YOKOGAWA CW120 User manual

User's
Manual CW120/121
CLAMP-ON POWER METERS
IM CW120-E
IM CW120-E
First Edition: Dec. 2001 (YG)
Before Use
Before starting measurement with your CW120 or CW121, fill in the Setting Check Sheet in the
back of the
Operation Guide (IM CW120P-E) with your particular settings, to facilitate setting on
site.

1
IM CW120-E
Disk No. CW120-E
1st Edition: Dec. 2001 (YG)
All Rights Reserved. Copyright © 2001, Yokogawa M&C Corporation
Introduction
Thank you for purchasing our CW120 or CW121 Clamp-on Power Meter.
This User’s Manual explains the functions of the CW120/121, as well as the
operating methods and handling precautions. Before using the CW120/121,
read this manual thoroughly to ensure correct use of the instrument.
The Operation Guide manual, available separately in addition to this manual,
describes the basic procedures for performing such tasks as measurement
operations and settings. Use the Operation Guide together with this in-depth
manual.
When you have finished reading this manual, carefully store it in a convenient
place for future reference.
Notes The contents of this manual are subject to change without prior notice. In
addition, figures and illustrations representing display appearances in this
manual may differ from the actual appearances.
Every effort has been made to ensure the accuracy of this manual. If you
notice any errors or have any questions, however, please contact one of the
Yokogawa M&C sales offices listed on the back cover of this manual or the
sales representative from which you purchased the instrument.
The contents of this manual may not be transcribed or reproduced, in part or
in whole, without prior permission.
Trademark Acknowledgments
All company and product names appearing in this document are trademarks
or registered trademarks of their respective holders.
Revision Information
December 2001: First edition

2IM CW120-E
Checking Items in the Package
After opening the package, check the product as follows before use. If the
delivered product is the wrong model, any item is missing, or the appearance
is defective, contact the vendor from which you purchased the product.
CW120/121 Main Unit
Check the model and suffix (specifications) codes in the MODEL and SUFFIX
fields of the nameplate at the back of the instrument to ensure that the
instrument is exactly as specified in your purchase order.
Model and Suffix Codes
Model
CW120
CW121
Power cord
Communication
interface
Option codes
Suffix Code
-D
-F
-R
-S -1
-2 /C1
/C2
/C3
/C4
/C5
/C6
/C7
/C8
/PB1
/PM1
/PM2
Specification
Clamp-on power meter for single-phase two-wire, single-phase three-wire,
and three-phase three-wire circuits
Clamp-on power meter for single-phase two-wire, single-phase three-wire,
three-phase three-wire, and three-phase four-wire circuits
UL/CSA standard
VDE standard
SAA standard
BS standard
With RS-232-C interface
With RS-485 interface
Clamp-on current probe for 20/200 A (2 pieces/set)
Clamp-on current probe for 20/200 A (3 pieces/set)
Clamp-on current probe for 50/500 A (2 pieces/set)
Clamp-on current probe for 50/500 A (3 pieces/set)
Clamp-on current probe for 200/1000 A (2 pieces/set)
Clamp-on current probe for 200/1000 A (3 pieces/set)
Clamp-on current probe for 5/50 A (2 pieces/set)
Clamp-on current probe for 5/50 A (3 pieces/set)
Meter case, carrying case, CF pack
Meter case, carrying case, CF pack, and 91011
Meter case, carrying case, CF pack, and 91009
No. (serial number):
Refer to this serial number on the nameplate when contacting the vendor
about the instrument.
Accessories Make sure that the package contains all the accessories listed below and that
they are all free from any damage.
Product Name Part Number Qty Remarks
1. Power cord B9988YA -D: UL/CSA standard
(One of the four options) B9988TB -F: VDE standard
B9988YC -R: SAA standard
B9988YD -S: BS standerd
2. Voltage probes (for CW120) 91018 3 Color: Black, red, yellow
Voltage probes (for CW121) 91007 4 Color: Black, red, yellow, blue
3. User’s Manual IM CW120-E 1
4. Operation Guide IM CW120P-E 1

3
IM CW120-E
Checking Items in the Package
1. 2. 3.
4.
Peripherals (Optional)
The products listed below are available as optional peripherals. For technical
and ordering inquiries concerning the peripherals, contact the vendor from
which you purchased the instrument. If you purchased any one of the
optional peripherals together with the CW120/121, make sure it is free from
any damage.
Product Name Part Number Minimum Order Qty Remarks
Clamp-on current probe for 20/200 A 96030 1 See the option codes for a choice of
probe kits.
Clamp-on current probe for 50/500 A 96031 1 See the option codes for a choice of
probe kits.
Clamp-on current probe for 200/1000 A 96032 1 See the option codes for a choice of
probe kits.
Clamp-on current probe for 5/50 A 96033 1 See the option codes for a choice of
probe kits.
Power supply cable 98030 1Not applicable to CE and UL(pending)
Voltage probes (for CW121) 91007 41set
Voltage probes (for CW120) 91018 3 1 set
RS-232 serial printer cable 91010 1
Printer 97010 1 With 1 thermal paper roll and 1
battery pack
AC adapter (for printer) 94006 1 Power supply 200-240 V AC
AC adapter (for printer) 94007 1 Power supply 100-120 V AC
Thermal printer paper 97080 10 rolls
Carrying case 93022 1 For CW120 Series
Meter case 93023 1 For CW120 Series
CF pack (16 MB) 97030 1 Compact flash memory and
compact flash adapter
TIP
Keep the packing box in case you need to transport the instrument.

4IM CW120-E
Checking Items in the Package
Housing CW120/121 and Accessories
The optional carrying case can accommodate the CW120 or CW121 main
unit with its current-sensing clamp-on probes and voltage probes connected
to the unit. The case can also hold such accessories as manuals and PC
cards, and so is useful for transporting a complete set of tools necessary for
measurement.
The optional meter case can be used as a stand during measurement as
shown below right. It also has a magnetic rear plate and so can be stuck to
the door of a power distribution panel or the like.
Note: Keep the meter case away from objects vulnerable to a magnetic field,
such as floppy disks.
Clamp-on current probes
Manual
CW120/121 main unit
Voltage probes Adjust the Velcro fastener.
Carrying Case Meter case

5
IM CW120-E
Precautions for Safe Use of the Instrument
When operating the instrument, be sure to observe the cautionary notes given below
to ensure correct and safe use of the instrument. If you use the instrument in any
other way than instructed in this manual, the instrument’s protective measures may
be impaired. Yokogawa M&C Corporation is by no means liable for any damage
resulting from use of the instrument in contradiction to these cautionary notes.
The following safety symbols are used in the instrument and this manual.
Danger! Handle with Care.
This symbol indicates that the operator must refer to an explanation in the instruction manual in
order to avoid risk of injury or death of personnel or damage to the instrument.
Direct Current
This symbol indicates DC voltage/current.
Alternating Current
This symbol indicates AC voltage/current.
ON
This symbol indicates On (power).
OFF
This symbol indicates Off (power).
Double Insulation
This symbol indicates double insulation.
WARNING
Indicates a hazard that may result in the loss of life or serious injury of the user unless the
described instruction is abided by.
CAUTION
Indicates a hazard that may result in an injury to the user and/or physical damage to the product
or other equipment unless the described instruction is abided by.
NOTE
Indicates information that is essential for handling the instrument or should be noted in order to
familiarize yourself with the instrument’s operating procedures and/or functions.
TIP
Indicates information that complements the present topic.
SEE ALSO
Indicates the reference location(s) for further information on the present topic.

6IM CW120-E
Precautions for Safe Use of the Instrument
Strictly observe the following cautionary notes in order to avoid the risk of
injury or death of personnel or damage to the instrument due to such hazards
as electrical shock.
WARNING
●Removal of Case from the Instrument
•Do not remove the case from the instrument or disassemble/modify the instrument itself.
•Some parts of the inside of the instrument contain high-voltage and, therefore, access to
the internal assembly is extremely hazardous. For inspection and/or adjustment of the in-
ternal assembly, contact the vendor from which you purchased the instrument.
●Use of the Instrument in a Gas Atmosphere
Do not operate the instrument in a location where any flammable or explosive gas/vapor is
present. It is extremely hazardous to operate the instrument in such an atmosphere.
●Inspection of Power Source
•Before turning on the instrument, always make sure the voltage of the power source to be
applied matches the instrument’s supply voltage.
●Use of Clamp-on Current Probes
•When using clamp-on current probes, keep the circuit voltage below 600 V AC in order to
avoid possible short-circuits or accidents resulting in injury or death.
•Ensure that the rated current of the circuit you measure matches the rating of the current
probe.
•Avoid using the instrument if it has been exposed to rain or moisture or if your hands are
wet.
•Do not use clamp-on current probes with any non-insulated conductors.
●Measures In Case of Anomalies
If the instrument begins to emit smoke, becomes too hot, or gives off an unusual smell, imme-
diately turn it off and disconnect the power cord from the outlet. Also turn off power to the
object under measurement that is connected to the instrument’s input terminals. Never at-
tempt to use the instrument again. If any such anomalies as noted above occurs, contact the
vendor from which you purchased the instrument. Do not attempt to repair the instrument
yourself, as doing so is extremely dangerous.
●Handling of Power Cord
•Use only the cord supplied fromYokogawa M&C to prevent electric shocks and fire.
•Do not place any load on the power cord or allow the power cord to come into accidental
contact with any heat source. When unplugging the power cord from the outlet, hold its
plug, rather than holding and pulling the cord itself.
•If the power cord is damaged, contact the vendor from which you purchased the instrument.
●Fuses
Fuses built into this instrument for protection cannot be replaced by the user. When any built-
in fuses need to be replaced such as because they have blown,contact the vendor from which
you purchased the instrument.

7
IM CW120-E
Contents
Introduction .............................................................................................................. 1
Checking Items in the Package ..............................................................................2
Precautions for Safe Use of the Instrument ..........................................................5
Chapter 1. Product Overview ...............................................................................1-1
1.1 Product Overview ........................................................................................ 1-1
Chapter 2. Components and Indications ............................................................2-1
2.1 Front Panel and Connector Block ............................................................... 2-1
2.2 Connecting Input Signals ............................................................................ 2-3
2.3 Operation Keys and Display........................................................................ 2-5
2.4 Overrange and Other Marks Shown during Measurement.......................... 2-6
Chapter 3. Precautions for Safe Measurement ..................................................3-1
3.1 Handling Precautions .................................................................................. 3-1
3.2 Installation Procedure.................................................................................. 3-3
3.3 Maintaining High Precision of Measurement............................................... 3-5
Chapter 4. Connecting Power Supply and Turning Power On/Off ...................4-1
4.1 When Using AC Power Supply.................................................................... 4-1
4.2 When Supplying Power from Voltage Input................................................. 4-3
4.3 Startup Screens........................................................................................... 4-4
4.4 Basic Operation Flow .................................................................................. 4-6
Chapter 5. Wiring ..................................................................................................5-1
5.1 Precautions for Wiring the Circuit under Test .............................................. 5-1
5.2 Diagrams of Basic Wiring ............................................................................ 5-2
5.3 Wiring the Circuit under Test with External VT/CT ...................................... 5-4
5.4 Indication and Change of Wiring Method .................................................... 5-5
5.5 Wiring Check Function ................................................................................ 5-6
Chapter 6. Setting Ranges and Wiring Method ..................................................6-1
6.1 Ranges and Display Digits .......................................................................... 6-1
6.2 Changing Voltage Range Setting ................................................................ 6-6
6.3 Changing Current Range Setting ................................................................ 6-7
6.4 Changing Wiring Method Setting............................................................... 6-10
Chapter 7. Making Settings ..................................................................................7-1
7.1 Setting Items and Item Selection................................................................. 7-1
7.2 Setting Each Item ........................................................................................ 7-4
7.3 Setting Name of Measured-data File......................................................... 7-32
Chapter 8. InstantaneousValue Measurement .................................................8-1
8.1 Measuring Instantaneous Values ................................................................ 8-1
8.2 Switching Display Contents......................................................................... 8-2
8.3 Saving Data................................................................................................. 8-4
8.4 Frequency Measurement ............................................................................ 8-7
8.5 Sampling Cycle and Integration Cycle ........................................................ 8-8
1
2
3
4
5
6
7
8
9
10
11
12
13
14
App
Index

8IM CW120-E
Contents
Chapter 9. Electric Energy Measurement ...........................................................9-1
9.1 Measuring Electric Energy .......................................................................... 9-1
9.2 Starting and Stopping Integration................................................................ 9-3
9.3 Switching Display Contents....................................................................... 9-10
9.4 Saving Data............................................................................................... 9-12
9.5 Backup Memory ........................................................................................ 9-15
9.6 External Control Input/Output.................................................................... 9-18
9.7 Meter Actions upon Power Failure and Recovery ..................................... 9-21
Chapter 10. PC Card ...........................................................................................10-1
10.1 PC Card Specifications ............................................................................. 10-1
10.2 Inserting and Removing PC Card.............................................................. 10-2
10.3 Storage Capacity....................................................................................... 10-3
10.4 Formatting PC Card .................................................................................. 10-4
10.5 Saving and Loading from/to PC Card........................................................ 10-5
10.6 Interface with Personal Computer ............................................................. 10-7
Chapter 11 Communication Functions ............................................................ 11-1
11.1 RS-232 ...................................................................................................... 11-1
11.2 RS-485 ...................................................................................................... 11-6
11.3 Data Format .............................................................................................. 11-9
Chapter 12. Auxiliary Functions ........................................................................12-1
12.1 Convenient Functions................................................................................ 12-1
12.2 Using Optional Printer ............................................................................... 12-3
Chapter 13. Troubleshooting .............................................................................13-1
13.1 Corrective Measures in Case of Failure .................................................... 13-1
13.2 Error Codes ............................................................................................... 13-2
Chapter 14. Specifications .................................................................................14-1
14.1 Specifications of CW120/121 .................................................................... 14-1
14.2 Specifications of Clamp-on Current Probes .............................................. 14-8
Appendix 1. Circuit Block Diagram ..............................................................App1-1
Appendix 2. Communication Commands ....................................................App2-1
1. Commands ......................................................................................... App2-2
1.1 Messages ..............................................................................................App2-2
1.2 Commands ............................................................................................App2-4
1.3 Response ..............................................................................................App2-5
1.4 Data.......................................................................................................App2-6
1.5 Messages on RS-485............................................................................App2-8
1.6 Communication Commands ..................................................................App2-9
Output Queue and Error Queue ..........................................................App2-12
1.7 Detailed Description of Communication Commands...........................App2-12
1.7.1 COMMunicate Group ...............................................................App2-12
1.7.2 SYSTem Group ........................................................................App2-13
1.7.3 INTEgrate Group......................................................................App2-15
1.7.4 MEASure Group.......................................................................App2-17

9
IM CW120-E
Contents
1.7.5 STATus Group ..........................................................................App2-17
1.7.6 MEMOry Group........................................................................App2-18
1.7.7 CARD Group............................................................................App2-18
1.7.8 Common Group .......................................................................App2-19
2. Error Messages ................................................................................ App2-20
3. Command Effectiveness Tables........................................................ App2-24
Appendix 3. File Structures and Data Items Printed .................................App3-1
1. Overview............................................................................................. App3-2
2. Measured Data ................................................................................... App3-3
2.1 File Format ............................................................................................App3-3
2.2 Print Format...........................................................................................App3-5
3. Settings............................................................................................... App3-6
3.1 File Format ............................................................................................App3-6
3.2 Output Format and Data Values ............................................................App3-7
3.3 Print Format...........................................................................................App3-9
4. Automatic File Naming...................................................................... App3-10
Index............................................................................................................... Index-1

1-1
IM CW120-E
Product Overview
1
Chapter 1. Product Overview
1.1 Product Overview
The CW120/121 clamp-on power meters measure the fundamental electric
power factors, namely, instantaneous power-related values and electric
energy (watt-hours).
• CW120: Supports single-phase two-wire, single-phase three-wire, and
three-phase three-wire circuits.
• CW121: Supports single-phase two-wire, single-phase three-wire, three-
phase three-wire, and three-phase four-wire circuits.
The following explains the features of the CW120/121, shows a schematic
diagram of their functions, and describes the contents displayed on the
screen in each measurement mode.
Features ●A Wealth of Functions
• Fast data saving for a long time: Data can be saved at 1-second intervals
at fastest. A PC card slot for large removable memories such as flash
ATA and compact flash cards allows measurement over a long time.
• Instantaneous value saving: Simply pressing the SAVE key will save the
measured values.
• Wiring error check: The connections are checked and any error is
displayed before the start of measurement.
●Broad Ranges
• Voltage range: 150/300/450 V
• Current range: 4 types of clamp-on probes can be used.
96033 clamp-on probe: 5/10/20/50 A
96030 clamp-on probe: 20/50/100/200 A
96031 clamp-on probe: 50/100/200/500 A
96032 clamp-on probe: 200/500/1000 A
●Ease of Data Processing and Communication
Data can be saved to a PC card. Via communication, data can be
transferred to a personal computer and the measurement conditions can
be set from a computer. As the communication interface, you can choose
(when ordering) RS-232 or RS-485; the RS-485 interface allows multiple
CW120s and CW121s to be connected on the same line for remote
monitoring.

1-2 IM CW120-E
1.1 Product Overview
●Compact Design
• The CW120/121 are sufficiently compact to be installed inside a cubicle or
power distribution panel during measurement.
• The 96033 current-sensing probe with a 5 to 50 A range is designed for
use in a narrow space, so is useful for measurement inside a power
distribution panel with dense wiring.
●Easy-to-see Display Screen
Despite the compact body, the large back-lit LCD enables easy
measurement in a dark place.

1-3
IM CW120-E
Product Overview
1
1.1 Product Overview
●Schematic Function Diagram
Power-on
Measurement
screen Setting screens
key
key
Chapter 7
Chapter 9
Chapter 8
PC Printer PC
PC card
7.2.10 Setting whether to
save data to PC card
RS-485RS-232 Communication interface
(chosen when ordering)
External control terminals
Input Output
7.2.11 Selecting communication device
7.2.1
7.2.2
7.2.3
7.2.4
7.2.5
7.2.6
7.2.7
7.2.8
7.2.9
7.2.10
7.2.11
7.2.12
7.2.13
7.2.14
7.2.15
7.2.16
Setting device number
Loading/saving settings
Deleting file and formatting PC card
Clearing electric energy count (watt-hours)
and resetting system
Copying and clearing backup memory
contents
Setting date
Setting output interval
Setting integration start time
Setting integration stop time
Setting whether to save data to PC card
Selecting communication device
Making communication settings
Setting VT ratio
Setting CT ratio
Selecting probe to be used
Setting decimal point and unit of electric
energy (watt-hours)
Saving settings
7.2.2 Loading/saving setting File: WTH000.SET
Electric energy (watt-hour)
measurement
Data saving
Auto-saving
7.2.7 Setting output interval
File: AWTH000.CSV
Instantaneous value
measurement
Data saving
File: MWTH000.CSV
key
Start of
integration End of
integration
7.2.8 Setting integration start time
7.2.9 Setting integration stop time
●On-screen Information (Measured Data)
There are two measurement modes: instantaneous measurement and
electric energy measurement. In the latter mode, the power is
continuously measured and integrated during the preset start and stop
times.
Instantaneous value measurement
Item Unit Displayed Name
Rms voltage V V1, V2, V3 (differs depending on the wiring method)
Rms current A A1, A2, A3 (differs depending on the wiring method)
Active power W W
Reactive power Var Var
Power factor — PF
Frequency Hz Hz (input frequency of V1)

1-4 IM CW120-E
Electric energy measurement
Item Unit Displayed Name
Active electric energy Wh Wh
Regenerative electric energy Wh Only saved; not displayed
Six items of instantaneous value measurement
The screen changes sequentially each time a cursor-movement (UP, DOWN,
LEFT, or RIGHT) key is pressed as follows (display contents differ depending
on the wiring method):
Screen
1
V1
A1
V1
V2
V1
V2
Screen
2
W
Var
A1
A2
V3
A1
Screen
3
PF
Hz
W
Var
A2
A3
Screen
4
Wh
TIME
PF
Hz
W
Var
Screen
5
Wh
TIME
PF
Hz
Screen
6
Wh
TIME
Displayed Item
Single-phase two wires (1∅2W)
Single-phase three wires (1∅3W)
Three-phase three wires (3∅3W)
Three-phase four wires (3∅4W)
Phase Wires Display
Position
Upper row
Lower row
Upper row
Lower row
Upper row
Lower row
1.1 Product Overview

2-1
IM CW120-E
Components and Indications
2
Chapter 2. Components and Indications
2.1 Front Panel and Connector Block
●Dimensions
Connector Block
FrontView
117 51
Unit: mm
161
SideView

2-2 IM CW120-E
●Connector Block
Voltage input terminals Current input terminals
CW120:Supports fromsingle-phase two-wiretothree-phase three-wirecircuits
Voltage input terminals: N, V1, V2
Current input terminals: CH1, CH2
CW121: Supports from single-phase two-wire to three-phase four-wire circuits
Voltage input terminals: N, V1, V2, V3
Current input terminals: CH1, CH2, CH3
●Side Panels
RS-485 screw
terminals
External control
terminals
Model with RS-232 interface Model with RS-485 interface
Power switch Power supply connector Power switch Power supply connector
PC card slot
PC card eject button PC card eject button
RS-232
connector PC card slot
RS-232 interface
RS-232 connector : Used to connect to a PC or printer
(optional).
Internal control input (IN) terminals : Used to connect the integration
start/stop input signals.
Internal control output (OUT) terminals : Used to connect the integration
start/stop output signals.
SEE ALSO
For details of external control input/output, see Section 9.6, “External Control Input/Output.”
RS-485 interface
RS-485 screw terminals : Used to connect a shielded cable
and terminator.
SEE ALSO
For details of the RS-485 interface, see Section 11.2, “RS-485.”
2.1 Front Panel and Connector Block

2-3
IM CW120-E
Components and Indications
2
2.2 Connecting Input Signals
Voltage probe (red)
Voltage probe (black)
Clamp-on current probe
Ring marker
WARNING
•Thoroughly read Section 5.1, “Precautions for Wiring the Circuit under Test.”
•When connecting the CW120/121, turn off the circuit under test. It is extremely dangerous to
connect or disconnect probes to/from a live circuit.
•Be extremely careful not to connect any voltage-mode circuit to the current input terminals or
any current-mode circuit to the voltage input terminals. Miswiring can result in not only dam-
age to the circuit or equipment under test but also injury to personnel.
•Do not connect any probes which are not necessary (i.e., not used) for the current measure-
ment, even though multiple probes can be connected to the CW120/121 at the same time.
•Do not use any probe other than the clamp-on current probes or voltage probes supplied.
•Do not use a clamp-on current probe for a non-insulated conductor.
•Ensure that the rating of the clamp-on current probe you use matches the rating of the mea-
sured current.
•Before connecting a clamp-on current probe to the CW120/121, make sure the plug is inserted
with the correct H/L polarities.

2-4 IM CW120-E
●Differentiating between Voltage Probes
Voltage probes are differentiated by color for correct connections.
•Probe for terminal N: Probe with a black alligator plug
•Probes for terminals V1 to V3: Probes with a red, yellow, or blue alligator
plug
Accompanying probes
CW120: Three (black, red, and yellow)
CW121: Four (black, red, yellow, and blue)
●Differentiating between Clamp-on Current Probes
Use accompanying ring markers (of four different colors) to differentiate
clamp-on current probes for correct connections.
CW120: Terminals CH1 to CH2
CW121: Terminals CH1 to CH3
Use of Ring Markers
Attach ring markers of the same color to both ends of the probe cable for easy
identification.
CAUTION
Be careful not to damage a probe when attaching ring markers.
2.2 Connecting Input Signals