AEMC 6550 Operating Manual



10kV and 15kV MEGOHMMETERS

6550

6555

ENGLISH

User Manual

Megohmmeter Models 6550 / 6555

Cat. #2130.31 / Cat. #2130.32

Ships with the following:

PRODUCT PACKAGING

Small Classic Tool Bag

Cat. #2133.72

10kV Megohmmeter Model 6550

Cat. #2130.31

or

15kV Megohmmeter Model 6555

Cat. #2130.32

Set of 3 color-coded (red/blue/black) 9 ft (15kV) integral leads and alligator clips

(1000V CAT IV), set of 2 color-coded test probes (red/black 1000V CAT IV)

15kV Jumper Lead

Cat. #2151.15

Also Includes:

• USB Stick with DataView
and User Manual

• 2x9.6V NiMH batteries (Cat. #2140.19 each)

®

Software

Optical USB Cable

Cat. #2135.41

Cat. #2151.14

115V US Power Cord

Cat. #5000.14

Statement of Compliance

Chauvin Arnoux®, Inc. d.b.a. AEMC® Instruments certies
that this instrument has been calibrated using standards and
instruments traceable to international standards.

We guarantee that at the time of shipping your instrument has

met its published specications.

An NIST traceable certicate may be requested at the time of

purchase, or obtained by returning the instrument to our repair
and calibration facility, for a nominal charge.

The recommended calibration interval for this instrument is
12 months and begins on the date of receipt by the customer.

For recalibration, please use our calibration services.
Refer to our repair and calibration section at www.aemc.com.

Serial #: ______________________________

Catalog #: 2130.31 / 2130.32

Model #: 6550 / 6555

Please ll in the appropriate date as indicated:

Date Received: ____________________________

Date Calibration Due: _______________________

Chauvin Arnoux®, Inc.
d.b.a AEMC® Instruments

www.aemc.com

Thank you for purchasing a Megohmmeter Model 6550/6555.
For best results from your instrument and for your safety, read the enclosed operating instructions carefully and

comply with the precautions for use. These products must be only used by qualified and trained users.

Signifies that the instrument is protected by double or reinforced insulation.

CAUTION - DANGER! Read the User Manual.

Risk of electric shock. The voltage at the parts marked with this symbol may be dangerous.

Refers to a type A current sensor. This symbol signifies that application around and removal
from HAZARDOUS LIVE conductors is permitted.

Refers to a type B current sensor. Do not apply around or remove from HAZARDOUS LIVE
conductors without additional protective means (de-energizing the circuit or wearing protec­tive clothing suitable for high voltage work).

Important instructions to read and to fully understand.

Useful information or tip to read.

USB socket.

Ground/Earth.

The CE marking guarantees conformity with European directives and with regulations covering
EMC.

Chauvin Arnoux® Inc. d.b.a. AEMC® Instruments has adopted an Eco-Design approach in order
to design this instrument. Analysis of the complete lifecycle has enabled us to control and
optimize the effects of the product on the environment. In particular this instrument exceeds
regulation requirements with respect to recycling and reuse.

The trash can with a line through it means that in the European Union, the product must
undergo selective disposal for the recycling of electric and electronic material, in compliance
with Directive WEEE 2002/96/EC.

Precautions Before Use

This instrument and its accessories comply with safety standards IEC 61010-1, IEC 61010-031, and
IEC 61010-2-030 for voltages of 1000V in Category IV at an altitude of less than 2000m, indoors, with
a degree of pollution of not more than 2. Failure to observe the safety instructions may result in electric
shock, fire, explosion, and destruction of the instrument and of the installations.

■ The operator and/or the responsible authority must carefully read and clearly understand the
various precautions to be taken in use. Sound knowledge and a keen awareness of electrical
hazards are essential when using this instrument.

■ If the instrument is used other than as specified, the protection it provides may be
compromised, thereby endangering you.

■ Do not use the instrument on networks of which the voltage or category exceeds those
mentioned.

■ Do not use the instrument if it seems to be damaged, incomplete, or poorly closed.

■ Before each use, check the condition of the insulation on the leads, housing, and accessories.
Any item of which the insulation is deteriorated (even partially) must be set aside for repair or
scrapping.

■ Use only the leads and accessories supplied. Using leads (or accessories) of a lower voltage or
category reduces the voltage or category of the combined instrument and leads (or accessories)
to that of the leads (or accessories).

■ Use personal protection equipment systematically.

■ Keep your hands away from the terminals of the instrument.

■ When handling the leads, test probes, and alligator clips, keep your fingers behind the physical
guard.

■ As a safety measure, and to avoid interference, do not move and do not handle the leads during
measurements.

Definition of Measurement Categories (CAT)

■ CAT IV - 3-Phase at utility connection, outdoor conductors:

- Origin of installation, or where low-voltage connection is made to utility power

- Electricity meters, primary overcurrent protection equipment

- Outside and service entrance, service drop from pole to building, runs between meter & panel

- Overhead line to detached building, underground line to well pump

■ CAT III - 3-Phase distribution, including single-phase commercial lighting:

- Equipment in fixed installations, such as switchgear and polyphase motors

- Bus and feeder in industrial plants

- Feeders and short branch circuits, distribution panel devices

- Appliance/equipment outlets with short connections to service entrance

■ CAT II - Single-phase, receptacle-connected loads:

- Appliances, portable tools, and other similar light industrial/household loads

- Outlet and long-branch circuits

- Outlets at more than 30 ft from CAT III source

- Outlets at more than 60 ft from CAT IV source

TABLE OF CONTENTS

1. INTRODUCTION ................................................................................................... 5

1.1 Receiving Your Shipment ....................................................................................................................... 5

1.1.1 Accessories and Replacement Parts .......................................................................................... 5

2. PRODUCT FEATURES .......................................................................................... 6

2.1 Description ............................................................................................................................................. 6

2.2 Front Panel Features .............................................................................................................................. 7

2.3 Display ................................................................................................................................................... 8

2.3.1 Example of Display Before Measurement ................................................................................... 8

2.3.2 Example of Display During Measurement ................................................................................... 8

2.3.3 Example of Display After Measurement ...................................................................................... 8

2.4 Button Functions ................................................................................................................................... 9

2.4.1 TEMP BUTTON ........................................................................................................................... 9

2.4.2 ALARM Button .......................................................................................................................... 10

2.4.3 CONFIG Button ......................................................................................................................... 11

2.4.3.1 Before the Measurement ................................................................................................... 11

2.4.3.2 During the Measurement ................................................................................................... 15

2.4.4 DISPLAY Button ........................................................................................................................ 16

2.4.5 GRAPH Button .......................................................................................................................... 16

2.4.5.1 During a Measurement ...................................................................................................... 16

2.4.5.2 After a Measurement ......................................................................................................... 16

2.4.6 FILTER Button ........................................................................................................................... 18

2.4.7 HELP Button .............................................................................................................................. 19

3. INSTRUMENT CONFIGURATION ......................................................................... 20

3.1 Adjusting the Brightness and Contrast ................................................................................................ 20

3.2 Selecting the Language ....................................................................................................................... 20

3.3 Choosing the Measurement of the Lead Compensation ..................................................................... 20

3.4 Configuring the Instrument (SET-UP) .................................................................................................. 21

3.4.1 Configuring the Instrument using the SET-UP Function ........................................................... 21

3.4.2 Configurable Parameters .......................................................................................................... 21

3.4.3 Resetting the Default Parameters ............................................................................................. 22

3.4.4 Measurement Parameters ......................................................................................................... 23

3.4.5 Adjustment of the Test Voltages ................................................................................................ 24

3.4.6 Adjustment of the Alarm Thresholds ......................................................................................... 25

4. OPERATION ........................................................................................................ 26

4.1 Charging the Batteries ......................................................................................................................... 26

4.2 Using the Leads ................................................................................................................................... 27

4.3 AC/DC Voltage Measurement .............................................................................................................. 27

2

Megohmmeter Models 6550/6555

4.4 Insulation Measurements ..................................................................................................................... 28

4.4.1 Description of the Measurement Principle ................................................................................ 28

4.4.2 Using a Fixed Voltage ................................................................................................................ 29

4.4.3 Using a Variable Voltage ............................................................................................................ 29

4.4.4 Using a Voltage Ramp ............................................................................................................... 30

4.4.5 Using a Stepped Voltage ........................................................................................................... 31

4.4.6 Connection ................................................................................................................................ 32

4.4.7 Before the Insulation Measurement .......................................................................................... 33

4.4.8 During the Insulation Measurement .......................................................................................... 34

4.4.9 After the Insulation Measurement ............................................................................................. 36

4.5 Error Indications ................................................................................................................................... 37

4.6 DAR (dielectric absorption ratio) and PI (polarization index) ............................................................... 37

4.6.1 DAR/PI Measurement ................................................................................................................ 38

4.6.2 Interpretation of the Results ...................................................................................................... 39

4.7 DD (dielectric discharge index) ............................................................................................................ 40

4.7.1 DD Measurement ...................................................................................................................... 40

4.7.2 Interpretation of Results ............................................................................................................ 41

4.8 Capacitance Measurement .................................................................................................................. 42

4.9 Measurement of the Residual Current ................................................................................................. 42

5. MEMORY FUNCTION .......................................................................................... 43

5.1 Recording a Measurement ................................................................................................................... 43

5.2 Reading Recorded Values .................................................................................................................... 45

5.3 Erasing the Memory ............................................................................................................................. 47

5.3.1 Erasing One Record .................................................................................................................. 47

5.3.2 Erasing All Records ................................................................................................................... 48

5.4 Error Codes .......................................................................................................................................... 48

6. DATAVIEW® SOFTWARE .....................................................................................49

6.1 Installing DataView ............................................................................................................................... 49

6.2 Connecting the Instrument to the PC .................................................................................................. 52

6.3 Megohmmeter Control Panel ............................................................................................................... 52

6.3.1 Opening the Control Panel ........................................................................................................ 52

7. SPECIFICATIONS ............................................................................................... 53

7.1 Reference Conditions .......................................................................................................................... 53

7.2 Electrical Specifications ....................................................................................................................... 53

7.2.1 Voltage .......................................................................................................................................53

7.2.2 Current....................................................................................................................................... 53

7.2.3 Insulation Resistance ................................................................................................................ 53

7.2.4 DAR, PI, and DD ........................................................................................................................ 58

7.2.5 Capacitance .............................................................................................................................. 58

Megohmmeter Models 6550/6555

3

7.3 Power Supply ....................................................................................................................................... 59

7.3.1 NiMH Technology ...................................................................................................................... 59

7.3.2 Battery Charger ......................................................................................................................... 59

7.3.3 Optimize Battery Charging ........................................................................................................ 60

7.3.4 Battery Life ................................................................................................................................ 60

7.3.5 “Defect” message .................................................................................................................... 60

7.4 Environmental Specifications ............................................................................................................... 61

7.5 Mechanical Specifications ................................................................................................................... 61

7.6 Safety Specifications ........................................................................................................................... 61

7.6.1 Electromagnetic Compatibility .................................................................................................. 62

7.6.2 Mechanical Protections ............................................................................................................ 62

7.7 Variations in the Domain of Use ........................................................................................................... 62

7.8 Inherent and Operating Accuracy ........................................................................................................ 62

8. MAINTENANCE .................................................................................................. 63

8.1 Recharging the Battery ........................................................................................................................ 63

8.2 Replacing the Battery .......................................................................................................................... 63

8.3 Replacing the Fuse .............................................................................................................................. 64

8.4 Cleaning ............................................................................................................................................... 64

8.5 Repair and Calibration ......................................................................................................................... 64

8.6 Technical and Sales Assistance ........................................................................................................... 64

8.7 Limited Warranty .................................................................................................................................. 65

8.8 Warranty Repairs ................................................................................................................................. 65

4

Megohmmeter Models 6550/6555

1. INTRODUCTION

1.1 Receiving Your Shipment

Upon receiving your shipment, make sure that the contents are consistent with the packing list. Notify your dis­tributor of any missing items. If the equipment appears to be damaged, file a claim immediately with the carrier
and notify your distributor at once, giving a detailed description of any damage. Save the damaged packing
container to substantiate your claim.

Megohmmeter Model 6550 (Graphical, Analog Bargraph, Backlight, Alarm, Timer, 500V, 1000V,

2500V, 5000V, 10kV, Ramp, StepV, Variable, Auto DAR/PI/DD, USB, w/DataView® Software) ...... Cat. #2130.31

Megohmmeter Model 6555 (Graphical, Analog Bargraph, Backlight, Alarm, Timer, 500V, 1000V,

2500V, 5000V, 15kV, Ramp, StepV, Variable, Auto DAR/PI/DD, USB, w/DataView® Software) ..... Cat. #2130.32

Both models include set of 3 color-coded (red/blue/black) 9 ft (15kV ) integral leads and alligator clips (1000V
CAT IV), one 15kV jumper lead (blue), set of 2 color-coded test probes (red/black - 1000V CAT IV), optical
USB cable, 115V US power cord, 9.6V rechargeable NiMH batteries, small classic tool bag, and a USB stick
with DataView® software and a user manual.

1.1.1 Accessories and Replacement Parts

Replacement - Small classic tool bag ............................................................................................ Cat. #2133.72

Replacement - Optical USB cable ................................................................................................. Cat. #2135.41

Replacement - One 9.6V NiMH battery (two are required) ............................................................Cat. #2140.19

Replacement - Set of 3 color-coded (red/blue/black) 9 ft (15kV ) integral leads and

alligator clips (1000V CAT IV).......................................................................................................... Cat. #2151.14

Replacement - 15kV jumper lead (blue) ......................................................................................... Cat. #2151.15

Replacement - Set of 2, color-coded (red/black) test probes (1000V CAT IV) ............................... Cat. #2152.23

Replacement - 115V US power cord ............................................................................................. Cat. #5000.14

Lead - Set of 3 color-coded (red/blue/black) 9 ft shielded safety leads with hippo clips (15kV) ... Cat. #2151.17

Lead - One shielded safety lead (black) 25 ft with hippo clips (15kV) ............................................ Cat. #2151.18

Lead - One shielded safety lead (blue) 25 ft with hippo clips (15kV) ............................................. Cat. #2151.19

Lead - One shielded safety lead (red) 25 ft with hippo clips (15kV) ............................................... Cat. #2151.20

Lead - One shielded safety lead (black) 45 ft with hippo clips (15kV) ............................................ Cat. #2151.21

Lead - One shielded safety lead (blue) 45 ft with hippo clips (15kV) ............................................. Cat. #2151.22

Lead - One shielded safety lead (red) 45 ft with hippo clips (15kV) ............................................... Cat. #2151.23

Power cord - 240V EU .................................................................................................................... Cat. #5000.32

DataView Software Updates are Available at www.aemc.com

Megohmmeter Models 6550/6555

5

2. PRODUCT FEATURES

2.1 Description

The Megohmmeter Models 6550 and 6555 are high-end portable measuring instruments capable of measuring
very high electrical insulation and resistance values. They are packaged in a rugged IP 54 rated case, have a
graphical LCD screen and can operate on battery or AC power.

The Model 6550 makes insulation measurements at voltages up to 10,000V, the Model 6555 up to 15,000V.

Their main functions are:

■ detection and measurement of input voltage, frequency, and current

■ quantitative and qualitative insulation measurement:

- measurement at a fixed test voltage of 500V, 1000V, 2500V, 5000V, 10,000V or 15,000VDC

- measurement at an adjustable test voltage from 40 to 15,000VDC

- measurement with a voltage ramp selectable in the ranges from 40 to 1100V or from 500 to 15,000V

- measurement with a voltage in steps from 40 to 15,000V with up to 10 steps and dwell times

- non-destructive (Early Break) test, test stopped at a preset current (Break at I-limit) or Burning

- calculation of the DAR, PI, and DD (dielectric discharge index) quality ratios

- calculation of the temperature corrected resistance

■ measurement of the capacitance of the circuit tested

■ measurement of the residual current

These megohmmeters contribute to the safety of electrical installations and equipment.

Their operation is managed by microprocessors that acquire, process, display, and store the measurements.

They have many advantages, such as:

■ digital filtering of insulation measurements

■ measurement of the voltage

■ programming of thresholds to trigger audible alarms

■ time controlled measurements

■ current limit programming

■ plotting of resistance, voltage, and current vs. time and current vs. voltage: R(t), V(t), I(t), and I(V)

■ fuse protection, with defective fuse indication

■ automatic discharge of the test voltage at the end of the measurement provides operator safety

■ auto power off mode to save battery power

■ battery charge condition indication

■ large graphical display with backlight capability

■ data storage of measurements

■ real-time clock, and a USB interface

■ configuration, real-time testing and data export to a PC (using the included DataView® software)

6

Megohmmeter Models 6550/6555

2.2 Front Panel Features

2 3 4

1000V CAT III

600V CAT IV

( 2500V )

110-230V 50/60 Hz

80 VA max

SET-UP

MR

Step

Voltage

V RAMP

V VAR

V FIXED

OFF

5

1

6

TEMP

HELP

ALARM

MEM

CONFIG

FILTER

DISPLAY

GRAPH

START

STOP

15

kV MEGOHMMETER

MODEL 6555

7

8

1

Safety connection terminals “+”, “G” and “-”.

2

Graphical, digital LCD (see § 2.3).

3

Power receptacle for recharging the batteries.

4

USB connection for communication with a PC.

5

Seven-position rotary function switch.

6

Navigation buttons for moving the cursor, selecting and changing values.

7

START/STOP measurement button.

8

Eight function buttons (see § 2.4).

Megohmmeter Models 6550/6555

7

2.3 Display

The display is a graphical, digital LCD with a resolution of 320 x 240 pixels. It has built-in backlight, which can
be controlled by a long press on the HELP/ button.

2.3.1 Example of Display Before Measurement

The alarm is enabled

No stop at current limit

Test with programmed duration

The blinking value can be modified

using the navigation arrow keys

Value of the next lowest

available test voltage

Value of the external voltage present

on the terminals and its frequency

Current flowing between the terminals

500 V 2500 V

Input voltage
Frequency
Input current

FIXED VOLTAGE

1000 V

Test Run Time 00:02:00

Date 2011.05.23

2.3.2 Example of Display During Measurement

The measurement smoothing filtering is

active, with a time constant of 20 seconds

Value of the insulation resistance

The voltage generated is >70V

and therefore, dangerous

True value of the test voltage

Value of the insulation resistance

on the bargraph

DC

984 V

kΩ

10

DF 20s

303.3 MΩ

Elapsed Time 00:00:48

100

MΩ

1

10

100

1

ALARM

BURN

-0.1 V DC

0.2 Hz

112 pA

Time 10:31

ALARM I-LIM

3.244 µA

TΩ

1

10

10

GΩ

100

Battery power level status

Measurement function

Value of the next highest
available test voltage

Programmed duration of the test

Date and Time

Stop at current limit

Current flowing between the terminals

Elapsed time since the beginning
of the measurement

2.3.3 Example of Display After Measurement

The measurement range is fixed

Value of the insulation resistance

True value of the test voltage at

the end of the measurement

Subsidiary results

The symbol indicates blinking.
If values are undetermined, they are represented by - - - -.

8

RANGE

995 MΩ

528 V

Elapsed Time 00:01:12

DAR (30s/60s)
PI (1.0m/10m)
Capacitance

E-BRKALARM

531 nA

1.00

---

2.201 nF

The insulation resistance is below the
alarm threshold

The type of measurement is a
non-destructive test

Current at the end of the measurement

Duration of the measurement

Megohmmeter Models 6550/6555

2.4 Button Functions

If the audible signal has not been deactivated in SET-UP (see § 3.4), the instrument confirms each button press
by an audible beep. If the beep has higher frequency, this indicates that pressing the button is prohibited and
will have no effect.

A long press (press maintained for more than two seconds) is confirmed by a second audible beep.

BUTTON DESCRIPTION

TEMP

ALARM

• Enter temperature and humidity information and calculate temperature corrected resistance

• Enables/Disables the alarms

HELP /

MEM

CONFIG

DISPLAY

FILTER

GRAPH

• Displays Help information; Enables/Disables the backlighting of the display

• Stores the measurements

• Configuration of the measurement parameters

• Switch between screens

• Smoothing of the measurements

• Switch graph mode ON/OFF

2.4.1 TEMP BUTTON

This function is accessible only when the measurement is completed for V-VAR and V-FIXED only. It is used to
reference the measurement result to a temperature other than the one at which the measurement was made.

Temperature causes the resistance to vary according to a quasi exponential law. To a rough approximation,
raising the temperature by 18°F (10°C) halves the insulation resistance; conversely, lowering the temperature by
18°F (10°C) doubles the insulation resistance.

Comparing measurements to a single reference temperature makes it easier to evaluate insulation resistance
measurements taken at different times and temperatures.

Similarly, measuring the humidity improves the correlation between the various measurements made on a given
device.

Procedure:

■ Make a measurement in V-FIXED or V-VAR mode.

■ Press the TEMP button.

R measured

TEMP

Megohmmeter Models 6550/6555

Rc at --- °C

TEMPERATURE
Air Temperature
Humidity
Probe Temperature
Rc Reference Temperature
∆T for R/2

--- °C

--- %

--- °C

--- °C

--- °C

5.00 GΩ

--- kΩ

9

Use the ◄ ►▲▼ arrow buttons to enter the various parameters:

■ Air Temperature: the ambient temperature (optional).

■ Humidity: the ambient relative humidity (optional).

■ Probe Temperature: the temperature of the device tested. If it has not warmed up during the

measurement, it is equal to the ambient temperature.

■ Rc Reference Temperature: the temperature to which the measured resistance will be referred.

■ ∆T for R/2: the temperature variation, known or estimated, sufficient to halve the insulation resistance.

To facilitate the programming, the instrument proposes default values.

The instrument then displays the insulation resistance referred to the reference temperature.

TEMPERATURE
Air Temperature
Humidity
Probe Temperature
Rc Reference Temperature
∆T for R/2

R measured
Rc at 40 °C

23 °C

40%
23 °C
40 °C
10 °C

5.00 GΩ

1.529 GΩ

If coefficient ∆T for R/2 is not known, it can be calculated from a minimum of 3 measurements made on the
same device at different temperatures.

Detail concerning the calculation performed:

The insulation resistance varies with the measurement temperature. This dependence can be approximated by
an exponential function:

Rc = Kt * Rt

where Rc: insulation resistance referred to 40°C

Rt: insulation resistance measured at temperature T

Kt: coefficient defined as follows:
Kt = (1/2) ^ ((40 - T)/∆T)
where ∆T: temperature difference at which the insulation resistance is halved

2.4.2 ALARM Button

Press the ALARM button to enable the alarm defined using the CONFIG button (see 2.4.3) or in
SET-UP (see § 3.4). The ALARM symbol is then displayed.

If the measurement is less than the alarm threshold, the instrument indicates this by blinking the
ALARM symbol on the display and emitting an audible signal.

10

ALARM

Press the ALARM button again to disable the alarm; the ALARM symbol disappears from the
display.

Megohmmeter Models 6550/6555

2.4.3 CONFIG Button

2.4.3.1 Before the Measurement

If the V-FIXED or V-VAR. test voltages have been chosen, there are two configuration screens. There is only one
for the V-RAMP and V-STEP test voltages.

Press the CONFIG button (press CONFIG again to exit):

CONFIG

Total Run Time ---

Manual Stop

Manual Stop + DD
Timed Run (m:s) 2:00
Timed Run + DD
DAR (s/s) 30/60
PI (m/m) 1.0/10

CONFIG

■ Manual Stop: measurements are stopped manually.

■ Manual Stop + DD: measurements are stopped manually and dielectric discharge ratio (DD) is

calculated at the end of the programmed duration.

■ Timed Run + DD: measurement is automatically stopped at the end of the programmed duration and
dielectric discharge ratio (DD) is calculated.

■ DAR: measurement is automatically stopped at the end of one minute
(or of the programmed time, if different).

■ PI: measurement is automatically stopped at the end of 10 minutes
(or of the programmed time, if different).

It is always possible to stop a measurement during a test with programmed duration by pressing the START/
STOP button.

The ▲▼ arrow buttons are used to select the measurement
configuration.

CONFIG

When Timed Run (test with programmed duration) or Timed Run + DD is selected, the duration of the measure­ment (m:s) can be set.

CONFIG

Total Run Time 00:02:00

Manual Stop
Manual Stop + DD

Timed Run (m:s) 2:00

Timed Run + DD
DAR (s/s) 30/60

To do this, use the ◄ ►▲▼arrow buttons.

PI (m/m) 1.0/10

Megohmmeter Models 6550/6555

11

The test will run for the time programmed. However, if, during the measurement, the rotary switch position is
changed or the START/STOP button is pressed, the measurement will stop.

Press the DISPLAY button to
see the second configuration
screen.

DISPLAY

The second configuration screen depends on the rotary switch setting.

The V-RAMP and V-STEP settings only use the second page of the configuration screen.

The second configuration screen is used to choose:

■ The type of test (Test Type)

■ Nondestructive test (Early Break)

The measurement will be stopped at the first breakdown current peak detected. This type of test is used for
non-destructive tests. The current is limited to 0.2mA.

The E-BRK symbol is displayed.

Test Type

Maximum Ouput Current
I-Range
Disturbance Level
2500V

CONFIG

Burn-in

1 mA

Auto(2)

Low

< 2.5 M

The ▲▼ arrow buttons are used to
select and modify a parameter.

Ω

E-BRK

FIXED VOLTAGE

500 V 2500 V

Input voltage
Frequency
Input current
Date 2011.05.23

■ Stopping the test at a preset current (Break at I-limit)

The measurement will be stopped when the current reaches the maximum value (Maximum Output Current)
defined by the user (see below). This type of test is useful for testing varistors or other types of voltage limiter.

The I-LIM symbol is displayed.

500 V 2500 V

1000 V

10 V AC

50.0 Hz

24.6 pA

Time 10:31

I-LIM

FIXED VOLTAGE

1000 V

12

Input voltage
Frequency
Input current
Date 2011.05.23

10 V AC

50.0 Hz

24.6 pA

Time 10:31

Megohmmeter Models 6550/6555

■ Burning

The measurement is not stopped depending on the current. Depending on the application, this type of test can
be used to determine the location of insulation faults when there is Burning: appearance of an electric arc during
the test or burn spot after the test.

The BURN symbol is displayed.

BURN

FIXED VOLTAGE

500 V 2500 V

Input voltage
Frequency
Input current
Date 2011.05.23

■ The Maximum Current (Maximum Output Current)

This is the current not to be exceeded in any type of test. (In the test type Break at I-limit the measurement is
stopped if this value is reached.).

Use the ▲▼ arrow buttons to set it between 0.2 and 5mA for test types Burning and Break at I-limit. For test
type Early break this value is fixed to 0.2mA.

■ The Current Range (I-range)

This function is used to make measurements more rapidly when their order of magnitude is already known.

Use the ▲▼ arrow buttons to set the value to Auto or Range 1, 2 or 3.

1000 V

10 V AC

50.0 Hz

24.6 nA

Time 10:31

Current < 300nA 60nA < I < 50µA 10µA < I < 6mA

Current range

For example for VN = 10,000V :

Current range 1 2 3

Resistance

*10MW because Imax = 1mA at 10,000V.

The fixed current range remains active until the instrument is switched off.

Megohmmeter Models 6550/6555

1 2 3

R > 30GW 200MW < R < 16,6GW 10MW* < R < 1 GW

13

The RANGE symbol is displayed.

RANGE

FIXED VOLTAGE

500 V 2500 V

Input voltage
Frequency
Input current
Date 2011.05.23

■ Interference of the Signal (Disturbance Level)

Use the ▲▼ arrow buttons to set the value, from Low to High. The DH symbol is then displayed.

500 V 2500 V

Input voltage
Frequency
Input current
Date 2011.05.23

1000 V

Time 10:31

DH

FIXED VOLTAGE

1000 V

Time 10:31

BURN

10 V AC

50.0 Hz

24.6 nA

10 V AC

50.0 Hz

24.6 nA

The High setting is recommended when measurements are made in the presence of strong electromagnetic
fields at the network frequency (for example near high-voltage lines).

■ In the V-FIXED and V-VAR Modes: the alarm threshold

Use the ▲▼ arrow buttons to set the alarm threshold.
The alarm threshold can also be set in SET-UP (see § 3.4).

The ALARM symbol is displayed if the alarm is enabled.

ALARM

FIXED VOLTAGE

500 V 2500 V

Input voltage
Frequency
Input current
Date 2011.05.23

1000 V

Time 10:31

BURN

10 V AC

50.0 Hz

24.6 nA

14

Megohmmeter Models 6550/6555

■ In the V-RAMP mode: the programming of the ramp (Set Ramp Function)

Use the ▲▼ arrow buttons to go to Set Ramp Function; the instrument displays the voltage ramp values
programming screen. This programming can also be done in SET-UP (see § 3.4).

■ In the V-STEP mode: the programming of the step (Set Step Function)

Use the ▲▼ arrow buttons to go to Set Step Function; the instrument displays the voltage step values
programming screen. This programming can also be done in SET-UP (see § 3.4).

2.4.3.2 During the Measurement

During the measurement (for V-VAR and V-FIXED), the CONFIG button is used to choose the current range:
automatic (default) or fixed. For more details, refer to the previous section.

■ Once the measurement has started, press the CONFIG button. The following screen appears:

BURN

502 MΩ

502 V

I-Range
Disturbance Level

Set 500V

Elapsed Time 00:00:12

CONFIG

978 nA

Auto(2)

Low

CONFIG

■ Use the ◄ ►▲▼ arrow buttons to modify the measurement current range. Changes are applied and
saved immediately after entry.

■ Confirm and exit by pressing the CONFIG button again.

■ If the range is fixed, the RANGE symbol is displayed.

■ The choice remains active until the rotary switch is moved to another position.

During the measurement, it is also possible to turn the analog filter ON/OFF (Disturbance Level). For more
details, refer to the previous section.

In the case of a variable test voltage, the voltage set is also displayed and can be modified during the
measurement.

RANGE

BURN

502 MΩ

2305 V

I-Range
Disturbance Level
Adjustable Voltage

Set 2300V

Elapsed Time 00:00:12

CONFIG

4.61 µA

Fix 2

Low

2300 V

Megohmmeter Models 6550/6555

15

2.4.4 DISPLAY Button

This button is used to browse through the various accessible screens containing all information available
before, during or after the measurement. Depending on the measurement mode and the configuration chosen
(CONFIG button), the screens are different.

2.4.5 GRAPH Button

During the measurement, and at the end of each measurement, pressing the GRAPH button displays a
graphical presentation of the measurement results. On the first screen, the insulation resistance vs. time R(t)
and the voltage vs. time V(t) are shown.

Minimum and maximum values of the
voltage and the resistance and time
at the location of the cursor

Test voltage axis

Curve V(t), identified by x's

Insulation resistance axis

508 V
508 V

MΩ

3050

3000

GRAPH

3.018 GΩ

3.018 GΩ

00:01:00
00:01:00

V

510

500

Curve R(t)

Time axis

2950

2900

2850

0 1:00 2:00 3:00 4:00

490

480

470

This curve is plotted using samples recorded during the measurement.

2.4.5.1 During a Measurement

There is no cursor. Each new measurement result is automatically added to the curve and its values are
shown in one line above the graphical area.

2.4.5.2 After a Measurement

The time indication in the upper right of the screen is blinking, this is the indication for cursor mode.

The ◄ ► arrow buttons can be used to move the time cursor along the curve. The minimum and maximum
values at the cursor position are shown in two lines above the graph area. If the time span on the time axis is
4 minutes (which is the smallest possible) these lines are the same and represent one sample.

Depending on the range of the left vertical scale it may be possible to move the vertical scale and the
corresponding curve with the ▲▼ arrow buttons.

16

Megohmmeter Models 6550/6555

The following is an example of the display when a measurement is performed in V-RAMP or V-STEP mode:

GRAPH

497 V
497 V

GΩ

10.0

7.5

5.0

2.5

0

0 1:00 2:00 3:00 4:00

3.045 GΩ

3.045 GΩ

00:00:25
00:00:25

V

1000

750

500

250

0

193 V
193 V

GΩ

10.0

7.5

5.0

2.5

0

0 1:00 2:00 3:00 4:00

GRAPH

2.996 GΩ

2.996 GΩ

00:00:17
00:00:17

V

1000

750

500

250

0

If the interval of the scale of an axis is big enough, it may be possible to zoom.

Press the CONFIG button.

■ The time indication in the upper right of the screen stops blinking, this is the indication for zoom mode.

■ The ◄ ► arrow buttons are used to modify the time scale of the graph.

■ The ▲▼ arrow buttons are used to modify the resistance scale of the graph.

Press the DISPLAY button to view the current vs. time curve.

GRAPH

DISPLAY

Axis of the current

Curve R(t)

Time axis

2.985 GΩ

2.985 GΩ

nA

170

165

160

155

150

0 1:00 2:00 3:00 4:00

167.8 nA

167.8 nA

00:02:00
00:02:00

Minimum and maximum values of the
current at the position of the cursor

Press the DISPLAY button again to view the current vs. voltage data points (not available for V-STEP).

GRAPH

nA

700

600

500

400

300

DISPLAY

0 1 2 3 4kV

This curve is useful primarily in the case of a measurement in V-RAMP mode.

There is no cursor and it is not possible to zoom on this curve.

Megohmmeter Models 6550/6555

17

2.4.6 FILTER Button

303.3 MΩ

984 V

Elapsed Time 00:00:48

DH

ALARM

I-LIM

3.244 µA

10

kΩ

100

MΩ

1

10

100

GΩ

1

100

10

TΩ

1

10

The FILTER button can be used to activate and deactivate a digital filter for the insulation measurements. This
filter affects only the displayed results (which are smoothed), not the measured values. The recorded data
therefore remains raw (no filter).

This function is useful in the case of high instability of the insulation values displayed, but it is also possible to
estimate the measurement on the bargraph.

Once the measurement starts, if interference is present, press the FILTER button. Start by applying the DF10s
filter. If that is not enough, go to the DF20s filter, then to the DF40s filter. The larger the time constant, the
smoother (and slower) the measurement.

Successive presses on the FILTER button will modify or remove the filter:

■ DF 10: time constant 10 seconds

■ DF 20: time constant 20 seconds

■ DF 40: time constant 40 seconds

■ no filter

The filter is calculated as follows:

RN = RN-1 + (R - R

N-1

)/N

If N is set to 20, the time constant of this filter will be approximately 20 seconds.

DH

FIXED VOLTAGE

500 V 2500 V

Input voltage
Frequency
Input current
Date 2011.05.23

1000 V

10 V AC

50.0 Hz

24.6 nA

Time 10:31

Selecting digital filtering (DF) is recommended for measurements of fluctuating high insulation resistance values.
Such fluctuations may be due to hand movement, when touching the cables, fluctuating capacitances in the
device tested, insulation that varies because of conducting dust, an ionizing and polarizing effect of this dust,
etc., or again to the presence of an AC voltage superposed on the measurement.

The FILTER button is active before and during the measurement (but is not available in graph mode).

18

Megohmmeter Models 6550/6555