YOKOGAWA CW10 User manual

User’s
Manual
保証書付
CW10
クランプ電力チェッカ
Clamp-on Power Meter
IM CW10-JA: Japanese
IM CW10-EN: English
5th Edition: April 2015 (YMI)
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大切に保管してください。
Store this manual in an easily accessible place
for quick reference.

1
Regarding the Safe Use of This Product
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 way other than as instructed in
this manual, the instrument’s protective measures may be impaired.
YOKOGAWA 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 on the instrument and in
this manual.
Danger! Handle with Care.
This symbol indicates that the operator must refer to an
explanation in the User’s Manual in order to avoid risk of
injury or death of personnel or damage to the instrument.
Hazardous Voltage
This operator must never attempt to touch equipment or
parts marked with this symbol.
This symbol indicates double insulation or reinforced
insulation.
This symbol indicates direct current (DC).
This symbol indicates aiternating current (AC).
This symbol indicates ground (earth).
This symbol indicates a battery.
This symbol indicates that this instrument designed to be
applied around or removed from HAZARDOUS LIVE
conductors provided if the RATED circuit-to-earth voltage
dose not exceed the value indicated in the measurement
category.
This symbol indicates, If the measured voltage is
greater than 30 V DC or AC RMS or Overload
(OL or –OL).
Indicates a hazard that may result in the loss of life
or serious injury of the user unless the described
instruction is abided by.
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.

2
Always observe the following instructions. Failure to do so may result
in electrical shock or other dangers that may lead to serious
injury or the loss of life.
• The instrument is a power measurement instrument that can measure
parameters such as voltage, current, and power.
Do not use this instrument for any other purpose.
• Do not use the instrument if there is a problem with its physical
appearance.
• Do not use the instrument in an atmosphere where any ammable or
explosive gas is present.
• To avoid a short-circuit or an accident to personnel, use this instrument
within the RATED circuit-to-earth voltage, maximum input voltage and
current.
• Avoid using the instrument if it has been exposed to rain or moisture or
if your hands are wet.
• Barrier is for to avoid touching the HAZARDOUS LIVE conductor.
Be careful not to across the Barrier when using the instrument.
• Do not use the instrument if there is any damage to the casing or
when the casing is removed.
• Use the test leads supplied by Yokogawa with this instrument.
• Do not use test leads that have deteriorated or are defective.
• Check the test leads continuity.
• When you attach or remove the test leads or remove the case
(for example to charge the battery), be sure to remove the test leads
from the circuit under measurement.
• When you remove the case (for example to change the battery),
be sure to remove the test leads from the instrument.
• Safety protectors such as rubber-insulated gloves should be worn to
prevent electrical shock when using the instrument.
• There are caps at the ends of the test leads. To ensure safety
(safety standard EN 61010-031), be sure to put the caps on the leads
when you use them.
• No person, except personnel from Yokogawa, is authorized to
disassemble this instrument.
Do not attempt to repair/modify the instrument yourself,
as doing so is extremely dangerous.
• The product is for domestic use (Class B) and meets the electromagnetic
compatibility requirements.
• Do not use the instrument near noise-emitting equipment or where
there may be sudden changes in temperature. Otherwise,
the instrument may produce an unstable readings or errors.
• Do not wipe the instrument using an organic solvent.
When cleaning the instrument, use a dry cloth.
• Do not leave the tester exposed to direct sunlight or in a hot and humid
location such as the inside of a car, for any prolonged length of time.
• If the instrument will not be used for long periods, remove the battery.

3
Contents
Regarding the Safe Use of This Product.......................1
1. Checking the Contents of the Package ....................4
2. Measurement Category ................................4
3. Components.........................................5
4. Display (LCD)........................................6
5. Power ON/OFF and Auto power off .......................6
6. Cursor/ENTER key....................................6
7. Making Basic Measurements ............................7
7.1 Measuring Voltage ...............................7
7.2 Measuring Current ...............................7
8. Others Function ......................................8
8.1 AUTO SENSE...................................8
8.2 RANGE ........................................8
8.3 Peak Hold (AC mode only) .........................9
8.4 Inrush current (AC mode only) .....................11
8.5 DCA ZERO ....................................12
8.6 Measuring Frequency Hz (AC mode only) ............12
8.7 MAX/MIN......................................13
8.8 Harmonic Measurement (AC mode only) .............13
8.8.1 THD Measurement..........................13
8.8.2 Individual Harmonic Mesurement ..............14
8.9 Low pass filter (AC mode only).....................14
8.10 Measuring Active Power ..........................15
8.10.1 Single phase 2 wire .........................15
8.10.2 3 phase 3 wire (balanced/unbalanced) ..........16
8.10.3 3 phase 4 wire (balanced/unbalanced) ..........16
8.10.4 Phase Rotation.............................17
8.11 Mesuring Resistance.............................19
8.11.1 Resistance (Ω) .............................19
8.11.2 Continuity Check ...........................20
8.11.3 Diode Test.................................20
8.12 HOLD ........................................20
8.13 Voltage Sanse..................................20
8.14 Buzzer........................................21
8.15 Additional Power-on Function......................21
9. Battery State display and Battery Replacement .............21
9.1 Battery State display .............................21
9.2 Bayttery Replacement............................21
10. Specifications .......................................22
10.1 General Specifications ...........................22
10.2 Accuracy ......................................23
11. Maintenance and After-Sales Service ....................26
12. Sales in Each Country or Region ........................26
12.1 Disposing the Product............................26
12.2 How to Replace and Dispose the Batteries............26
12.3 Authorized Representative in the EEA ...............26
12.4 For the Pollution Control of Electronic and
Electrical Products of the People's Republic of China ...27
Disk No. CW10
5th Edition: April 2015
All Rights Reserved, Copyright ©2011,
Yokogawa Meters & Instruments Corporation
Printed in Taiwan

4
1. Checking the Contents of the Package
After opening the package, be sure to check the product as
instructed below before use.
1. Main Unit: CW10 (including battery)
2. Test leads: 1set (Black and Red)
3. User’s Manual
4. Soft Case
2. Measurement Category
When you use the test leads, attach or remove the caps
according to the measurement category.
CW10 main unit:
1000V
CAT III, 600V CAT IV
Test leads:
With Caps: 1000V 10A CAT III, 600V 10A CAT IV
Without Caps: 1000V 10A CAT II
Measurement
Category Description Remarks
O
None
Other
Other circuits that are not
directly connect to MAINS.
Circuits not
connected to a
mains power source.
CAT II For measurement performed on circuits directly connected
to the low-voltage installation.
Appliances,
portable equipment,
etc.
CAT III For measurement performed
in the building installation. Distribution board, circuit breaker, etc.
CAT IV For measurement performed at the source of the low-voltage
installation.
Overhead wire,
cable systems, etc.

5
3. Components
10.Terminals of test leads
5.Hold and Zero key
6.Function switch
9.Cursor/
Enter key
8.LCD display
1.Jaw section
4.Barrier
7.Open/
close lever
3.Voltage sense
LED
2.Light
CW10
Red
Black
Test leads
Caps of Test leads
Main Unit: CW10
1. Is a precision sensor for detecting currents.
2. When the jaws are open, the light will illuminate.
3. In case voltage is detected by the jaw, the red LED lights up.
4. Prevents contact with the wires.
5. Retains the measured data or DCA ZERO: Zero adjustment
6. Use this switch to turn the power on and off and to select
the measurement mode.
7. Opens and closes the jaws.
8. LCD display
9. Cursor and Enter key
10. Input terminals for test leads
[NOTE]
There is the mark on the terminal, but this device does not
have a function for measuring capacitance.

6
4. Display (LCD)
5. Power ON/OFF and Auto power off
Check that the meter operates normally.
Turn the function switch to the measurement (any) position from OFF.
To end measurement, turn the function switch off.
<Auto power off>
Indication: APO
This instrument automatically turns off about 15 minutes after
the last switch operation.
Recovering the Auto power off function:
Turn off the power. Turn on the power.
When the function is not use (cancellation):
Turn off the power. Hold down Downward of cursor key,
turn the function switch to any position.
(The APO display goes off.)
If the instrument is used with the Auto power off function
cancelled, take care not to let the battery run down.
6. Cursor/ENTER key
ENTER
LEFT
UP
DOWN
RIGHT
UP
Cursor key: Moves the Cursor (four directions) to the item (mode)
of display you wish select. Press the convex key
toward selecting mode.
ENTER key: Confirms the item (mode).
[NOTE]
Push whole key toward requisite item.
Push down the center position of key to confirm (ENTER key).

7
7. Making Basic Measurements
7.1 Measuring Voltage
Do not apply more than 1000 VDC or 1000 Vrms (1414.2 Vpk).
Plug the test leads to the input terminals.
[NOTE]
When connecting the test leads to the circuit under measurement,
connect the black (common) before connecting the red (live);
when removing the test leads, remove the red (live) before
removing the black (common).
Turn the function switch to the Voltage position.
Read the voltage value of display.
On Auto Sense mode, the CW10 automatically detects AC or DC.
DC AC
Black Red
Test leads
7.2 Measuring Current
• Do not apply more than 600 ADC or 600 Arms (848.5 Apk).
• When you measure the current, be sure to remove the test leads
from the instrument.
Squeeze the open/close lever to open the jaws. Insert a wire from the
measurable conductors under the test though the jaws, making sure
the tops of the jaws are tightly shut.
Turn the function switch to the Current position.
Read the current value of display.
Using Auto Sense mode, the CW10 automatically detects AC or DC.
[NOTE]
• When performing a measurement, hold the instrument so that
the measured conductor cable runs at the center of the clamp.
• Ensure that the orientation of the clamp to the direction of
the conductor wire is correct as shown right.

8
AC
DC
8. Others Function
8.1 AUTO SENSE
Using Auto Sense mode, the CW10 automatically detects AC or DC.
(The detection is determined by whichever input is greater.)
To select manual mode (Example: DC mode);
Use the cursor key to select under “DC” (flash) and then press the
ENTER key to confirm.
Upper “DC” indication is fixed and AUTO (AUTO RANGE) is displayed.
To return AUTO SENSE, press the ENTER key
for more than 2 seconds.
8.2 RANGE
To select manual range (fixed);
Use the cursor key to select “RANGE” and then press the ENTER key
to confirm.
(To cancel manual range, press the ENTER key
for more than 2 seconds.)
Example: ACV 100 V range ← → 1000 V range
ENTER
On Auto sense mode, the measuring range is automatic.

9
8.3 Peak Hold (AC mode only)
(1) AC Voltage
Turn the function switch to the voltage (V) position.
After using the ENTER key to confirm AC mode, use the cursor key to
select Peak Hold and then press the ENTER key to confirm.
Press the ENTER key to switch between PEAK MAX (polarity+) and
PEAK MIN (polarity-).
(To cancel Peak Hold, press the ENTER key
for more than 2 seconds.)
>2SEC
"ENTER"
[NOTE]
Bar-graph indication is not PEAK value.
Bar-graph indication is affected by the ACV value.
(Example: 500.0 V)

10
(2) AC Current
Turn the function switch to the current (A) position.
After using the ENTER key to confirm AC mode,
use the cursor key to select Peak Hold.
Press the ENTER key for more than 2 seconds
to select PEAK MAX.
Press the ENTER key to switch between PEAK MAX (polarity+) and
PEAK MIN (polarity-).
(To cancel Peak Hold, press the ENTER key
for more than 2 seconds.)
[NOTE]
Bar-graph indication is not PEAK value.
Bar-graph indication is affected by the ACA value.
(Example: 500.0 A)
>2SEC
>2SEC
"ENTER"

11
8.4 Inrush current (AC mode only)
The CW10 has a function for measuring Inrush current.
Turn the function switch to the current position.
Using the ENTER key to confirm AC mode.
Using the cursor key to select Peak Hold (Inrush current) and
then press the ENTER key to confirm. (INRUSH)
Waiting state, after trigger, the Inrush current value (RMS)
for 100m seconds (measurement period) is displayed.
Press the ENTER key once to return ACA mode.
Press the ENTER key once again to return waiting state (restart).
[NOTE]
If the Inrush current is expected to exceed 100 ACA,
select 600 A range in advance of measuring.
30.0A 10.0A
100msec
Motor
Off Motor On
Trigger
Point Time
After Trigger
Waiting Trigger
A
0.0A
ENTER
<1>
<2>
<1> <2>

12
8.5 DCA ZERO
We recommend that you perform zero adjust (DCAZERO) before
measuring DCA mode.
[NOTE]
Remove the jaws out of the conductor.
Press the HOLD key of right side for more than 2 seconds.
After ”----“ is displayed, ZERO adjustment is confirmed.
DCA Zero is only available in AUTO SENSE, DC and AC+DC mode.
HOLD> 2 Sec
HOLD
8.6 Measuring Frequency Hz (AC mode only)
<1> Turn the function switch to the voltage or
current position.
<2> Using the ENTER key to confirm AC mode.
<3> Using the cursor key to select “Hz” and then
press the ENTER key to confirm.
(The unit of Hz and the frequency value are displayed.)
Using ENTER key to change unit (to cancel).
ENTER
"Hz"
< RANGE >
On measuring frequency, Using the cursor key to select “RANGE” and
then press the ENTER key to confirm. The frequency range is fixed.
Each time “RANGE” (ENTER) key is pressed, range is changed.
On measuring frequency, ACV or ACA range is fixed.

13
8.7 MAX/MIN
The minimum and maximum value during measurement are updated
(displayed).
Using the cursor key to select “MAX/MIN” and then
press the ENTER key to MAX/MIN mode.
(To cancel the function, press the ENTER key
for more than 2 seconds.)
[NOTE]
HOLD key is pressed in MAX/MIN mode, the MAX and MIN
values are not updated. (“HOLD” is appeared)
To cancel the function, press the HOLD key again.
8.8 Harmonic Measurement (AC mode only)
8.8.1 THD Measurement
Harmonic measurements (fundamental wave to 25th harmonics) can
be displayed. In ACV or ACA mode (after confirming AC using the
ENTER key), use the cursor key to select “THD,” and then press the
ENTER key to confirm.
Press the ENTER key to toggle between the rms value and the
distortion factor.
THD-F=
∑
n=2
25 (nth order harmonic voltage(current) rms value) 2
(fundamental wave voltage(current) rms value)
2
×100%
"THD"
"ENTER"

14
8.8.2 Individual Harmonic Mesurement
Harmonic measurements individual order (fundamental wave to 25th)
can be displayed. In ACV or ACA mode (after confirming AC using the
ENTER key), use the cursor key to select , and then
press the ENTER key to confirm.
(To cancel the function, press the ENTER key
for more than 2 seconds.)
H
n=
nth order harmonic voltage (current) rms value
fundamental wave voltage (current) rms value
×100
%
"RIGHTWARD"
"LEFTWARD"
"DOWNWARD"
"UPWARD"
"LEFTWARD"
"RIGHTWARD"
"DOWNWARD"
"UPWARD"
ENTER
>2SEC
8.9 Low pass filter (AC mode only)
The CW10 has a function for turning the filter on (use) /off.
On ACV or ACA mode (using ENTER key to confirm AC),
Using the cursor key to select “LPF” and then
press the ENTER key to confirm.
"LPF"
ENTER
[NOTE]
Cut of frequency: approximately 1 kHz

15
8.10 Measuring Active Power
• Do not apply more than 1000 VDC or 1000 Vrms (1414.2 Vpk).
• Do not apply more than 600 ADC or 600 Arms (848.5 Apk).
8.10.1 Single phase 2 wire
<1> Turn the function switch to the Active power position.
<2> Connect the red test lead to Line (+) and the black test lead to N (-).
<3> Squeeze the open/close lever to open the jaws and clamp them
onto the wire under test. (Ensure that the jaws are properly closed
and the conductor runs thru the center of the clamp.)
<4> When measuring Active power:
Use the cursor key to select “W” and then
press the ENTER key to confirm.
When measuring Power factor:
Use the cursor key to select “PF” and then
press the ENTER key to confirm.
ENTER
"PF" "W"
600V
+Line
-N
600A
No.1
W1
Power source
Load
[NOTE]
• The “ + ” symbol on the jaw must face on the power source side.
• In Auto sense mode, The CW10 can detect ACW or DCW automatically.
Overload (over range) Description
OL.U: Voltage overload
OL.A: Current overload
OL.UA: Both Voltage and current overload.
OL kW, -OL kW: Active Power > 1000 kW or < -1000 kW.
Active power polarity
Non-display (+):
Indicates the power flows from the power source to the load.
Minus (-):
Indicates the power flows from the load to the power source.
Power factor polarity
Non-display (+): The phase of the current signal is lagging behind
the voltage signal (inductive load).
Minus (-): The phase of the current signal is leading the
voltage signal (capacitive load).

16
8.10.2 3 phase 3 wire (balanced/unbalanced)
To use two the CW10
<1> Turn the function switch to the Active power position.
<2> Connect following connecting diagram.
<3> Use the cursor key to select "W" and then
press the ENTER key to confirm.
Active power (W) = W1+W2: sum total
Black
Red
Black
Re
d
W=W1+W2
3P3W
Y(star-connection),
Delta-connection
3
2
1
No.1
W1
No.2
W2
8.10.3 3 phase 4 wire (balanced/unbalanced)
To use three the CW10
<1> Turn the function switch to the Active power position.
<2> Connect following connecting diagram.
<3> Use the cursor key to select "W" and then
press the ENTER key to confirm.
Active power (W) = W1+W2+W3: sum total

17
Re
d
Red
No.1
W1
No.2
W2
No.3
W3
1
N
2
Black
Black
Black
Red
W=W1+W2+W3
3P4W
3
8.10.4 Phase Rotation
The CW10 can measure (test) phase rotation.
(Only if the system frequency is stable.)
<1> Turn the function switch to the Active power position.
<2> Use the cursor key to select “RST” and then
press the ENTER key to confirm.
<3> Connect the red test lead to the phase Line1and the black test
lead to the phase Line3.
If connecting is normal, “L1” is displayed
(flash for about 3 seconds.)
Indication
(flash) Condition
OLU Voltage > 1000 V
LoU Voltage < 30 V
outF Frequency < 45 Hz, 65 Hz < Frequency

18
Black
Red
Black Red
No.1
No.1
Line 1
Line 2
Line 3
<4> “L2” is displayed and then buzzer beeps twice.
Switch over the red test lead to connect to the phase Line2
immediately before “L2” disappears.
<5> After “L2” disappears, the following testing result is displayed.
Indication
(testing result) Explanation
123 Forward sequence;
The phase Line1 is ahead of Line2.
321 Reversed sequence;
The phase Line2 is ahead of Line1.
---- It is not possible to judge.
LoU It is possible that you remove the test
leads before completing the whole
testing procedures.
<6> To repeat the test, use the cursor key to select “RST” again
and then press the ENTER key to confirm.

19
8.11 Mesuring Resistance
To avoid damage to instrument
Turn off the power to the circuit under test before starting
measurement in order to prevent any excessive voltage from
being applied to the instrument.
On measuring resistance , useAUTO SENSE mode to measure
three items automatically: Resistance, Continuity check and Diode test
[NOTE]
Maximum open circuit voltage;
Resistance (continuity check): approximately +3 V
Diode test: approximately -1.8 V, +1.8 V
Manual setting (When you do not use the AUTO SENSE)
8.11.1 Resistance (Ω)
<1> Turn the function switch to the Resistance position.
<2> Plug the test leads to terminals.
<3> Use the cursor key to select Resistance Ω and then
press the ENTER key to confirm.
<4> Read the measured value.
(To return AUTO SENSE, press the cursor key for more
than 2 seconds)
[NOTE]
To measure manual range (the range is fixed), use the cursor key to
select RANGE and then press the ENTER key to confirm.
Function switch position
Resistance Continuity
Test leads
Red Black
Test leads
Red +
Black -
Buzzer(Beep)
Diode Test
Test leads
Red Black
Test leads
Red Black
Forward-bias
Reverse-bias