YOKOGAWA CW140 User manual

User's
Manual CW140
CLAMP-ON POWER METER
IM CW140-E
IM CW140-E
3rd Edition July 2001 (YK)

1
IM CW140-E
Disk No. CW140-E
3rd Edition: July 2001 (YK)
All Rights Reserved. Copyright © 2000, Yokogawa M&C Corporation
Introduction
Thank you for purchasing our CW140 Clamp-on Power Meter. This User’s
manual explains the functions of the CW140, as well as its operating methods
and handling precautions. Before using the CW140, read this manual
thoroughly to ensure correct use of the instrument.
The Operation Guide manual is available separately, in addition to this
manual. The Operation Guide manual briefly describes the basic procedures
for performing such tasks as measurement operations and settings. Use the
manual together with this in-depth User’s manual.
When you have finished reading this manual, carefully store it in a place that
provides ease of access for later reference. This manual will come in handy
when you are unsure of how to operate the instrument.
Notices The contents of this manual are subject to change without prior notice. In
addition, figures and illustrations representing display views in this manual
may differ from real views.
Every effort has been made to ensure accuracy in the preparation of this
manual. Should any doubts arise or errors come to your attention 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
The company and product names referred to in this document are either
trademarks or registered trademarks of their respective holders.
Revision Information
February 2000: First edition
July 2001: 3rd edition

IM CW140-E
2
Examining Items Contained in the Package
After opening the package, be sure to examine the product as instructed
below before use. Should the delivered product be the wrong model, lack any
item, or show any flaw in its appearance, contact the vendor from which you
purchased the product.
CW140 Main Unit
Check the model name and the suffix (specifications) code in the MODEL and
SUFFIX fields of the nameplate located at the back of the instrument to
ensure that the instrument is exactly as specified in your purchase order.
Model Name and Suffix Codes
Model Suffix Code Specifications
CW140
AC adapters D Power cord: UL/CSA standard
FVDE standard
RSAA standard
SBS standard
Option codes /DA D/A output
/C1 Clamp-on probe for 20/200A (2 pcs/set)
/C2 Clamp-on probe for 20/200A (4 pcs/set)
/C3 Clamp-on probe for 50/500A (2 pcs/set)
/C4 Clamp-on probe for 50/500A (4 pcs/set)
/C5 Clamp-on probe for 200/1000A (2 pcs/set)
/C6 Clamp-on probe for 200/1000A (4 pcs/set)
/PM1 NiMH (nickel-hydrogen) battery pack and carrying case
/PM2 “PM1” and FDD unit
No. field: Denotes the instrument number.
Refer to this number when inquiring to 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. AC adapter for power supply 788011 1 set Yokogawa’s AC adapter
2. AA alkaline dry cells — 6 (alkaline batteries)
3. Voltage probes 91007 4 Supplied together with two sets of ring
markers of three different colors.
4. Instruction manual IM CW140-E 1
5. Operation Guide manual IM CW140P-E 1
1. 2. 3.
4. 5.

3
IM CW140-E
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 the instrument you purchased
includes any one of the optional peripherals, make sure it is free from any
damage.
Product Name Part Number Minimum Order Qty Remarks
Clamp-on probe for 20/200 A 96030 1 * See the option codes for a choice of
probe kits.
Clamp-on probe for 50/500 A 96031 1 *
Clamp-on probe for 200/1000 A 96032 1 *
Voltage probe 91007 4
Floppy disk drive unit 97020 1 set FDD unit
Carrying case 93020 1
AC adapter 788011 1 set Yokogawa’s AC adapter
NiMH battery pack 94004 1
Printer 97010 1
AC adapter (for printer, Europe) 94006 1
AC adapter (for printer, USA) 94007 1
Thermal paper for printers 97080 10 rolls
TIP
It is advisable that the packing box be stored, as it is useful when you transport the instrument.
●Housing CW140 Main Unit and Accessories
An optional carrying case can accommodate the CW140 main unit with its
current-sensing clamp-on probes and voltage probes connected to the unit.
The case can also house such accessories as an AC adapter, NiMH battery
pack, floppy drive unit, instruction manual, floppy disks, recording paper, and
so on. It therefore comes in handy when transporting a complete kit of tools
necessary for your measurement.
Example of Housing:
Instruction manual
NiMH battery pack
Floppy drive unit
AC adapter
Clamp-on probes
CW140 main unit
Voltage probes
Examining Items in the Package

IM CW140-E
4
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.

5
IM CW140-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 internal
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.
•When using alkaline batteries or an NiMH battery pack,carefully read the cautionary notes on
battery handling later in this manual.
●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.
• 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 Cords
Do not place any load on the power cord or allow the power cord to come into accidental
contact with any heat source. Hold the plug of the power cord, rather than holding and pulling
the cord itself, when disconnecting it from the outlet. If the power cord is damaged, contact
the vendor from which you purchased the instrument. See page 2 for information on the AC
adapter that is necessary when ordering a replacement power cord.

IM CW140-E
6
Contents
Introduction .............................................................................................................. 1
Examining Items Contained in the Package.......................................................... 2
Precautions for Safe Use of the Instrument ..........................................................4
Chapter 1. Product Overview ...............................................................................1-1
1.1 Product Overview ........................................................................................ 1-1
Chapter 2. Components,Their Use and Overrange, and Error Indications .....2-1
2.1 Front Panel and Connector Block................................................................ 2-1
2.2 Operation and Functions Keys .................................................................... 2-2
2.3 Connecting Input Signals to Be Measured and External Input Terminals ... 2-3
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 Precautions for Wiring the Circuit under Test .............................................. 3-4
3.4 Diagrams of Basic Wiring ............................................................................ 3-5
3.5 Wiring the Circuit under Test Using External VT/CT.................................... 3-8
3.6 Connecting a Power Supply and Turning It On/Off ...................................... 3-9
3.7 Performing Measurements with Higher Precision ..................................... 3-18
Chapter 4. Basic Operation Flow andTop Menu Screen ...................................4-1
4.1 Basic Operation Flow .................................................................................. 4-1
4.2 Top Menu Screen ........................................................................................ 4-2
Chapter 5. System Settings..................................................................................5-1
5.1 System Settings .......................................................................................... 5-1
5.2 System Reset .............................................................................................. 5-4
Chapter 6. File Handling .......................................................................................6-1
6.1 File Handling ............................................................................................... 6-1
6.2 File Name and File Attribute........................................................................ 6-4
6.3 Entering a File Name................................................................................... 6-5
Chapter 7. Common Functions of All Modes .....................................................7-1
7.1 Wiring .......................................................................................................... 7-1
7.2 Checking Wiring .......................................................................................... 7-3
7.3 Ranges and Number of Digits ..................................................................... 7-6
7.4 Sampling Frequencies and Integration Periods......................................... 7-14
7.5 Frequency Measurement and Low-pass Filters ........................................ 7-16
7.6 Averaging Function.................................................................................... 7-18
7.7 Scaling Function (VT/CT) .......................................................................... 7-19
Chapter 8. Instant Measure Mode........................................................................8-1
8.1 Detailed View of Data Items on Instant Measure Mode Screen .................. 8-1
8.2 Working with the Function Keys .................................................................. 8-4
8.3 Expanded View of Data Items on Instant Measure Mode Screen ............... 8-5

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IM CW140-E
Contents
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
App
Index
8.4 Logging in Instant Measure Mode ............................................................... 8-7
8.5 Setup Data Items of Instant Measure Mode.............................................. 8-10
8.6 Computational Expressions....................................................................... 8-15
Chapter 9. Electric Energy Measure Mode .........................................................9-1
9.1 Data Items on Electric Energy Measure Mode Screen ............................... 9-1
9.2 Working with the Function Keys .................................................................. 9-3
9.3 Integration in Electric Energy Measure Mode ............................................. 9-4
9.4 Setup Data Items of Electric Energy Measure Mode .................................. 9-7
Chapter 10. Key .............................................................................................10-1
10.1 Simple Electric Energy Measurement with Key .................................. 10-1
Chapter 11 Demand Measure Mode .................................................................11-1
11.1 About Demand .......................................................................................... 11-1
11.2 Data Items Shown on Demand Measure Mode Screen ............................ 11-2
11.3 Working with the Function Keys ................................................................ 11-4
11.4 Demand Measurement in Demand Measure Mode .................................. 11-5
11.5 Setup Data Items of Demand Measure Mode ........................................... 11-8
Chapter 12. Harmonics Measure Mode .............................................................12-1
12.1 ShowingTables in Harmonics Measure Mode .......................................... 12-1
12.2 Showing Graphs in Harmonics Measure Mode......................................... 12-3
12.3 Working with the Function Keys ................................................................ 12-5
12.4 Logging in Harmonics Measure Mode ...................................................... 12-6
12.5 Setup Data Items of Harmonics Measure Mode ....................................... 12-9
12.6 Computational Expressions..................................................................... 12-15
Chapter 13. File Functions .................................................................................13-1
13.1 Saving, Loading and Printing with File Functions...................................... 13-1
Chapter 14. External I/O Functions ...................................................................14-1
14.1 Optional D/A Output .................................................................................. 14-1
14.2 External Control Input ............................................................................... 14-8
14.3 Event Input ................................................................................................ 14-9
Chapter 15. RS-232C Communication Function ..............................................15-1
15.1 RS-232C Interface Specifications ............................................................. 15-1
15.2 Connecting CW140 through RS-232C Interface ....................................... 15-2
15.3 Handshake Methods ................................................................................. 15-4
15.4 Matching the Data Format......................................................................... 15-7
Chapter 16. In the Event of a Power Failure .....................................................16-1
16.1 In the Event of a Power Failure ................................................................. 16-1
Chapter 17. Auxiliary Functions ........................................................................17-1
17.1 Auxiliary Functions .................................................................................... 17-1
17.2 Floppy Disk Drive (Optional)...................................................................... 17-7
17.3 Printer (Optional) ....................................................................................... 17-8
Chapter 18. Troubleshooting .............................................................................18-1
18.1 Corrective Action in Case of Failure .......................................................... 18-1
18.2 Messages and Corrective Measures ......................................................... 18-2

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8
Contents
Chapter 19. Specifications .................................................................................19-1
19.1 Specifications ............................................................................................ 19-1
19.2 Specifications of Current Clamps ............................................................ 19-15
Appendix.........................................................................................................App1-1
Appendix 1 Block Diagram of CW140 Main Unit.............................................App1-1
Appendix 2. Communication Commands..........................................................App2-1
Appendix 3. Explanation of Data Item to be Saved/Printed .............................App3-1
Appendix 4. Terminology..................................................................................App4-1
Appendix 5. Explanation of Reactive Power Method........................................App5-1
Appendix 6. Settings Check Sheet...................................................................App6-1
Index............................................................................................................... Index-1

1-1
IM CW140-E
Product Overview
1
Chapter 1. Product Overview
1.1 Product Overview
The CW140 clamp-on power meter is basically designed for measuring root-
mean-square voltage and current rms values and thereby electric energy. With its
computing capabilities, the CW140 can measure and analyze a wide variety of
parameters related to electric power.
This section explains the features of the CW140 and shows a schematic diagram
representing the functions of the CW140. It also explains the screen views (i.e.,
measuring objects) presented by each measurement mode of the CW140.
Features ●Supports a variety of measurement modes and continuous
measurement.
The CW140 has four measurement modes which support continuous
measurement.
• Instant Measure mode (logging)
• Electric Energy Measure mode (integration)
• Demand Measure mode (demand measurement)
• Harmonics Measure mode (logging)
●Efficient Measurement using the Wh Key
This feature simplifies operations required for the Electric Energy Measure mode
most often used.
●Supports a variety of wiring methods.
• Supports single-phase two-wire systems, single-phase three-wire systems,
three-phase three-wire two-current systems, three-phase three-wire three-
current systems, and three-phase four-wire systems.
• Supports dual-load systems in a single-phase two-wire, single-phase three-
wire, or three-phase three-wire configuration (except when in the Harmonics
Measure mode).
●Data Management
• Measured values or measurement settings can be stored in internal memory
or on a 3.5-inch floppy disk inserted in an optional floppy drive attached
externally to the CW140.
• Allows simultaneous data saving to internal memory and a floppy disk, or
copying internal memory data to a floppy disk.
• An optional printer connected externally to the CW140 allows you to print
measured values or measurement settings.
●Communication
With an RS-232-C interface, it is possible to transfer data to or receive
measurement settings from a personal computer. The CW140 stores
measurement data in CSV format, facilitating data processing (such as creating
graphs) using commercial spreadsheet software.
●Setting Operations
• Easy-to-operate Display Screen
You can easily change settings by selecting items highlighted on the screen using
Range keys, Cursor key, and function keys.
●Settings Check Sheet
The settings check sheet in Appendix 6 lists required setting items for each
measurement mode. Use this sheet for reference and to improve efficiency when
making settings in the field.

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1-2
1.1 Product Overview
Schematic Function Diagram
key key
TOP MENU
screen (Chapter 5) (Chapter 6)
(Chapter 10)
(Chapter 8) (Chapter 9) (Chapter 11) (Chapter 12)
(Chapter 15)
System Setting
mode Screens
1/2 and 2/2
File Handling
mode
Instant Measure
mode
Logging
Electric Energy
Measure mode
Integration
Demand Measure
mode
Demand
Harmonics
Measure mode
(Graph display)
Logging
Condition setting Condition setting Condition setting Condition setting
Electric Energy
Measure mode
Last condition
Setting condition 1
Setting condition 2
Setting condition 3
Setting condition 4
D/A
output
(Optional)
Internal
memory
Storage of data and setup conditions
Reading of setup conditions
RS-232C interface
for personal computer or printer
Floppy disk drive unit
(connected externally)
(Section 17.2)
Event input function
(Section 14.3)
External trigger function
(Section 14.2)
Averaging function (Section 7.6)
Scaling function (Section 7.7)
Low-pass filter function (Section 7.5)
Frequency measurement
Wiring check function (Section 7.2)
Power failure handling function (Chapter 16)
Auxiliary functions (Chapter 17)
Clock
Language selection (Japanese, English)
Hold of on-screen readings
NiMH battery recharging
LCD contrast
LCD backlight
Beep (confirmation of key operation)
Key locking
Power-saving mode
System reset
Low battery indicator
Testing backup batteries
Saving set conditions
(Section 17.3)

1-3
IM CW140-E
Product Overview
1
1.1 Product Overview
On-screen Information (Data Items) Provided by Each Measurement Mode
In each measurement mode, you can measure and calculate on-screen data
items, as shown below.
Rms voltage value (V)
Rms current value (A)
Active power (W)
Reactive power 1 and 2 (Var)
1:With reactive power meter method
2:Without reactive power meter method
Apparent power (VA)
Power factor
Phase angle (°)
Frequency (Hz)
Three-phase unbalance factor (%) (for three-phase wiring only)
Instant Measure mode
(Chapter 8)
Active power (Wh)
Regenerative power (Wh)
Lagging reactive power (Varh)
Leading reactive power (Varh)
Electric Energy Measure mode
(Chapter 9)
Demand Measure mode
(Chapter 11)
Indication at the End of Demand
• Maximum demand and its time
• Average of respective demands
• Electric energy integrated from the
start to the end of demand
• Average power factor
• Average load factor
Indication During Demand Interval
• Maximum demand and its time
• Demand of one demand period earlier
• Electric energy integrated since the
start of demand
• Electric energy integrated during the
present demand period
• Power factor
• Load factor
• Remaining time of demand interval
Table displays • Voltage/current Rms value, harmonic content, phase angle
Total rms value (All-RMS)
Total harmonic distortion
IEEE (relative to fundamental wave);
CSA (relative to total rms value)
Fundamental wave frequency
• Power
Power value, power content, power phase angle
Total power value
Total power factor
Fundamental wave frequency
Graph displays • Voltage/current Rms value, harmonic content, phase angle
• Power
Power value, power content, power phase angle
Harmonics Measure mode
(Chapter 12) Analysis of 1st- through 13th-order harmonics
(The CW140 does not support the Harmonics Measure mode when wired to
2-system load.)
NOTE
The CW140 can show a screen of instantaneous values whether it is in the Electric Energy Mea-
sure mode or the Demand Measure mode.

2-1
IM CW140-E
Product Overview
2
Chapter 2. Components, Their Use and Overrange, and Error Indications
2.1 Front Panel and Connector Block
v1
N
v 2
L1
2
3
4
N
LN
LN
N
L
v 3
L1NLNLN L2NL3NL4N
FFF
23
F
ENTER
4
F
51
INPUT / OUTPUT
START
&STOP
Wh
AW TOP MENU
CLAMP ON POWER METER
184 (7.24)
65 (2.56) 206 (8.11)
<Connector Block>
<FrontView>
<SideView>
AC adapter
jack
Power
switch
ESC
V
LOCK
KEY
LIGHT
Unit: mm
(
a
pp
rox. inches
)
Battery charge
LED indicator
(for optional
NiMH battery)

IM CW140-E
2-2
2.2 Operation and Functions Keys
Status LED
indicator* for
continuous
measurement
Name
Key Symbol Description
Display
Set data appropriate for information
shown in their respective
corresponding fields along the
bottom edge of the display.
Turns on/off the backlight.
Holding this key down for more than 3 seconds places the CW140 in a key
lock state. To cancel the state, hold this key down again for more than 3
seconds.
Function keys
START&STOP
key
Backlight key
Allows you to measure electric energy easily without selecting the Electric
Energy Measure mode from the TOP MENU screen.
Watt-hour key
Cancels such data as setup conditions.
Escape key
Confirms such data as setup conditions.
Enter key
Moves the cursor through on-screen data items so an item can be selected.
Cursor key
Shows/resets the voltage range.
(You can change the setpoint with a function key.)
V Range key
Shows/resets the current range.
(You can change the setpoint with a function key.)
A Range key
Shows/resets the setting of a wiring method.
(You can change the setting with a function key.) Also see "Checking Wiring."
Wiring key
Changes the display to the TOP MENU screen for selecting each
measurement mode.
TOP MENU key
Starts/stops logging when the CW140 is in the Instant Measure or Harmonics Measure
mode.
Starts/stops integration when the CW140 is in the Electric Energy Measure mode.
Starts/stops demand when the CW140 is in the Demand Measure mode.
ESC
ESC
LIGHT
LIGHT
*Status LED indicator: Remains lit when the CW140 is performing continuous measurement (whether the
meter is in a stand-by state or taking measurements) in each measurement mode.
to

2-3
IM CW140-E
Product Overview
2
2.3 Connecting Input Signals to Be
Measured and External Input Terminals
● Terminal Assignments
v1
N
v 2
L1
2
3
4
N
LN
LN
N
L
v 3
L1NLNLN L2NL3NL4N
Voltage input terminals
Connector for connection with
an external floppy disk drive unit
Current (clamp) input terminals
RS-232C connector for
printer/personal computer
Event input terminals D/A output terminals
(optional)
External control (trigger)
input terminals
FDD
RS-232C
LOGIC INPUT START/STOP D/A OUTPUT
CH
CH
CH
CH
Event input terminals: Receive ON/OFF signals from equipment
under test.
External control input terminals: Receive START/STOP signals informing
of the start and end of logging,
integration or demand measurement.
D/A output terminals: Terminals for D/A output
(not available if the CW140 is not
equipped with a D/A output option).

IM CW140-E
2-4
2.3 Connecting Input Signal Lines to Be Measured and External Input Terminals
●Connection of Input Signal Lines to Be Measured and External Input
Terminals (Example)
v
1
N
v
2
v
3
LL1
CH
H
LHL H
V INPUT
V INPUT
600V~MAX
600V~MAX
TERMINALS 600V ~ MAX
TERMINALS 600V ~ MAX
TOEAR
O EAR
TH
TH
L
2
H
L
CH
CH
1H
L
CH
CH
CA
CA
T.
FDD
FDD
RS-232C
RS-232C
LOGIC NIPUT
LOGIC NIPUT
ST
ST
AR
AR
T/ST
T/ST
OP
OP
5.5V MAX
5.5V MAX
Voltage probe (black)
Voltage probe (red/yellow/blue)
Current clamp
Ring marker
WARNING
• Thoroughly read Section 3.3, "Precautions for Wiring the Circuit UnderTest."
• When wiring the CW140, turn off the circuit under test.
It is extremely dangerous to connect or disconnect measuring lead wires without turning off
the circuit under test.
• 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 an injury to personnel.
• The CW140 can be connect to a maximum of four voltage input probes or four current-sensing
clamps. Do not connect any probe or clamp that is not necessary for measurement.
• Do not use any other probes or current-sensing clamps than those supplied with the CW140.
• Before connecting a current-sensing clamp to the CW140, make sure the H and L polarities are
correctly identified.
●Differentiating among Voltage Input Probes and among Current-
sensing Clamps
• Voltage Input Probes
Probe for Input terminal N: Black (one)
Probes for Input terminals V1 to V3: Three different colors: Red, Yellow and Blue.
• Current-sensing Clamps
Clamps for Input terminals CH1 to CH4: Differentiated by ring markers of four different
colors

2-5
IM CW140-E
Product Overview
2
2.3 Connecting Input Signal Lines to Be Measured and External Input Terminals
●Use of Ring Markers (Standard Accessories)
Attach ring markers of the same color to both the terminal connection side
and alligator clip side of a voltage input probe or to both the terminal
connection side and clamping side of a current-sensing clamp. This enables
you to differentiate between the input signal lines.
CAUTION
Be careful not to damage a probe when attaching ring markers.
●Connection of External I/O Terminals
Signal wire
Tool such as a flat-tip screwdriver
●Connection Procedure
Insert the signal wire into the hole while pressing the rectangular area at the
bottom of the external I/O terminal using such a tool as a flat-tip screwdriver.
Removing the screwdriver from the terminal fixes the signal wire in place.
CAUTION
• Do not apply voltages outside the allowable input voltage range (-0.5 to 5.5 V), otherwise the
input circuit may be damaged.
• When wiring the CW140, be careful not to mistake an input terminal for an output terminal.
●Applicable Signal Wires
Standard wire: φ1.0 single-core wire (AWG18) or 0.75 mm2stranded wire
Adaptable wire: φ0.4 to 1.0 single-core wire (AWG26 to 18) or 0.35 to 0.75
mm2stranded wire (AWG22 to 20) with a minimum strand
diameter of 0.18 mm; typical length of stripping = 10 mm
●Applied Terminals
LOGIC INPUT: Event input terminals (receive ON/OFF signals from
equipment under test)
START/STOP: Terminals for inputting signals informing the start and end of
logging, integration or demand measurement.
D/A OUTPUT: Terminals for D/A conversion output (optional)

IM CW140-E
2-6
2.4 Overrange and Other Marks Shown
during Measurement
●Overrange Indications during Measurement
:Conditions for current overrange indication
This mark appears if the sampled value exceeds 300% of the rated
current range or if the rms value of the measured current exceeds
110% of the rated range. If a fixed range is used, step up the range.
:Conditions for voltage overrange indication
This mark appears if the sampled value exceeds 300% of the rated
voltage range or if the rms value of the measured voltage exceeds
110% of the rated range. If a fixed range is used, step up the range.
TIP
• The current overrange mark appears if an input signal to one of the terminals CH1 to CH4
satisfies the conditions noted above.
•The voltage overrange mark appears if an input signal to one of the terminalsV1 toV3 satisfies
the conditions noted above.
Indication of Overrange Marks When Auto-ranging Is Used
The CW140 steps up or down the range, as discussed in Section 7.3,
"Ranges and Number of Digits." Then, the CW140 shows the or
mark if the conditions noted above become true under the maximum range.
Indication of OR Symbol
The CW140 shows the OR symbol, instead of a usual four-digit value, if the
result of measurement (calculation) satisfies the conditions noted above.
(If a fixed range is used, step up the range.)
Indication of OR Symbol When Auto-ranging Is Used
The CW140 steps up or down the range, as discussed in Section 7.3,
"Ranges and Number of Digits." Then, the CW140 shows the OR
symbol if the conditions noted above become true under the maximum
range.
WARNING
The CW140 shows an overrange mark under the maximum range only if the input level exceeds
the maximum allowable input level. Do not apply any input level higher than the maximum allow-
able input level.