YOKOGAWA WT200 User Manual

Digital Power Meter

IM 253421-01E

1st Edition

Notes

Trademarks

Revisions

Thank you for purchasing the YOKOGAWA WT200 Digital Power Meter.
This User’s Manual contains useful information regarding the instrument’s functions
and operating procedures, as well as precautions that should be observed during use.
To ensure proper use of the instrument, please read this manual thoroughly before
operating it.
Keep the manual in a safe place for quick reference whenever a question arises.

• The contents of this manual are subject to change without prior notice.

• Every effort has been made in the preparation of this manual to ensure the accuracy
of its contents. However, should you have any questions or find any errors, please
contact your dealer or YOKOGAWA sales office.

• Copying or reproduction of all or any part of the contents of this manual without
YOKOGAWA’s permission is strictly prohibited.

Company and product names that are used in this manual are trademarks or registered
trademarks of their respective holders.

1st Edition: April 2000

Disk No. BA36
1st Edition: April 2000(YK)
All Rights Reserved, Copyright © 2000 Yokogawa Electric Corporation

IM 253421-01E

i

Checking the Contents of the Package

Unpack the box and check the contents before operating the instrument. In case the
wrong instrument or accessories have been delivered, or if some accessories are not
present, or if they seem abnormal, contact the dealer from which you purchased them.

WT200 Main Unit

Check that the model code and suffix code given on the name plate located at the right
side of the main body are according to your order.

WT200 (model code: 253421)

MODEL
SUFFIX

NO.

Madein Japan

MODEL
SUFFIX

NO.

Made inJapan

Model and Suffix codes

Model code Suffix code Specifications

253421.........................................WT200

Power cord -D ..................... UL,CSA Standard Power Cord (Part NO.: A1006WD)

-F......................VDE Standard Power Cord (Part No.: A1009WD)

-R .....................SAA Standard Power Cord (Part No.: A1024WD)

-Q ..................... BS Standard Power Cord (Part No.: A1054WD)

Options

Communication Interface /C1.......GP-IB interface

(Select either one) /C2.......RS-232-C interface

External sensor input function /EX1 .... 2.5/5/10 V range

(Select either one) /EX2 .... 50/100/200 mV range

Harmonic analysis function /HRM ... –
External input/output function /DA4 ... 4-channel D/A output

(Select either one) /CMP .. 4-channel comparator, 4-channel D/A output

Ex: GP-IB interface, with UL/CSA power cord, with external sensor input 50/100/200 mV range,

with harmonic analysis function, and 4 channels D/A output →253421-D/C1/EX2/HRM/DA4

[Maximum rated voltage: 125 V; Maximum rated current: 7 A]

[Maximum rated voltage: 250 V; Maximum rated current: 10 A]

[Maximum rated voltage: 240 V; Maximum rated current: 10 A]

[Maximum rated voltage: 250 V; Maximum rated current: 10 A]

NO. (instrument number)

When contacting the dealer from which you purchased the instrument, please quote the
instrument No.

ii

IM 253421-01E

Standard Accessories

The following standard accessories are supplied with the instrument. Make sure that
all items are present and undamaged.

Name Part No. Q’ty Remarks

1 Power cord see page ii 1 —
2 24-pin connector A1004JD 1 For remote, D/A output

3 Rubber feet A9088ZM 1 set
4 User’s Manual IM253421-01E 1 this manual

Checking the Contents of the Package

(only provided with options /DA4 or /CMP)

1. An appropriate power cord according to
the instrument's suffix code is supplied.

D F

2. 3.

Q

4.

R

Note

We recommend you keep the packing box. The box is useful when you need to transport the
instrument.

IM 253421-01E

iii

Safety Precautions

This instrument is a IEC safety class I instrument (provided with terminal for protective
grounding).
The following general safety precautions must be observed during all phases of
operation, service and repair of this instrument. If this instrument is used in a manner
not sepecified in this manual, the protection provided by this instrument may be
impaired.
Also,YOKOGAWA Electric Corporation assumes no liability for the customer’s failure to
comply with these requirements.

The following symbols are used on this instrument.

To avoid injury, death of personnel or damage to the instrument, the operator
must refer to an explanation in the User's Manual or Service Manual.

Danger, risk of electric shock

Alternating current

ON (power)

OFF (power)

In-position of a bistable push control

Out-position of a bistable push control

Ground

iv

IM 253421-01E

Safety Precautions

Make sure to comply with the following safety precautions. Not complying might
result in injury or death.

WARNING

Do not Operate in an Explosive Atmosphere

Do not operate the instrument in the presence of flammable liquids or vapors.
Operation of any electrical instrument in such an environment constitutes a
safety hazard.

Protective Grounding

Make sure to connect the protective grounding to prevent an electric shock
before turning ON the power.

Necessity of Protective Grounding

Never cut off the internal or external protective grounding wire or disconnect the
wiring of protective grounding terminal. Doing so poses a potential shock
hazard.

Defect of Protective Grounding

Do not operate the instrument when protective grounding or fuse might be
defective.

Power Cord and Plug

To prevent an electric shock or fire, be sure to use the power cord supplied by
YOKOGAWA. The main power plug must be plugged in an outlet with
protective grounding terminal. Do no invalidate protection by using an extension
cord without protective grounding.

Power Supply

Ensure the source voltage matches the voltage of the power supply before
turning ON the power.

External Connection

To ground securely, connect the protective grounding before connecting to
measurement or control unit.

Fuse

The power fuse of this instrument cannot be replaced by the user, because it is
located inside the case. If you believe the fuse inside the case is blown, contact
your nearest YOKOGAWA dealer as listed on the back cover of this manual.

Do not Remove any Covers

There are some areas with high voltage. Do not remove any cover if the power
supply is connected. The cover should be removed by qualified personnel only.

IM 253421-01E

v

Structure of this Manual

This User's Manual consists of the following 16 chapters and an index.

Chapter 1 Functional Overview and Digital Display

Chapter 2 Names and Uses of Parts and the Overrange and Error Displays

Chapter 3 Before Starting Measurements

Chapter 4 Setting Measurement Conditions and Measurement Range

Chapter 5 Displaying the Results of the Measurement and Computation

Chapter 6 Integration

Chapter 7 Using the Harmonic Analysis Function (Optional)

Chapter 8 Storing/Recalling Measured Data and Setting Parameters from the Internal

Chapter 9 Using External Input/Output

Chapter 10 Using the GP-IB Interface (Optional)

Chapter 11 Using the RS-232-C Interface (Optional)

Chapter 12 Initializing Setup Parameters and Performing Zero Level Compensation

Chapter 13 Communication Commands 1 (System of Commands before the IEEE 488.2-

Chapter 14 Communication Commands 2 (System of Commands Complying to the IEEE

Chapter 15 Adjustment, Calibration and Trouble-Shooting

Chapter 16 Specifications

Index Index of contents.

Describes the input signal flow, functional overview, digital numbers/characters,
initial menus that are displayed when a key is pressed, and other information..

Gives the name of each part and each key, and describes how to use it. This
chapter also gives the displays in case of overrange/error during measurement.

Describes points to watch during use and describes how to install the instrument,
wire the measuring circuits, connect the power cord and switch the power ON/OFF.

Explains settings such as measurement mode, filter ON/OFF, measurement range,
scaling in case of external PT/CT or external sensor (such as shunt or clamp),
averaging and measurement conditions.

Explains the procedures for displaying the voltage, current, active power, apparent
power, reactive power, power factor, phase angle, frequency, peak value, value
derived from four arithmetical operations, and crest factor.

Explains the procedures for integration of active power and current.

Explains the procedures when using the harmonic analysis function.

Memory

Explains the procedures when storing or recalling measured data or setting
parameters from the internal memory.

Explains the procedures for remote control, D/A output (option), external plotter/
printer output and comparator (option).

Explains the procedures for controlling the instrument by personal computer and
for sending measurement/computed data to a personal computer using the GP-IB
interface.

Explains the procedures for controlling the instrument by personal computer/
controller and for sending measurement/computed data to a personal computer/
controller using the RS-232-C interface.

Explains the procedures such as backing up setting parameter and initializing
settings.

1987 Standard)

Describes communication commands and sample programs that follow the rules
that existed before the establishment of the IEEE 488.2-1987 Standard.

488.2-1987 Standard)

Describes communication commands and sample programs that comply with the
IEEE 488.2-1987 Standard.

Explains the procedures for calibration, adjustment, the way to verify trouble, the
contents of error messages and the way to replace the fuse.

Describes the specifications of the instrument.

vi

IM 253421-01E

Conventions Used in this Manual

Symbols Used

The following symbol marks are used throughout this manual to attract the operator’s
attention.

A symbol mark affixed to the instrument. Indicates danger to
personnel or instrument and the operator must see the User's
Manual. The symbol is used in the User's Manual to indicate the
reference.

WARNING

CAUTION

Note

Displayed Characters on the 7-Segment LED

In order to display all numbers and alphabetic characters on the 7-segment LED, some
of them are displayed in a slightly altered format. For details, see section 1.3.

Describes precautions that should be observed to prevent the
danger of serious injury or death to the user.

Describes precautions that should be observed to prevent the
danger of minor or moderate injury to the user, or the damage to
the property.

Provides information that is important for proper operation of the
instrument.

IM 253421-01E

vii

Conventions Used in this Manual

Markings used for Descriptions of Operations

Keys

Indicates the relevant panel keys and indicators to carry out the
operation.

Procedure

The procedure is explained by a flow diagram. For the meaning of
each operation, see the example below. The operating procedures
are given with the assumption that you are not familiar with the
operation. Thus, it may not be necessary to carry out all the steps
when changing settings.

Explanation

Describes settings and restrictions relating to the operation.

An example of an Operating Procedure

2.

(Display C)

3.

ENTER

1.

SHIFT

SETUP

OUTPUT

4.

(Display C)

5.

ENTER

End of
setting

The items in this figure are obtained by the following setting procedures. The blinking
part of the display can be set.

1. After pressing the SHIFT key and the SHIFT indicator is lit, press the SETUP
(OUTPUT) key. The output setting menu will appear on display C.

2. Select

rELAY

using the up/down keys.

Pressing either key, 4 selectable items will be displayed consecutively.

3. Verify the setting by pressing the ENTER key.
The setting menu corresponding to the item selected at step 2 will appear at
display
C.

4. Select

oFF

or on using the up/down keys.

Pressing either key, 6 selectable items will be displayed consecutively.

5. Verify the setting by pressing the ENTER key.

viii

IM 253421-01E

Contents

1

Checking the Contents of the Package ...........................................................................................ii

Safety Precautions .........................................................................................................................iv

Structure of this Manual .................................................................................................................vi

Conventions Used in this Manual..................................................................................................vii

Chapter 1 Functional Overview and Digital Display

1.1 System Configuration and Block Diagram ....................................................................... 1-1

1.2 Functions .........................................................................................................................1-2

1.3 Digital Numbers/Characters, and Initial Menus................................................................1-5

Chapter 2 Names and Uses of Parts and the Overrange and Error Displays

2.1 Front Panel, Rear Panel and Top View............................................................................ 2-1

2.2 Operation Keys and Function Display..............................................................................2-2

2.3 Displays in case of Overrange/Error during Measurement .............................................. 2-3

Chapter 3 Before Starting Measurements

3.1 Usage Precautions...........................................................................................................3-1

3.2 Installing the Instrument ................................................................................................... 3-2

3.3 Wiring Precautions ........................................................................................................... 3-4

3.4 Improving the Measurement Accuracy............................................................................. 3-6

3.5 Connecting the Power Supply.......................................................................................... 3-7

3.6 Wiring the Measurement Circuit....................................................................................... 3-8

3.7 Wiring the Measurement Circuit when Using External PT/CT ......................................... 3-9

3.8 Wiring the Measurement Circuit when Using the External Sensor ................................ 3-10

3.9 Turning the Power ON/OFF, Opening Messages...........................................................3-12

2

3

4

5

6

7

8

9

10

Chapter 4 Setting Measurement Conditions and Measurement Range

4.1 Selecting the Measurement Mode ................................................................................... 4-1

4.2 Selecting the Measurement Synchronization Source ...................................................... 4-3

4.3 Turning the Filter ON/OFF ............................................................................................... 4-4

4.4 Selecting the Measurement Range in case of Direct Input.............................................. 4-5

4.5 Setting the Scaling Constant when External PT/CT is Used ...........................................4-8

4.6 Selecting the Measurement Range and Setting the Scaling Constant when External

Sensor is Used (option) ................................................................................................. 4-10

4.7 Using the Averaging Function ........................................................................................ 4-12

4.8 Using the MAX Hold Function ........................................................................................ 4-14

4.9 Using the Four Arithmetical Operation Function ............................................................ 4-15

4.10 Computing the Crest Factor........................................................................................... 4-18

4.11 Computing the Average Active Power during Integration............................................... 4-19

4.12 Selecting the Number of Displayed Digits...................................................................... 4-20

Chapter 5 Displaying the Results of the Measurement and Computation

5.1 Displaying Voltage, Current, and Active Power................................................................ 5-1

5.2 Displaying Apparent Power, Reactive Power, and Power Factor.....................................5-3

5.3 Displaying the Phase Angle ............................................................................................. 5-4

5.4 Displaying the Frequency ................................................................................................ 5-5

5.5 Displaying Peak Value, Four Arithmetic Operation Value, and Crest Factor.................... 5-7

11

12

13

14

15

16

Index

IM 253421-01E

ix

Contents

Chapter 6 Integration

6.1 Integrator Functions ......................................................................................................... 6-1

6.2 Setting Integration Mode, Integration Type, and Integration Timer .................................. 6-4

6.3 Displaying Integrated Values ........................................................................................... 6-6

6.4 Precautions Regarding Use of Integrator Function .......................................................... 6-9

Chapter 7 Using the Harmonic Analysis Function (Optional)

7.1 Harmonic Analysis Function............................................................................................. 7-1

7.2 Setting the PLL Source and Harmonic Distortion Method................................................ 7-3

7.3 Switching the Harmonic Analysis Function ON/OFF........................................................ 7-5

7.4 Setting the Harmonic Order and Displaying the Results of Harmonic Analysis ............... 7-6

Chapter 8 Storing/Recalling Measured Data and Setting Parameters from the

Internal Memory

8.1 Storing/Recalling Measured Data .................................................................................... 8-1

8.2 Storing/Recalling Setting Parameters .............................................................................. 8-5

Chapter 9 Using External Input/Output

9.1 Remote Control and D/A Output Connector (optional)..................................................... 9-1

9.2 Remote Control (optional) ................................................................................................ 9-2

9.3 D/A Output (optional) ....................................................................................................... 9-3

9.4 Comparator Function (optional) ....................................................................................... 9-7

9.5 Setting the Comparator Mode (optional) ........................................................................ 9-10

9.6 Setting the Comparator Limit Values (optional).............................................................. 9-11

9.7 Comparator Display (optional) ....................................................................................... 9-15

9.8 Turning the Comparator Function ON/OFF (optional).................................................... 9-17

9.9 Outputting to an External Plotter or Printer .................................................................... 9-18

Chapter 10 Using the GP-IB Interface (Optional)

10.1 GP-IB Interface Functions and Specifications ............................................................... 10-1

10.2 Responses to Interface Messages................................................................................. 10-3

10.3 Status Byte Format (before the IEEE 488.2-1987 Standard)......................................... 10-4

10.4 Output Format................................................................................................................ 10-5

10.5 Setting the Address/Addressable Mode....................................................................... 10-11

10.6 Setting the Output Items .............................................................................................. 10-13

10.7 System of Commands before the IEEE 488.2-1987 Standard .................................... 10-16

Chapter 11 Using the RS-232-C Interface (Optional)

11.1 RS-232-C Interface Functions and Specifications ......................................................... 11-1

11.2 Connecting the Interface Cable ..................................................................................... 11-3

11.3 Setting the Mode, Handshaking Method, Data Format and Baud Rate ......................... 11-6

11.4 Format and Commands of Output Data (before the IEEE 488.2-1987 Standard) ......... 11-9

Chapter 12

Initializing Setup Parameters and Performing Zero Level Compensation

12.1 Back-up of Setting Parameters...................................................................................... 12-1

12.2 Initializing Setting Parameters ....................................................................................... 12-2

12.3 Performing Zero Level Compensation ........................................................................... 12-4

x

IM 253421-01E

Contents

Chapter 13 Communication Commands 1 (System of Commands before the

IEEE 488.2-1987 Standard)

13.1 Commands.....................................................................................................................13-1

13.2 Sample Program.......................................................................................................... 13-13

13.3 For Users Using Communication Commands of Digital Power Meter 2533E.............. 13-21

Chapter 14 Communication Commands 2 (System of Commands Complying to

the IEEE 488.2-1987 Standard)

14.1 Overview of IEEE 488.2-1987........................................................................................14-1

14.2 Program Format............................................................................................................. 14-3

14.2.1 Symbols Used in Syntax Descriptions ............................................................... 14-3

14.2.2 Messages........................................................................................................... 14-3

14.2.3 Commands......................................................................................................... 14-5

14.2.4 Responses ......................................................................................................... 14-7

14.2.5 Data ................................................................................................................... 14-7

14.2.6 Synchronization with the Controller ................................................................... 14-9

14.3 Commands...................................................................................................................14-10

14.3.1 Command List.................................................................................................. 14-10

14.3.2 AOUTput Group ............................................................................................... 14-14

14.3.3 COMMunicate Group ....................................................................................... 14-15

14.3.4 CONFigure Group............................................................................................ 14-17

14.3.5 DISPlay Group ................................................................................................. 14-21

14.3.6 HARMonics Group ........................................................................................... 14-22

14.3.7 INTEGrate Group............................................................................................. 14-23

14.3.8 MATH ............................................................................................................... 14-24

14.3.9 MEASure Group............................................................................................... 14-25

14.3.10 RECall Group................................................................................................. 14-32

14.3.11 RELay Group ................................................................................................. 14-33

14.3.12 SAMPle Group ............................................................................................... 14-35

14.3.13 ST ATus Group................................................................................................ 14-36

14.3.14 STORe Group ................................................................................................ 14-37

14.3.15 Common Command Group............................................................................ 14-38

14.4 Status Report............................................................................................................... 14-41

14.4.1 Overview of the Status Report ......................................................................... 14-41

14.4.2 Status Byte....................................................................................................... 14-42

14.4.3 Standard Event Register.................................................................................. 14-43

14.4.4 Extended Event Register ................................................................................. 14-44

14.4.5 Output Queue and Error Queue....................................................................... 14-45

14.5 Sample Program.......................................................................................................... 14-46

14.6 ASCII Character Codes ............................................................................................... 14-50

14.7 Communication-related Error Messages ..................................................................... 14-51

Chapter 15 Maintenance and Troubleshooting

15.1 Adjustments ................................................................................................................... 15-1

15.2 Calibration...................................................................................................................... 15-5

15.3 In Case of Malfunctioning ............................................................................................ 15-11

15.4 Error Codes and Corrective Actions............................................................................. 15-12

15.5 Replacing the Fuse...................................................................................................... 15-14

15.6 Recommended Replacement Parts............................................................................. 15-15

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

Index

IM 253421-01E

xi

Contents

Chapter 16 Specifications

16.1 Input............................................................................................................................... 16-1

16.2 Measurement Functions ................................................................................................ 16-3

16.3 Frequency Measurement............................................................................................... 16-5

16.4 Communication (optional).............................................................................................. 16-5

16.5 Computing Functions..................................................................................................... 16-5

16.6 Display Functions........................................................................................................... 16-6

16.7 Integrator Function......................................................................................................... 16-6

16.8 Internal Memory Function .............................................................................................. 16-7

16.9 D/A Converter (optional) ................................................................................................ 16-7

16.10 External Input (optional)................................................................................................. 16-7

16.11 Comparator Output (optional) ........................................................................................ 16-7

16.12 External Contorol and Input Signals (in combination with the D/A converter and

comparator options) ....................................................................................................... 16-8

16.13 Total Harmonic Analysis Function (optional) .................................................................. 16-8

16.14 General Specifications ................................................................................................... 16-9

16.15 External Dimensions .................................................................................................... 16-10

Index

xii

IM 253421-01E

Chapter 1 Functional Overview and Digital Display

1.1 System Configuration and Block Diagram

System Configuration

Block Diagram

VOLTAGE INPUT

LPF

CURRENT INPUT

LPF

Equipment

under

test

A/D

Zero Cross

A/D

Zero Cross

INPUT

Detector

Detector

PT

CT

sensor

ISO

ISO

Ext.

Voltage

input

Current

input

A/D

interface

Lead/Lag

Detector

EEPROM

DSP

Input
either
one

Input
either
one

WT200
(253421)

COUNTER × 2
CLOCK

Contact / relay output

Analog output

GP-IB or

RS-232-C

CPU

SAMPLING

CLOCK

Bus

Arbiter

FREQUENCY

HARMONICS

PLL
DMAC
RAM

(Option)

Arbiter

CPU

Bus

Recorder

Personal

Computer

Ext. printer

or plotter

ROM
RAM

KEY&DISPLAY

CONTROLLER

GP-IB

or

RS-232-C

D/A OUTPUT

EEPROM

(Option)

COMPARATOR

(Option)

1

Functional Overview and Digital Display

IM 253421-01E

This instrument consists of various sections: input (voltage input and current input
circuits), DSP, CPU, display and interface section.
In the voltage input circuit, the input voltage is formalized by a voltage divider and
operational amplifier, then sent to the A/D converter.
In the current input circuit, the input current passes through a shunt resistor that forms
a closed circuit. The voltage across shunt resistor is amplified and normalized and
then input to the A/D converter. This method enables switching of the current range
without opening the current measurement circuit, so the current range can be switched
while electricitiy is supplied to the circuit. This also enables remote control via
communications outputs.
The output from the A/D converter in the current input and voltage input circuits is sent
to the DSP (Digital Signal Processor) via a photo-isolator, which is used to provide
insulation between the current input circuit (or voltage circuit) and the DSP. One DSP
is provided for each input element (current/voltage). For example, a total of 3 DSP’s
are used for the three-phase, four-wire model. The DSP performs averaging of
voltage, current and active power for each sampled data sent from the A/D converter.
After processing of a certain number of sets of data has been completed, computation
of apparent power, reactive power, power factor and phase angle starts.
Computation results are then sent from the DSP to the CPU, where computation such
as range conversion, and scaling is carried out. Control of display and outputs is also
performed by the CPU.

1-1

1.2 Functions

Input Functions

Voltage and Current Input Sections

A voltage or current supplied to each input terminal is normalized then sent to the A/D
converter, where the voltage or current is converted into digital signals. The digital
signals are then sent via photo-isolator to a 16-bits high-speed DSP (Digital Signal
Processor) or CPU, where computation of the measured value is carried out.

Frequency Measuring Range

Measurement of DC voltage, current and power as well as AC voltage and current in
the frequency range 10 Hz to 50 kHz.

Filter

This instrument carries out various measurements after synchronizing the frequency of
the input signals. Therefore, correct measurements are necessary. Thus, a filter is
being applied to the frequency measurement circuit to eliminate noise of waveforms,
such as inverted and distortion waveforms.

Wiring Method

The wiring method indicates the circuit configuration used to measure the voltage,
current, and power. The WT200 uses a single-phase, two-wire (1φ2W) wiring method.

Display Functions

This function enables display of measured/computed values using three red high­intensity 7-segment LED displays. A total of three values can be displayed at once.

Peak Measurement Function

This function measures the peak values of the voltage and current. This value is used
to compute the crest factor.

MAX Hold Function

This function holds the maximum values of the voltage, current, active power, apparent
power, reactive power, voltage peak, and current peak. It holds the maximum value
that exists while the MAX hold function is enabled.

Computing Functions

Apparent Power, Reactive Power, Power Factor and Phase Angle

Based on the measurement values of voltage, current and active power, the values of
apparent power, reactive power, power factor and phase angle can be computed.

Scaling

When performing voltage or current measurements with an external PT, CT, shunt,
external sensor (clamp) or such connected, you can set a scaling factor to the primary/
secondary ratio. This is called scaling. This function enables display of the measured
values of voltage, current, active power, reactive power, integrated current and
integrated power factor in terms of primary-side values.

Averaging

This function is used to perform exponential or moving averaging on the measured
values before displaying them in cases where the measured values are not stable.

Four Arithmetic Operation

Results from six types of arithmetic operations can be displayed. (A+B, A–B, A

2

/B, A/B2)

A

*B, A/B,

1-2

Crest Factor

This function determines the crest factor of the voltage and current using peak and
RMS values.

IM 253421-01E

1.2 Functions

Integrator Functions

Average active power during integration

This function computes the average active power within the integration period. It is
derived by dividing the watt hour (integrated active power) by the elapsed time of
integration.

This function enables integration of active power and current. All measurement values
(and computed values) can be displayed, even when integration is in progress, except
for the integrated values (watt hour and ampere hour) and elapsed integration time.
Since also integrated values of negative polarity can be displayed, the consumed watt
hour (ampere hour) value of the positive side and the watt hour value returning to the
power supply of the negative side can be displayed seperately.

The following two integration methods are available:

• Standard type
Integrates the active power or current that is obtained using the normal measurement
method, which obtains the active power or current from the sampled data over the
period that is synchronized to the input signal. Select the standard type for steady­state input signals that have a constant period such as a sinusoid.

• Advanced type
Integrates the active power or current obtained over a fixed period of sampled data,
irrespective of the period of the input signal. Select the advanced type for intermittent
signals with a frequency of 50 or 60 Hz.

1

Functional Overview and Digital Display

Frequency Measurement Function

This function measures the frequency of the voltage and current.
Measuring range is from 10 Hz to 50 kHz (however, depending on the internal timing of
the instrument, measurement might be carried out in the range from 4 Hz to 10 Hz
also).

Harmonic Analysis Function (optional)

This function enables computation of voltage, current, active power and so forth of up
to the 50th order, the relative harmonic content of harmonic orders and the phase angle
of each order compared to the fundamental (first order). Furthermore, the total rms
value (fundamental + harmonic) of the voltage, current and active power, and the
harmonic distortion factor (THD) can be calculated.

Storing/Recalling Measured Data and Setting Parameters

This function enables the storage of measured data and setting parameters into the
internal memory. Furthermore, after recalling measured data or setting parameters,
these data can be displayed or output by communication interface.

D/A Output Function (optional)

This function enables output of measured values of voltage, current, active power,
apparent power, reactive power, power factor and phase angle as a DC analog signal
with full scale of ±5 V. Output items of up to 4 channels can be selected.

Comparator Function (optional)

This function compares the measured values of voltage, current, active power,
apparent power, reactive power, power factor and phase angle and such with preset
limit values. When the measured values cross those preset limits, a contact output
relay will be activated. Output items up to 4 channels can be set.

IM 253421-01E

1-3

1.2 Functions

Remote Control Functions (optional)

External Input

This instrument can be controlled using the following TTL-level, low pulse, logic
signals.
EXT HOLD (when options /DA4, /CMP are installed)

Holds updating of the displayed values or releases the hold status.

EXT TRIG (when option /DA4 is installed)

Updates the displayed values in hold mode.

EXT START (when option /DA4 is installed)

Starts integration.

EXT STOP (when option /DA4 is installed)

Stops integration.

EXT RESET (when option /DA4 is installed)

Resets the integration results.

External Output

This instrument can output the following TTL-level, low pulse, logic signals.
EXT BUSY (when option /DA4 is installed)

Outputs continuously from integration start through integration stop.

Communication Functions (Option)

Either a GP-IB or RS-232-C interface is provided as standard according to the
custormer’s preference. Measured/computed data of up to 14 channels can be output.
It is also possible to control this instrument from the personal computer.

Output Function to an External Plotter and Printer

Measured/computed data can be printed on an external plotter or printer using the GP­IB or RS-232-C interface.

Other Useful Functions

Backup of Setting Parameters

This instrument backs up the setting parameters (including computed values) in case
power is cut off accidentally as a result of a power failure or for any other reason.

Initializing Setting Parameters

This function enables you to reset the setting parameters to initial (factory) settings.

Zero-level compensation

Zero level compensation refers to creating a zero input condition inside the WT200 and
setting the level at that point as the zero level. Zero level compensation must be
performed in order to satisfy the specifications of this instrument. When the
measurement range is changed, zero level compensation is performed automatically.
However, if the measurement range is not changed for a long time, the zero level may
shift due to environmental changes around the instrument. In such case, you can
manually perform zero level compensation.

1-4

IM 253421-01E

1.3 Digital Numbers/Characters, and Initial Menus

Digital Numbers/Characters

This instrument is equipped with a 7-segment LED which imposes some restrictions on
the usable characters. The numbers/characters are styled as follows.

Initial Menus

0
1
2
3
4
5
6
7
8
9

A
B

Small c

C
D
E
F
G

Small h

H
I
J

K
L
M
N
O
P
Q
R
S
T

U
V
W
X
Y
Z

+

−
×
÷

Every function of this instrument can be set using the menus on the display. The initial
displays which appear when the operation keys are pressed, are shown below.

• Voltage Range Setting

1.

V RANGE

(Display C)

2.

^(Exponent)

1

Functional Overview and Digital Display

• Current Range Setting

1.

A RANGE

(Display C)

2.

(A)
(A)

(A)
(A)
(A)
(A)
(mA)
(mA)

(mA)
(mA)
(mA)
(mA)

When equipped with
option /EX1
(Display C)

2.

(A)
(A)

(A)
(A)
(A)
(A)
(mA)
(mA)

(mA)
(mA)
(mA)
(mA)
(V)
(V)

(V)

When equipped with
option /EX2
(Display C)

2.

(A)
(A)

(A)
(A)
(A)
(A)
(mA)
(mA)

(mA)
(mA)
(mA)
(mA)
(mV)
(mV)

(mV)

IM 253421-01E

1-5

1.3 Digital Numbers/Characters, and Initial Menus

Setting the Filter, Averaging, Scaling, Ext. Sensor Input,

•
and Initializing Setting Parameters

1.

SETUP

( Display C )

2.

• Integration Setting

1.

SHIFT

RESET

INTEG SET

2.

(Filter setting)
(Averaging setting)
(Scaling setting)
(Ext. sensor input setting)
(Initiallizing set-up parameters)
(Computation, crest factor settings)
(Measurement synchronization source setting)
(MAX hold setting)
(Number of displayed digits)

( Display C )

(Setting integration mod)
(Setting integration timer)
(Setting integration preset time)
(Integration type setting)

• Turning the Harmonic Analysis Function ON/OFF

1.

SHIFT

START

HARMONICS

(Display C)

2.

(Setting the element)
(Setting PLL source)
(Setting computation methood

of harmonic distortion)

• Storing/Recalling to/from Internal Memory

1.

SHIFT

STOP

MEMORY

2.

( Display C )

(Storing measurement data)
(Recalling measurement data)
(Storing setting parameters)
(Recalling setting parameters)

• Setting Output

2.

( Display C )

(Setting items for communication,

plotter, or printer output)

(Execute plotter or printer output)
(Setting D/A output)
(Comparator setting:relay output setting)

1.

SHIFT

SETUP

OUTPUT

1-6

IM 253421-01E

1.3 Digital Numbers/Characters, and Initial Menus

SHIFT

LOCAL

INTERFACE

( Display C )

2.

(Setting normal mode)
(Setting talk-only mode)

1.

• Setting Communication Interface (RS-232-C)

(Setting communication commands
according to IEEE 488.2-1987)

(Print mode setting: Setting plotter

or printer output)

• Setting Communication Interface (GP-IB)

1.

SHIFT

LOCAL

INTERFACE

( Display C )

2.

(Print mode setting: Setting plotter

(Setting addressable mode A)
(Setting addressable mode B)
(Setting talk-only mode)

or printer output)

(Setting communication commands
according to IEEE 488.2-1987)

1

Functional Overview and Digital Display

IM 253421-01E

1-7

Chapter 2 Names and Uses of Parts and the Overrange and Error Displays

2.1 Front Panel, Rear Panel and Top View

Front Panel

Rear Panel

7-segment display

Function/Unit display

Operation keys

Power switch

page 3-12

→

External sensor input terminal

page 3-10

→

Ventilation slot

Current input terminal

page 3-8 to 3-11

→

Voltage input terminal

page 3-8 to 3-11

→

page 2-2

→

2

Names and Uses of Parts and the Overrange and Error Displays

Handle

Top View

Ext. I/O connector

→

chapter 9

Rear panel

Power connector

page 3-7

→

GP-IB or RS-232-C connector

→

chapter 10, 11

Ventilation slot

IM 253421-01E

Front panel

2-1

2.2 Operation Keys and Function Display

Indicators for operation conditions

Shows sampling, voltage/current overrange and
measurement mode.

V RANGE

Shows the voltage range setting menu (section 4.4).

A RANGE

Shows the current range setting menu (section 4.4).

V RANGE

SHIFT

MODE

Switches between modes (section 4.1).

AUTO indicator

Lights up when range is AUTO.

FUNCTION

Sets the displayed function
(chapter 5, sections 6.3 and 7.4).

Function/unit display

A RANGE

SHIFT

Turns ON/OFF the MAX hold function.

MAX HOLD

When turned ON, the MAX HOLD indicator lights.
This is the same as the MAX hold setting under
the SETUP key (section 4.8).

HOLD

Holds the displayed value. The HOLD
indicator lights. Pressing the key again turns
OFF the indicator and releases the hold.

HOLD

SHIFT

When in the HOLD condition this results in

TRIG

updating the displayed value.

For decreasing the voltage/current range,
and for setting of functions/values.

SAMPLE

V OVER

A OVER

MODE

RMS

V MEAN

DC

A

B

C

SCALING AVG FILTER STORE RECALL HARMONICS

mV

VA
var

kA

TIME

MW
mV PF

deg

kA
MW

mV Hz
kA h
MW h

START

HARMONICS

SHIFT

Shows the setting menu for harmonics ON/OFF, PLL
source, and element selection (sections 7.2 and 7.3).

STOP

SHIFT

MEMORY

Shows the setting menu for storing/recalling
measurement data and set-up information (chapter 8).

LOCAL

When the REMOTE indicator is lit, the remote
function will be canceled. When the REMOTE
indicator is not lit, the setting menu for
communication/printing will appear.

LOCAL

INTERFACE

SHIFT

Shows the setting menu for communication/printing
(sections 9.9, 10.5, and 11.3).

SETUP

SHIFT

OUTPUT

Shows the setting menu for communication output items, D/A
output, plotter/printer output and comparator output (sections 9.3,

9.5 to 9.9, and 10.6).

Indicators for operating functions

When a function is set and in operation, this indicator will light up.

FUNCTION

FUNCTION

FUNCTION

AUTO

AUTO

A RANGEV RANGE

MODE TRIGMAX HOLD

START

HARMONICS

REMOTE

LOCAL SETUP

INTERFACE OUTPUT SHIFT

HOLD

ENTER

CAL

INTEGRATOR

STOP RESET

MEMORY INTEG SET

SETUP

Sets the filter, averaging, scaling, computation, external
sensor input, measurement synchronization source, MAX
hold, and the initialization of the set-up information (see
sections 4.2, 4.3, 4.5 to 4.11, and 12.2).

For increasing the voltage/current range,
and for setting of functions/values.

ENTER

For verifying the set range/function/value.

SHIFT

Moves the cursor of a value from left to right.

SHIFT

Moves the decimal point from left to right.

ENTER

SHIFT

CAL

Performs zero level compensation
(section 12.3).

START

Starts integration (see section 6.3).

STOP

Stops integration (see section 6.3).

RESET

Sets the integration value and elapsed time of
integration to zero (0) (see section 6.3).

SHIFT

RESET

INTEG SET

Shows the setting menu for integration
mode/type/time, and rated integration time
(see sections 6.2 and 9.3).

2-2

IM 253421-01E

2.3 Displays in case of Overrange/Error during Measurement

Overrange display

Overrange occurs when the measured voltage or current exceeds 140% of the rated
measurement range. In that case the range will automatically be increased, however
up to 140% of the maximum range. When this level is exceeded, the overrange display
wil appear, which looks as follows.

Computation over display
When the computed value becomes too high during the computation process, the
following display will appear.

Peak over display

When the sampled data (instantaneous voltage or instantaneous current) exceed
approx. 300% of the measurement range, the “V over” or “A over” indicators at the
front panel will light up.

V OVER

2

Names and Uses of Parts and the Overrange and Error Displays

A OVER

Note

The “V over” and “A over” indicators at the front panel will light up in case of overrange or
peak-over of any signal.

Display in case the measurement value is too small

In case either the measured voltage or measured current drops below 0.5% of the
measurement range, the display will indicate as follows. This is only in case the
measurement mode is RMS or V MEAN (see section 4.1, “Selecting the Measurement
Mode”).

Function Display

V(voltage)
A(current) displays zero
var(reactive power)

PF(power factor)
deg(phase angle)

Interruption during measurement

If the measurement range or function is changed and the contents of the display
changes, the display will indicate as follows.

IM 253421-01E

2-3

Chapter 3 Before Starting Measurements

3.1 Usage Precautions

Safety Precautions

• Before using the instrument for the first time, make sure you have read the safety
precautions on pages iv and v.

• Do not remove the case from the instrument. Some areas in the instrument use high
voltages, which are extremely dangerous. When the instrument needs internal
inspection or adjustment, contact your nearest YOKOGAWA representative.
Addresses may be found on the back cover of this manual.

• If you notice smoke or unusual odors coming from the instrument, immediately turn
OFF the power and unplug the power cord. Also turn OFF the power to all the objects
being measured that are connected to the input terminals. If such an irregularity
occurs, contact your nearest YOKOGAWA representative. Addresses may be found
on the back cover of this manual.

• Do not place anything on the power cord and keep it away from any heat generating
articles. When unplugging the power cord from the power outlet, always hold the plug
and pull it, never pull the cord itself. If the power cord becomes damaged, contact
your nearest YOKOGAWA representative. Addresses may be found on the back
cover of this manual.Refer to page ii for the part number of the appropriate power cord
when placing an order.

3

Before Starting Measurements

General Handling Precautions

• Never place anything on top of the instrument, especially objects containing water.
Entry of water into the instrument may result in breakdowns.

• When Moving the Instrument, first turn off the power of the objects to be measured
and disconnect the connected cables such as for measurement and communication.
Then turn off the power switch and unplug the power cord from the power outlet.
Always carry the instrument by the handles as shown below.

• To prevent internal temperature rise, do not block the vent holes in the instrument
case.

• Keep input terminals away from electrically charged articles as they may damage
internal circuits.

• Do not allow volatile chemicals to come into contact with the case or operation panel.
Also do not leave any rubber or vinyl products in contact with them for prolonged
periods. The operation panel is made of thermoplastic resin, so take care not to allow
any heated articles such as a soldering iron to come in contact with it.

IM 253421-01E

• For cleaning the case and the operation panel, unplug the power cord first, then
gently wipe with a dry, soft and clean cloth. Do not use chemicals such as benzene
or thinner, since these may cause discoloration or damage.

• If the instrument will not be used for a long period, unplug the power cord from the AC
outlet.

3-1

3.2 Installing the Instrument

Installation Conditions

The instrument must be installed in a place where the following conditions are met.

Ambient temperature and humidity

• Ambient temperature: 5 to 40˚C

• Ambient humidity: 20 to 80% RH (no condensation)

Horizontal position

The instrument must be installed horizontally. A non-horizontal or inclining position can
impede proper measurement of the instrument.

Well-ventilated location

Vent holes are provided on the top and bottom of the instrument. To prevent rise in internal
temperature, do not block these vent holes.
In case you removed the feet for rack-mounting the instrument, make sure to keep a space of
at least 20 mm as not to block the vent holes.

Never install the instrument in any of the following places

• In direct sunlight or near heat sources;

• Near noise sources such as high voltage equipment or power lines ;

• Where an excessive amount of soot, steam, dust or corrosive gases is present;

• Where the level of mechanical vibration is high;

• Near magnetic field sources;

• In an unstable place.

Installation Position

Note

• To ensure high measurement accuracy, the instrument should only be used under the following
conditions.
Ambient temperature: 23 ± 5˚C
Ambient humidity: 30 to 75% RH (no condensation)
When using the instrument in the temperature ranges of 5 to 18 or 28 to 40˚C, add the temperature
coefficient to the accuracy as specified in chapter 16 “Specifications”.

• If the ambient humidity of the installation site is 30% or below, use an anti-static mat to prevent
generation of static electricity.

• Internal condensation may occur if the instrument is moved to another place where both ambient
temperature and humidity are higher, or if the room temperature changes rapidly. In such cases
acclimatize the instrument to the new environment for at least one hour before starting operation.

Desktop

As shown below, place the instrument on a flat even surface. When using the handle for
installation, check that the handle is in one of the fixed positions. To change the fixed position of
the handle, pull the handle approximately 2 to 3 mm outward along the rotational axis and slowly
move the handle.

Fixed positions of the handle
(We recommend the positions 1, 3, 5, or 8. When
using no 4, don't put any weight on the instrument.)

7

6

5

4

8

1

2

3

Turning axis

Turn the stands after
pulling them approx.
2-3 mm on both sides.

3-2

3

1

IM 253421-01E

3.2 Installing the Instrument

Rack mount

To install the instrument in a rack, use one of the following optional rack mount kits.

• Rack mount kit (option)

Specifications
EIA Standard (for single mount)
JIS Standard (for single mount)
EIA Standard (for multiple mount)
JIS Standard (for multiple mount)

Kit
751533-E2
751533-J2
751534-E2
751534-J2

• Mounting procedure

1. Turn the handle to position 8 (see the figure on the previous page) and remove it
by pulling the handle outward along the rotational axis approximately 10 mm.

Turn the handle to

Turning axis

position 8 and remove
it by pulling it approx.
10 mm from the turning
axes on both sides.

2. Remove the feet from the instrument.

3. Remove the seals covering the mounting holes from the front side of the
instrument.

4. Mount the rack mount brackets.

5. Mount the instrument in the rack.

3

Before Starting Measurements

For more detailed information regarding the rack mount procedure, refer to the
instruction manual accompanied with the rack mount kit.

Note

• When rack mounting the instrument, allow at least 20 mm of space around the vent holes to

prevent internal overheating.

• Make sure to have adequate support for the bottom of the instrument. However, do not block

the vent holes in the process.

IM 253421-01E

3-3

3.3 Wiring Precautions

• To prevent hazards, make sure to apply a ground protection before connecting the
object being measured.

• Always turn OFF the power to the object being measured before connecting it to the
instrument. Never connect or disconnect the measurement lead wires from the object
while power is being supplied to it, otherwise a serious accident may result.

• When the power switch is ON, never apply a voltage or current exceeding the level
specified in the table below to the voltage input or current input terminal. When the
power switch is OFF, turn off the power of the instrument under measurement as well.
For details regarding the other terminals, such as the external input terminal, refer to
chapter 16 “Specifications.”

Max allowable input Voltage input Current input

Instantaneous max Peak value of 2000 V or 20 A to 0.5 A range
(for 1s) RMS value of 1500 V, Peak value of 150 A or RMS value of

Continuous Peak value of 1500 V or 20 A to 0.5 A range

WARNING

whichever is less. 40 A, whichever is less.

200 mA to 5 mA range

Peak value of 30 A or RMS value of
20 A, whichever is less.

RMS valueof 1000 V, Peak value of 100 A or RMS value of
whichever is less. 25 A, whichever is less.

200 mA to 5 mA range

Peak value of 30 A or RMS value of
20 A, whichever is less.

• In case you are using an external potential transformer (PT) or current transformer (CT),
use one which has a sufficient withstand voltage against the voltage to be measured (a
withstand voltage of 2E + 1000 V is recommended, where E is the measurement
voltage.) Also be sure not to allow the secondary side of the CT to go open-circuit while
power is supplied, otherwise an extremely dangerous high voltage will be generated on
the secondary side of the CT.

• If the instrument is used in a rack, provide a power switch so that power to the
instrument can be shut off from the front of the rack in an emergency.

• For safety reasons, make sure that the bare end of the measurement lead wire
connected to each input terminal does not protrude from the terminal.
Also make sure that the measurement lead wires are connected to the terminals
securely.

• The voltage rating across the input (voltage and current) and ground varies depending
on the operating conditions.

• When protective covers are used on GP-IB or RS-232-C and external input/output

connectors;

Voltage across each measuring input terminal and ground 600 Vrms max.

• When protective covers are removed from GP-IB or RS-232-C and from external

input/output connectors; or when connectors are used;

Voltage across A, ±(V and A side) input terminals and ground 400 Vrms max.
Voltage across V terminal and ground 600 Vrms max.

3-4

IM 253421-01E

3.3 Wiring Precautions

CAUTION

Use lead wires that have sufficient margin in withstand voltage and current
against the signal being measured. The lead wires must also have insulation
resistance that is appropriate for the ratings.
Ex. If measurement is carried out on a current of 20 A, use copper wires with a

conductor cross-sectional area of at least 4 mm

Note

• When measuring high currents, or currents or voltages that contain high-frequency
components, wiring should be made with special attention paid to possible mutual
interference and noise problems.

• Keep the lead wires short as possible.

• For current circuits indicated by thick lines in the wiring diagrams shown in section 3.4 and
later, use thick lead wires appropriate for the current to be measured.

• The lead wire to the voltage input terminal should be connected as close to the load of the
object under measurement as possible.

• To minimize stray capacitance to ground, route both lead wires and grounding wires so that
they are as away from the instrument's case as possible.

2

.

3

Before Starting Measurements

IM 253421-01E

3-5

3.4 Improving the Measurement Accuracy

SOURCE

LOAD

V

A

i

V

i

L

SOURCE

LOAD

A

V

Input terminal

WT200

±

±

±

±

By wiring the circuit to match the load, you can minimize the effect of the power loss on
the measurement accuracy. We will consider a circuit consisting of a current source
(SOURCE) and load resistance (LOAD) below.

• When the measurement current is relatively large

In this case, the voltage measurement circuit is connected to the load side. The
current measurement circuit measures the sum of the current that flows through the
load of the circuit under measurement (i
voltage measurement circuit (i
measurement is i

, iV is the error. The input resistance of the voltage measurement

L

). Since the current flowing through the circuit under

V

circuit is approximately 2 MΩ. For a 600-V input signal, i
(600 V/2 MΩ). If the load current i
200 Ω or less), the effect of the voltage measurement circuit on the measurement
accuracy is less than or equal to 0.01%. As another example, if the input signal is

200 V and 10 A, i

= 0.1 mA (200 V/ 2 MΩ). The effect on the measurement accuracy

V

is 0.001% (0.1 mA/10 A) in this case.

) and the current that flows through the

L

is approximately 0.3 mA

V

is greater than or equal to 3 A (load resistance is

L

3-6

The following figure shows the relationship between the voltage and current that leads
to 0.1%, 0.01%, and 0.001% errors.

Effect or 0.1%

600

Measured voltage (V)

500
400
300
200
100

0

0 2 4 6 8 101214161820

300 mA 3 A

Effect of 0.01%

Less effect

• When the measurement current is relatively small

Connect the current measurement circuit to the load side. In this case, the voltage
measurement circuit measures the sum of the load voltage (eL) and the voltage drop
of the current measurement circuit (e

A). The voltage drop eA is the error. The input

resistance of the current measurement circuit is approximately 6 mΩ. If the load
resistance is 600 Ω, for example, the effect on the measurement accuracy is
approximately 0.001% (6 mΩ/600 Ω).

A

LOAD

e

L

SOURCE

V

±

±

e

A

WT200

Effect of 0.001%

Measured current (A)

IM 253421-01E

3.5 Connecting the Power Supply

Before Connecting the Power Supply

Connecting Procedure

WARNING

• Ensure that the supply voltage matches the rated supply voltage of the
instrument before connecting the power cable.

• Check that the power switch is turned OFF before connecting the power cord.

• Make sure to connect the protective earth to prevent electric shock. Connect
the power cord to a three-pin power outlet with a protective earth terminal.

• Do not use an extension cord without protective earth ground. This act will
invalidate the protection.

1. Make sure that the power switch of the instrument is turned OFF.

2. Connect the accessory power cord to the power connector on the back of the

instrument.

3. Insert the power cord to the power outlet which conforms to the following

specifications.
Make sure that you use an outlet with a protective grounding terminal only.

Item Specifications

Rated supply voltage 100 to 240 VAC
Permitted supply voltage range 90 to 264 VAC
Rated supply voltage frequency 50/60 Hz
Permitted supply voltage frequency range 48 to 63 Hz
Maximum power consumption 25 VA (at 120 VAC) or 35 VA (at 240 VAC)

3

Before Starting Measurements

3 pin consent

WT200

Power cord
(accessory)

IM 253421-01E

3-7