depends on whether the current transformer provides a single winding with multiple taps, or separate secondary windings.

Figure 9 : Connecting to Tapped Current Transformers

If the transformer is equipped with a tapped secondary, it is also possible to test the secondary by connecting it as an autotransformer to evaluate the relationship between the individual taps.

16 Connection and Setup

4.8 Bushing Current Transformers

Figure 10 : Connecting to Single Phase BCT

It is possible to test bushing current transformers once they are in-situ. This relies on the minimal loading of the test circuit by the secondary measurement system of the TTR instrument. The primary (or secondary depending on the configuration) connections of the transformer should also be jumped out to create a shorted turn and minimize the inductance of the secondary (or primary). Suitable jumper cables will need to be provided by the user.

When testing BCT systems on three phase transformers, the method of setting up the measurement depends on whether the BCT are mounted on a Y or a Delta connection. The BCT are tested using a three-phase configuration, though do not use automatic configuration or phase determination. The measurement configuration used depends on the winding to which the Bushing current transformers connect. If there is an accessible neutral, test the transformer using YNyn0 otherwise test using Yyn0. The transformers are connected as follows:

Connection and Setup 17

Figure 11 : Connecting to three phase BCT

18 Connection and Setup

4.9 Transformer Look Up Tables

4.9.1 Definitions

The term “Turns Ratio” (TR) is defined as the theoretical voltage ratio, the term “Voltage Ratio” (VR) as the ratio of the rated voltages (“boilerplate voltages”).

TR = Windings Low Voltage side (LV turns)

VR = Phase to Phase Voltage (Low Voltage side)

TR Turns Ratio

VR Voltage Ratio

As a rule, the voltage ratio of three-phase transformers can be measured using a single-phase supply, as long as the distribution of magnetic flux in the core is taken into consideration. Only windings, winding segments and winding combinations which have the same magnetic flux applied, can be compared with one another. The measuring circuit can be derived from the phasor diagram of the test transformer's vector group. The two voltages which are to be compared must be in phase and have the same orientation. But –depending on the winding configuration and phase rotation of the transformer - it’s not possible to have always phase voltages which are being compared. The TTR 2796 therefore internally corrects the measurement with the “TR/(V

A/Va

)” factor and displays automatically the correct ratio value.

The TR/(V

A/Va

) factor determines how the turns ratio is calculated from the ratio of the energizing voltage to the output voltage of the winding. The ratio of the measured voltages are multiplied by this factor to give the turns ratio for that winding/tap.

Due to similar reasons the voltage ratio VR and the turns ratio TR is –depending on the winding configuration and phase rotation of the transformer – not always equal. The TTR 2796 therefore internally corrects the entered rated voltages (VR) with the “VR/TR” factor and displays automatically the correct ratio deviation which is calculated out of the rated voltages (boilerplate voltages) as reference and the actually measured (and corrected) ratio value.

The VR/TR factor determines the multiplier applied to the measured voltage ratio (VR) to get the turns ratio (TR) of the transformer. When the boilerplate voltages for the transformer are set up, the calculated voltage ratio is divided by this factor to give the nominal turns ratio for that winding/tap.

Note for the transformer configuration look up tables:

The “HV Connect” and “LV Connect” give the basic configuration for measuring the transformer to determine the turns ratio (TR). The actual applied configuration depends on the phase rotation of the transformer (see the “Phase Displacement” Info line)

Example: Dyn11 Transformer, HV-LV: 150kV-50kV, N

HV: 520 turns, NLV: 100 turns

TR = N

HV / NL V = 520 / 100 = 5.2 (=>VR*√3=3*√3=5.2).

VR = 150/50 = 3.

TR Turns Ratio VR Voltage Ratio NHV Number of HV-windings NLV Number of LV-windings

Windings High Voltage side (HV turns)

Phase to Phase Voltage (HighVoltage side)

Connection and Setup 19

4.9.2 Tables

HV Winding LV Winding VR/TR

D D 1

Phase Displacement

:a = 0

:b = 8

:c = 4

:-a = 6

:-b = 2

:-c = 10

Notes:

HV Winding LV Winding VR/TR

D Y

1/3

Phase Displacement

:a = 1

:b = 9

:c = 5

:-a = 7

:-b = 3

:-c = 11

Notes:

HV Winding LV Winding VR/TR

D Yn

1/3

Phase Displacement

:a = 1

:b = 9

:c = 5

:-a = 7

:-b = 3

:-c = 11

Notes:

lternatively measure as D-Y

HV Winding LV Winding VR/TR

D Z 2/3

Phase Displacement

:a = 0

:b = 8

:c = 4

:-a = 6

:-b = 2

:-c = 10

Notes:

HV Winding LV Winding VR/TR

D Zn 2/3

Phase Displacement

:a = 0

:b = 8

:c = 4

:-a = 6

:-b = 2

:-c = 10

Notes:

lternatively Measure as D-Z

HV Winding LV Winding VR/TR

Y D

3

Phase Displacement

:a = 1

:b = 9

:c = 5

:-a = 7

:-b = 3

:-c = 11

Notes:

20 Connection and Setup

HV Winding LV Winding VR/TR

Y Y 1

Phase Displacement

:a = 0

:b = 8

:c = 4

:-a = 6

:-b = 2

:-c = 10

Notes:

HV Winding LV Winding VR/TR

Y Yn 1

Phase Displacement

:a = 0

:b = 8

:c = 4

:-a = 6

:-b = 2

:-c = 10

Notes:

lternatively treat as Y-Y

HV Winding LV Winding VR/TR

Y Z

2/3

Phase Displacement

:a = 1

:b = 9

:c = 5

:-a = 7

:-b = 3

:-c = 11

Notes:

HV Winding LV Winding VR/TR

Y Zn

2/3

Phase Displacement

:a = 1

:b = 9

:c = 5

:-a = 7

:-b = 3

:-c = 11

Notes:

lternatively treat as Y-Z

HV Winding LV Winding VR/TR

Yn Dd

3

Phase Displacement

:a = 1

:b = 9

:c = 5

:-a = 7

:-b = 3

:-c = 11

Notes:

lternatively treat as Y-D

HV Winding LV Winding VR/TR

Yn Y 1

Phase Displacement

:a = 0

:b = 8

:c = 4

:-a = 6

:-b = 2

:-c = 10

Notes:

lternatvely treat as Y-Y

Connection and Setup 21

HV Winding LV Winding VR/TR

Yn Yn 1

Phase Displacement

:a = 0

:b = 8

:c = 4

:-a = 6

:-b = 2

:-c = 10

Notes:

lternatively treat as Y-Y

HV Winding LV Winding VR/TR

Yn Z

2/3

Phase Displacement

:a = 1

:b = 9

:c = 5

:-a = 7

:-b = 3

:-c = 11

Notes:

HV Winding LV Winding VR/TR

Yn Zn

2/3

Phase Displacement

:a = 1

:b = 9

:c = 5

:-a = 7

:-b = 3

:-c = 11

Notes:

lternatively measure as Y-Zn - preferred option

HV Winding LV Winding VR/TR

Z D 3/2

Phase Displacement

:a = 0

:b = 8

:c = 4

:-a = 6

:-b = 2

:-c = 10

Notes:

HV Winding LV Winding VR/TR

Z Y

3/2

Phase Displacement

:a = 1

:b = 9

:c = 5

:-a = 7

:-b = 3

:-c = 11

Notes:

HV Winding LV Winding VR/TR

Z Yn

3/2

Phase Displacement

:a = 1

:b = 9

:c = 5

:-a = 7

:-b = 3

:-c = 11

Notes:

22 Control Knob

5 Control Knob

5.1 Control Knob

The control knob is used once to scroll the selected line item:

Rotate the knob to the left and the selector moves down, ..

.. rotate to the right and the selector moves up.

To change or edit the selected line item – press (PUSH) the knob..

..the system then enters an edit screen and allows the value to be edited. When the parameter has been edited and confirmed, the system returns back up to the parameter selection list.

5.2 Editing Parameters

After entering the edit screen the cursor will stand on the first edit-field. There are three types of edit-Fields: Number, List and Text.

Number

Control Knob 23

By rotating the knob the value can be increased respectively decreased. The cursor jumps to the next edit-field by

pressing the knob. Jump one field back by pressing “PREVIOUS”. “DELETE” sets the edit-field back to default (0).

List

By rotating the knob the entry in the list can be selected. By pressing the knob the selected entry is taken over and

the system returns back up to the superior parameter selection list.

Text

A select-character-box is shown above the edit-field. By rotating the knob the desired character can be selected. By

pressing the knob the character is taken to the edit field and the cursor jumps to the next position. Jump one field back by pressing “PREVIOUS”. “DELETE” sets the edit-field back to default (empty).

By pressing “CANCEL” the system returns back up to the parameter selection list without changing anything on the

parameter.

“OK” takes over and safes the edited parameter and the system returns back up to the parameter selection list.

24 Startup

6 Startup

6.1 Startup

After switching on the system it enters the Startup display:

Serial No. The serial number of this instrument

FirmWare Version The Version of the actual used firmware (system software)

Last Calibration The date of the last factory calibration of the instrument

After 3 seconds the following display will appear:

With the soft keys in the bottom line the single sub-menus can be entered:

Start To run a test on a (Dyn) transformer

TRAFO To set-up test configurations, DUT parameters etc.

MEMORY To access all stored data

OPTIONS To set global system options like date, time, etc.

Setting Up Tests 25

7 Setting Up Tests

7.1 Setting Up Tests

To set-up a new test on the system or to load a saved test, the set-up menu should be selected from the startup

display. Press “UP” until the leftmost button indicates “SETUP”. Press this button and the system will enter the setup menu. The following screen is shown:

HV Config The HV configuration sets the winding configuration of the HV side of the transformer. The

options for setting the “LV Config” and “Ph Displacement” may or may not be displayed depending on the HV configuration selected.

Config LV Config Ph Displ. Comments

Auto 3 Ph Hidden Hidden Attempt to automatically determine

config

D Shown Shown Delta (D) Winding

Y Shown Shown Star (Wye) Winding

Yn Shown Shown Star (Wye) Winding with Neutral

Z Shown Shown Zig-Zag Winding

Zn Shown Shown Zig-Zag Winding with Neutral

CT Hidden Hidden Current Transformer

Single Hidden Hidden Single Phase

LV Config The LV configuration sets the winding configuration of the LV side of the transformer. It is

not displayed if the HV Configuration is set to “Auto 3 Ph” because the system attempts to determine the LV winding automatically. Furthermore it is not shown if the HV configuration is set to “CT” or “Single” because there are no alternative configuration possibilities. The options for the LV Configuration are

d y yn z zn

26 Setting Up Tests

Ph Displacement The Phase displacement is only displayed if a three-phase transformer configuration has

been set (both HV Config and LV Config have been set). It allows the user to set the phase displacement of the transformer, or to select automatic determination of the phase displacement. The phase displacement values set depend on the HV and LV configuration of the transformer:

Configuration Displacements

D-d, D-z, D-zn, Z-d, Zn-d, Y-y, Y-yn, Yn-y, Yn-yn 0-2-4-6-8-10

D-y, D-yn, Y-d, Y-z, Y-zn, Yn-d, Yn-zn, Z-y, Z-yn, Zn-y, Zn-yn 1-3-5-7-9-11

Test Voltage The test voltage allows the user to set the voltage applied to the transformer for the test to be set. The options are:

Auto 2.5V 25V 100V 250V

In automatic mode, the voltage is set based no the current drawn by the transformer. The system will use the highest voltage it can without overloading itself.

HV Nom Voltage The HV Nom Voltage is the boilerplate voltage for the high voltage winding of the transformer. Where a transformer is tapped, it is the HV winding voltage for the nominal (center) tap.

LV NomVoltage The LV Nom Voltage is the boilerplate voltage for the low voltage winding of the transformer. Where a transformer is tapped, it is the LV winding voltage for the nominal (center) tap

Total Taps The Total number of taps sets whether the transformer is tapped or not and the number of taps on the transformer. If there are no taps on the transformer the “Total Taps” should be set to one. If only the LV or HV winding is tapped, it should be set to the number of taps plus one, i.e. the number of outputs. If the transformer is tapped on both the HV and LV sides, then the “Total Taps” is set to the total number of possible combinations. The maximum number of taps that can be set is 125.

Bot Tap Number The bottom tap number sets the reference number for the lowest tap on the transformer. All the other taps are referenced relative to this tap. The method of referencing depends on whether Alphabetic or Numeric tap numbering is used. For more information see the later section on setting up tapped transformer tests.

Nom Tap Number This sets the reference number for the nominal tap on the transformer - this is the tap that the “Nom HV Voltage” and “Nom LV Voltage” above refer to.

Tap Setup This sets how the transformer is tapped respectively how the taps are entered. “HV” for a tap changer on HV side, “LV” for taps on the Low Voltage LV side and “Manual” to enter each tap (HV and LV) value manually when leaving this menu-point. To change already manual entered tap values just re-set the tap setup as “Manual”.

Step Tap-Tap The Step Tap-Tap sets the change in output voltage between each tap. If tap stepping is set as voltage in the options menu, it is set in terms of voltage steps, otherwise it is set in terms of a percentage of nominal voltage.

Max Deviation The Maximum % deviation sets the limit for how far the measured ratio for a tap is allowed to differ from the theoretical value based on the nominal HV and LV voltages. If the deviation exceeds this level then the system reports the transformer as having failed the test. If the Max Deviation is set to zero, there is no checking of winding deviation.

DUT Serial No. The DUT Serial No field allows the user to set a serial number, asset tag number or other code to uniquely identify the specific Device Under Test under test. When a set of test results are stored on the unit, they are identified by the DUT Serial No in the memory window. The Serial number must not be longer than 20 characters.

DUT Type The DUT Type field allows the user to set the type code or reference of the transformer being tested, such as a manufacturers code for the unit. If the test setup is stored in memory, it is identified by the DUT Type field.

DUT Location The DUT location allows an indication of where the unit is being tested, so for example tests before and after shipping can be made and identified, or where an indication of the location of a unit would be useful.

Operator The Operator field allows the person performing the test to be identified.

Setting Up Tests 27

To change a parameter for the test, rotate the control knob unit the required parameter is highlighted and press it to select the option. The system allows the value to be edited. When the parameter has been edited, the system returns to the parameter selection list.

When a test has been setup on the unit, it is held and used until it is changed by the user or a setup is loaded from the memory. This allows multiple tests to be performed using the same configuration. If the unit is switched off, the last test setup is maintained in the memory and is available as soon as the unit is turned back on.

In the Trafo menu, the user has four option buttons:

Up Moves the system back to the top-level menu

Default Changes the configuration to a default Dyn transformer, 1 tap to be measured at 250V and clock number to be determined by the TTR.

Load Loads a test setup from the internal memory ready for use. The display shows a list of

setups and test results stored on the system. Highlight the required one using the rotary control and press “OK” to load it. If a test result set is selected, only the setup information is loaded for the test, the data is not copied over.

Save Stores the current test setup into memory. When the option is selected, the system asks which memory location the data is to be saved into. It indicates the next free memory location that is available, if that is not the desired location, enter the memory location number that the information should be saved to.

7.2 Setting Up Transformer Configuration

The way the HV Config (Side connected using ‘H’ leads), LV Config (Side connected using ‘X’ leads), Phase Displacement and Test Voltage are set depends on the type of transformer being tested. The test voltage should be selected according to the type and rating of the transformer being tested. Furthermore the voltage should be high enough to ensure that the transformer is properly magnetized.

If the automatic voltage selection is used, it works on the current drawn by the transformer - it uses the highest voltage it can without overloading itself. If the system seems to be giving anomalous results, the voltage should be set manually to a lower level.

If a three-phase transformer is being tested, the fastest way to measure is by giving in the transformer configuration (e.g. Dyn) followed by the clock number (e.g. 11).

The simplest way for the user to perform a measurement is to set the automatic winding connection identification AWCI option “Auto 3Ph.However this attempt to determine the configuration of the transformer and the phase

28 Setting Up Tests

displacement automatically by the TTR is not infallible. The voltage ratios for some transformer configurations can be overlapping for certain factors/ratios and this causes the TTR sometimes too choose the wrong one or to display: “unable to determine the transformer configuration”. If this occurs, the configuration has to be set manually. The Automatic determination should not be used with Zig-zag windings without a neutral, while it cannot distinguish between a Delta (D) winding and a Zig-zag (Z) winding. If “Auto 3 Ph” is selected, the automatic phase displacement determination is also automatically selected.

The automatic determination system is intended as an aid, for instance where the boilerplate cannot be read. Using automatic determination system will extend the testing time by around 1 minute . It is not guaranteed to detect correctly in all cases. In the event of the transformer failing to detect the correct configuration, please generate a debug report on the printer (see section “OPTIONS”) and send it via fax or e-mail (see contact infos in support section). This will allow us to further improve the determination procedure and make it even more reliable for all possible transformer configurations. If the configuration system fails to correctly determine the transformer configuration, it will be necessary to set the configuration manually.

If the configuration for the transformer is manually entered, it is still possible to have the phase displacement

determined automatically. In this case set the displacement to “Auto”. The phase displacement or clock-number is always properly detected. Of course the user must ensure that the ‘H’ and ‘X’ leads are correctly connected to the system, otherwise the phase displacement will be wrongly detected.

When testing a single-phase transformer or a CT, the “HV Config” should be set to “Single”

mode, in this case it is not necessary to enter a phase displacement.

7.3 Setting Test Voltage

It is important to select the appropriate test voltage for the system - too high a voltage could saturate the core of a small transformer, too low a voltage and there is the possibility of not magnetizing the core properly. Ordinarily, the highest test voltage possible should be used for the transformer. The voltage chosen for the test will depend on the transformer. In most cases, it is adequate to set the test voltage to “Auto” - this selects the test voltage based on the current drawn by the transformer. The system chooses the highest voltage it can without going into over-current. This is not infallible as different test configurations can draw different amounts of current. If the system repeatedly fails the test with an “Over Current” error, note the voltage automatically selected by the system for testing and retry the test while selecting a lower test-voltage. Even if a specific test voltage is selected, the system performs a pre-check and if it cannot achieve the selected voltage without risking overloading itself, it will use a lower test-voltage.

If Automatic voltage setting is selected, the system will use automatic selection each time a test is run irrespective of the voltage determined on the last test performed.

7.4 Setting up an Untapped Transformer

To set up an untapped transformer, the parameters set depend on whether the deviation from the boilerplate ratio is to be determined. If no check against the boilerplate ratings is to be performed, the “Max Deviation” should be set to 0. The “Total Taps” should be set to 1 indicating there is only one main output voltage on the transformer.

When the test is run, the system will perform its integrity checks, determine the test voltage, configuration and displacement if required and will then run the test on the transformer.

If the system is to perform a check on the deviation of the results from the nominal turns ratio, it is necessary to enter values for the “HV Nom Voltage” (the boilerplate voltage for the side connected using the ‘H’ cables) and the “LV Nom Voltage” (the boiler plate voltage for the side connected using the ‘X’ cables). This allows the instrument to calculate how far the measured turns ratio deviates from the ideal value. It is also necessary to enter the maximum allowable deviation from that nominal ratio in terms of percentage. This is set using the “Max Deviation” parameter.

Setting Up Tests 29

Setting up a Transformer with Regularly Spaced Taps

A transformer with regularly spaced taps is a transformer where the output voltages on the various taps differ by the same amount between adjacent taps. This is found in applications such as a tap changer type voltage stabilizer where each tap provides a specific amount of adjustment from the nominal value. If the taps are not equally spaced see the next section for details.

To indicate to the system that it is testing a tapped transformer, the “Total Taps” field is set to a value > 1 . The value to be set is the number of all outputs. To set up the transformer it is necessary to set up the “HV Nom Voltage” and the “LV Nom Voltage” - this sets the voltages for the nominal output. It is then necessary to set the number of the lowest tap (“Bot Tap Number”) and the number of the nominal tap (“Nom Tap Number”) The way these are set depends on the “Tap Numbering” option in the Options screen. The numbering can be set up as alphabetic (A, B, C, D...) or numeric (-1, 0, 1, 2, 3). It is also necessary to set up:”The step between each tap” (“Step Tap to Tap”). This is either in terms of an actual voltage step or as a percentage of the nominal value. This is selected using the Options screen.

If checking of the deviation of the tap from ideal is required, the “Max Deviation” value should be set. If you are not interested in the tap voltage appearing on the test report, it is only necessary to set the “Total Taps” parameter.

Example 1

A transformer with 3 equally spaced taps, numbered 1 to 3. The nominal output is the middle one. Each tap gives an adjustment of 500V, with a nominal output voltage of 16kV at the HV-side and 408V at the LV-side;

TAP Primary

Voltage

Secondary Voltage

1 16.5kV 0.408kV

2 16.0kV 0.408kV

3 15.5kV 0.408kV

Using Tap stepping entered in percentage set:

“HV Nom Voltage” = 16.0kV “HV Nom Voltage” = 0.408KV “Total Taps” = 3 “Bot Tap Number” = 1 “Nom Tap Number” = 2 “Tap Setup” = HV “Step Tap to Tap” = 0.03125%

Using Tap stepping entered in voltage set:

“HV Nom Voltage” = 16.0kV “HV Nom Voltage” = 0.408KV “Total Taps” = 3 “Bot Tap Number” = 1 “Nom Tap Number” = 2 “Tap Setup” = HV “Step Tap to Tap” = 0.500kV

30 Setting Up Tests

Example 2

A transformer with 9 equally spaced taps, numbered 1 to 9. The nominal output is the middle one. Each tap gives an

adjustment of 100V, with a nominal output voltage of 1kV from a 6.6KV primary thus

TAP Primary

Voltage

Secondary Voltage

1 6.6kV 0.6kV

2 6.6kV 0.7kV

3 6.6kV 0.8kV

4 6.6kV 0.9kV

5 (nominal) 6.6kV 1kV

6 6.6kV 1.1kV

7 6.6kV 1.2kV

8 6.6kV 1.3kV

9 6.6kV 1.4kV

Using Tap stepping entered in percentage set:

“HV Nom Voltage” = 6.6kV “HV Nom Voltage” = 1KV “Total Taps” = 9 (Nominal output plus 8 additional) “Bot Tap Number” = 1 “Nom Tap Number” = 5 “Tap Setup” = LV “Step Tap to Tap” = 10%

Using Tap stepping entered in voltage set:

“HV Nom Voltage” = 6.6kV “HV Nom Voltage” = 1KV “Total Taps” = 9 (Nominal output plus 8 additional) “Bot Tap Number” = 1 “Nom Tap Number” = 5 “Tap Setup” = LV “Step Tap to Tap” = 0.1kV

Example 3

A transformer with 16 outputs numbered -7 to +8, each tap gives an adjustment of 5V from a 240V nominal. The primary voltage is 1kV. The nominal tap is tap 0:

TAP Primary

Voltage

Secondary Voltage

-7 1kV 0.205kV

-6 1kV 0.21kV

-5 1kV 0.215kV

-4 1kV 0.25kV

-3 1kV 0.225kV

-2 1kV 0.23kV

-1 1kV 0.235kV

0 (nominal) 1kV 0.24kV

1 1kV 0.245kV

2 1kV 0.25kV

3 1kV 0.255kV

4 1kV 0.26kV

Setting Up Tests 31

5 1kV 0.265kV

6 1kV 0.27kV

7 1kV 0.275kV

8 1kV 0.28kV

Using Tap stepping entered in percentage set:

“HV Nom Voltage” = 1kV “HV Nom Voltage” = 0.24KV “Total Taps” = 16 (Nominal output plus 15 additional) “Bot Tap Number” = -7 “Nom Tap Number” = 0 “Tap Setup” = LV “Step Tap to Tap” = 2.083%

Using Tap stepping entered in voltage set:

“HV Nom Voltage” = 1kV “HV Nom Voltage” = 1KV “Total Taps” = 16 (Nominal output plus 15 additional) “Bot Tap Number” = -7 “Nom Tap Number” = 0 “Tap Setup” = LV “Step Tap to Tap” = 0.005kV

7.5 Setting Up a transformer with irregularly spaced taps

If the transformer has irregularly spaced taps, or it has taps on the primary as well as the secondary, it is not possible for the system to calculate the taps for itself and they have to be entered manually. It is still necessary to set the “Total Taps” to a value > 1. This should be set to one less than the total number of ratio possibilities for the transformer. For any transformer, if all the possible ratios are to be tested the number to be entered is: (Number of inputs on the primary * Number of outputs on the secondary)

The “HV Nom Voltage” and “LV Nom Voltage” should be set to the nominal output (as defined by the user). This is to allow the values to appear on the test report. The user should also set the “Bot Tap Number” and “Nom Tap Number” so the windings are identified correctly. If the measured winding deviation is going to be measured, the “Max Deviation” value should be set accordingly. The “Tap Setup” field must be set to “Manual”. After selecting the “Manual” Tap Setup (and “Total Taps” have a value > 1) then the system will display a message box:

Pressing “NO” will clear the message box and the individual tap voltages will not be set respectively changed. If “YES” is selected the system will display the tap setup screen:

32 Setting Up Tests

Each tap is indicated with the tap number, the HV voltage and LV voltage. To set the voltage for a particular tap, turn

the knob until the required tap is highlighted. Clicking the knob will allow the user to enter first the HV and then the LV voltage for that tap. Once the taps that are required to be set have been, press “OK” to exit from the tap setup screen.

To change already entered tap values select the “Tap Setup” field as “Manual” again and the tap voltage message

box is displayed and all tap values are accessible again.

7.6 Loading A Stored Setup For Use

To load a previously stored instrument setup from the internal memory, select the “LOAD” option from the menu at the

bottom of the SETUP screen. This will display any information stored in the memory:

The left-hand column shows the description of the data held a specific memory. If this is a Setup (that is, there are no

results associated with the entry) the text that is displayed is that held in the “DUT Type” field. If the If the entry in the memory is a set of test results, then the text displayed is the information held in the “DUT Serial No.” field. If a set of test results is selected to be loaded, only the information relating to the setup of the test plus the DUT and operator identification information is copied over. No result information is copied. The second column indicates whether the data stored is Setup or Test information. The final column indicates the memory location where the information is stored.

Setup information is loaded by rotating the knob until the required Test or Setup is highlighted. It is loaded by

pressing the “OK” button. Pressing “CANCEL” returns to the main setup screen.

7.7 Saving a Setup

Once a setup has been defined, it can be saved to memory by pressing the “SAVE” button. This displays a number

entry edit box, which is preset to the next available memory. To save the data into this memory press “OK”. Otherwise

Setting Up Tests 33

enter the required number as described in section 4.3. If there is no available memory, the system will report that it cannot save the data. Once the data has been saved into the memory, the system will display a message box confirming the operation. Press “OK” to return to the Setup menu.

Printing a Setup

To print a setup, press “PRINT” This will print all the information relating to the test onto the built-in printer unit. The format of the printout is:

******** TTR TEST REPORT ******* Transformer: DUT Serial No. Type: DUT Type Location: DUT Location Tested By: Operator

Instrument: TETTEX2796 Serial No.: 1234-56-78

Date Of Test : 09/22/04 Time of Test : 08:23:45 Test Voltage : Auto Max Deviation: 0.5% Configuration: Auto 3ph HV Nom Volt : 3.0 kV LV Nom Volt : 1.0kV Total Taps : 4 Bottom Tap : -2 Nominal Tap : 0 Step Tap-Tap : 0.05kV

Tap -2 (1 of 5) HV: 3.0 kV LV: 0.90kV

Tap -1 (2 of 5) HV: 3.0 kV LV: 0.95kV

Tap 0 (3 of 5) HV: 3.0 kV LV: 1.0kV

Tap 1 (4 of 5) HV: 3.0 kV LV: 1.05kV

Tap 2 (5 of 5) HV: 3.0 kV LV: 1.0kV

******** END OF REPORT ********

34 Running A Test

8 Running A Test

8.1 Running A Test

Before connecting the instrument to the transformer, make sure that the transformer is fully disconnected from both its supply and load and ensure that it is fully de-energized.

Ensure that the instrument is correctly connected to the transformer - the ‘X’ cables must be connected to the low voltage side, the ‘H’ cables to the high voltage side. Refer to section 3 for instructions on how to connect the instrument.

A few seconds after the TTR2796 has been switched ON, the following screen appears:

The top bar indicates that the TTR is ready to start the measurements.

On the left-side of the screen, the configuration that will be tested is indicated. If automatic configuration determination is being used, the configuration is reported as “Auto 3 Ph” until the determination process is completed and the first phase has been measured. If the configuration has been set, but automatic phase displacement determination is being used, the phase displacement is reported as “??” until the first phase has been measured.

In the Middle the Nominal voltages for the windings of the transformer or particular tap of the transformer are displayed. HV for High Voltage side and LV for the Low-Voltage side.

The “Tap” field shows which tap will be measured next. In between brackets is displayed, which number in the sequence that represents and the total number of taps programmed.

Below the line are the results displayed for the transformer. These are blank until at least one of the phases has been measured. If a single-phase transformer is being tested only the “Phase A” line is displayed. The parameters shown for each phase are:

T-Ratio The measured turns ratio of the phase

TR-Dev The measured deviation of the turns ratio from the theoretical ideal. The deviation is

measured in terms of percentage deviation from the nominal value. If the HV and LV voltages are not set, then the deviation is not calculated and the system reports a deviation of -------.

Ph-Dev The measured phase deviation between the primary and the secondary of the transformer

in degrees

Current The current drawn by the transformer under test in [mA].

Running A Test 35

The user has four menu options available:

Start starts the measurement. Trafo brings the user to the setup of the “Device Under Test” Memory brings the user to the memory, which might contain stored measurement results and

setups.

Options brings the user to the general settings for the TTR (e.g. Time/Date/Debug-report, etc)

8.2 Errors & Warnings While Testing

As soon as the testing process is started, the system check to see if there is still data in the working memory that will

be overwritten if the test is run. This is usually the result of the last test. If there is, as soon as the “START” button is pressed it displays

SAVE This saves the data into the next available memory. When the data has been saved the

system displays a second message box

This indicates the location where the data was stored in the memory. If there is not enough memory to store the

result, the system gives a warning of this. To store the data in this case, it will be necessary to go into the MEMORY menu and delete some of the information stored there to make some room for last data taken. Once the data has been stored the test will be run

DELETE This deletes the current result data and runs the test CANCEL This abandons the test and returns to the testing menu.

While running the testing process, there are a number of conditions that will halt the testing process altogether,

requiring the test to be re-started these errors are:

No Cables Connected The system has failed to detect cables on either the ‘H’ or the ‘X’ socket. Check that the

cables are firmly locked onto the sockets. If extension cables are being used ensure that the cables are connected the correct way round and that all the connections are firmly locked tight. If the system detects that the cables are not connected it places itself into a safe condition.

Emergency Stop Pressed The system has detected the Emergency Stop on the front panel has been pressed.

This forces the whole of the energization system to shut down. The Emergency Stop button is a locking type - it must be twisted clockwise to release it before operation can be continued.

Over Current Detected The system has detected an excessive current draw from the ‘H’ connection and

has shut the system down. Possible reasons for this are that the transformer is drawing too much current or that the connections are reversed on the transformer and the protection components are starting to operate. In the first case,

36 Running A Test

repeat the test with a lower test voltage; in the second case, correct the connections to the transformer - exchange the primary with the secondary connections. If no connection errors are found, there may be short circuit within the transformer itself.

Output Voltage Fail A short or overload has been detected on the energization system preventing the required output voltage from being applied to the transformer. Check for any unexpected shorts in the connections or in the transformer.

In each of these cases, if the error occurs, the test will be aborted and will have to be re-run. Press “CANCEL” to clear the error message, then re-run the test once the reason for the error has been determined and rectified.

8.3 Testing Stage 1 - Pretest stage

Once the test procedure has been started, the first stage of the process is to check the integrity of the test system. The system check each voltage up to the voltage selected for the test, making sure that the system does not appear to have the connections reversed and that the transformer under test is not drawing too much current for the selected test voltage to be used. If it is unable to supply enough current for the transformer to be tested at the selected voltage, it attempts to use the closest voltage it can without overloading the system. If the system considers that the connections to the transformer are reversed (it measured a turns ratio of less than 0.8) it reports:

If this message box appears, check the connections are attached to the transformer correctly - that the “X” cables are connected to the low voltage terminals of the transformer. Also check that there is no residual voltage on the transformer, or that there is no significant voltage being induced onto the terminals of the transformer or the connecting cables. Refer to section 3 for more information on routing the cables.

YES This rechecks the connection on the actual voltage - this should be chosen after the

connections have been checked, once you are certain that the transformer is correctly tested.

CANCEL This abandons the test and returns the system to the ready to start state.

CONTINUE This overrides the determination process and moves onto the next voltage setting. It

should be used with a certain amount of caution. It could result in tripping of the supply in the instrument. If there is a connection problem and the connections are reversed, there is the possibility of damage to the transformer or the instrument.

Once the reversed connection process is completed, the system continues the pretest stage. It checks the connections to the system an, if Auto 3Ph or automatic phase determination is selected, it attempts to determine the correct configuration and phase displacement. If it is unable to do so it reports:

Running A Test 37

Press cancel to clear the error box and the system will be ready to start testing again. If the problem persists, go to

the OPTIONS menu and turn on the Debug Report. The system will report the measurements made in determining the transformer configuration and where in the process the measurement failed. Send a copy of this report to Tettex- or Haefely-support or the local agent that sold you the instrument. Please note on the form what the correct configuration of the transformer is. This will allow the determination system to be refined and made more accurate.

If the system persistently fails to determine the configuration or the displacement they will have to be entered

manually from the SETUP screen.

8.4 Testing an Untapped Transformer

If an untapped transformer is being tests, once the connection checking process and the configuration and determination processes have completed, the testing process continues automatically. The system will test phase A, and if a three-phase transformer is being tested, Phase B and Phase C. As the results are taken the tables on the screen are filled out with the data that has been gathered from the system.

Once the test has been completed, the instrument will beep three times to signal the end of the test.

Testing a Tapped Transformer Using The Front Panel

When testing a tapped transformer from the front panel, the sequence of operations is slightly different from when an untapped transformer is being tested. Once the connection checking process, the configuration determination process and the phase displacement determination process are completed, the system stops and produces a single beep. This indicates that it is waiting for the first tap to be set up. Depending on the type of the transformer, this could involve resetting the connections or the tap changer switch. While the system is waiting the user has the following options:

Print Pressing this but will start to print the results obtained till that point

Measure Pressing this button will start the measurement at the indicated tap, makes sure that the

tap is correctly set on the transformer and the instrument can perform the measurement.

38 Running A Test

V-Ratio This toggles the Turns-ratio display to the Voltage-ratio and back again to Turns-ratio,

when pressed again.

Save/Exit This Pauses the measurement process part way through and shows a menu where the

previous obtained data can either be saved or deleted followed by an exit or by pressing [Cancel] the Pause can be broken off and the measurements can be continued.

When the system is ready to test the next tap, it produces a single beep. This signals that the tap-changer can be changed onto the next one by the user. Once the test has completed, it produces three beeps to indicate the end of tests.

If a transformer with irregularly spaced taps is being tested and the measurement of deviation is being performed, it is imperative that the taps are set up on the transformer in the same sequence they are defined in the test setup otherwise the deviation will be calculated incorrectly.

If a transformer with regularly spaced taps is being tested, the test should start from the lowest output tap and work upwards otherwise the deviation will not be calculated correctly.

8.5 Testing A Tapped Transformer using the Tap Changer Button

When testing large transformers with tap changers, it can be awkward to place the TTR where it can be conveniently operated at the same time as the tap changer system. Tettex supply an optional control button that connects to the system via the Tap Changer socket on the front panel.

The test is started from the front panel in the normal way. When the connection check, configuration determination and phase displacement determination is complete, the system will bleep once and the light in the tap changer button will light. The user can then go to the tap changer controls and set the required tap. Once the tap is in place, the button is pressed to start the test for that tap. The lamp on the button will extinguish while the test is in process. Once the test for that tap is finished, the lamp will illuminate again to indicate that the tap can be changed. When the tap is set the user presses the button to perform the test.

The instrument takes approximately 20 seconds to measure a three phase transformer, if the button does not illuminate to indicate the system is ready to start the next stage, either the test has completed or there has been a fault.

8.6 Options When the Test has Completed

When the test has completed, the system provides a number of options for reviewing and handling the data that has been recorded. The options are spread over two menus, which are switched between using the “MORE >” button. The options are:

Print Prints a test report on the internal printer

V-Ratio This toggles the Turns-ratio display to the Voltage-ratio and back again to Turns-ratio,

when pressed again.

Save/Exit Saves the test result into the system memory.

MORE > Switches between the two menus

Edit DUT- Serial nr/Type/Location and Operator can be modified

GRAPH This option is only available when a tapped transformer has been tested. It displays the

results of the test in graphical rather than tabular form.

Running A Test 39

8.7 Saving the Test Results

When “Save/Exit” is pressed, the test results are saved into the next available memory location on the system. This

is indicated on the screen using a message box. Press “Cancel” to return to the test menu.

Press “Save” to store the measured results in the memory and exit. Press “Delete” to exit without string the measured results.

If there is insufficient memory to save the results, the instrument reports an error. In this case it will be necessary to

go to the memory menu to delete some results or setup and then save the data from there.

Saving the results clears them from the main memory so the results displayed on the screen are cleared. If you wish to review the results after they have been saved it is necessary to use the Memory menu and access the location indicated when “SAVE” was pressed.

8.8 Printing the Test Results

Pressing “PRINT” causes the system to print out the test results on the internal printer. The header of the report

indicates the current test setup in the same format as the print from the SETUP menu

******** TTR TEST REPORT ******* Transformer: DUT Serial No. Type: DUT Type Location: DUT Location Tested By: Operator

Instrument: TETTEX2796 Serial No.: 1234-56-78

Date Of Test : 09/22/04 Time of Test : 08:23:45 Test Voltage : Auto Max Deviation: 0.5% Configuration: Auto 3ph HV Nom Volt : 3.0 kV LV Nom Volt : 1.0kV Total Taps : 4 Bottom Tap : -2

40 Running A Test

Nominal Tap : 0 Step Tap-Tap : 0.05kV

For set of measurements on the transformer the instrument reports the measurements in this format:

Tap -2 (1 of 5) HV: 5.00kV LV: 1.00kV

Phase T-Ratio TR-Dev PH-Dev Current

A 5.0168 0.33 -0.7 48mA P B 5.0168 0.33 -0.8 55mA P C 5.0681 1.36 -0.7 66mA F

If the transformer is untapped, then the report only has a single set of measurement results, and no tap identification information is displayed. If the transformer is tapped, the report shows the tap identification and where it is in the sequence of taps.

For each phase the report indicates the turns ratio, the deviation of that turns ratio from the nominal, the phase shift between primary and secondary and the current drawn. On the right hand side of the report it indicates “P” if the turns ratio is within the acceptable deviation (Passed), or if no deviation checking is performed. If the ratio is outside the acceptable deviation limit it indicates “F” to show the transformer has failed the test at that point.

8.9 Graphing the Test Results

The GRAPH option is only available if a tapped transformer was being tested. It allows the user to see the taps measured drawn on an X-Y graph so the relationship between them can be seen. This allows step deviations and unexpected non-linearity in the measured results to be picked out. The X-axis indicates the tap number while the Yaxis indicates the turns ratio running from the minimum value recorded to the maximum.

In the upper right hand corner of the graph, the system indicates the currently selected tap and the turns ratios measured for that tap. A vertical line drawn on the graph indicates the currently indicated tap.

In the lower right hand corner, the instrument displays a legend, which can be switched on or off as required.

The buttons for the graph option are:

UP This returns the instrument to the testing menu

< Moves the cursor line and the ratio readout onto the next tap down in the sequence

> Moves the cursor line and the ratio readout onto the next tap up in the sequence

Memory Functions 41

9 Memory Functions

9.1 Memory Functions

The MEMORY menu allows access to the information stored in the memory on the instrument. Two different types of

information are stored in the memory:

Setup These memories just hold information on how the test is to be performed on a transformer

and what the taps are. In the selection screen, the transformer type information is used as the description

Test These memories hold information taken when a test was run on a transformer. The

transformer serial number is used as the description.

On entering the menu the system displays the memory selection window

Each of the used memories is shown in the list. The description is shown on the left of the screen; this is the transformer serial number or the transformer type depending on whether the memory is a setup memory or a test memory. Next to that the system shows whether the memory is a setup or a test memory. The last column shows which location the memory is using. To select a memory rotate the control knob until the required memory is highlighted by a box around it. This memory can then be viewed or deleted by using the control buttons:

UP This returns the instrument to the top-level menu

PRINT This prints out the contents of the memory on the internal printer

SHOW This displays the contents of the memory on the screen

DELETE This deletes the contents of the selected memory

Clicking the control knob has the same effect as pressing the “SHOW” button.

9.2 Printing the Memory Information

Pressing the “PRINT” button prints the information held in the selected memory. The format of the printout depends on whether the memory is a Setup or a Test memory. For both types of memory the header information is the same, a typical example is shown below:

42 Memory Functions

******** TTR TEST REPORT ******* Transformer: DUT Serial No. Type: DUT Type Location: DUT Location Tested By: Operator

Instrument: TETTEX2796 Serial No.: 1234-56-78

If the memory holds a setup for an untapped transformer, then this is the only information that is printed. If it holds a setup for a tapped transformer then it prints out for each tap the HV and LV voltages set up for that tap, the tap identification number and where in the sequence of taps that comes:

Tap -2 (1 of 5) HV: 3.0 kV LV: 0.90kV

If the memory holds test results for either an untapped or a tapped transformer then it prints out the results for each output measured:

Tap -2 (1 of 5) HV: 5.00kV LV: 1.00kV

Phase T-Ratio TR-Dev PH-Dev Current

A 5.0168 0.33 -0.7 48mA P B 5.0168 0.33 -0.8 55mA P C 5.0681 1.36 -0.7 66mA F

9.3 Showing Memory Info On The Screen

The contents of the highlighted memory are shown on the instrument display when either control knob is clicked or the “SHOW” button is pressed. The system writes up the contents of the memory onto the screen. The information can be scrolled through to read it all using the control knob. The user has two buttons:

OK Returns the instrument to the main memory menu

VIEW TAP Allows the nominal tap voltages to be displayed.

The line at the top of the screen indicates the memory being viewed:

Memory Functions 43

It indicates the date and time the test was performed, whether it is a test or a setup and the number of the memory it

is stored in. Beneath that it shows the basic setup information for the stored in the memory

Configuration YYn0 Test Voltage 100V HV Nom Voltage 9.00kV LV Nom Voltage 1.00kV Total Taps 0 Bot Tap Number 0 Nom Tap Number 0

Step Tap-Tap 0.5kV Max Deviation 0.05% DUT Serial No 12345678 DUT Type 87654321 DUT Location xyz Operator F. Bloggs

If the contents of the memory is a test, the configuration is shown as above as a complete definition . If the memory is

a setup, the configuration is split up into Primary configuration, secondary configuration and phase displacement. If the primary configuration is set to “Auto 3ph”, “Single” or “CT” then the secondary configuration and phase displacement Fields: are not shown.

For a test memory, beneath the basic setup information, the display shows the test configuration for each of the

phases tested:

Phase Descr. : A H1-(H2H3):X1-(X2X3)

B H2-(H1H3):X2-(X1X3) C H3-(H1H2):X3-(X1X2)

Underneath that it displays the results for each tap

Tap: 0 (1 of 5) HV: 9.00kV LV: 1.00kV

--------------------------------------Phase T-Ratio TR-Dev PH-Dev Current A 9.0136 0.15 0.2 38mA B 9.0135 0.15 0.4 42mA C 9.0136 0.15 0.1 32mA

If the memory holds information on a tapped transformer pressing the “View Tap” button will display the nominal HV

and LV voltages set for the transformer

44 Memory Functions

If there are more taps than can be shown on the screen, rotating the control knob will scroll through the values. Press “OK” to return to the SHOW memory screen.

Deleting Memory Information

The highlighted memory can be deleted by pressing the “DELETE” button. This displays a message box asking for confirmation. Press the new “DELETE” button to delete the data or “CANCEL” to return to the memory menu without deleting the data.

Options 45

10 Options

10.1 Options

The general options of the TTR 2796 system can be set by selecting the “OPTION” button from the start-up screen.

The following screen is shown:

10.2 Editable Options

Date The used system date (dd-mm-yy) can be set. Time The used system time (hh:mm:ss) can be set. Standard The used base standard(s) can be set. Depending on that selection, the phase descriptions are shown / printed (e.g. H0, H1,.. X1, .. U, V, W, u,.. ) Step Tap-Tap Step Tap-Tap The unit [V] or [%], in which the tap-to-tap stepping is entered. Tap Numbering The unit [Numeric] or [Alphabetic], in which the tap identification

is done.

Debug Report If this option is set ON then the printer prints out additional measuring and debug values to support an eventual bug fix or function improvement.

Display Ratio The unit [Turns] or [Voltage], in which the ratio is shown

Show Confirmations The options [Yes] or [No]can be chosen, in order to make the TTR stop in between

each action

So if the user faces any problem with the measurement of a test object with this instrument – the Debug Report has to be set ON and the printout (together with other related information like DUT type, occurred problems etc.) shall be submitted to our customer support department. Send it via fax or e-mail (see contact info in support section). This will allow us to fix or further improve the firmware of this instrument.

46 Options

10.3 Fixed Options & Information

The following entries are factory set and therefore not changeable by the user:

Instrument ID The identification of the instrument (TTR-2796)

Serial No The serial number of this instrument (also shown in the stat-up screen) FirmWare Version The Version of the actual used firmware (system software) Last Calibration The date of the last factory calibration of the instrument Next Calib. The date of the next (recommended) factory calibration of the instrument.

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11 Remote Control

11.1 RemoteControl

The 2796 TTR can be remotely controlled via the RS-232 link or the IRDA link. The system uses a standard RS-232 cable (Straight through extension type) to connect to a standard 9 way RS-232 connector on a PC. For other connector configurations, a suitable adaptor should be used. The configuration of the serial port on the TTR 2796 is fixed at 9600 Baud, 8 bits, No parity, 1 Stop Bit.

The data is transferred between the host computer and the TTR using a command-response system. Once a connection has been established, the TTR waits for a command to be sent from the host processor. As soon as it receives the command, it decodes it and transmits a response back to the host processor. There is no mechanism for the TTR to generate an output in the absence of a command from the remote host.

11.2 Transfer Protocol

Data is transferred as strings of ASCII text characters. All messages start with a ‘+’ character. Strings of characters or single characters follow which are interpreted as directives, commands, sub-commands, or data Fields:. Fields: are separated by a colon character ‘:’. A tilde character ‘~’ enclosed in field delimiters, indicates the end of a message.

+<field 1>:<field 2>:<field n>:~:

The separator, control and field characters are:

+ indicates the start of a message.

: is the field separator delimiting the boundary between Fields:, except for the start of the first field of a message,

where the next character after the start character is assumed to be the first field character.

~ is the message terminator character, which must be enclosed within field delimiter characters – ‘:~:’

/ is a literal control character inserted into a field string before a +,:,~ or / character to indicate the following character

is not a control. This allows these characters to be embedded in a filed as part of a text string

The composition of the Fields: is not fixed, the encoding and decoding of messages depends on the particular command being called. No assumptions are made about the encoding of the data by the operating system.

A command message must have a command in the first field, subsequent Fields: can contain sub-commands and data. Command and sub-commands are single characters, additional characters are allowed in the field but are ignored by the protocol and can be used to make the command strings more human readable, for example +Q:D:~: and +Query:Date:~: are equivalent.

When a command has been interpreted by the sever instrument and no data or specific response is required, the server will send an OK acknowledgement message:

+OK:~:

When a command requires specific data or a specific response, the OK acknowledgement is sent at the start of the specific response:

+OK:<response field 1>:<response field n>:~:

When a command cannot be interpreted or replied to, or if there was a problem processing the command an error message with an error number is sent:

48 Remote Control

+ERROR:nnnn:~:

Data is encoded into the Fields: using a “big endian”, that is with the highest order bytes transmitted first. The Fields:

are encoded as follows:

Strings are transmitted with the terminating NULL character removed. The string should be scanned to determine the position of control characters. If ‘:’, ‘~’, ‘+’ or ‘/’ occur within a string to be transmitted, they should be replaced with ‘/:’, ‘/~’, ‘/+’ or ‘//’ respectively. A string returned from the instrument should be scanned and if ‘/:’, ‘/~’, ‘/+’ or ‘//’ are detected, they should be replaced with ‘:’, ‘~’, ‘+’ or ‘/’ respectively

Integers are passed as 4 (16 bit) or 8 (32bit) character ASCII coded hexadecimal strings. If an 8-byte string is coded into 16-bit variable, only the most significant bytes are used.

Floating-point numbers are passed as an 8 character ASCII coded memory representation of a 4-byte IEEE format float.

TimeDate information is passed as a 12 character string in a compressed format of YYMMDDHHMMSS.

11.3 Remote Control System Error Codes

The following error codes are defined for the TTR remote control system:

ES_MEMERR (0x0901) - Error occurred processing memory request

ES_MEMUSED (0x0902) - Requested memory is used already

ES_MEMFREE (0x0903) - Requested memory has no data

ES_MEMCORRUPT (0x0904) - Memory data is corrupted

ES_MEMOOR (0x0905) - Memory Index out of range

ES_MEMFULL (0x0906) - Memory is full

ES_TAPOOR (0x0907) - Tap number out of range

ES_NOCONN (0x0908) - Connection refused

ES_VECTORINV (0x0909) - Vector group invalid

ES_VOLTINV (0x090A) - Voltage Invalid

ES_BADBOTTAP (0x090B) - Bottom tap invalid

ES_MEASRUN (0x090C) - Measurement already running

ES_CANNOTRUN (0x090D) - Measurement cannot run

ES_TAPNOTMEAS (0x090E) - Tap has not been measured

ES_INVALIDREC (0x090F) - Invalid Recipe index

ES_BADINDEX (0x0910) - Bad Text Index

ES_CONFIGINV (0x0911) - Switching Matrix Configuration Invalid

ES_CAL_IDXOOR (0x0912) - Calibration factor index out of range

ES_CONFIGINV (0x0913) – Configuration Invalid

ES_CALINVALID (0x0914) - Calibration EEPROM checksum failed

ES_STEPPERINV (0x0915) - Step Percent Value is an invalid value

ES_INVRECDATA (0x0940) - Unrecognised data received.

ES_TESTRUNNING (0x0300) - Test Procedure is running

These codes are used by the TTR to indicate the status of the system or any errors that have been detected.

11.4 Communications Functions

The communications functions are responsible for creating and managing connections with the unit. When a communications link has been established, the remote system should ensure that the link is kept alive by sending a

Remote Control 49

“maintain” command to indicate connection is to be maintained if it is not transmitting commands. If the host is not going to be transmitting data to the TTR for a period, it should send a “maintain” command every 2 seconds to keep the link active. If the line is allowed to go idle for more than 2 seconds, the TTR will assume that the remote host has disconnected and will reset the communications system and return itself to manual control.

Communications:Open

This attempts to place the TTR in remote control mode

Structure: +C:O:~:

Fields: None Returns: +OK:~: indicates a successful connection

+ERROR:0908:~: indicates the connection is refused because the TTR is being

controlled via the other port already (Error ES_NOCONN).

No Response - system shut off or the link is broken or system printing Comments: The TTR will generate no response if it is either shut down, or the remote is trying to

connect via the RS-232 port and the system is currently printing. The remote should retry the connection periodically to see if connection can be gained.

Communications:Close

This closes down the communications link and ends remote control

Structure: +C:C:~:

Fields: None

Returns: +OK:~: - indicates the connection has been closed. Comments: The TTR will generate no response if it is either shut down, or the remote is trying to

connect via the RS-232 port and the system is currently printing. The remote should retry the connection periodically to see if connection can be gained.

Communications:Maintain

This maintains the communications link when the remote end is idle

Structure: +C:M:~:

Fields: None

Returns: +OK:~: - indicates the maintain request has been received Comments: The Communications:Maintain command should be sent within two seconds of the last

command if the line is going to be idle for a period, to ensure that the communications link is maintained.

Identify

This gets the identity of the TTR being communicated with.

Structure: +I:~:

Fields: None Returns: +OK:TETTEX2796:<Serial No>:<Version>:~:

50 Remote Control

The instrument identification field is always returned as “TETTEX2796” irrespective of the instrument options, as these do not affect the operation of the system

<Serial No> is the serial number of the instrument. This is passed as a text string.

<Version> is the current software version. This is passed as a text string of the form “Vx.xx”

Comments: None

11.5 Test Control Functions

The test control functions allow the remote system to run a test on a connected transformer and to gather the results from the unit under test. The user can set up a complete test profile over the remote link, or just set up the parts that need to be updated for the current test. These functions all operate on the working memory, and do not affect the main memory system.

The Test command has a number of sub-commands:

Setup: Setup the basic test parameters - this is the minimum set of parameters

required to perform a test.

Info: Setup the additional information for the test

Measure: Run/Monitor/Control the measurement sequence

Results: Review the gathered results for the test

Test:Setup:VectorGroup

This sets the vector group of the transformer to be tested

Structure: +T:S:V:<VectorGroup>:<TestVoltage>:~:

Fields: <VectorGroup> (integer) is the vector group of the transformer under test. This is an

integer value that determines the configuration of the transformer and the phase displacement. Bits 15-12 determine the HV winding configuration, bits 11-8 determine the LV winding configuration and bits 7-0 determine the phase displacement. The possible values for the winding configurations are: 0x00 – Delta 0x01 – Star, no neutral 0x02 – Star, with neutral 0x03 – Zig-zag, no neutral 0x04 – Zig-zag, with neutral 0x05 – Single Phase (conventional transformer) 0x06 – Single Phase (current transformer) 0x0E – Use Range Extension transformer 0x0F – Attempt to auto determine winding configuration. The phase displacement is set at a value of 0 to 11, to indicate the actual displacement of the transformer. If it is set at 0xFF, the system will attempt to auto-determine the phase displacement. Note: if the HV winding is set as single phase (conventional or current), use range extension transformer or Attempt to auto determine winding configuration, the setting for the LV winding is ignored.

<TestVoltage> (integer) determines the voltage at which the transformer will be tested. If it is set as zero, or as an invalid value, the system will use automatic voltage determination. The valid voltage levels for the test are: 0x0A (10) - 10 Volts energization 0x28 (40) - 40 Volts energization 0x64 (100) - 100 Volts excitations

Returns: +OK:<VectorGroup>:<TestVoltage>:~: - Vector group updated

+ERROR:0909:~: - Vector group is invalid

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+ERROR:090A:~: - Voltage is invalid

+ERROR:0902:~: - Working Memory has data

+ERROR:0300:~: - No update - test running

The vector group is returned in the response as a confirmation. If there was a problem with the vector group, the function gives a negative response and returns the actual vector group being used. The function also returns the test voltage to be used. If an invalid test voltage is specified, a positive result will still be generated (as long as the vector group is valid), and the test voltage set to automatic determination.

Comments: The vector group will be updated as the test runs, the vector group reported at the end of the testy may differ from that at the start of the test, especially if automatic determination is being used.

Test:Setup:Taps

This sets up the number of taps, the bottom tap, the nominal tap, the tap setup and the step voltage value on the system. The HV Nominal Voltage and LV Nominal Voltage have to be set before setting the Tap values.

Structure: +T:S:T:<NumTaps>:<BotTap>:<NomTap>:<StepValue>:~:

Fields: <NumTaps> (integer) is the number of taps on the transformer. A value of zero indicates

no taps on the transformer. A value of one indicates a single tap (i.e 2 outputs) and so on.

<BotTap> (integer) is the number of the bottom tap on the transformer.

<NomTap> (integer) is the index of the Nominal Tap on the transformer.

<StepValue> (float) is the tap-to-tap Step value. This is in percentage or voltage deviation from the Nominal Voltage. If the tap is on the HV side of the transformer, Step value is negative. If the tap is on the LV side of the transformer, step value is positive. For manual setup, the step value is zero. Based on the values of the the stepvoltage or percent, the tapsetup field is updated as HV or LV or Manual.

Returns: +OK:<NumTaps>:<BotTap>:<> NomTap:< StepValue >:~: -Taps updated

+ERROR:0902:~: - Working Memory has data

+ERROR:0907:~: - Number of taps out of range

+ERROR:090B:~: - Bottom tap out of range

+ERROR:0915:~: - Invalid Step Percent value

+ERROR:0916:~: - Invalid Step Voltage value

+ERROR:0917:~: - Nominal Tap out of range

+ERROR:0300:~: - No update - test running

Comments: If the tap definition is invalid (more than 40 taps selected or bottom tap out of the range +/- 128 or the nominal tap out of range) the system returns an invalid response with the original settings. Also the step percent or step voltage, whichever is applicable is checked for validity. The requested settings are ignored unless all the above are valid.

In cases where there are one tap or more and the tapsetup field is HV or LV, the system updates the individual tap voltages, based on the step value and the LV or HV nominal voltage of the setup memory.

Test:Setup:NominalTapVoltage

This sets the primary and secondary voltages for the nominal tap.

Structure: +T:S:N:<HV Nominal Voltage>:<LV Nominal Voltage>:~:

52 Remote Control

Fields: <HV Voltage> (float) is the voltage for the HV side of the nominal tap.

This is entered in units of kV.

<LV Voltage> (float) is the voltage for the LV side of nominal tap. Returns: +OK:~: - Nominal Tap voltages set OK

+ERROR:0300:~: - No update - test running Comments: There is no checking performed on the HV and LV voltages.

Test:Setup:IndividualTap

This sets the primary and secondary voltages for the individual tap to be measured.

Structure: +T:S:I:<TapNo>:<HV Voltage>:<LV Voltage>:~: Fields: <TapNo> (integer) is the number of the tap being set. This is in the range 0 to <NumTaps>.

If a value outside this range is entered, the system will generate an error

<HV Voltage> (float) is the boilerplate voltage for the HV side of the tap being set. This is

entered in units of kV.

<LV Voltage> (float) is the boilerplate voltage for the LV side of the tap being set . Returns: +OK:~: - Tap voltages set OK

+ERROR:0902:~: - Working Memory has data

+ERROR:0907:~: - Tap No is invalid.

+ERROR:0300:~: - No update - test running Comments: The function will return an error if the tap number is outside the range 0 to <TapNo>. There

is no checking performed on the HV and LV voltages.

Test:Info:Serial

This sets up the serial number of the unit

Structure: +T:I:S:<Serial No>:~: Fields: <Serial No> (string) is a 20 character unit identification string. Returns: +OK:~: - The Serial number has been updated.

+ERROR:0902:~: - Working Memory has data

+ERROR:0300:~: - No update - test running Comments: If a string longer than 20 characters is received it is truncated to 20 characters (plus

terminating null).

Test:Info:Location

This sets up the location of the UUT

Structure: +T:I:L:<Location>:~: Fields: <Location> (string) is a 20 character unit location string. Returns: +OK:~: - The location has been updated.

+ERROR:0902:~: - Working Memory has data

+ERROR:0300:~: - No update - test running Comments: If a string longer than 20 characters is received it is truncated to 20 characters (plus

terminating null).

Remote Control 53

Test:Info:Type

This sets up the type of the UUT

Structure: +T:I:T:<Type>:~:

Fields: <Type> (string) is a 20 character type identification string.

Returns: +OK:~: - The type has been updated.

+ERROR:0902:~: - Working Memory has data

+ERROR:0300:~: - No update - test running

Comments: None

Test:Info:Operator

This sets up the operator testing the unit

Structure: +T:I:O:<Operator>:~:

Fields: <Operator> (string) is a 20 character user identification string.

Returns: +OK:~: - The Operator ID has been updated.

+ERROR:0902:~: - Working Memory has data

+ERROR:0300:~: - No update - test running

Comments: None

Test:Info:Deviation

This sets up the maximum allowable deviation of the turns ratio from nominal.

Structure: +T:I:D:<Deviation>:~:

Fields: <Deviation> (float) is the deviation limit expressed in percent (i.e. a value of 1 represent

1%).

Returns: +OK:~: - The deviation has been set.

+ERROR:0902:~: - Working Memory has data

+ERROR:0300:~: - No update - test running

Comments: If the deviation is set as <=0, no checking of the deviation is performed.

Test:Measure:Run

This runs the measurement procedure.

Structure: +T:M:R:~:

Fields: None

Returns: +OK:~: - Measurement Sequence running

+ERROR:090C:~: - Measurement sequence already running

+ERROR:090D:~: - Unable to run measurement sequence

Comments: The system will report that it is unable to run if the parameters are not set correctly or it has determined there is a fault with the unit.

54 Remote Control

Test:Measure:Halt

This halts the measurement sequence Structure: +T:M:H:~:

Fields: None Returns: +OK:Y:~: - Measurement Sequence is being halted

+OK:H:~: - Measurement sequence already halted.

Comments: None

Test:Measure:Query

This returns the current state of the measurement system, and the last results gathered. Structure: +T:M:Q:~:

Fields: None Returns: +OK:<State>:<VectorGroup>:<Voltage>:<TapNo>:~:

<State> (integer) - current state of the measurement system. The value returned will be one of the following: TS_IDLE (0x00) - Test system is not running a test TS_CONN (0x01) - Test system checking for correct connection. TS_CONFIG (0x02) - Test system checking configuration TS_DISP (0x03) - Test system measuring phase displacement TS_MEAS (0x04) - Test system measuring ratio TS_TAPWAIT(0x05) - System waiting to test next tap TS_SYS (0x06) - Checking System Integrity TS_VOLT (0x07) - Determining test voltage TS_FIVDLFT (0xF8) – Floating input voltage detected TS_USDATAFLT (0xF9) - Unsaved Data in working memory TS_NOMEMFLT (0xFA) - No memory to save results In TS_ESFLT (0xFB) - Emergency stop pressed TS_IFLT (0xFC) - Excessive current draw fault TS_OORFLT (0xFD) - Out of Measurement Range TS_CFGFLT (0xFE) - Configuration setup fault TS_REVFLT (0xFF) - HV-LV connection reversal

<VectorGroup> (Integer) - vector group of the transformer. If automatic configuration detection is completed, it will hold the transformer configuration. It the phase displacement has been measured, it will hold the measured phase displacement.

<Voltage> (integer) the test voltage used for the measurement

<TapNo> (integer) the current tap being measured (0..<NumTaps>)

Comments: If the test system is idle, this will return the results of the last measurement made. Once a test is started, but before any measurements are made, the system will report 0 for <TR>,<I> and <P>. If the test was faulted, the function returns the appropriate fault code. This can be cleared by running another test or by calling the Test:Measure:Halt command while the test system is idle.

Test:Measure:Continue

When testing a tapped transformer, this indicates the next tap is ready to be tested

Structure: +T:M:C:~:

Fields: None

Returns +OK:~:

Comments If the system is not waiting to test the next tap in sequence this command is ignored.

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Test:Results:Setup

Returns the basic setup parameters for the last test performed. Structure: +T:R:S:~:

Fields: None Returns: +OK:<VectorGroup>:<Voltage>:<HVNomVoltage>:

<LVNomVoltage>:<NumTaps>:<BotTap>:<NomTap>:

<StepVal>:<MeasTap>:~:

<VectorGroup> (integer) is the vector group of the transformer under test. This defines the configuration of the transformer and the phase displacement. Bits 15-12 indicate the HV winding configuration, bits 11-8 indicate the LV winding configuration and bits 7-0 indicate the phase displacement. The possible values for the winding configurations are: 0x00 – Delta 0x01 – Star, no neutral 0x02 – Star, With neutral 0x03 – Zig-zag, no neutral 0x04 – ZigZag, with neutral 0x05 – Single Phase (conventional transformer) 0x06 – Single Phase (current transformer) 0x0E – Use Range Extension transformer The phase displacement is between 0 to 11.

<Voltage> (integer) indicates the voltage at which the transformer was tested. It will be one of: 0x0A (10) - 10 Volts energization 0x28 (40) - 40 Volts energization 0x64 (100) - 100 Volts energization

<HVNomVoltage> (float) is the Voltage of the nominal tap on the HV Side.

<LVNomVolatge> (float) is the Voltage of the nominal tap on the LV Side.

<NumTaps> (integer) is the number of taps that have been defined for the transformer.

<BotTap> (integer) is the index of the bottom tap of the transformer.

<NomTap> (integer) is the index of the nominal tap of the transformer.

<StepVal> (float) is the tap-to-tap step value, which is either in Volts or a percentage of the nominal tap voltage, based on the Step Unit set. A negative step value indicates that the tap is on the HV side. A positive step value indicates that the tap in on the LV side. A step value of zero indicates that the tap voltages should be set manually.

<MeasTap> (integer) indicates the number of taps that have actually been measured. If a test has been performed, and this parameter is 0, only a single winding has been tested.

Comments: None

Test:Results:Info

This returns the test information for the last test performed

Structure: +T:R:I:~:

Fields: None

Returns: +OK:<Serial>:<Location>:<Type>:<Operator>:<Deviation>:<TimeDate>:~:

<Serial> (string) is the 20 character unit serial number

<Location> (string) is the 20 character unit location code

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<Type> (string) is the 20 character manufacturers type code

<Operator> (string) is the 20 character operator code

<Deviation> (float) is the maximum acceptable turns ratio deviation.

<TimeDate> (float) is the Time and Date of the test.

Comments: None

Test:Results:Taps

This returns the result for the individual taps on the transformer.

Structure: +T:R:T:<TapNum>:~: Fields: <TapNum> (integer) is the number of the tap for which the results are to be shown. If the

transformer is not tapped, this should be 0. The maximum value is <NumTaps>

Returns: +OK:<HV>:<LV>:<TRA>:<IA>:<PA>:<TRB>:<IB>:<PB>:<TRC>: <IC>:<PC>:<Pass>:~:

- The results of the test

+ERROR:0907:~: - The value of <TapNum> is out of range

+ERROR:090E:~: - The value of <NumTap> is valid, but that tap has not been

measured. This will occur if the test was halted before completion

<HV> (float) is the boilerplate HV side voltage for this tap

<LV> (float) is the boilerplate LV side voltage for this tap

<TRA> (float) is the measured turns ratio for phase A

<IA> (float) is the measured energization current for phase A

<PA> (float) is the measured phase shift for phase A

<TRB> (float) is the measured turns ratio for phase B

<IB> (float) is the measured energization current for phase B

<PB> (float) is the measured phase shift for phase B

<TRC> (float) is the measured turns ratio for phase C

<IC> (float) is the measured energization current for phase C

<PC> (float) is the measured phase shift for phase C

<Pass> (integer) indicates whether all three phases are within the acceptable percentage deviation from nominal. If <Pass> is zero, one or more of the ratios are out of specification. If it is non zero they are within acceptable limits.

Comments: None

Test:Results:Leg

This returns the results of the currently measured leg(s) (Leg A, Leg B, Leg C).

If Leg A was measured, it returns Leg A results and Leg B, C results are zero.

If Leg B was measured, it returns Leg A, B results and Leg C results are zero.

If Leg C was measured, it returns Leg A, B, C results.

Structure: +T:R:L:<TapNum>:~:

Fields: <TapNum> (integer) is the number of the tap for which the results are to be shown. If the

transformer is not tapped, this should be 0. The maximum value is <NumTaps>

Returns: +OK:<HV>:<LV>:<TRA>:<IA>:<PA>:<TRB>:<IB>:<PB>:<TRC>: <IC>:<PC>:<Pass>:~:

- The results of the test

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+ERROR:0907:~: - The value of <TapNum> is out of range

+ERROR:090E:~: - The value of <NumTap> is valid, but that tap has not been

measured. This will occur if the test was halted before completion

<HV> (float) is the boilerplate HV side voltage for this tap

<LV> (float) is the boilerplate LV side voltage for this tap

<TRA> (float) is the measured turns ratio for phase A, if Leg A was measured, otherwise 0.

<IA> (float) is the measured energization current for phase A, if Leg A was measured,

otherwise 0.

<PA> (float) is the measured phase shift for phase A, if Leg A was measured, otherwise 0.

<TRB> (float) is the measured turns ratio for phase B, if Leg B was measured, otherwise 0.

<IB> (float) is the measured energization current for phase B, if Leg B was measured,

otherwise 0.

<PB> (float) is the measured phase shift for phase B, if Leg B was measured, otherwise 0.

<TRC> (float) is the measured turns ratio for phase C, if Leg C was measured,

otherwise 0.

<IC> (float) is the measured energization current for phase C, if Leg C was measured,

otherwise 0.

<PC> (float) is the measured phase shift for phase C, if Leg C was measured, otherwise 0.

Comments: None

11.6 Memory Control Functions

The memory control functions give the remote user full access to the result memory on the system. All transfers to the memory are handled via the working memory. This ensures that the data is correctly validated. The functions that set up parameters in the memory operate only on the working memory and therefore must be transferred from the working memory into the internal memory if they are to be retained in the instrument.

Memory:Initialise

This initializes the memory system

Structure: +M:I:~:

Fields: None

Returns: +OK:~:

Comments: This function should be used with extreme care. It resets the whole of the memory system to the empty state. All data stored in the memory is lost.

Memory:CheckFree

This checks to see if a specified memory location is free.

Structure: +M:C:<MemNo>:~:

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Fields: <MemNo> (integer) is the number of the memory to be checked. It is in the

range 0 to 100 (0x0000 to 0x0064).

Returns: +OK:F:~: - Memory <MemNo> is free

+OK:U:~: - Memory <MemNo> is used

+ERROR:0903:~: - <MemNo> is out of range

+ERROR:0904:~: - Memory <MemNo> is used but corrupted Comments: Memory 0 refers to the working memory, memories 1 to 100 are the main storage

memories.

Memory:GetStatus

This gets the status of each of the 100 memory locations on the system

Structure: +M:G::~: Fields: None. Returns: +OK:<StateString>:~:

<StateString> is a 100 character string that returns the state of the memory locations. The first character refers to memory 1, the second to memory 2 and so on. The character indicates the status of the memory:

‘F’ - the memory is currently free

‘S’ - the memory holds settings information

‘D’ - the memory holds data information

Comments: None

Memory:Free

This frees up all the storage associated with a particular memory location

Structure: +M:F:<MemNo>:~:

Fields: <MemNo> (integer) is the number of the memory to be checked. It is in the

range 0 to 100 (0x0000 to 0x0064).

Returns: +OK:~: Memory <MemNo> is now free

+ERROR:0905:~: - <MemNo> is out of range

Comments: Memory 0 refers to the working memory, memories 1 to 100 are the main storage memories.

Memory:Working

This transfers the contents of the working memory with all its associate data to the specified memory location

Structure: +M:W:<MemNo>:~:

Fields: <MemNo> (integer) is the number of the memory into which the data in the working

memory is to be transferred. This is in the range 1 to 100 (0x0001 to 0x0064). Alternatively, if a <MemNo> of 0 (0x0000) is specified, the contents of the working memory are transferred into the first available memory.

Returns: +OK:<MemNo>:~: - Data has been written in memory <MemNo>

+ERROR:0902:~: - The requested memory was not free

+ERROR:0906:~: - The memory system is full

+ERROR:0904:~: - The data transferred but corruption detected.

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+ERROR:0905:~: - <MemNo> is out of range Comments: If the command is called with <MemNo> = 0, when the response is received from the TTR,

it indicates which memory was actually used to store the data.

Memory:Memory

This copies the content of the specified memory to the working memory.

Structure: +M:M:<MemNo>:~: Fields: <MemNo> (integer) is the number of the memory into which the data in the working

memory is to be transferred. This is in the range 1 to 100 (0x0001 to 0x0064).

Returns: +OK:~: - Data written from memory <MemNo>

+ERROR:0903:~: - Memory <MemNo> had no data

+ERROR:0904:~: - Data transferred but corruption detected

+EEROR:0905:~: - <MemNo> is out of range Comments: The data is retained in the memory, and a copy is made in the working memory.

Memory:Available

This returns the amount of available memory on the system.

Structure: +M:A:~:

Fields: None Returns: +OK:<NumHdrs>:<NumData>:~:

<NumHdrs> (integer) is the number of header blocks that are currently free.

This is will be between 0 and 100 (0x0064).

<NumData> (integer) is the number of data blocks that are available.

This is between 0 and 1500 (0x05DC).

Comments: None.

Memory:NextAvailable

This returns the index of the next available memory header block

Structure: +M:N:~:

Fields: None Returns: +OK:<MemNo>:~:

<MemNo> is the number of the next available memory block. If this is zero,

the memory is full and there are no blocks available.

Comments: None

Memory:Read:Setup

Returns the basic setup parameters for the specified memory.

Structure: +M:R:S:<MemNo>:~: Fields: <MemNo> (integer) is the memory number to be read. This is in the range of 0 to 100.

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Returns: +OK:<VectorGroup>:<Voltage>:<HVNomVoltage>:

<LVNomVolatge>:<NumTaps>:BotTap>:<NomTap>:

<StepVal>:<MeasTap>:~: - Memory read OK

+ERROR:0903:~: - Memory has no data

+ERROR:0904:~: - Memory Corruption detected

+ERROR:0905:~: - Specified memory is out of range

<HVNomVolatge> (float) is the Voltage of the nominal tap on the HV Side.

<LVNomVolatge> (float) is the Voltage of the nominal tap on the LV Side.

<NumTaps> (integer) is the number of taps that have been defined for the transformer.

<BotTap> (integer) is the index of the bottom tap of the transformer.

<NomTap> (integer) is the index of the nominal tap of the transformer.

<StepVal> (float) is the Tap-Tap step value, which is either in Volts or a percentage of the nominal tap voltage, based on the Step Unit set. . A negative step value indicates that the tap is on the HV side. A positive step value indicates that the tap in on the LV side. A step value of zero indicates that the tap voltages should be set manually.

<MeasTap> (integer) indicates the number of taps that have actually been measured. If a test has been performed, and this parameter is 0, only a single winding has been tested.

Comments: None

Memory:Read:Info

This returns the test information for the specified

Structure: +M:R:I:~:

Fields: <MemNo> (integer) is the memory number to be read. This is in the range of 0 to 100.

Returns: +OK: <Serial>:<Location>:<Type>:

<Operator>:<Deviation>:<TimeDate>:~: - Memory read OK

+ERROR:0903:~: - Memory has no data

+ERROR:0904:~: - Memory Corruption detected

+ERROR:0905:~: - Specified memory is out of range

<Serial> (string) is the 20 character unit serial number

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<Location> (string) is the 20 character unit location code

<Type> (string) is the 20 character manufacturers type code

<Operator> (string) is the 20 character operator code

<Deviation> (float) is the maximum acceptable turns ratio deviation.

<TimeDate> (DateTime) is the time and date the test was performed.

Comments: None

Memory:Read:Taps

This returns the result for the individual taps from the memory.

Structure: +M:R:T:<MemNo>:<TapNum>:~: Fields: <MemNo> (integer) is the memory number to be read. This is in the range of 0 to 100.

<TapNum> (integer) is the number of the tap for which the results are to be shown. If the

transformer is not tapped, this should be 0. The maximum value is <NumTaps>

Returns: +OK:<HV>:<LV>:<TRA>:<IA>:<PA>:<TRB>:<IB>:<PB>:<TRC>: <IC>:<PC>:<Pass>:~: -

The results of the test

+ERROR:0903:~: - Memory has no data

+ERROR:0904:~: - Memory Corruption detected

+ERROR:0905:~: - Specified memory is out of range

<HV> (float) is the boilerplate HV side voltage for this tap

<LV> (float) is the boilerplate LV side voltage for this tap

<TRA> (float) is the measured turns ratio for phase A

<IA> (float) is the measured energization current for phase A

<PA> (float) is the measured phase shift for phase A

<TRB> (float) is the measured turns ratio for phase B

<IB> (float) is the measured energization current for phase B

<PB> (float) is the measured phase shift for phase B

<TRC> (float) is the measured turns ratio for phase C

<IC> (float) is the measured energization current for phase C

<PC> (float) is the measured phase shift for phase C

Comments: None

11.7 System Setup and Calibration

All the system setup and calibration is handled over the remote link. There is no access to the setup from the keypad. Also before any changes to the calibration on the system can be permanently stored, it is necessary to insert the

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calibration enable jumper of the processor board within the TTR. This requires the unit to be opened and therefore will invalidate the existing calibration.

The system setup flags option is used to set options on the system that could affect the operation of the unit; there

are two flags:

0x0001 System has printer. If this flag is set the system has a printer available,

so should print test reports.

Setup:SystemType

This sets the system type for the unit

Structure: +S:T:<Type>:~: Fields: <Type> (string) is the type of the instrument. This is typically TETTEX2796 or

TETTEX2796R

Returns: +OK:~: - The System type was set successfully

+ERROR:0006:~: - Calibration Jumper not inserted

+ERROR:0007:~: - Error writing the data Comments: This parameter is used on the test report and as part of the startup screen, to indicate the

instrument type. If the string is longer than 16 bytes including the terminating null, it is truncated and the terminating null placed in the last place.

Setup:SerialNo

This sets the serial number of the unit

Structure: +S:S:<Serial No>:~: Fields: <Serial No> (string) is the serial number of the unit. Returns: +OK:~: - The System type was set successfully

+ERROR:0006:~: - Calibration Jumper not inserted

+ERROR:0007:~: - Error writing the data Comments: This parameter is used on the test report and as part of the startup screen, to indicate the

identification of the instrument. If the string is longer than 16 bytes including the terminating null, it is truncated and the terminating null placed in the last place.

Setup:calibrator

This sets the identity of the last person to calibrate the system

Structure: +S:A:<Calibrator>:~: Fields: <Calibrator> (string) is the serial number of the unit. Returns: +OK:~: - The System type was set successfully

+ERROR:0006:~: - Calibration Jumper not inserted

+ERROR:0007:~: - Error writing the data Comments: This parameter is used to identify the technician/engineer who last calibrated the

instrument. If the string is longer than 16 bytes including the terminating null, it is truncated and the terminating null placed in the last place.

Setup:calDateTime

This sets the date and time of this calibration and the due date of the next one.

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Structure: +S:D:<CalDate>:<NextCalDate>:~:

Fields: <CalDate> (TimeDate) is the date and time the calibration was performed.

<NextCalDate> is the date and time the next calibration is due.

Returns: +OK:~: - The dates and times were set successfully

+ERROR:0006:~: - Calibration Jumper not inserted

+ERROR:0007:~: - Error writing the data

+ERROR:0009:~: - One of the parameters was invalid

Comments: The system checks the validity of both TimeDate Structure:s before writing them to the memory. If either are invalid, the data is not written and the function returns an error

Setup:calreadInfo

This reads the calibration information that is currently stored in the instrument.

Structure: +S:I:~:

Fields: None

Returns: +OK:<Calibrator>:<CalDate>:<NextCalDate:~:

<Calibrator> is the identity of the last person to calibrate the system

<CalDate> (TimeDate) is the date of the last calibration held in EEPROM

<NextCalDate> is the date of next calibration held in Battery powered memory.

Comments: This allows the user to query the calibration information before and after it is set up. The values read back depend on whether they have been updated by the user during the calibration session. If the values are changed, then those changes will be reflected in the data returned when the calreadInfo function is called.

Setup:CurrentTimE

This sets the real time clock

Structure: +S:E:<TimeDate>:~:

Fields: <TimeDate> is the time and date to be set

Returns: +OK:~: - The time was updated successfully

+ERROR:0009:~: - The TimeDate Structure: was invalid.

Comments: None

Setup:SetGain

This sets the gain of the measurement system

Structure: +S:G:<Gain>:~:

Fields: <Gain> (integer) is the bit wise combination of the following constants as required:

MEAS_FILT60 (0x80) - Sets 60Hz filter MEAS_PRIAUTO (0x70) - automatic gain determination MEAS_PRIX1 (0x00) - x1 Primary Gain MEAS_PRIX8 (0x30) - x8 Primary Gain MEAS_SECAUTO (0x0F) - automatic gain determination MEAS_SECX1 (0x00) - x1 Secondary Gain MEAS_SECX2 (0x01) - x2 Secondary Gain

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MEAS_SECX4 (0x02) - x4 Secondary Gain MEAS_SECX8 (0x03) - x8 Secondary Gain MEAS_SECX16 (0x04) - x16 Secondary Gain MEAS_SECX32 (0x05) - x32 Secondary Gain MEAS_SECX64 (0x06) - x64 Secondary Gain MEAS_SECX128 (0x07) - x128 Secondary Gain MEAS_SECX256 (0x08) - x256 Secondary Gain MEAS_SECX512 (0x09) - x512 Secondary Gain MEAS_SECX1024 (0x0A) - x1024 Secondary Gain MEAS_SECX2048 (0x0B) - x2048 Secondary Gain MEAS_SECX4096 (0x0C) - x4096 Secondary Gain

Returns: +OK:~: - indicates the gain was successfully set. Comments: If an invalid setting was specified, the configuration of the system is indeterminate.

MEAS_PRIAUTO and MEAS_SECAUTO are legacy constants and are not used by the system. If they are passed to the function, they are ignored and the gain setting is not updated. If the function is called when auto ranging is switched on, the autorange function is switched off and the gain is set to the current value.

Setup:SetAutORange

This sets the automatic ranging system on or off

Structure: +S:O:<Autorange>:~: Fields: <Autorange> (integer) is the desired autorange state. If it is zero, auto ranging is turned

off. If it is non-zero, auto ranging is turned on.

Returns: +OK:~: indicates auto ranging state was updated. Comments: The autorange state is also affected by setting the measurement gain manually. This

automatically turns auto ranging off. The remote software should never assume the state of the auto ranging system, but should explicitly set it whenever it is needed.

Setup:SetConfiguration

This sets the configuration of the test circuit.

Structure: +S:C:<Configuration>:<Voltage>:~: Fields: <Configuration> (integer) is the configuration of the test circuit switching matrix. It is the bit

wise combination of the specified HV and LV configurations as below: MEAS_PRIH1-H3 - 0x00 - Energize H1 - H3 MEAS_PRIH2-H1 - 0x10 - Energies H2 - H1 MEAS_PRIH3-H2 - 0x20 - Energize H3 - H2 MEAS_PRH1-H2H3 - 0x30 - Energize H1 - H3 Link H2 - H3 MEAS_PRIH2-H1H3 - 0x40 - Energize H2 - H1 Link H1 - H3 MEAS_PRIH3-H1H2 - 0x50 - Energize H3 - H2 Link H1 - H2 MEAS_PRH1-H0 - 0x60 - Energize H1 - H0 MEAS_PRIH2-H0 - 0x70 - Energize H2 - H0 MEAS_PRIH3-H0 - 0x80 - Energize H3 - H0 MEAS_PRICAL - 0x90 - Primary Calibration mode MEAS_SECX1-X3 - 0x00 - Measure X1 - X3 MEAS_SECX2-X1 - 0x01 - Measure X2 - X1 MEAS_SECX3-X2 - 0x02 - Measure X3 - X2 MEAS_SECX1-X2X3 - 0x03 - Measure X1 - X3 Link X2 - X3 MEAS_SECX2-X1X3 - 0x04 - Measure X2 - X1 Link X1 - X3 MEAS_SECX3-X1X2 - 0x05 - Measure X3 - X2 Link X1 - X2 MEAS_SECX1-X0 - 0x06 - Measure X1 - X0 MEAS_SECX2-X0 - 0x07 - Measure X2 - X0 MEAS_SECX3-X0 - 0x08 - Measure X3 - X0 MEAS_SECCAL - 0x09 - Primary Calibration mode

<Voltage> (integer) is the required output voltage to energize the transformer.

This is one of: MEAS_EN1V - 0x01 - Energize at 1V

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MEAS_EN10V - 0x0A - Energize at 10V MEAS_EN40V - 0x28 - Energize at 40V MEAS_EN100V - 0x64 - Energize at 100V MEAS_EN10VCT - 0xFF - Energize at 10V for CT

Returns: +OK:~: - The configuration and voltage were set successfully

+ERROR:090A:~: - The voltage was invalid

+ERROR:0911:~: - The specified configuration was bad

Comments: The user should allow the system to stabilize before making any measurements.

Setup:Querycurrentsetup

This returns the current gain, configuration and voltage set for the instrument.

Structure: +S:Q:~:

Returns: +OK:<Gain>:<Configuration>:<Voltage>:~:

<Gain> (integer) is the system gain

<Configuration> (integer) is the system configuration

<Voltage> (integer) is the system output voltage

Comments: The values returned for <Gain>, <Configuration> and <voltage> can be determined from the constants defined for the Setup:SetGain and Setup:SetConfiguration functions.

Setup:GetRawMeterReadings

This returns the current raw (unprocessed) meter readings and measurement status.

Structure: +S:M:~:

Returns: +OK:<PriV>:<SecV>:<PriI>:<Status>:~:

<PriV> (integer) is the primary voltage magnitude

<SecV> (integer) is the secondary voltage magnitude

<PriI> (integer) is the primary current magnitude

<Status> (integer) is the current status of the measurement system. The lowest 8 bits onstitute a rolling counter. This is updated each time a new meter reading is taken - by checking this rolling counter, the user can determine whether the meter readings have updated since last time they were read. The upper bits carry status information for the metering system as follows: MEAS_PVOR D10 (0x0800) - Primary Voltage Overrange MEAS_SVOR D12 (0x1000) - Sec. Voltage Overrange MEAS_RANGE D13 (0x2000) - System Autoranging MEAS_VFAIL D14 (0x4000) - Output voltage fail MEAS_MATOK D15 (0x8000) - Switching Matrix Stable

Comments: None

Setup:ReadCalFactors

This reads the calibration factors from the EEPROM, so they can be backed up.

Structure: +S:R:<Index>:~:

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Fields: <Index> is the index number in the EEPROM to be read. This is one of:

0 Pri. Volts. Range 1, Sec. Volts. Range 1 1 Pri. Volts. Range 1, Sec. Volts. Range 2 2 Pri. Volts. Range 1, Sec. Volts. Range 4 3 Pri. Volts. Range 1, Sec. Volts. Range 8 4 Pri. Volts. Range 1, Sec. Volts. Range 16 5 Pri. Volts. Range 1, Sec. Volts. Range 32 6 Pri. Volts. Range 1, Sec. Volts. Range 64 7 Pri. Volts. Range 1, Sec. Volts. Range 128 8 Pri. Volts. Range 1, Sec. Volts. Range 256 9 Pri. Volts. Range 1, Sec. Volts. Range 512 10 Pri. Volts. Range 1, Sec. Volts. Range 1024 11 Pri. Volts. Range 1, Sec. Volts. Range 2048 12 Pri. Volts. Range 1, Sec. Volts. Range 4096 13 Not Used 14 Not Used 15 Not Used 16 Pri. Volts. Range 8, Sec. Volts. Range 1 17 Pri. Volts. Range 8, Sec. Volts. Range 2 18 Pri. Volts. Range 8, Sec. Volts. Range 4 19 Pri. Volts. Range 8, Sec. Volts. Range 8 20 Pri. Volts. Range 8, Sec. Volts. Range 16 21 Pri. Volts. Range 8, Sec. Volts. Range 32 22 Pri. Volts. Range 8, Sec. Volts. Range 64 23 Pri. Volts. Range 8, Sec. Volts. Range 128 24 Pri. Volts. Range 8, Sec. Volts. Range 256 25 Pri. Volts. Range 8, Sec. Volts. Range 512 26 Pri. Volts. Range 8, Sec. Volts. Range 1024 27 Pri. Volts. Range 8, Sec. Volts. Range 2048 28 Pri. Volts. Range 8, Sec. Volts. Range 4096 29 Not Used 30 Not Used 31 Current Measurement Factor 32 Secondary Current Burden Resistance

Returns: +OK:<Factor>:~: - Factor (float) is returned.

+ERROR:0910:~: - The requested factor was out of range Comments: This function returns the data held in the EEPROM, rather than the calibration data array.

It will not reflect any changes made by setting the calibration.

Setup:NewCalFactor

This sets a new calibration factor.

Structure: +S:N:<Index>:<Factor>:~: Fields: <Index> is the index of the calibration factor to be updated by the system. The same

indexes are used as for the Setup:ReadCalFactors command.

<Factor> is the new calibration factor for that range to be used. Returns: +OK:~: - The calibration factor has been updated.

+ERROR:0910:~: - The requested index was out of range. Comments: This function updates the contents of the calibration factor array, not the EEPROM. The

changes to a calibration factor become effective immediately. The Setup:UpdateEEPROM function must be called to commit them to the EEPROM.

Setup:UpdateEEPROM

This commits the updated calibration factors to the EEPROM.

Structure: +S:U:~:

Remote Control 67

Fields: None

Returns: +OK:~: - The dates and times were set successfully

+ERROR:0006:~: - Calibration Jumper not inserted

+ERROR:0007:~: - Error writing the data

Comments: None

Setup:ReadProcessedMeters

This reads the calibrated meter readings from the system

Structure: +S:P:~:

Fields: None

Returns: +OK: <Ratio>:<PriV>:<SecV>:<PriI>:<Freq>:<Phase>:<Status>:~:

<Ratio> (float) is the calibrated primary/secondary voltage ratio.

<PriV> (float) is the primary voltage magnitude in ADC counts

<SecV> (float) is the secondary voltage magnitude in ADC counts

<PriI> (float) is the primary current magnitude in mA

<Freq> (float) is the measured frequency in Hz

<Phase> (float) is the measured primary-secondary phase difference in degrees

<Status> (integer) is the current status of the measurement system. The lowest 8 bits constitute a rolling counter. This is updated each time a new meter reading is taken - by checking this rolling counter, the user can determine whether the meter readings have updated since last time they were read. The upper bits carry status information for the metering system as follows: D10 (0x0800) - Primary Voltage Overrange D12 (0x1000) - Secondary Voltage Overrange D13 (0x2000) - System Autoranging D14 (0x4000) - Output voltage fail D15 (0x8000) - Switching Matrix Stable

Comments: None

Setup:Flags

This sets the system operating flags

Structure: +S:F:<value>:~:

Fields: <value> (Integer) is the 16 bit flags value that defines the operation of the system.

Returns: +OK:<flags>:~: - The flag was set successfully and the new flag value returned

+ERROR:0006:~: - Calibration Jumper not inserted

+ERROR:0007:~: - Error writing the data

+ERROR:0009:~: - One of the parameters was invalid

Comments If the top bit of the flags register is set (i.e. the standard flag position is set) the flag setting is not updated, but the function returns the current flag register setting. This allows the current configuration of the system to be determined.

68 Remote Control

Setup:Standard

This sets the Standard for the system.

Structure: +S:Z:<Standard>:~: Fields: <Standard> (Integer) sets the standard. It is one of the following

0 - Do not change standard, this allows the standard to be queried 1 - Set to ANSI standard. 2 - Set to IEC standard. 3 - Set to AUS standard.

Returns: +OK:<StandID>:~: - The standard was set successfully

+ERROR:0007:~: - Error writing the data Comments: The zero value allows the remote host to query standard followed. The function returns the

Standard ID code.

Setup:StepUnit

This sets the Step Unit for the system.

Structure: +S:X:<StepUnit>:~: Fields: < StepUnit > (Integer) sets the tap-to-tap Step Unit of the transformer. It is one of the

following 0 - Do not change Step Unit, this allows the Step Unit to be queried 1 - Set to Step Unit to VOLT 2 - Set to Step Unit to PERCENT

Returns: +OK:<StepUnit>:~: - The Step Unit was set successfully

+ERROR:0007: ~: - Error writing the data Comments: The zero value allows the remote host to query Step Unit of the transformer. The function

returns the Step Unit

Setup:TapNumbering

This sets the Standard for the system.

Structure: +S:Y:<TapNumbering>:~: Fields: < TapNumbering > (Integer) sets the Tap Numbering. It is one of the following

0 - Do not change Tap Numbering, this allows the Tap Numbering to be queried 1 - Set to Numeric format. 2 - Set to alphabetic format.

Returns: +OK:< TapNumbering >:~: - The Tap Numbering was set successfully

+ERROR:0007: ~: - Error writing the data Comments: The zero value allows the remote host to query Tap Numbering format. The function

returns Tap Numbering.

Application Software APSW 2796 69

12 Application Software

APSW 2796

12.1 Application Software APSW 2796

The application software APSW 2796 allows remote operation of the Transformer Turns Ratio Meter TTR 2796. It simplifies the report handling and can be used to integrate the TTR measurements in a complete transformer test system.

Measurement values are transferred via the RS-232 to USB adapter interface. Use only the supplied Remote Control Cable (RS 232 to USB, 1:1, pin 6+7 removed) Do NOT use normal RS-232 or RS-232-to-USB cables without removed pins 6&7. This could damage the unit!

The software is running on Microsoft Windows XP, Win2000 and Win 7 and supports input assistance for operating the software with a touch-screen. The APSW 2796 is especially designed for easy gathering, exchanging and analyzing of measuring data.

12.2 Start-up

After the software has been properly installed the program can be started by clicking the TTR icon.

The program supports two modes: a normal mode which is used for measurements and a simulation mode which can be used for making post-processing, preparing measurement setups or training maintenance/test personnel.

The simulation mode can be started by specifying the argument /SIM in the program call. All functionalities of the normal mode are supported with the exception that measurement values are simulated rather than measured.

70 Application Software APSW 2796

Once the program has been started the following start-up window appears:

If a TTR meter is connected the status message TTR 2796 connected will be displayed. Otherwise the message

TTR 2796 not connected will appear.

When the program is started in the simulation mode the status message

TTR 2796 simulated will be shown.

When the program can not communicate to the TTR although the instrument is connected to the computer most likely the wrong COM port was selected. To correct this press “Quick Measurement”, select tab sheet “SETUP” and click menu “Options”. There you can adjust under the column “TTR 2796 Device” the correct COM port (by default COM1). After that save all changes and restart the program.

At the bottom of the start-up window two buttons could be selected.

Select

to start the system straight on. The default file for storing measuring data will be used.

Select

to launch a dialog window in which you have the possibility to load an existing file, to use a template, to save a file or to create a new file. The button is always shown throughout the program. The functions of the individual elements can be summarized as follows:

Button “New”

By pressing this button the File Selector Dialog pops up where you can enter a name for the new file. All further measured data will be stored in this file.

Button “New based on Template”

If this button is pressed the File Selector Dialog pops up and a new test file can be generated which will be based on an existent file. The setup data will be used from the source file, the measuring data will be deleted. All further operations will be stored in this file.

Button “Load”

By pressing this button a dialog pops up where you can load an existing file to continue your work.

Button “Save”

To save the actual test file press this button.

Button “Save As”

With this button the actual file can be saved with a different filename.

Button “Report”

If this button is pressed the internet explorer with the actual test file will open. There you can print the file and

Application Software APSW 2796 71

configure the appearance of the document.

See section “Report“ for more information.

Button “Previous Test(s)”

This button will load the shortcuts of the three last used files and display them for quick access.

12.3 Structure

The interface of the application software consists of four designated areas:

- title bar: as common under Windows operating system a title bar is displayed at the top of the window.

- tab bar: on the right hand side of the window three tab sheets can be selected which allow access to the main

functions of the program (SETUP, MEASURE, ANALYSIS).

- key bar: at the bottom of the window a key bar is located which includes all buttons necessary to perform

measurements, prepare setups or analyze test results. The buttons are case sensitive, i.e. they change according to the selected tab sheet or menu.

- active window: this area contains the information selected by the appropriate tab sheets, menus and buttons.

Title bar

The title bar (header line) has following Structure:

Device Name

Path and name of the actual active file

Status if operation mode is “Simulated” “not connected” or normal

Help Button

Minimize Button

Close Button

The functional descriptions of the title bar elements are:

Device Name

Name of the controlled device (TTR 2796).

Document Name

The actual active (loaded) test file and its path is shown here. All data are stored in this file.

72 Application Software APSW 2796

Status Message

If the APSW 2796 is started in simulation mode the message “Simulation” appears in this field. If no TTR 2796 is connected but the program is started in the normal mode the message “TTR 2796 not connected” is shown.

The “Simulated” mode provides the same functionality as in the real mode, but no system hardware is needed. The measuring values are simulated.

Help Button

Pressing this button will open an explorer with help screen.

Minimize Button

The display of the software will be minimized and you have access to the Windows OS desktop.

Close Button

By pressing this button you can select between “Exit to Windows” and “Shut Down”.

Press “Exit to Windows” button to terminate the software and exit to Windows Operating System.

Press “Shut Down” button to terminate the software and shut down the system.

It’s strongly recommend to shut down the system correctly before switching the main power off.

Application Software APSW 2796 73

Tab bar

The tab bar contains three tab sheets. Their function can be summarized as follows:

Tab Sheet Setup

Pressing this button provides access to the definition of the Device under Test (DUT), measuring conditions and auxiliary information.

See section “Tab Sheet SETUP” for more details.

Tab Sheet Measure

This sheet contains alls necessary buttons and displays for remote controlling of the TTR 2796, such as TTR status indication, displaying of applied test, vector group configuration, etc.

See section “Tab Sheet MEASURE” for more details.

Tab Sheet Analysis

This sheet is used to sort and analyse the measured data in a graphical way. Trends or different comparisons can be generated without an extraordinary effort. As a result, you may predict the actual state of your equipment.

See section “Tab sheet ANALYSIS” for details.

12.4 Tab Sheet SETUP

This tab sheet consists of following sub chapters.

Menu DUT Info

All general information about the device under test can be entered in this panel.

See section “Menu DUT Info” for more information.

Menu Trafo Data

In this panel the rating and the configuration of the transformer under test can be specified. If the transformer is equipped with a tap changer, it can also be defined here.

See section ”Menu Trafo Data” for more information.

Menu Conditions

This panel is intended for specifying ambient temperature, humidity and pressure.

See section “Menu Settings” for more information.

Menu Options

In this panel, you have the possibility to change the temperature unit (Celsius or Fahrenheit), phase labels, startup modes and communication ports. Currently the user interface is available in English only.

See section “Menu Options” for more information.

Menu Auxiliary

You can enter additional information for your special purpose in this panel. This information will be included when you print out the document.

See section “Menu Auxiliary” for more information.”

74 Application Software APSW 2796

Menu DUT Info

Under this menu all general information like transformer type, operator name, location etc. can be specified.

Simultaneously it is possible to

enter

additional information in the field labeled “Notes”.

Menu Trafo Data

Here the transformer winding system is defined and rated. Although the TTR 2796 detects automatically the vector

group and phase displacement if known it will be manually entered in this menu.

If a winding system is equipped with a tap changer the corresponding check box Tap Changer should be activated

and the corresponding tap number and steps should be entered by clicking the button “Tap Parameters”.

Application Software APSW 2796 75

The following dialog pops up when clicking “Tap Parameters”:

The Tap parameters can be entered here in the same way as in the firmware of the instrument itself.

76 Application Software APSW 2796

With the field “Activate” it can be selected if a defined tap shall be measured (yes) or not (no).

If the tap voltages are evenly distributed they can be calculated automatic: By pressing the

button the minimal

and maximum tap voltage can be entered and the single tap voltages are evenly calculated and filled in the list.

If the tap voltages are not evenly distributed the final values in the list can be edited by the user.

Menu Conditions

This menu offers the possibilities to enter environmental conditions such as temperature, humidity and pressure.

Menu Options

In this menu you can set some general options

Drop-down list “Language”

Here you can select the operating language. Please contact our sales department for further support if you could not find your desired language in the list.

Drop-down list “Startup Mode”

Select Startup: This button allows you to select the startup of the system. By pressing this button a list appears, where you can select your startup mode.

Quick Startup: System will start directly in manual mode.

File Manager: System will start automatically with FileManager dialogue

Load Last File: The file with which you have worked the last time will be automatically loaded. The system will continue at the same place, where you have left it.

Application Software APSW 2796 77

Drop-down list “Temperature Unit”

Here you can select the unit for temperature, if you choose “Celsius °C” the unit meter “m” will be automatically used for lengths. If “Fahrenheit °F” is selected the unit feet “ft” will be used.

Drop-down list "Terms according"

Currently three different conventions for phase labels are supported.

IEC/VDE primary: U, V, W, N secondary: u, v, w, n

ANSI/IEEE primary: H0, H1, H2, H3 secondary: X0, X1, X2, X3

AUSTRALIAN primary: A, B, C, N secondary: a, b, c, n

Drop-down list "User Interface"

With “Standard” user interfaces all inputs are windowslike. For numerical inputs the engineering unit like kilo, nano a.s.o. can be set by pressing

‘G’ Giga ’M’. Mega ’k’ Kilo ’m’ milli ’u’ mikro ’n’ nano ’p’ pico

after the number. The Unit like Volt will be automatically added.

For “Touchscreen” a menu will popup, where you can enter the value.

Drop-down list "User Input"

If "Use Input Lists" is selected all inputs where stored in a file. After pressing first few character all window will popup with all stored values. So it is very easily to make you inputs.

Drop-down list "Data Storage"

With this button it is possible to select in which file format the data are stored.

XML Extended Markup Language. All data are always stored in this data format. This format is text based and can be read by any editor. Together with the Stylesheet file “HTAGDoc.xsl”, where all information about the appearance of data are stored, this file can be shown with internet explorer in a well formatted way.

CSV Comma Separated Values All data are stored as comma separated values. This format allows easily import of data into Microsoft Excel

HTML HyperText Markup Language. This file can be shown be any Internet Explorer.

Drop-down list "Port"

The port number used to remote control the TTR must be specified here.

78 Application Software APSW 2796

Menu Auxiliary

Here you can enter your own documentation fields. The title and field of each line can be free defined by the user.

All titles and text field are also shown in the final printed document.

Application Software APSW 2796 79

12.5 Tab Sheet MEASURE

The tab sheet MEASURE is split into five parts.

Display of Measurement Values

At the top of the window the actual measurement values are displayed including vector group, test voltage, voltage

ratio, ratio deviation and phase deviation.

Control of Test Voltage and Tap Changer

The editable elements in the middle section are used to specify the test voltage, the tap changer position and - if

tertiary winding exists – the windings between which the ratio should be measured.

In the example shown above the ratio between the tap position T1 of the high voltage and the middle tap position T0 of the low-voltage winding will be measured at the selected voltage of 250V. Only the taps, which have been activated and defined in Menu “Trafo Data” can be selected.

Control of Test Procedure

At the bottom of the window the buttons for start and stop a measurement are shown. If a test is started by clicking “Test a Single Tap” the program adopts the selected tap changer position and performs a ratio measurement at the selected tap position. If “Start Testing all Taps” is selected the instrument will start at the selected tap and run through the others.

80 Application Software APSW 2796

Display of Test Progress and Measurement Status

A “Progress” bar shown at the left side under the voltage selection dialog indicates the actual test progress of the

measurement.

Beside the “Progress bar” a status message is displayed which reflects the actual state of the system.

Following status messages appear:

Status “System Ready”

This status message is displayed as long as the system is in idle mode. When this status is active the system is awaiting the start order to begin with the measurements.

Status “Checking Connections”

This message will appear when a measurement is initiated. The system checks now if the leads are connected properly and if all conditions necessary to perform measurements are met.

Status “Measuring..”

When this status message is shown the instrument applies the specified voltage to the DUT and measures the current.

Status “Checking Configuration”

During the time when this status is active the system tries to determine the correct vector group of the transformer (e.g. Dyn).

Status “Checking Displacement”

This is the last status which appear during a measurement. The instrument tries to figure out which phase displacement exists between primary and secondary winding.

Handling of Measurement Results

After a measurement has finished the test results are automatically transferred into the list displayed at the bottom of

the window.

The same list can also be seen in the tab sheet ANALYSIS. The elements of the list can edited by clicking the button

Application Software APSW 2796 81

12.6 Tab Sheet ANALYSIS

This sheet is intended for making post analysis in a graphical way. New measured data can be compared with older ones for trending purposes or simple threshold levels can be entered to specify PASS/FAIL criteria. Measured values can also be displayed against each other, for example to determine if the voltage ratio is linear with the tap changer position.

The axis of the graphic can be configured by clicking the Fields:

or .

Different views can be defined by pressing

. A Menu with following buttons will popup

Button Add View

Pressing this button will store the actual graphic under a free definable name.

Button Rename View

Pressing this button will rename the actual view.

Button Delete View

Pressing this button will delete the actual selected view.

82 Application Software APSW 2796

Button Save View

Pressing this button will store the current view under the actual selected name.

Button Show Actual Diagram

Opens the actual diagram in program, which is associated with the file extension ‘.jpg’, where you can print it.

The yellow, green and red area of the graphic can be set by clicking

12.6.1 More Analysis

This tool is used to analyze several files at the same time. The feature is especially helpful, if you want to analyze the

measured data from different test objects.

Analysis File Selection

Pressing the button will open the following dialog in which you can manage files for analyzing.

The descriptions of the buttons are as follow:

Button Add File

Pressing this button will add a file to the list.

Button Remove File

Pressing this button will remove the current selected file from the list.

Application Software APSW 2796 83

Button Remove All

Pressing this button will remove all files from the list.

Button Save List As

Pressing this button will store the actual list in a file.

Button Load List

Pressing this button will load a list from a file.

Button Show Analysis

Pressing this button will open a dialog with all files from the list.

Analysis with data from different files

All selected measurement files are shown here. By pressing the column name “File Name”, you can manage this list. See related chapter for details.

84 Application Software APSW 2796

Measurement Report

The APSW 2796 can generate detailed test reports which can be saved, loaded or printed. The format of the report is

XML (EXtended Markup Language). By clicking

in the “File Manager” menu an explorer

will open and the report can be previewed and printed.

The layout of the report can be completely customized. The logo can be changed by replacing the file

“C:\company.jpg” by your own logo. The appearance of the report can be edited by changing the file “C:\HTAGdoc.xsl”.

For further information about the XML/XSL language please refer to the appropriate technical literature or the internet

www.w3.org.

At the top of the explorer window a small header with check boxes and a print link is placed. With this menu the elements which should be displayed in the report can be controlled. It is possible to hide or display the test sequences, the measurement values and the analysis window. Clicking on the Logo on the right side of the explorer window will show or hide the menu. The Print Command will hide the menu and open the print dialog.

An example of a test report looks like follows:

12.7 Data transfer

For transferring data from the TTR 2796 to the computer press button in the key bar at the bottom of the window. A dialog window will pop up where you can choose which measurements shall be uploaded to the computer.

Application Software APSW 2796 85

12.8 Arbitrary Phase Shift

Arbitrary phase displacement (those that don’t follow the 30° clock steps) between the primary and secondary winding are an usual feature in multi-winding transformers like rectifier transformers, to reduce harmonics injected into the system (increasing the number of rectifier phases to increase the number of pulses in the rectified dc signal). The traditional practice of achieving this is by using a three phase transformer turns ratio meter (TTR) that necessitates the use of a three-phase AC voltage supply or single-phase to three phase voltage supply converter. Having the necessity for a three-phase supply is disadvantages because it is usually difficult to source one during field tests. The solution with an additional kit to generate three-phase supply from a single-phase source means extra cables and cumbersome to transport and use.

In the Tettex TTR 2796, arbitrary phase shift (APS) measurement is achieved by using a single-phase supply and with no extra hardware as elaborated earlier. The necessary three phase equivalent voltages at different transformer terminals are simulated by energising a pair of the transformer terminals and interconnecting certain other terminals using a custom approach. The resulting voltages at different terminals is fed to a custom algorithm to determine the arbitrary phase shift. This approach inherently eliminates the disadvantages associated with the traditional practice and leads to a solution that is compact , flexible and easier to use.

To enable arbitrary phase shift measurement, click on the drop down box opposite the label Phase Displacement and

select from the drop down list – Arbitary Phase Shift.

86 Application Software APSW 2796

Once this option is selected a small window pops-up and prompts the user to give-in the activation code.

Obtain the activation code from Tettex-Haefely Test AG. Once the correct activation code is given, a message pops

up (see image below) confirming that arbitrary phase shift module is activated.

Application Software APSW 2796 87

To continue with the arbitrary phase shift measurements, following information should be known.

(a) Type of the transformer to be tested.

Transformer having at least two three phase windings

Transformer having at least one winding in three phase and one winding in single-phase.

(b) Primary and secondary winding configuration of the transformer. For example, Delta-delta, Delta-star,

etc.

Example.

Transformer 3ph, Rated power 5500 kVA, HV: 11000+

2x2.5 V; LV1: 2202V. Vector group: Dd11.75 (or phase displacement=-7.5°) Vector group: Dd 0.75 (or phase displacement=+22.5°)

(Images courtesy: Trasfor, Lugano, Switzerland).

This is the case of a transformer having at least two three-phase windings, with primary and secondary side winding of the transformer configured respectively as Delta and delta, the vector group settings on the primary and secondary should be set-up as shown in the image below.

88 Application Software APSW 2796

The remaining steps to turns ratio and phase shift measurement are as detailed earlier in section 12.5.

The resulting display is as follows (for vector group Dd0.75)

For the case of a transformer having at least one winding in three-phase and one winding in single-phase, with the primary side winding of the transformer configured as delta, the vector group settings on the primary and secondary should be set-up as shown in the image below.

Application Software APSW 2796 89

The remaining steps to turns ratio and phase shift measurement are as detailed earlier in section 12.5.

90 Accessories

13 Accessories

13.1 Accessories

13.2 Verification Box 2796V

The Verification Box is used to check the correct functionality of the Ratio Meter and its connected test cables.

Different ratios (1, 10, 100, 1000) can be selected by the selector knob on top.

Test cables have to be connected following the description on the front respectively the color code.

The verification measurements shall be within an overall accuracy of 1% of the nominal ratio. If the displayed values exceed this limit the unit has to be sent back to the manufacturer for recalibration respectively repair.

Figure 12 : Verification box 2796V

13.3 External Tap Switch 279XTAP

The external tap switch cable is used for convenient tap changer testing.

After the TTR has measured a tap it stands by waiting for the operator to move the transformer tap changer to the next tap position and continue the TTR measurement by pressing “CONTINUE” on the unit. The tap changer operation box on power transformers is normally not placed at the same place where the TTR2796 is placed. The external tap switch cable allows the operator to continue the next tap measurement from a remote position (normally at the tap changer box of the transformer).

If the built-in indicator lamp in the knob is lit, then the TTR is ready for the next measurement: Move the tap changer to the next position and press the button to start the measurement.

The light goes off while the TTR is busy with the measurement.

As soon as the unit is ready to measure the next tap the built-in indicator lamp is lit again.

Figure 13 : External Tap Test Start Switch 279XTAP

Miscellaneous 91

14 Miscellaneous

14.1 Miscellaneous

14.2 Care and Maintenance

The TTR 2796 instrument is basically service free, as long as the specified environmental conditions are adhered to. As a result, service and maintenance is restricted to cleaning of the equipment and calibration at intervals stipulated by the application for which the instrument is used.

The insulation of all cables should be periodically checked for damage. If any damage to the insulation is detected then a new measuring cable should be ordered from HAEFELY TEST AG.

Cleaning the Instrument

The instrument should be cleaned with a lint free cloth, slightly moistened using mild household cleanser, alcohol or spirits. Caustic cleansers and solvents (Trio, Chlorothene, etc.) should definitely be avoided.

In particular, the protective glass of the display should be cleaned from time to time with a soft, moist cloth such as used by opticians.

Instrument Calibration

When delivered new from the factory, the instrument is calibrated in accordance with the calibration report provided. A periodical calibration of the instrument every two years is recommended.

As the calibration process is fairly extensive, the instrument can only be calibrated and, if necessary, adjusted at HAEFELY TEST AG’s factory. An updated calibration report will then be issued.

Changing Fuses

Before changing the mains fuse, remove the mains power cord. Fuses should only be replaced with the same type and value.

14.3 Instrument Storage

If the instrument is to remain unused for any length of time, it is recommended to unplug the mains lead. In addition, it is advisable to protect this high precision instrument from moisture and accumulation of dust and dirt with a suitable covering.

92 Miscellaneous

14.4 Packing and Transport

The packing of the TTR 2796 instrument provides satisfactory protection for normal transport conditions. Nevertheless, care should be taken when transporting the instrument. If return of the instrument is necessary, and the original packing crate is no longer available, then packing of an equivalent standard or better should be used.

Whenever possible protect the instrument from mechanical damage during transport with padding. Mark the container with the pictogram symbols „Fragile“ and „Protect from moisture“.

Figure 14 : Pictograms

14.5 Recycling

When the instrument reaches the end of its working life it can, if required, be disassembled and recycled. No special instructions are necessary for dismantling.

The instrument is constructed of metal parts (mostly aluminum) and synthetic materials. The various component parts can be separated and recycled, or disposed of in accordance with the associated local rules and regulations.

14.6 Customer Support

All error messages appear on the display of the TTR 2796 measuring instrument. If persistent problems or faulty operation should occur then please contact the Customer Support Department of HAEFELY TEST AG or your local agent.

The Customer Support Department can be reached at the following address:

HAEFELY TEST AG

Customer Service - Tettex

Lehenmattstrasse 353

CH-4052 Basel

Switzerland

Tel: +41 61 373 4422

Fax: +41 61 373 4914

e-mail: tettex-support@haefely.com

We prefer contact via email. Then the case is documented and traceable. Also the time zone problems and occupied telephones do not occur.

Remember: Complete information describing the problem clearly (Debug

Report, printouts, firmware version, DUT type, etc.) helps us to help you.

Miscellaneous 93

14.7 Conformity

Haefely Test AG TTR 2796 Operating Instructions Manual

Specifications and Main Features

Frequently Asked Questions

User Manual