Hioki CM4371, CM4372, CM4373, CM4374 Instruction Manual

EN

AC/DC CLAMP METER

Instruction Manual

June 2016 Revised edition 2
CM4371A961-02 16-06H

CM4371
CM4372
CM4373
CM4374

Video

Scan this code to watch an
instructional video.
Carrier charges may apply.

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

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



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.

• Android

TM

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 of Apple 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

DM4910 熱電対

DT4911TestLead

DT4912TestLead

L4930 接続ケーブル

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

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

9243 graber

L4937 マグネットアダプ

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

L4937 マグネットアダプ
タ

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)

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

L4937 マグネットアダプ
タ

L4934 小ワニグチ

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

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

DM4910 熱電対

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

1

2

3

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

1 Ω or 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)

3

Clamp the wire.

2

Press 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.

18

Manual Hold / Auto Hold

Measurement function Fluctuation range Threshold value

AC current
DC current
AC+DC current

20.00 A range: within 100 counts

600.0 A range: within 120 counts
2000 A range: within 40 counts

20.00 A range: 100 counts

600.0 A range: 120 counts
2000 A range: 40 counts

AC voltage
DC voltage
(excluding the 600.0 mV
range)
AC+DC voltage

6.000 V/ 60.00 V/ 600.0 V range:
within 120 counts
1000 V range: within 20 counts
1500 V range: within 30 counts

6.000 V/ 60.00 V/ 600.0 V range:
120 counts
1000 V range: 20 counts
1500 V range: within 30 counts

Resistance, Continuity 600.0

Ω

/6.000 kΩ/60.00 kΩ/600.0 kΩ

range: within 100 counts

600.0 Ω/6.000 kΩ/60.00 kΩ/600.0 kΩ
range: 4900 counts

Diode 1.800 V range: within 40 counts 1.800 V range: 1460 counts

The auto hold function only operates for the above measurement functions.

19

Switching ranges

Switching ranges

AUTO range MANUAL 2000 A rangeMANUAL 600.0 A range

AUTO range

MANUAL 600.0 A rangeMANUAL 20.00 A range

e.g. 1: Current measurement with the CM4373, CM4374

e.g. 2: Current measurement with the CM4371, CM4372

20

Filter Function

Filter Function

FILTER OFF

Measured value including noise

Press for
1 sec.

Frequency [Hz]

Measurement value [A]

FILTER OFF
FILTER ON Passband 100 [Hz]

Measured value with reduced noise

Frequency characteristics when

using the lter

(600.0 A AC range, 100 A input)

Turn off the lter function when performing

measurement of power supply frequencies
in excess of 100 Hz, for example on an
aircraft or ship.

Filter OFF

FILTER ON

21

MAX/MIN/AVG/PEAK

MAX/MIN/AVG/PEAK

Can not be used at
AUTO AC/DC.

1
2

Hz

AUTO

(AUTO AC/DC)

(AC+DC A)

(DC A)(AC A)

3

Press for 1 sec.

→Cancel

PEAK MAX

PEAK MIN

MAX

Display refresh interval

Waveform

Measured value
(RMS value)

MIN

The instrument
performs true RMS
measurement.

→ Measured value retains.

4

22

Simultaneous display of DC current/voltage peak values

Simultaneous display of DC current/voltage peak values

Red

Black

1

Press for 1 sec.

→PEAK display ON

2

Press for 1 sec.

→Cancel

4

(p. 28)

PEAK MIN

PEAK MAX

PEAK MIN

PEAK MAX

DC current

DC voltage

3

Engine starts
(PEAK occurrence)

Voltage: 60.00 V range (xed)

Current: 600.0 A range (xed) (CM4371, CM4372)

Trigger level: ±60 A
Current: 2000 A range (xed) (CM4373, CM4374)
Trigger level: ±200 A

23

Backlight / Auto Power Save (APS)

Backlight / Auto Power Save (APS)

Backlight

Backlight ON

Power OFF

To restart the instrument, briey set the rotary switch to “OFF.”

Backlight OFF

No operation for 45 min.

You can turn the display back on by
pressing a key or by turning the rotary
switch.

No operation for 15 min.

(Always on)
Cancelation method: p. 34

Auto Power Save (APS)

24

Rush current (INRUSH)

Rush current (INRUSH)

600.0 A range (xed) (CM4371, CM4372)

Trigger level: ±10 A

2000 A range (xed) (CM4373, CM4374)

Trigger level: ±100 A

1

MOTOR OFF

6

MOTOR ON

7

Rush current
occurrence

5

Press for 1 sec.

→INRUSH ON

4

Clamp the wire.

3

Press for 1 sec.

→Zero adjustment

2

Maximum wave height (PEAK)

Example screen: 250 A

Interval during which rush

current occurs

(Dozens to hundreds of

milliseconds in duration)

AC current

RMS value (INRUSH)

DC current

Maximum wave height (PEAK)

Example
screen: 100 A

RMS value (INRUSH)

Interval during which rush

current occurs

(Dozens to hundreds of

milliseconds in duration)

25

Other Measurement Functions

Other Measurement Functions

DC voltage polarity detection function (p. 34)

If the measured value is negative, the buzzer will

sound, and the display will turn red (threshold: −10 V).

(Red display)

2

3

e.g.: commercial power supply (AC voltage measurement)

Do not touch.

Do not input excessively

high voltage.

NO

Red Black

NO

1

Voltage

Hz

AUTO

(AUTO AC/DC)

(AC+DC V)

(DC V)

(AC V)

26

Other Measurement Functions

Continuity Check

2

Black

Red

Black

Red

BlackRed

2

Press for 1 sec.

Zero adjustment

1

Press for 1 sec.

Zero adjustment

1

Resistance Diode

(Red display)

27

Other Measurement Functions

Capacitance

DT4910

: when DT4910
is broken.

Red

Black

+

−

Black Red

Temperature

To change the temperature display unit: p. 35

28

Other Measurement Functions

e.g.: Checking a car battery

Red

Black

Press for 1 sec.

→PEAK display

(p. 22)

Simultaneous display of

DC current and DC voltage

e.g.: Solar power

system maintenance

DC power

Grip as shown in gure.

Electric Charge

Detection

(Red display)

The current range is xed:

600.0 A range (xed): CM4371, CM4372

2000 A range (xed): CM4373, CM4374

29

Bluetooth® Communications (only for CM4372, CM4374)

Bluetooth® Communications (only for CM4372, CM4374)

The CM4372 and CM4374 are clamp-style meters with Bluetooth® Smart (Bluetooth® Low Energy) support.
When the Bluetooth

®

function is enabled, you can review measurement data and create measurement reports

on mobile devices (iPhone

®

, iPad®, iPad Mini™, iPad Pro™, iPod Touch®, and Android™ devices). For more

information about this functionality, see the Help function in the application software GENNECT Cross.

1

Install the GENNECT Cross on your mobile device. (p. 30)

2

Enable the Bluetooth® function on the CM4372 or CM4374. (p. 31)

Press for
1 sec.

3

Launch the GENNECT Cross and pair it with the CM4372 or
CM4374. (p. 32)

4

Select the General Measurement, Logging (Recording), or

Waveform Graph function. (p. 33)

30

Bluetooth® Communications (only for CM4372, CM4374)

Installing the application software GENNECT Cross

Search for “GENNECT Cross” on the App Store

®

from your iPhone®, iPad® or other Apple device, or on
Google Play™ from your Android™ device. Then download and install the GENNECT Cross. You will need
an Apple ID to download the app from the App Store

®

, or a Google account to download the app from Google
Play™. For more information about how to register an account, contact the store at which you purchased your
device.

• Because the CM4372 and CM4374 emit radio waves, use in a country or region where they have not

been approved may be subject to nes or other penalties as a violation of applicable laws or regulations.
For more information, see the attached “Precautions Concerning Use of Equipment That Emits Radio
Waves” or go to our website.

• The CM4372 and CM4374 availability is limited to certain countries. For more information, contact your
authorized Hioki distributor or reseller.

• Bluetooth

®

communications range varies greatly with distance from obstructions (walls, metal obstruction,

etc.) as well as distance from the oor or ground. To ensure stable measurement, verify adequate signal

strength.

• Although this app is provided free of charge, downloading or use of the app may incur Internet connection
charges. Such charges are the sole responsibility of the user.

• This app is not guaranteed to operate on all mobile devices.

31

Bluetooth® Communications (only for CM4372, CM4374)

Turning on the Bluetooth® function

Bluetooth® function OFF Bluetooth® function ON

icon will ash when the instrument

is connected to a mobile device.

Press for 1 sec.

32

Bluetooth® Communications (only for CM4372, CM4374)

Pairing the app with the CM4372 or CM4374

1

2

3

• When the app is launched for the rst time (before being paired with any instrument), the Instrument

Settings screen will be displayed.

• While the mobile device is displaying the Instrument Settings screen, simply move it close to a CM4372 or
CM4374 to automatically pair it with the instrument (the app can be paired with up to 8 instruments).

• Allow about 5 to 30 seconds for the instrument to pair with the app after being turned on. If the instrument
fails to pair within 1 minute, relaunch GENNECT Cross and cycle the instrument’s power.

33

Bluetooth® Communications (only for CM4372, CM4374)

Making measurements with the Bluetooth® function

Select the General Measurement, Logging (Recording), or Waveform Graph function on
the Home screen. For more information about each function, see the Help function in the
GENNECT Cross.

General Measurement

Saves measured values from

multiple channels

Logging (Recording)

Simple logging (up to 24 hours)

Waveform Graph

Simple oscilloscope

(voltage/current)

34

Power-on Option Table

Power-on Option Table

+

Turn on the power while pressing the operation key.
(Turn the rotary switch from OFF.)

Setting Operating instruction

Factory

setting

Setting

retained?

Canceling the auto power save
(APS) function

ON

No

(Set each time)

DC current and DC voltage
polarity detection function
(ON/OFF)

OFF Yes

Displaying all indicators
(Version of software/Model

number)

− −

Buzzer sound (ON/OFF)

ON Yes

Automatic backlight
deactivation (ON/OFF)

ON Yes

35

Power-on Option Table

Setting Operating instruction

Factory

setting

Setting

retained?

Switching the temperature unit

To change the
temperature unit:

Press for 1 sec.

To save the setting:

Press for 1 sec.

°C Yes

36

Repairs, Inspections, and Cleaning

Repairs, Inspections, and Cleaning

Cleaning

To clean the instrument, wipe it gently with a soft cloth moistened with water or mild detergent.

Troubleshooting

Symptom Verication and/or Solution

• The instrument is indicating

an abnormal measured
value for current.

• Is the measured current value too small for the instrument’s measurement
range?
Wrap the wire around the clamp sensor one or more times. Each additional
wrap of the wire will increase the measured value, so that wrapping it once
yields a measured value that is twice the actual value and wrapping it
twice yields a measured value that is three times the actual value.

• Are the tips of the clamp sensor’s jaws open?

• Is the clamp sensor damaged?
If the sensor is damaged or cracked, it will not be able to measure current
accurately. Send the instrument for repair.

37

Repairs, Inspections, and Cleaning

Symptom Verication and/or Solution

• When readings from the
instrument are compared
with those of another
clamp-on current meter, the
measured values differ.

• The instrument cannot accurately measure waveforms that contain a
component that falls outside the frequency characteristics range.

• Since the instrument performs true RMS measurement, it can accurately
measure distorted waveforms. When measuring a distorted waveform,
the measured value will differ from a clamp-on current meter that uses the
averaging method.

• The current value is larger
than expected.

• A current value is displayed
even though there is no
input.

• The instrument cannot perform measurement accurately in the presence

of a strong magnetic eld from a source such as a nearby transformer
or high-current circuit or in the presence of a strong electric eld from a

source such as a wireless device.

• A sound is being emitted
by the instrument’s clamp
sensor.

• The clamp sensor may emit sound when measuring AC currents in excess
of approx. 500 A, however, there is no effect on the measurement.

• The measured value does
not appear.

• No measured value is
displayed, even when the
test leads are shorted.

• Zero adjustment is
impossible.

• Check the continuity of the test leads. (p. 26)
If a wiring break is found, replace the test leads.

• Insert the test leads all the way.

• Use the proper measurement method.
If no problem can be found, the instrument may be damaged.
Send the instrument for repair.

• When performing current measurement, perform zero-adjustment while no
measurement target is being clamped.

38

Repairs, Inspections, and Cleaning

Error display

Error display Description Solution

Err 001

ROM error

Program

When the error appears in the display, it is
necessary to repair the instrument.
Please contact your authorized Hioki
distributor or reseller.

Err 002

ROM error

Adjustment data

Err 005

ADC error

Hardware malfunction

Err 008

Bluetooth® error

Hardware malfunction
(only for

CM4372, CM4374)

39

Specications

Specications

General Specications

Dimensions CM4371, CM4372: Approx. 65W × 215H × 35D mm (2.56″W × 8.46″H × 1.38″D)

CM4373, CM4374: Approx. 65W × 250H × 35D mm (2.56″W × 9.84″H × 1.38″D)
(excluding protruding parts, operation grip, and jaw)

Jaw dimensions CM4371, CM4372: Approx. 69W × 14D mm (2.72″W × 0.55″D)

CM4373, CM4374: Approx. 92W × 18D mm (3.62″W × 0.71″D)

Maximum measurable
conductor diameter

CM4371, CM4372:

φ

33 mm

CM4373, CM4374:

φ

55 mm

Mass CM4371, CM4372: Approx. 340 g (12.0 oz.) (excluding batteries)

CM4373, CM4374: Approx. 530 g (18.7 oz.) (excluding batteries)

Product warranty period 3 years

(Measurement accuracy is dened in terms of a 1-year accuracy and a 3-year
accuracy.) (3 years: reference values)
Number of jaw open/close cycles: 30,000

Operating environment Indoors, pollution degree 2, altitude up to 2000 m (6562 ft.)

Operating temperature
and humidity

-25°C to 65°C (-13°F to 149°F), 90% RH or less (no condensation)

Storage temperature and
humidity

-30°C to 70°C (-22°F to 158°F), 90% RH or less (no condensation)

40

Specications

Dustproof and waterproof Jaw, barrier: IP50

Grip: IP54 (when measuring an insulated conductor only)
Risk of electric shock from the conductor being measured increases when wet.

Electrical Characteristics

Display update rate
(measured value)

• Measured value excluding electrostatic capacity, frequency, and temperature:

5 times/s (after the range is xed)

• Electrostatic capacity: 0.5 to 5 times/s (The number of times varies depending

on the capacitance.)

• Frequency: 0.3 to 5 times/s (The number of times varies depending on the

capacitance.)

• Temperature: 1 times/s (including thermocouple wiring break check)

(Dened within the measurement range (excluding range changes)).

Maximum terminal-to­terminal rated voltage

1000 V AC (up to 1 kHz) /1700 V DC

Maximum rated voltage
to earth

1000 V AC (Measurement category III)
600 V AC (Measurement category IV)
Anticipated transient overvoltage: 8000 V

Rated supply voltage 1.5 V DC ×2

LR03 Alkaline battery ×2

41

Specications

Continuous operating
time

• Approx. 45 hours, at 23°C (73.4°F): 10 A AC measurement (CM4371, CM4372),

100 A AC measurement (CM4373, CM4374)
Backlight OFF, Bluetooth OFF

• Approx. 24 hours, at 23°C (73.4°F): 10 A AC measurement (CM4372),

100 A AC measurement (CM4374)
Backlight OFF, Bluetooth ON

Standards

Safety EN61010
EMC EN61326

Specication for Model DT4910 Thermocouples (K)

Sensor type Thermocouples (K)

Tolerance ±2.5°C (Class 2)

Temperature measuring
junction

Exposed type (welding)

Sensor length Approx. 800 mm

Measuring temperature -40°C to 260°C (-40°F to 500°F) (temperature detector)

Operating temperature -15°C to 55°C (5°F to 131°F)

Storage temperature -30°C to 60°C (-22°F to 140°F)

42

Specications

CM4372, CM4374 Individual Specications

Bluetooth® Function

Bluetooth® communications
function

Display of measured values on a smartphone or a tablet while using
Bluetooth

®

communications.

External Interface Specications

Interface

Bluetooth

®

4.0LE ( )

Antenna power Maximum +0 dBm (1 mW)

Communications range Approx. 10 m (line of sight)

Communications prole GATT (Generic Attribute Prole)

Supported devices iOS (iPhone

®

5, 3rd iPad®, iPad miniTM, iPad ProTM, 5th iPod Touch® or later)

Android

TM

(Only for or model)

Supported OS iOS 8 or later, Android

TM

4.3 or later

43

Specications

Accuracy specications and measurement specications

Guaranteed accuracy period 1 year “Accuracy shown in accuracy table”

3 years (reference values) “Accuracy shown in accuracy table ×1.5”

Guaranteed accuracy period
after adjustment made by Hioki

1 year

Guaranteed accuracy for
temperature and humidity

23°C±5°C (73°F±9°F), 90% RH or less (no condensation)

Temperature characteristic Within the operating temperature range, add “measurement accuracy ×

0.1/°C” (excluding 23°C±5°C (73°F±9°F)).

Other conditions When using the L4931 Extension Cable Set, accuracy is guaranteed for

up to two connected cables (totaling 3 m in length).

AC measurement method True RMS measurement

Conditions of AC accuracy
guarantee

Sine wave input

44

Specications

AC current/DC current/AC+DC current common specication

Effects of conductor
position

CM4371, CM4372: within ±1.5% rdg.
CM4373, CM4374: within ±1.0% rdg.
At all positions around the jaw’s center-point reference

Effects of external
magnetic elds

60 Hz AC/DC, with a 400 A/m external magnetic eld
CM4371, CM4372: 2.00 A or less
CM4373, CM4374: 2.0 A or less

Maximum allowable
input (AC/DC)

CM4371, CM4372: 600 A continuous
CM4373, CM4374: 2000 A continuous
Frequency derating characteristics with continuous input (See the graph below)

Input current frequency [Hz]

Maximum allowable input current [A]

Frequency derating characteristics

(CM4371, CM4372)

Input current frequency [Hz]

Maximum allowable input current [A]

Frequency derating characteristics

(CM4373, CM4374)

45

Accuracy Table

Accuracy Table

Accuracy

We dene measurement tolerances in terms of f.s. (full scale), rdg. (reading) and dgt. (digit) values with the
following meanings:

f.s.
(maximum display

value/range)

The maximum displayable value.
This is usually the name of the currently selected range.

rdg.
(displayed value)

The value currently being measured and displayed on the measuring instrument.

dgt.
(resolution)

The smallest displayable unit on a digital measuring instrument, i.e., the input value
that causes the digital display to show a “1” as the least-signicant digit.

1

AC current 20.00 A/600.0 A (CM4371, CM4372)

Conditions of guaranteed accuracy: After zero adjustment has been performed
Zero-display range: 5 counts or less
Coupling type: AC coupling
Crest factor: For the 20.00 A range, 7.5

For the 600.0 A range (500.0 A or less), 3
For the 600.0 A range (greater than 500.0 A and less than or equal to

600.0 A), 2.5

Peak detection time width: 1 ms or more (Filter off)

46

Accuracy Table

AC current (Measurement value/MAX/MIN/AVG)

Range

(Accuracy guarantee
range)

Resolution

Accuracy
guarantee
frequency range

Measurement accuracy

Filter off Filter on

20.00 A (1.00 A to 20.00 A) 0.01 A 10 Hz≤f<45 Hz ±1.8% rdg.±0.10 A ±2.3% rdg.±0.10 A
45 Hz≤f≤66 Hz ±1.3% rdg.±0.08 A ±1.8% rdg.±0.08 A
66 Hz<f≤1 kHz ±2.0% rdg.±0.10 A -

600.0 A (1.0 A to 600.0 A) 0.1 A 10 Hz≤f<45 Hz ±1.8% rdg.±0.5 A ±2.3% rdg.±0.5 A
45 Hz≤f≤66 Hz ±1.3% rdg.±0.3 A ±1.8% rdg.±0.3 A
66 Hz<f≤1 kHz ±2.0% rdg.±0.5 A -

Auto range movement threshold: 2000 counts or more for upper range, 180 counts or less for lower range.

AC current (PEAK MAX/PEAK MIN)

Range

(Accuracy guarantee
range)

Resolution

Accuracy
guarantee
frequency range

Measurement accuracy

20.00 A (±1.0 A to ±150.0 A) 0.1 A 10 Hz≤f<45 Hz ±1.8% rdg.±0.7 A
45 Hz≤f≤66 Hz ±1.3% rdg.±0.7 A
66 Hz<f≤1 kHz ±2.0% rdg.±0.7 A

600.0 A (±10 A to ±1500 A) 1 A 10 Hz≤f<45 Hz ±1.8% rdg.±7 A

45 Hz≤f≤66 Hz ±1.3% rdg.±7 A
66 Hz<f≤1 kHz ±2.0% rdg.±7 A

47

Accuracy Table

2

DC current and auto A DC detection 20.00 A/600.0 A (CM4371, CM4372)

Conditions of guaranteed accuracy: After zero adjustment has been performed
Zero-display range: 5 counts or less
Coupling type: DC coupling
Peak detection time width: 1 ms or more (Filter off)

DC current (Measurement value/MAX/MIN/AVG)

Range

(Accuracy guarantee
range)

Resolution

Measurement accuracy

(Values apply regardless of whether the lter is on or off.)

20.00 A (±1.00 A to ±20.00 A) 0.01 A ±1.3% rdg.±0.08 A

600.0 A (±1.0 A to ±600.0 A) 0.1 A ±1.3% rdg.±0.3 A

Auto range movement threshold: 2000 counts or more for upper range, 180 counts or less for lower range.

DC current (PEAK MAX/PEAK MIN)

Range (Accuracy guarantee range) Resolution Measurement accuracy

20.00 A (±1.0 A to ±150.0 A) 0.1 A ±1.3% rdg.±0.7 A

600.0 A (±10 A to ±1500 A) 1 A ±1.3% rdg.±7 A

48

Accuracy Table

3

AC+DC current and auto A AC detection 20.00 A/600.0 A (CM4371, CM4372)

Conditions of guaranteed accuracy: After zero adjustment has been performed
Zero-display range: 5 counts or less
Coupling type: DC coupling
Crest factor: For the 20.00 A range, 7.5

For the 600.0 A range (500.0 A or less), 3
For the 600.0 A range (greater than 500.0 A and less than or equal to

600.0 A), 2.5

Peak detection time width: 1 ms or more (Filter off)

AC+DC current (Measurement value/MAX/MIN/AVG)

Range

(Accuracy guarantee
range)

Resolution

Accuracy guarantee
frequency range

Measurement accuracy

Filter off Filter on

20.00 A (1.00 A to 20.00 A) 0.01 A 10 Hz≤f<45 Hz ±1.8% rdg.±0.10 A ±2.3% rdg.±0.10 A

DC, 45 Hz≤f≤66 Hz ±1.3% rdg.±0.13 A ±1.8% rdg.±0.13 A
66 Hz<f≤1 kHz ±2.0% rdg.±0.10 A -

600.0 A (1.0 A to 600.0 A) 0.1 A 10 Hz≤f<45 Hz ±1.8% rdg.±0.7 A ±2.3% rdg.±0.7 A

DC, 45 Hz≤f≤66 Hz ±1.3% rdg.±1.3 A ±1.8% rdg.±1.3 A
66 Hz<f≤1 kHz ±2.0% rdg.±0.7 A -

Auto range movement threshold: 2000 counts or more for upper range, 180 counts or less for lower range.

49

Accuracy Table

AC+DC current (PEAK MAX/PEAK MIN)

Range

(Accuracy
guarantee range)

Resolution

Accuracy guarantee
frequency range

Measurement accuracy

20.00 A (±1.0 A to ±150.0 A) 0.1 A 10 Hz≤f<45 Hz ±1.8% rdg.±0.7 A

DC, 45 Hz≤f≤66 Hz ±1.3% rdg.±0.7 A
66 Hz<f≤1 kHz ±2.0% rdg.±0.7 A

600.0 A (±10 A to ±1500 A) 1 A 10 Hz≤f<45 Hz ±1.8% rdg.±7 A

DC, 45 Hz≤f≤66 Hz ±1.3% rdg.±7 A
66 Hz<f≤1 kHz ±2.0% rdg.±7 A

4

Rush current (INRUSH) 600.0 A (CM4371, CM4372)

Conditions of guaranteed accuracy: After zero adjustment has been performed
INRUSH trigger level: For 600.0 A range, detection of current of +10 A or more or -10 A or less
Coupling type: DC coupling
Crest factor: For the 600.0 A range (500.0 A or less), 3

For the 600.0 A range (greater than 500.0 A and less than or equal to

600.0 A), 2.5

Peak detection time width: 1 ms or more

50

Accuracy Table

Rush Current (INRUSH)

Range

(Accuracy
guarantee range)

Resolution

Accuracy guarantee
frequency range

Measurement accuracy

(Values apply regardless of whether the
lter is on or off.)

600.0 A (10.0 A to 600.0 A) 0.1 A DC, 20 Hz≤f≤500 Hz ±5.0% rdg.±1.3 A

Rush Current (INRUSH peak value)

Range

(Accuracy
guarantee range)

Resolution

Accuracy guarantee
frequency range

Measurement accuracy

600.0 A (±10 A to ±1500 A) 1 A DC, 20 Hz≤f≤500 Hz ±6.0% rdg.±10 A

5

AC current 600.0 A/2000 A (CM4373, CM4374)

Conditions of guaranteed accuracy: After zero adjustment has been performed
Zero-display range: 5 counts or less
Coupling type: AC coupling
Crest factor: For the 600.0 A range (500.0 A or less), 3

For the 600.0 A range (greater than 500.0 A and less than or equal to

600.0 A), 2.5
For the 2000 A range (1000 A or less), 2.84
For the 2000 A range (greater than 1000 A and less than or equal to
2000 A), 1.42

Peak detection time width: 1 ms or more (Filter off)

51

Accuracy Table

AC current (Measurement value/MAX/MIN/AVG)

Range

(Accuracy
guarantee range)

Resolution

Accuracy guarantee
frequency range

Measurement accuracy

Filter off Filter on

600.0 A (1.0 A to 600.0 A)* 0.1 A 10 Hz≤f<45 Hz ±1.8% rdg.±0.5 A ±2.3% rdg.±0.5 A

45 Hz≤f≤66 Hz ±1.3% rdg.±0.3 A ±1.8% rdg.±0.3 A
66 Hz<f≤1 kHz ±2.0% rdg.±0.5 A -

2000 A (10 A to 1800 A) 1 A 10 Hz≤f<45 Hz ±1.8% rdg.±5 A ±2.3% rdg.±5 A

45 Hz≤f≤66 Hz ±1.3% rdg.±3 A ±1.8% rdg.±3 A
66 Hz<f≤1 kHz ±2.0% rdg.±5 A -

(1801 A to 2000 A) 1 A 10 Hz≤f<45 Hz ±2.8% rdg.±5 A ±3.3% rdg.±5 A

45 Hz≤f≤66 Hz ±2.3% rdg.±3 A ±2.8% rdg.±3 A
66 Hz<f≤1 kHz - -

Auto range movement threshold: 6000 counts or more for upper range, 540 counts or less for lower range.
* For 30.0 A or less, add 0.5 A to the measurement accuracy.

52

Accuracy Table

AC current (PEAK MAX/PEAK MIN)

Range

(Accuracy guarantee
range)

Resolution

Accuracy guarantee
frequency range

Measurement accuracy

600.0 A (±10 A to ±1500 A) 1 A 10 Hz≤f<45 Hz ±1.8% rdg.±7 A

45 Hz≤f≤66 Hz ±1.3% rdg.±7 A
66 Hz<f≤1 kHz ±2.0% rdg.±7 A

2000 A (±10 A to ±2300 A) 1 A 10 Hz≤f<45 Hz ±1.8% rdg.±7 A

45 Hz≤f≤66 Hz ±1.3% rdg.±7 A
66 Hz<f≤1 kHz ±2.0% rdg.±7 A

(±2301 A to ±2840 A) 1 A 10 Hz≤f<45 Hz ±6.5% rdg.±7 A

45 Hz≤f≤66 Hz ±6.0% rdg.±7 A
66 Hz<f≤1 kHz -

6

DC current and auto A DC detection 600.0 A/2000 A (CM4373, CM4374)

Conditions of guaranteed accuracy: After zero adjustment has been performed
Zero-display range: 5 counts or less
Coupling type: DC coupling
Peak detection time width: 1 ms or more (Filter off)

53

Accuracy Table

DC current (Measurement value/MAX/MIN/AVG)

Range

(Accuracy guarantee
range)

Resolution

Measurement accuracy

(Values apply regardless of whether the lter is on or off.)

600.0 A (±1.0 A to ±600.0 A)* 0.1 A ±1.3% rdg.±0.3 A

2000 A (±10 A to ±2000 A) 1 A ±1.3% rdg.±3 A

Auto range movement threshold: 6000 counts or more for upper range, 540 counts or less for lower range.
* For 30.0 A or less, add 0.5 A to the measurement accuracy.

DC current (PEAK MAX/PEAK MIN)

Range

(Accuracy guarantee
range)

Resolution Measurement accuracy

600.0 A (±10 A to ±1500 A) 1 A ±1.3% rdg.±7 A

2000 A (±10 A to ±2300 A) 1 A ±1.3% rdg.±7 A

(±2301 A to ±2840 A) 1 A ±6.0% rdg.±7 A

54

Accuracy Table

7

AC+DC current and auto A AC detection 600.0 A/2000 A (CM4373, CM4374)

Conditions of guaranteed
accuracy: After zero adjustment has been performed

Zero-display range: 5 counts or less
Coupling type: DC coupling
Crest factor: For the 600.0 A range (500.0 A or less), 3

For the 600.0 A range (greater than 500.0 A and less than or equal to 600.0 A), 2.5
For the 2000 A range (1000 A or less), 2.84
For the 2000 A range (greater than 1000 A and less than or equal to 2000 A), 1.42

Peak detection time width: 1 ms or more (Filter off)

AC+DC current (Measurement value/MAX/MIN/AVG)

Range

(Accuracy
guarantee range)

Resolution

Accuracy guarantee
frequency range

Measurement accuracy

Filter off Filter on

600.0 A (1.0 A to 600.0 A) 0.1 A 10 Hz≤f<45 Hz ±1.8% rdg.±0.7 A ±2.3% rdg.±0.7 A

DC, 45 Hz≤f≤66 Hz ±1.3% rdg.±1.3 A ±1.8% rdg.±1.3 A
66 Hz<f≤1 kHz ±2.0% rdg.±0.7 A −

2000 A (10 A to 1800 A) 1 A 10 Hz≤f<45 Hz ±1.8% rdg.±7 A ±2.3% rdg.±7 A

DC, 45 Hz≤f≤66 Hz ±1.3% rdg.±13 A ±1.8% rdg.±13 A
66 Hz<f≤1 kHz ±2.0% rdg.±7 A −

(1801 A to 2000 A) 1 A 10 Hz≤f<45 Hz ±2.8% rdg.±7 A ±3.3% rdg.±7 A

DC, 45 Hz≤f≤66 Hz ±2.3% rdg.±13 A ±2.8% rdg.±13 A
66 Hz<f≤1 kHz − −

Auto range movement threshold: 6000 counts or more for upper range, 540 counts or less for lower range.

55

Accuracy Table

AC+DC current (PEAK MAX/PEAK MIN)

Range

(Accuracy guarantee
range)

Resolution

Accuracy guarantee
frequency range

Measurement accuracy

600.0 A (±10 A to ±1500 A) 1 A 10 Hz≤f<45 Hz ±1.8% rdg.±7 A

DC, 45 Hz≤f≤66 Hz ±1.3% rdg.±7 A
66 Hz<f≤1 kHz ±2.0% rdg.±7 A

2000 A (±10 A to ±2300 A) 1 A 10 Hz≤f<45 Hz ±1.8% rdg.±7 A

DC, 45 Hz≤f≤66 Hz ±1.3% rdg.±7 A
66 Hz<f≤1 kHz ±2.0% rdg.±7 A

(±2301 A to ±2840 A) 1 A 10 Hz≤f<45 Hz ±6.5% rdg.±7 A

DC, 45 Hz≤f≤66 Hz ±6.0% rdg.±7 A
66 Hz<f≤1 kHz -

8

Rush Current (INRUSH) 2000 A (CM4373, CM4374)

Conditions of guaranteed accuracy: After zero adjustment has been performed
INRUSH trigger level: For 2000 A range, detection of current of +100 A or more or -100 A or

less
Coupling type: DC coupling
Crest factor: For the 2000 A range (1000 A or less), 2.84

For the 2000 A range (greater than 1000 A and less than or equal to

2000 A), 1.42
Peak detection time width: 1 ms or more

56

Accuracy Table

Rush Current (INRUSH) of AC+DC current

Range (Accuracy guarantee range) Resolution

Accuracy guarantee
frequency range

Measurement accuracy

2000 A (100 A to 1800 A) 1 A DC, 20 Hz≤f≤500 Hz ±3.3% rdg.±13 A

(1801 A to 2000 A) 1 A DC, 20 Hz≤f≤66 Hz ±5.0% rdg.±13 A

Rush Current (INRUSH peak value) of AC+DC current

Range (Accuracy guarantee range) Resolution

Accuracy guarantee
frequency range

Measurement accuracy

2000 A (±100 A to ±2300 A) 10 A DC, 20 Hz≤f≤500 Hz ±6.0% rdg.±100 A

(±2310 A to ±2840 A) 10 A DC, 20 Hz≤f≤66 Hz ±8.0% rdg.±100 A

9

AC voltage

CMRR: -60 dB or more (DC, 50 Hz/60 Hz, 1 kΩ unbalance)
Zero-display range: 5 counts or less
Coupling type: AC coupling
Crest factor: For 4000 counts or less, 3

For greater than 4000 counts and less than or equal to 6000 counts, 2
For 850 V or less, 2 (1000 V range only)

For greater than 850 V and less than or equal to 1000 V, 1.7
Peak detection time width: 1 ms or more (Filter off)
Overload protection: Lower of 1870 V DC/1100 V AC or 2×10

7

V • Hz (energized for 1 minute)

Transient overvoltage: 8000 V

57

Accuracy Table

AC voltage (Measurement value/MAX/MIN/AVG)

Range

(Accuracy
guarantee
range)

Resolution

Accuracy
guarantee
frequency range*

Measurement accuracy Input

impedance
(at AC 50 Hz)

Filter off Filter on

6.000 V (0.000 V to

0.299 V)

0.001 V 15 Hz≤f<45 Hz ±1.5% rdg.±0.015 V ±2.0% rdg.
±0.015 V

3.2 M

Ω

±5%

45 Hz≤f≤66 Hz ±0.9% rdg.±0.013 V ±1.4% rdg.

±0.013 V

66 Hz<f≤1 kHz ±1.5% rdg.±0.015 V -

6.000 V (0.300 V to

6.000 V)

0.001 V 15 Hz≤f<45 Hz ±1.5% rdg.±0.005 V ±2.0% rdg.
±0.005 V

3.2 M

Ω

±5%

45 Hz≤f≤66 Hz ±0.9% rdg.±0.003 V ±1.4% rdg.

±0.003 V

66 Hz<f≤1 kHz ±1.5% rdg.±0.005 V -

60.00 V (3.00 V to

60.00 V)

0.01 V 15 Hz≤f<45 Hz ±1.5% rdg.±0.05 V ±2.0% rdg.±0.05 V 3.1 M

Ω

±5%
45 Hz≤f≤66 Hz ±0.9% rdg.±0.03 V ±1.4% rdg.±0.03 V
66 Hz<f≤1 kHz ±1.5% rdg.±0.05 V -

600.0 V (30.0 V to

600.0 V)

0.1 V 15 Hz≤f<45 Hz ±1.5% rdg.±0.5 V ±2.0% rdg.±0.5 V 3.0 M

Ω

±5%
45 Hz≤f≤66 Hz ±0.9% rdg.±0.3 V ±1.4% rdg.±0.3 V
66 Hz<f≤1 kHz ±1.5% rdg.±0.5 V -

1000 V (50 V to

1000 V)

1 V 15 Hz≤f<45 Hz ±1.5% rdg.±5 V ±2.0% rdg.±5 V 3.0 M

Ω

±5%
45 Hz≤f≤66 Hz ±0.9% rdg.±3 V ±1.4% rdg.±3 V
66 Hz<f≤1 kHz ±1.5% rdg.±5 V -

Auto range movement threshold: 6000 counts or more for upper range, 540 counts or less for lower range

.

* Frequency range of 15 Hz≤f<20 Hz is designed value.

Within the frequency range of f<45 Hz, the accuracy guarantee assumes a superposed DC voltage of less
than 500 V.

58

Accuracy Table

AC voltage (PEAK MAX/PEAK MIN)

Range

(Accuracy guarantee
range)

Resolution

Accuracy guarantee
frequency range*

1

Measurement accuracy

6.000 V (0 V to ±12.00 V) 0.01 V 15 Hz≤f<45 Hz ±1.8% rdg.±0.07 V
45 Hz≤f≤66 Hz ±1.5% rdg.±0.07 V
66 Hz<f≤1 kHz ±1.8% rdg.±0.07 V

60.00 V (±3.0 V to ±120.0 V) 0.1 V 15 Hz≤f<45 Hz ±1.8% rdg.±0.7 V
45 Hz≤f≤66 Hz ±1.5% rdg.±0.7 V
66 Hz<f≤1 kHz ±1.8% rdg.±0.7 V

600.0 V (±30 V to ±1000 V)*

2

1 V 15 Hz≤f<45 Hz ±1.8% rdg.±7 V

45 Hz≤f≤66 Hz ±1.5% rdg.±7 V
66 Hz<f≤1 kHz ±1.8% rdg.±7 V

1000 V (±50 V to ±1000 V)*

3

1 V 15 Hz≤f<45 Hz ±1.8% rdg.±7 V

45 Hz≤f≤66 Hz ±1.5% rdg.±7 V
66 Hz<f≤1 kHz ±1.8% rdg.±7 V

Maximum display count for all ranges: 1200/1700 counts
*1 Frequency range of 15 Hz≤f<20 Hz is designed value.

Within the frequency range of f<45 Hz, the accuracy guarantee assumes a superposed DC voltage of less
than 500 V.

*2 Values of up to ±1200 V are displayed, but accuracy is not dened for display values in excess of 1000 V

(which are provided as reference values).

*3 Values of up to ±1700 V are displayed, but accuracy is not dened for display values in excess of 1000 V

(which are provided as reference values).

59

Accuracy Table

10

DC voltage and auto V DC detection

NMRR: -60 dB or more (50 Hz/60 Hz)
CMRR: -100 dB or more (DC, 50 Hz/60 Hz, 1 k

Ω

unbalance)
Coupling type: DC coupling
Peak detection time width: 1 ms or more (Filter off)
Overload protection: Lower of 1870 V DC/1100 V AC or 2×10

7

V • Hz (energized for 1 minute)

DC voltage (Measurement value/MAX/MIN/AVG)

Range (Accuracy guarantee range) Resolution Measurement accuracy

Input impedance
(DC input)

600.0 mV (0.0 mV to ±600.0 mV) 0.1 mV ±0.5% rdg.±0.5 mV 6.7 M

Ω

±5%

6.000 V (0.000 V to ±6.000 V) 0.001 V ±0.5% rdg.±0.003 V 6.7 M

Ω

±5%

60.00 V (0.00 V to ±60.00 V) 0.01 V ±0.5% rdg.±0.03 V 6.1 M

Ω

±5%

600.0 V (0.0 V to ±600.0 V) 0.1 V ±0.5% rdg.±0.3 V 6.0 M

Ω

±5%

1500 V* (0 V to ±1000 V) 1 V ±0.5% rdg.±3 V

6.0 M

Ω

±5%

(±1001 V to ±1700 V) 1 V ±2.0% rdg.±5 V

Auto range movement threshold: 6000 counts or more for upper range, 540 counts or less for lower range.
* In the 1500 V range, the instrument can withstand input of up to 1000 V continuously or input in excess of

1000 V for no greater than 1 minute.

60

Accuracy Table

DC voltage (PEAK MAX/PEAK MIN Zero to Peak)

Range (Accuracy guarantee range) Resolution Measurement accuracy

600.0 mV (0 mV to ±1200 mV) 1 mV ±1.0% rdg.±7 mV

6.000 V (0.00 V to ±12.00 V) 0.01 V ±1.0% rdg.±0.07 V

60.00 V (0.0 V to ±120.0 V) 0.1 V ±1.0% rdg.±0.7 V

600.0 V (0 V to ±1000 V) 1 V ±1.0% rdg.±7 V
(±1001 V to ±1200 V) 1 V ±5.0% rdg.±7 V

1500 V (0 V to ±1000 V) 1 V ±1.0% rdg.±7 V

(±1001 V to ±1700 V) 1 V ±5.0% rdg.±7 V

11

AC+DC voltage and auto V AC detection

CMRR: -60 dB or more (DC, 50 Hz/60 Hz, 1 kΩ unbalance)
Zero-display range: 5 counts or less
Coupling type: DC coupling
Crest factor: For 4000 counts or less, 3

For greater than 4000 counts and less than or equal to 6000 counts, 2
For 850 V or less, 2 (1000 V range only)

For greater than 850 V and less than or equal to 1000 V, 1.7
Peak detection time width: 1 ms or more (Filter off)
Overload protection: Lower of 1870 V DC/1100 V AC or 2×10

7

V • Hz (energized for 1 minute)

Transient overvoltage: 8000 V

61

Accuracy Table

AC+DC voltage (Measurement value/MAX/MIN/AVG)

Range
(Accuracy
guarantee range)

Resolution

Accuracy
guarantee
frequency range*

Measurement accuracy Input impedance

(DC input,

AC 50 Hz input)

Filter off Filter on

6.000 V

(0.000 V
to 0.299 V)

0.001 V 10 Hz≤f<45 Hz ±1.5% rdg.±0.023 V ±2.0% rdg.±0.023 V DC: 6.7 M

Ω

±5%

AC: 3.2 M

Ω

±5%

DC,

45 Hz≤f≤66 Hz

±1.0% rdg.±0.023 V ±1.5% rdg.±0.023 V

66 Hz<f≤1 kHz ±1.5% rdg.±0.023 V -

6.000 V

(0.300 V
to 6.000 V)

0.001 V 10 Hz≤f<45 Hz ±1.5% rdg.±0.013 V ±2.0% rdg.±0.013 V DC: 6.7 MΩ±5%
AC: 3.2 M

Ω

±5%

DC,

45 Hz≤f≤66 Hz

±1.0% rdg.±0.013 V ±1.5% rdg.±0.013 V

66 Hz<f≤1 kHz ±1.5% rdg.±0.013 V -

60.00 V

(3.00 V to

60.00 V)

0.01 V 10 Hz≤f<45 Hz ±1.5% rdg.±0.13 V ±2.0% rdg.±0.13 V DC: 6.1 MΩ±5%
AC: 3.1 M

Ω

±5%

DC,

45 Hz≤f≤66 Hz

±1.0% rdg.±0.13 V ±1.5% rdg.±0.13 V

66 Hz<f≤1 kHz ±1.5% rdg.±0.13 V -

600.0 V

(30.0 V to

600.0 V)

0.1 V 10 Hz≤f<45 Hz ±1.5% rdg.±0.7 V ±2.0% rdg.±0.7 V DC: 6.0 MΩ±5%
AC: 3.0 M

Ω

±5%

DC,

45 Hz≤f≤66 Hz

±1.0% rdg.±0.7 V ±1.5% rdg.±0.7 V

66 Hz<f≤1 kHz ±1.5% rdg.±0.7 V -

1000 V

(50 V to
1000 V)

1 V 10 Hz≤f<45 Hz ±1.5% rdg.±7 V ±2.0% rdg.±7 V DC: 6.0 MΩ±5%

AC: 3.0 M

Ω

±5%

DC,

45 Hz≤f≤66 Hz

±1.0% rdg.±7 V ±1.5% rdg.±7 V

66 Hz<f≤1 kHz ±1.5% rdg.±7 V -

Auto range movement threshold: 6000 counts or more for upper range, 540 counts or less for lower range.
* Frequency range of 10 Hz≤f<20 Hz is designed value.

62

Accuracy Table

AC+DC voltage (PEAK MAX/PEAK MIN)

Range

(Accuracy guarantee
range)

Resolution

Accuracy guarantee
frequency range*

1

Measurement accuracy

6.000 V (0.00 V to ±12.00 V) 0.01 V 10 Hz≤f<45 Hz ±1.5% rdg.±0.07 V
DC, 45 Hz≤f≤66 Hz ±1.0% rdg.±0.07 V
66 Hz<f≤1 kHz ±1.5% rdg.±0.07 V

60.00 V (±3.0 V to ±120.0 V) 0.1 V 10 Hz≤f<45 Hz ±1.5% rdg.±0.7 V
DC, 45 Hz≤f≤66 Hz ±1.0% rdg.±0.7 V
66 Hz<f≤1 kHz ±1.5% rdg.±0.7 V

600.0 V*

2

(±30 V to ±1000 V) 1 V 10 Hz≤f<45 Hz ±1.5% rdg.±7 V

DC, 45 Hz≤f≤66 Hz ±1.0% rdg.±7 V
66 Hz<f≤1 kHz ±1.5% rdg.±7 V

1000 V*

3

(±50 V to ±1000 V) 1 V 10 Hz≤f<45 Hz ±1.5% rdg.±7 V

DC, 45 Hz≤f≤66 Hz ±1.0% rdg.±7 V
66 Hz<f≤1 kHz ±1.5% rdg.±7 V

*1 Frequency range of 10 Hz≤f<20 Hz is designed value.
*2 Values of up to ±1200 V are displayed, but accuracy is not dened for display values in excess of 1000 V

(which are provided as reference values).

*3 Values of up to ±1700 V are displayed, but accuracy is not dened for display values in excess of 1000 V

(which are provided as reference values).

63

Accuracy Table

12

Frequency (same for all models)

Frequency is displayed at the same time as the AC current/AC voltage (the frequency is shown on the sub­display when performing ACA/ACV detection with the auto A/auto V function or when using the ACA/ACV
function, and on the main display when using the Hz function).

Only auto-range operation is available when performing frequency measurement using the ACA/ACV function
(the RANGE key is used to switch the current/voltage range).

Minimum detectable current/voltage:
AC voltage 10% of each range’s f.s. value

AC current 20.00 A range 4.00 A or more (CM4371, CM4372)

600.0 A range 20.0 A or more (CM4371, CM4372)

600.0 A range 40.0 A or more (CM4373, CM4374)
2000 A range 200 A or more (CM4373, CM4374)

In the following circumstances, the instrument will display [----Hz] as the value is outside the measurement
range:

• Less than 1 Hz.

• If the AC current or AC voltage is less than the minimum detectable current or voltage or outside the input

range.

• If there is a superposed DC component when performing ACA/ACV detection with the auto A/auto V

function.

64

Accuracy Table

Frequency (Measurement value/MAX/MIN/AVG)

Range (Accuracy guarantee range) Resolution Measurement accuracy

9.999 Hz (1.000 Hz to 9.999 Hz) 0.001 Hz ±0.1% rdg.±0.003 Hz

99.99 Hz (1.00 Hz to 99.99 Hz) 0.01 Hz ±0.1% rdg.±0.01 Hz

999.9 Hz (1.0 Hz to 999.9 Hz) 0.1 Hz ±0.1% rdg.±0.1 Hz

Auto range movement threshold: 9999 counts or more for upper range, 900 counts or less for lower range.

13

Continuity check (same for all models)

Continuity on threshold: 25 Ω±10 Ω (continuous buzzer sound, red warning backlight lights up)
Continuity off threshold: 245

Ω

±10

Ω

Conditions of guaranteed accuracy: After zero adjustment has been performed
Response time: Detection of open or short for 0.5 ms or more
Overload protection: Lower of 1700 V/1000 V AC or 2×10

7

V • Hz (energized for 1 minute)

Overload current: 30 mA or less at steady state, 1.5 A or less at transient state

Range

(Accuracy
guarantee range)

Resolution

Measurement
current

Measurement
accuracy

Open terminal
voltage

600.0

Ω

(0.0 Ω to 600.0 Ω) 0.1

Ω

200 µA±20% ±0.7% rdg.±0.5

Ω

2.0 V DC or less

65

Accuracy Table

14

Resistance measurement (same for all models)

Maximum capacity load: 10 mF
Maximum inductive load: 10 H
Conditions of guaranteed accuracy: After zero adjustment has been performed
Overload protection: Lower of 1700 V DC/1000 V AC or 2×10

7

V • Hz (energized for 1 minute)

Overload current: 30 mA or less at steady state, 1.5 A or less at transient state

Resistance measurement (Measurement value/MAX/MIN/AVG)

Range

(Accuracy guarantee
range)

Resolution

Measurement
current

Measurement accuracy

Open terminal
voltage

600.0

Ω

(0.0 Ω to 600.0 Ω) 0.1

Ω

200 µA±20% ±0.7% rdg.±0.5

Ω

2.0 V DC or
less

6.000 k

Ω

(0.000 kΩ to 6.000 kΩ) 0.001 k

Ω

100 µA±20% ±0.7% rdg.±0.005 k

Ω

2.0 V DC or
less

60.00 k

Ω

(0.00 kΩ to 60.00 kΩ) 0.01 k

Ω

10 µA±20% ±0.7% rdg.±0.05 k

Ω

2.0 V DC or
less

600.0 k

Ω

(0.0 kΩ to 600.0 kΩ) 0.1 k

Ω

1 µA±20% ±0.7% rdg.±0.5 k

Ω

2.0 V DC or
less

Auto range movement threshold: 6000 counts or more for upper range, 540 counts or less for lower range.

66

Accuracy Table

15

Diode (same for all models)

Overload protection: Lower of 1700 V DC/1000 V AC or 2×107 V • Hz (energized for 1 minute)
Overload current: 30 mA or less at steady state, 1.5 A or less at transient state

Range

(Accuracy guarantee
range)

Resolution Short-circuit current

Measurement
accuracy

Open terminal
voltage

1.800 V (0.000 V to 1.800 V) 0.001 V 200 µA±20% ±0.7% rdg.±0.005 V 2.0 V DC or less

Beeping buzzer tone at forward connection (0.15 V to 1.8 V).
Continuous buzzer tone and red backlight lights up if less than 0.15 V.

16

Electrostatic capacity (same for all models)

Overload protection: Lower of 1700 V DC/1000 V AC or 2×107 V • Hz (energized for 1 minute)
Overload current: 30 mA or less at steady state, 1.5 A or less at transient state

67

Accuracy Table

Electrostatic capacity (Measurement value/MAX/MIN/AVG)

Range

(Accuracy guarantee
range)

Resolution Discharge current

Measurement
accuracy

Open
terminal
voltage

1.000 µF (0.000 µF to 1.100 µF) 0.001 µF 10 n/100 n/1 µA±20% ±1.9% rdg.±0.005 µF 2.0 V DC

or less

10.00 µF (0.00 µF to 11.00 µF) 0.01 µF 100 n/1 µ/10 µA±20% ±1.9% rdg.±0.05 µF 2.0 V DC

or less

100.0 µF (0.0 µF to 110.0 µF) 0.1 µF 1 µ/10 µ/100 µA±20% ±1.9% rdg.±0.5 µF 2.0 V DC

or less

1000 µF (0 µF to 1100 µF) 1 µF

10 µ/100 µ/200 µA±20%

±1.9% rdg.±5 µF 2.0 V DC

or less

Auto range movement threshold: 1100 counts or more for upper range, 100 counts or less for lower range.

17

Temperature (same for all models)

Thermocouple: Use the DT4910 Thermocouples (K).

Accuracy gures do not include the DT4910 Thermocouples (K)
error component. [DT4910 error: ±2.5°C (Class 2)]

Instrument reference contact temperature
correction stabilization time:

120 minutes (when ambient temperature is varied abruptly from
60°C to 23°C)

Overload protection: Lower of 1700 V DC/1000 V AC or 2×10

7

V • Hz (energized for 1

minute)

Overload current: 30 mA or less at steady state, 1.5 A or less at transient state

68

Accuracy Table

Temperature (Measurement value/MAX/MIN/AVG)

Thermocouple type Range Resolution Accuracy*

1

K

-40.0°C to 400.0°C 0.1°C ±0.5% rdg.±3.0°C

-40°F to 752°F*

2

0.1°F ±0.5% rdg.±5.4°F

*1: In an environment where the temperature of the instrument is ±1°C and stable, the accuracy is specied.
*2: Instrument can be made to display readings in Fahrenheit (°F) by means of special operation.

18

Electric charge detection

During voltage detection, a continuous buzzer sounds and the red warning backlight lights up.

Range (detection sensitivity) Detection voltage range* Detection target frequency

Hi 40 V AC to 600 V AC 50 Hz/60 Hz

Lo 80 V AC to 600 V AC 50 Hz/60 Hz

* In contact with the insulated wire that is equivalent to IV2 mm

2

.

69

Accuracy Table

19

DC power 600.0 A (CM4371, CM4372)

Displays the product of DC current and DC voltage.
Accuracy guarantee conditions, zero-display range, connection method, and band depend on the DC current
and DC voltage.

Display range switching* Minimum resolution Measurement accuracy

0.0 VA to 1020 kVA 0.1 VA ±2.0% rdg.±20 dgt.

* Switches the display range automatically based on the voltage range.

20

DC power 2000 A (CM4373, CM4374)

Displays the product of DC current and DC voltage.
Accuracy guarantee conditions, zero-display range, connection method, and band depend on the DC current
and DC voltage.

Display range switching* Minimum resolution Measurement accuracy

0.000 kVA to 3400 kVA 1 VA ±2.0% rdg.±20 dgt.

* Switches the display range automatically based on the voltage range.