Hioki CM4371 User manual

EN
AC/DC CLAMP METER
Instruction Manual
June 2016 Revised edition 2
CM4371A961-02 16-06H
CM4371
CM4372
CM4373
CM4374
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i
CM4371A961-02
Contents
Introduction................................................................................................................1
Options (sold separately)..........................................................................................3
Safety Notes ...............................................................................................................4
Usage Notes ...............................................................................................................8
Part Names ...............................................................................................................11
Insert/Replace Batteries..........................................................................................12
Inspection Before Measurement.............................................................................14
Current Measurement..............................................................................................15
Manual Hold / Auto Hold..........................................................................................16
Switching ranges .....................................................................................................19
Filter Function..........................................................................................................20
MAX/MIN/AVG/PEAK................................................................................................21
Simultaneous display of DC current/voltage peak values...................................22
Backlight / Auto Power Save (APS)........................................................................23
Rush current (INRUSH)............................................................................................24

ii
Contents
Other Measurement Functions...............................................................................25
Voltage.............................................................................................................25
Continuity Check ............................................................................................26
Resistance.......................................................................................................26
Diode................................................................................................................26
Capacitance.....................................................................................................27
Temperature ....................................................................................................27
Electric Charge Detection..............................................................................28
Simultaneous display of DC current and DC voltage..................................28
DC power.........................................................................................................28
Bluetooth®Communications (only for CM4372, CM4374)....................................29
Power-on Option Table............................................................................................34
Repairs, Inspections, and Cleaning .......................................................................36
Specifications...........................................................................................................39
Accuracy Table.........................................................................................................45

1
Introduction
Introduction
Thank you for purchasing the Hioki CM4371, CM4372, CM4373, CM4374 AC/DC
Clamp Meter. To obtain maximum performance from the instrument, please read this
manual rst, and keep it handy for future reference.
This instrument is a clamp meter that can perform true RMS measurement of current
simply by clamping it around a circuit. In addition to current, it provides voltage
measurement, frequency measurement, rush current measurement, resistance
measurement, diode measurement, capacitance measurement, temperature
measurement, voltage detection, and DC power measurement.
The CM4372 and CM4374 also provide Bluetooth communications functionality,
allowing measurement data to be monitored and logged from a smartphone or tablet.

2
Introduction
Package contents
AC/DC Clamp Meter L9207-10 Test lead
9243 graber L4937 マグネットアダプ
タ
L4934 小ワニグチ
マグネ付ストラップ
L9207-10
DM4910 熱電対
DT4911TestLead
DT4912TestLead
L4930 接続ケーブル
L4931renketu
L4931 延長ケーブル
L4932(+9207-10cap)
L4933 コンタクトピン
L4935 ワニ口
L4936 バスバー
C0203 Carrying Case
LR03 Alkaline battery × 2
Instruction Manual*
Precautions Concerning Use of
Equipment That Emits Radio Waves
(only for CM4372, CM4374)
* Instruction manuals may also be available in other languages. Please visit our website at http://www.hioki.com
Registered trademark
•Bluetooth®is a registered trademark of Bluetooth SIG, Inc.(USA). The trademark is used by HIOKI E.E.
CORPORATION under license.
•AndroidTM and Google PlayTM are registered trademarks of Google, Inc.
•IOS is a registered trademark of Cisco in the U.S. and other countries.
•iPhone®, iPad®, iPad miniTM, iPad ProTM, and iPod Touch®are registered trademarks of Apple Inc.
•The App Store is a service mark ofApple Inc.

3
Options (sold separately)
Options (sold separately)
9243 graber L4937 マグネットアダプ
タ
L4934 小ワニグチ
マグネ付ストラップ
L9207-10
DM4910 熱電対
DT4911TestLead
DT4912TestLead
L4930 接続ケーブル
L4931renketu
L4931 延長ケーブル
L4932(+9207-10cap)
L4933 コンタクトピン
L4935 ワニ口
L4936 バスバー
9243 graber L4937 マグネットアダプ
タ
L4934 小ワニグチ
マグネ付ストラップ
L9207-10
DM4910 熱電対
DT4911TestLead
DT4912TestLead
L4930 接続ケーブル
L4931renketu
L4931 延長ケーブル
L4932(+9207-10cap)
L4933 コンタクトピン
L4935 ワニ口
L4936 バスバー
9243 graber L4937 マグネットアダプ
タ
L4934 小ワニグチ
マグネ付ストラップ
L9207-10
DM4910 熱電対
DT4911TestLead
DT4912TestLead
L4930 接続ケーブル
L4931renketu
L4931 延長ケーブル
L4932(+9207-10cap)
L4933 コンタクトピン
L4935 ワニ口
L4936 バスバー
9243 graber L4937 マグネットアダプ
タ
L4934 小ワニグチ
マグネ付ストラップ
L9207-10
DM4910 熱電対
DT4911TestLead
DT4912TestLead
L4930 接続ケーブル
L4931renketu
L4931 延長ケーブル
L4932(+9207-10cap)
L4933 コンタクトピン
L4935 ワニ口
L4936 バスバー
9243 graber L4937 マグネットアダプ
タ
L4934 小ワニグチ
マグネ付ストラップ
L9207-10
DM4910 熱電対
DT4911TestLead
DT4912TestLead
L4930 接続ケーブル
L4931renketu
L4931 延長ケーブル
L4932(+9207-10cap)
L4933 コンタクトピン
L4935 ワニ口
L4936 バスバー
9243 graber L4937 マグネットアダプ
タ
L4934 小ワニグチ
マグネ付ストラップ
L9207-10
DM4910 熱電対
DT4911TestLead
DT4912TestLead
L4930 接続ケーブル
L4931renketu
L4931 延長ケーブル
L4932(+9207-10cap)
L4933 コンタクトピン
L4935 ワニ口
L4936 バスバー
9243 graber L4937 マグネットアダプ
タ
L4934 小ワニグチ
マグネ付ストラップ
L9207-10
DM4910 熱電対
DT4911TestLead
DT4912TestLead
L4930 接続ケーブル
L4931renketu
L4931 延長ケーブル
L4932(+9207-10cap)
L4933 コンタクトピン
L4935 ワニ口
L4936 バスバー
9243 graber L4937 マグネットアダプ
タ
L4934 小ワニグチ
マグネ付ストラップ
L9207-10
DM4910 熱電対
DT4911TestLead
DT4912TestLead
L4930 接続ケーブル
L4931renketu
L4931 延長ケーブル
L4932(+9207-10cap)
L4933 コンタクトピン
L4935 ワニ口
L4936 バスバー
9243 graber L4937 マグネットアダプ
タ
L4934 小ワニグチ
マグネ付ストラップ
L9207-10
DM4910 熱電対
DT4911TestLead
DT4912TestLead
L4930 接続ケーブル
L4931renketu
L4931 延長ケーブル
L4932(+9207-10cap)
L4933 コンタクトピン
L4935 ワニ口
L4936 バスバー
9243 graber L4937 マグネットアダプ
タ
L4934 小ワニグチ
マグネ付ストラップ
L9207-10
DM4910 熱電対
DT4911TestLead
DT4912TestLead
L4930 接続ケーブル
L4931renketu
L4931 延長ケーブル
L4932(+9207-10cap)
L4933 コンタクトピン
L4935 ワニ口
L4936 バスバー
L4933 Contact Pin Set *6
L4934 Small Alligator Clip Set *5
L4935 Alligator Clip Set *2
9243 Grabber Clip *3
L4936 Bus Bar Clip Set *4
L4937 Magnetic Adapter Set *3
L4932 Test Pin Set *1
L9207-10 Test lead *1
L4930 Connection Cable Set *2
(Length: 1.2 m)
L4931 Extension Cable Set *2
(Length: 1.5 m, with the
coupling connector)
9243 graber L4937 マグネットアダプ
タ
L4934 小ワニグチ
マグネ付ストラップ
L9207-10
DM4910 熱電対
DT4911TestLead
DT4912TestLead
L4930 接続ケーブル
L4931renketu
L4931 延長ケーブル
L4932(+9207-10cap)
L4933 コンタクトピン
L4935 ワニ口
L4936 バスバー
DT4910 Thermocouples (K)
L4938 Test Pin Set *7
L4939 Breaker Pin Set *4
*1: CAT IV 600 V/ CAT III 1000 V/ CAT II 1000 V *4: CAT III 600 V
*2: CAT IV 600 V/ CAT III 1000 V *5: CAT III 300 V/ CAT II 600 V
*3: CAT III 1000 V *6: 33 V AC/ 70 V DC
*7: CAT III 600 V/ CAT II 600 V

4
Safety Notes
Safety Notes
This instrument is designed to conform to IEC 61010 Safety Standards, and has been
thoroughly tested for safety prior to shipment. However, using the instrument in a way not
described in this manual may negate the provided safety features.
Before using the instrument, be certain to carefully read the following safety notes.
DANGER
Mishandling during use could result in injury or death, as well as damage to the
instrument. Be certain that you understand the instructions and precautions in
the manual before use.
WARNING
With regard to the electricity supply, there are risks of electric shock, heat
generation, re, and arc ash due to short circuits. If persons unfamiliar with
electricity measuring instruments are to use the instrument, another person
familiar with such instruments must supervise operations.

5
Safety Notes
WARNING
Protective gear
This instrument is measured on a live line. To prevent electric shock, use
insulated protective wear such as rubber gloves and rubber boots designed for
electrical work as well as a safety helmet as required by occupational health
and safety regulations.
Notation
In this document, the risk seriousness and the hazard levels are classied as follows.
DANGER Indicates an imminently
hazardous situation that will
result in death or serious injury
to the operator.
IMPORTANT
Indicates information related to
the operation of the instrument
or maintenance tasks with
which the operators must be
fully familiar.
WARNING Indicates a potentially hazardous
situation that may result in death
or serious injury to the operator. Indicates prohibited actions.
CAUTION
Indicates a potentially hazardous
situation that may result in
minor or moderate injury to
the operator or damage to the
instrument or malfunction.
Indicates the action which
must be performed.

6
Safety Notes
Symbols afxed to the instrument
Indicates cautions and hazards.
When the symbol is printed on the
instrument, refer to a corresponding
topic in the Instruction Manual.
Indicates DC (Direct Current) or AC
(Alternating Current).
Indicates that dangerous voltage may
be present at this terminal. Indicates DC (Direct Current).
Indicates that the instrument may be
connected to or disconnected from a
live conductor. Indicates a grounding terminal.
Indicates a instrument that has been
protected throughout by double
insulation or reinforced insulation.
Indicates the Waste Electrical and
Electronic Equipment Directive (WEEE
Directive) in EU member states.
Indicates that the product incorporates
Bluetooth®wireless technology. Indicates that the product conforms to regulations set out by the EC Directive.

7
Safety Notes
Measurement categories
This instrument conforms to the safety requirements for CAT III 1000 V, CAT IV 600 V
measuring instruments.
T Outlet
Internal wiring
Distribution panel
Service entrance
Service drop
CAT IV
(≤600 V)
Power meter
CAT III
(≤1000 V)
Fixed installation
CAT II
(≤1000 V)

8
Usage Notes
Usage Notes
Follow these precautions to ensure safe operation and to obtain the full benets of the various
functions.
DANGER
Do not input a voltage or current in excess of the
measurement range indicated by the ratings and
specications shown on instrument labeling. Doing
so may damage the instrument or cause it to become
hot, resulting in bodily injury.
To prevent an electric shock, conrm that the white portion (insulation layer)
inside the cable is not exposed. If a color inside the cable is exposed, do not
use the cable.

9
Usage Notes
WARNING
Do not allow the instrument to get wet, and do not take measurements with wet
hands. This may cause an electric shock.
To prevent electric shock, when measuring the voltage of a power line use a
test lead that satises the following criteria:
•Conforms to safety standards IEC61010 or EN61010
•Of measurement category III or IV
•Its rated voltage is higher than the voltage to be measured
The optional test leads for this instrument conform to the safety standard
EN61010. Use a test lead in accordance with its dened measurement category
and rated voltage.
CAUTION
Do not drop the instrument or subject it to excessive mechanical shock. Doing so
may damage the surfaces at the tips of the clamp sensor’s jaws, adversely affecting
measurement.

10
Usage Notes
Current measurement precautions
Do not clamp
around two wires.
NO
Do not touch.
Do not pinch wire
between jaws.
NO
Do not input
excessively high
currents.
NO
(Red display)
NO

11
Part Names
Part Names
Rotary switch
LCD Display
Barrier
HOLD key
Measurement
terminals
SHIFT key
(Selects function
indicated in blue
lettering.) Operation keys
(p.8)
Battery cover
Front Rear
(CM4372)
Jaw
(clamp sensor)
Operation
grip

12
Insert/Replace Batteries
Insert/Replace Batteries
WARNING
•To prevent electric shock, disconnect test leads before inserting or replacing
the batteries.
•Handle and dispose of batteries in accordance with local regulations.
•To prevent instrument damage or electric shock, use only the screw for
securing the battery cover in place that are originally installed. If you have
lost a screw or nd that a screw is damaged, please contact your Hioki
distributor for a replacement.
•The indicator lights up when the battery charge diminishes. Replace the batteries as
soon as possible.
The batteries may die if the backlight turns on or the buzzer sounds.
•After use, be sure to turn off the instrument.

13
Insert/Replace Batteries
Insert/Replace Batteries
123
5
4
Battery
indicator Description
Fully charged.
As the battery charge diminishes, black charge bars disappear, one by one,
from the left of the battery indicator.
The battery voltage is low. Replace the batteries as soon as possible.
(Blinks) The battery is exhausted. Replace the batteries.

14
Inspection Before Measurement
Inspection Before Measurement
Verify that the instrument operates normally to ensure that no damage occured during storage
or shipping. If you nd any damage, contact your authorized Hioki distributor or reseller.
Check item
The battery cover is closed and its screw
has been securely tightened.
There is no damage to the test lead
insulation, and neither the white sheathing
nor metal conductor inside the wire are
exposed.
There is no foreign matter on the
measurement terminals. (p.11)
The instrument is neither damaged nor
cracked.
The test leads are not broken.
OK
NO NONO
OK NO NO NO
1 Ωor less
No indicators are missing.
(All lit up)
The battery voltage (p. 13) is sufcient.

15
Current Measurement
Current Measurement
DC current polarity detection function (p.34)
If the measured value is negative, the buzzer will
sound, and the display will turn red (threshold: -10 A).
e.g.: 3P4W (3-phase, 4-wire) circuit
breaker (AC current measurement)
4
HzAUTO
(AUTO AC/DC) (AC+DC A)
(DC A)
(AC A)
3Clamp the wire.
2Press for 1 sec.
→Perform zero adjustment
1
Current
direction
Frequency detection range of AC current
CM4371, CM4372:
20.00 A range 4.00 A or more
600.0 A range 20.0 A or more
CM4373, CM4374:
600.0 A range 40.0 A or more
2000 A range 200 A or more

16
Manual Hold / Auto Hold
Manual Hold / Auto Hold
→ Measured value retains.
(Measured value stabilizes.)
Measured value automatically retains.
To measured
target
Pressing the HOLD key again cancels
the measured value hold function.
→blinks.
Pressing the HOLD key for 1 second cancels
the auto hold function.
Press for 1 sec.
Disconnect
MANUAL HOLD AUTO HOLD

17
Manual Hold / Auto Hold
Auto hold conditions
Display value updates are stopped when the following two conditions are satised:
•When the measured value exceeds the threshold value described in the table in the next page.
(voltage, current)
When the measured value is less than the threshold value described in the table in the next page.
(resistance, continuity, diode)
• When the range over which the measured value is uctuating stabilizes within the uctuation range
described in the table in the next page.
Auto hold
e.g.: 100.0 A Auto hold
e.g.: 99.0 A
Held
measured
value
Measured
value
Start
End End End
Fluctuation range Fluctuation range
Fluctuation
range Threshold value
e.g.: 12.0 A
Measurement
Start
Start Time
If the measured value falls below the threshold value (voltage, current) or exceeds the threshold value
(resistance, continuity, diode) after display value updates are stopped, display value updates will stop once
more if the two conditions are satised again.