AC/DC CLAMP METER
HIOKI CM4371A971-00
Feb. 2021 Edition 1
CM4371A971-0
5 Commonwealth Ave
Woburn, MA 01801
Phone 781-665-1400
Toll
Free 1-800-517-8431
CM4371
CM4372
CM4373
CM4374
Instruction Manual
EN
HIOKI CM4371A971-00
Video
Scan this code to watch an
instructional video.
Carrier charges may apply.
Operating Precautions
HIOKI CM4371A971-00
Your instrument can be used to measure voltages in excess of 1000 V
DC if and only if both of the following conditions are satisfied:
1. The circuit under measurement is isolated from the commercial
power grid.
2. The circuit under measurement is isolated from ground.
e.g.: when measuring the no-load voltage of an ungrounded PV panel
Do not use the instrument with circuits whose terminal-to-ground voltage
exceeds 1000 V. Doing so may result in electric shock.
CM4371A971-00
WARNING
HIOKI CM4371A971-00
Introduction ................................................................................................................1
HIOKI CM4371A971-00
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) ........................................................................24
Rush current (INRUSH) ............................................................................................25
Contents
i
Contents
HIOKI CM4371A971-00
Other Measurement Functions ...............................................................................26
Voltage .............................................................................................................26
Continuity Check ............................................................................................27
Resistance .......................................................................................................27
Diode ................................................................................................................27
Capacitance .....................................................................................................28
Temperature ....................................................................................................28
Electric Charge Detection ..............................................................................29
Simultaneous display of DC current and DC voltage ..................................29
DC power .........................................................................................................29
Bluetooth® Communications (only for CM4372, CM4374) ..................................................30
Power-on Option Table ............................................................................................35
Repairs, Inspections, and Cleaning .......................................................................37
Specications ...........................................................................................................40
Accuracy Table .........................................................................................................46
ii
Introduction
HIOKI CM4371A971-00
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.
Introduction
1
Introduction
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
HIOKI CM4371A971-00
Package contents
AC/DC Clamp Meter
* Instruction manuals may also be available in other languages. Please visit our website.
Trademark
• Bluetooth® is a registered trademark of Bluetooth SIG, Inc.(USA). The trademark is used by HIOKI E.E.
CORPORATION under license.
and Google Play are registered trademarks of Google, Inc.
• Android
• IOS is a registered trademark of Cisco in the U.S. and other countries.
• iPhone, iPad, iPad mini, iPad Pro, and iPod Touch are trademarks of Apple Inc.
• The App Store is a service mark of Apple Inc.
2
L9207-10 Test lead
C0203 Carrying Case
LR03 Alkaline battery × 2
Instruction Manual*
Precautions Concerning Use of
Equipment That Emits Radio Waves
(only for CM4372, CM4374)
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
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
9243 graber
L4937 マグネットアダプ
タ
DM4910 熱電対
HIOKI CM4371A971-00
Options (sold separately)
L9207-10 Test Lead *
4930 ConneL4930L
(Length: with the coupling m, 1.5
connector)
DT4910 Thermocouples (K)
C0203 Carrying CaseC0203
*1: CAT IV 600 V/ CAT III 1000 V/ CAT II 1000 V, 10 A
*2: CAT IV 600 V/ CAT III 1000 V, 10 A
*3: CAT III 1000 V, 2 A
*4: CAT III 600 V, 5 A
m)1.2(Length:
Extension L4931 Cable Set *
1
ction Cable Set
2
*
2
4933 ContaL ct Pin Set
6
*
L4934 Small Alligator Clip Set
L4935 Alligator Clip Set
2
*
L9243 Grabber Clip *9
LL4936 Bus Bar Clip Set *
4
L4937 Magnetic Adapter Set
9804 Magnetic Adapter *
L4932 Test Pin Set
L4938 Test Pin Set
8
1
*
7
*
L4939 Breaker Pin Set
*
5: CAT III 300 V/ CAT II 600 V, 3 A
*6: 30 V AC/ 60 V DC, 3 A
7: CAT III 600 V/ CAT II 600 V, 10 A
*
*8: CAT IV 1000 V, 2 A
*9: CAT II 1000 V, 1 A
5
*
3
*
4
*
3
Safety Notes
HIOKI CM4371A971-00
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.
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.
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.
4
DANGER
WARNING
Protective gear
HIOKI CM4371A971-00
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 classied as follows.
DANGER
WARNING
CAUTION
WARNING
Indicates an imminently
hazardous situation that will
result in death or serious injury
to the operator.
Indicates a potentially hazardous
situation that may result in death
or serious injury to the operator.
Indicates a potentially hazardous
situation that may result in
minor or moderate injury to
the operator or damage to the
instrument or malfunction.
IMPORTANT
Safety Notes
Indicates information related to
the operation of the instrument
or maintenance tasks with
which the operators must be
fully familiar.
Indicates prohibited actions.
Indicates the action which
must be performed.
5
Safety Notes
HIOKI CM4371A971-00
Symbols afxed 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 that dangerous voltage may
be present at this terminal.
Indicates that the instrument may be
connected to or disconnected from a
live conductor.
Indicates a instrument that has been
protected throughout by double
insulation or reinforced insulation.
Indicates that the product incorporates
Bluetooth
6
®
wireless technology.
Indicates DC (Direct Current) or AC
(Alternating Current).
Indicates DC (Direct Current).
Indicates a grounding terminal.
Indicates the Waste Electrical and
Electronic Equipment Directive (WEEE
Directive) in EU member states.
Indicates that the product conforms to
regulations set out by the EU Directive.
Measurement categories
HIOKI CM4371A971-00
This instrument conforms to the safety requirements for CAT III 1000 V, CAT IV 600 V
measuring instruments.
Distribution panel
Service entrance
Service drop
CAT IV
(≤600 V)
Power meter
Internal wiring
CAT III
(≤1000 V)
Fixed installation
Safety Notes
CAT II
(≤1000 V)
T
Outlet
7
Usage Notes
HIOKI CM4371A971-00
Usage Notes
Follow these precautions to ensure safe operation and to obtain the full benets of the various
functions.
Do not input a voltage or current in excess of the
measurement range indicated by the ratings and
specications 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, conrm 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.
8
DANGER
Do not allow the instrument to get wet, and do not take measurements with wet
HIOKI CM4371A971-00
hands. This may cause an electric shock.
To prevent electric shock, when measuring the voltage of a power line use a
test lead that satises 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 dened measurement category
and rated voltage.
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.
Usage Notes
WARNING
CAUTION
9
Usage Notes
HIOKI CM4371A971-00
Current measurement precautions
Do not touch.
Do not pinch wire
between jaws.
10
Do not clamp
around two wires.
NO
NO
Do not input
excessively high
currents.
NO
NO
(Red display)
Part Names
HIOKI CM4371A971-00
Front Rear
Part Names
Jaw
(clamp sensor)
Barrier
Operation
grip
SHIFT key
(Selects function
indicated in blue
lettering.)
(CM4372)
Rotary switch
HOLD key
LCD Display
Battery cover
Operation keys
Measurement
terminals
(p. 8)
11
Insert/Replace Batteries
HIOKI CM4371A971-00
Insert/Replace Batteries
• 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.
12
WARNING
Insert/Replace Batteries
HIOKI CM4371A971-00
Insert/Replace Batteries
1
5
Battery
indicator
4
2
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.
3
13
Inspection Before Measurement
NO
NONO
HIOKI CM4371A971-00
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 foreign matter on the
measurement terminals. (p. 11)
The test leads are not broken.
There is no damage to the test lead
insulation, and neither the white sheathing
nor metal conductor inside the wire are
exposed.
The instrument is neither damaged nor
cracked.
No indicators are missing.
OK
The battery voltage (p. 13) is sufcient.
14
1 Ω or less
(All lit up)
Current Measurement
HIOKI CM4371A971-00
1
Clamp the wire.
3
Current Measurement
e.g.: 3P4W (3-phase, 4-wire) circuit
breaker (AC current measurement)
2
Press for 1 sec.
→Perform zero adjustment
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
DC current polarity detection function (p. 35)
If the measured value is negative, the buzzer will
sound, and the display will turn red (threshold: -10 A).
4
(AUTO AC/DC)
(AC A)
Current
direction
(DC A)
(AC+DC A)
HzAUTO
15
Manual Hold / Auto Hold
HIOKI CM4371A971-00
Manual Hold / Auto Hold
MANUAL HOLD AUTO HOLD
Pressing the HOLD key again cancels
the measured value hold function.
16
→ Measured value retains.
→ blinks.
Press for 1 sec.
To measured
target
(Measured value stabilizes.)
Disconnect
Measured value automatically retains.
Pressing the HOLD key for 1 second cancels
the auto hold function.
Manual Hold / Auto Hold
HIOKI CM4371A971-00
Auto hold conditions
Display value updates are stopped when the following two conditions are satised:
• 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.
Held
measured
value
Measured
value
Auto hold
e.g.: 100.0 A
Fluctuation range
Fluctuation
range
Auto hold
e.g.: 99.0 A
Fluctuation range
Threshold value
e.g.: 12.0 A
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 satised again.
Start
End
End
Start
Measurement
Start
End
Time
17
Manual Hold / Auto Hold
HIOKI CM4371A971-00
Measurement function Fluctuation range Threshold value
AC current
DC current
AC+DC current
AC voltage
DC voltage
(excluding the 600.0 mV
range)
AC+DC voltage
Resistance, Continuity 600.0
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.
18
20.00 A range: within 100 counts
600.0 A range: within 120 counts
2000 A range: within 40 counts
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 kΩ/60.00 kΩ/600.0 kΩ
Ω
range: within 100 counts
20.00 A range: 100 counts
600.0 A range: 120 counts
2000 A range: 40 counts
6.000 V/ 60.00 V/ 600.0 V range:
120 counts
1000 V range: 20 counts
1500 V range: within 30 counts
600.0 Ω/6.000 kΩ/60.00 kΩ/600.0 kΩ
range: 4900 counts
Switching ranges
HIOKI CM4371A971-00
e.g. 1: Current measurement with the CM4373, CM4374
AUTO range MANUAL 2000 A rangeMANUAL 600.0 A range
e.g. 2: Current measurement with the CM4371, CM4372
Switching ranges
AUTO range
MANUAL 600.0 A rangeMANUAL 20.00 A range
19
Filter Function
HIOKI CM4371A971-00
Filter Function
FILTER OFF
Measured value including noise
Frequency characteristics when
using the lter
(600.0 A AC range, 100 A input)
Measurement value [A]
20
FILTER OFF
FILTER ON Passband 100 [Hz]
Frequency [Hz]
FILTER ON
Measured value with reduced noise
Press for
1 sec.
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
MAX/MIN/AVG/PEAK
HIOKI CM4371A971-00
1
2
3
4
The instrument
performs true RMS
measurement.
AUTO
(AUTO AC/DC)
→ Measured value retains.
PEAK MIN
(DC A)(AC A)
PEAK MAX
MAX
(AC+DC A)
MIN
MAX/MIN/AVG/PEAK
Hz
Can not be used at
AUTO AC/DC.
Press for 1 sec.
→Cancel
Waveform
Measured value
(RMS value)
AVG: The average
value of all the
measured values
Display refresh interval
21
Simultaneous display of DC current/voltage peak values
HIOKI CM4371A971-00
Simultaneous display of DC current/voltage peak values
Engine starts
1
Black
(p. 29)
Red
3
(PEAK occurrence)
2
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
The input current that equals to the trigger level or
less does not trigger any peak measurement.
22
Press for 1 sec.
→PEAK display ON
4
HIOKI CM4371A971-00
Simultaneous display of DC current/voltage peak values
While measuring currents, the instrument,
which measures peak values of current and
voltage alternately, does not display any
voltage values even when a voltage is applied.
To measure peak values of each of current and
voltage, perform measurement using the MAX/
MIN/AVG/PEAK procedure.
Press for 1 sec.
→Cancel
DC voltage
Trigger level
DC current
20 ms 50 ms 100 ms
Current
measurement
PEAK MAX
PEAK MIN
PEAK MIN
No
measurement
PEAK MAX
Voltage
measurement
23
Backlight / Auto Power Save (APS)
HIOKI CM4371A971-00
Backlight / Auto Power Save (APS)
Backlight
Backlight OFF
Backlight ON
Automatically switched off
when the instrument is not
in use for 40 s.
24
Auto Power Save (APS)
No operation for 15 min.
You can turn the display back on by
pressing a key or by turning the rotary
switch.
No operation for 45 min.
Power OFF
To restart the instrument, briey set the rotary switch to “OFF.”
(Always on)
Cancelation method: p. 35
Rush current (INRUSH)
HIOKI CM4371A971-00
Rush current (INRUSH)
MOTOR OFF
1
2
3
Clamp the wire.
4
600.0 A range (xed) (CM4371, CM4372)
Trigger level: ±10 A
2000 A range (xed) (CM4373, CM4374)
Trigger level: ±100 A
Press for 1 sec.
→Zero adjustment
5
Press for 1 sec.
→INRUSH ON
MOTOR ON
6
Rush current
7
occurrence
RMS value (INRUSH)
Example
screen: 100 A
AC current
Example screen: 250 A
Maximum wave height (PEAK)
Interval during which rush
current occurs
(Dozens to hundreds of
milliseconds in duration)
RMS value (INRUSH)
DC current
Maximum wave height (PEAK)
Interval during which rush
current occurs
(Dozens to hundreds of
milliseconds in duration)
25
Other Measurement Functions
HIOKI CM4371A971-00
Other Measurement Functions
Voltage
e.g.: commercial power supply (AC voltage measurement)
1
Do not input excessively
high voltage.
NO
(Red display)
26
2
Red Black
Do not touch.
NO
3
(AUTO AC/DC)
AUTO
(AC V)
(DC V)
(AC+DC V)
Hz
DC voltage polarity detection function (p. 35)
If the measured value is negative, the buzzer will
sound, and the display will turn red (threshold: −10 V).
Other Measurement Functions
HIOKI CM4371A971-00
Continuity Check
Zero adjustment
1
Press for 1 sec.
2
Red
(Red display)
Black
Resistance Diode
Zero adjustment
1
Press for 1 sec.
2
BlackRed
Red
Black
27
Other Measurement Functions
HIOKI CM4371A971-00
Capacitance
28
Red
Black
Temperature
DT4910
+
−
Black Red
To change the temperature display unit: p. 36
: when DT4910
is broken.
Other Measurement Functions
HIOKI CM4371A971-00
Electric Charge
Detection
Grip as shown in gure.
(Red display)
Simultaneous display of
DC current and DC voltage
e.g.: Checking a car battery
Black
The current range is xed:
600.0 A range (xed): CM4371, CM4372
2000 A range (xed): CM4373, CM4374
Red
Press for 1 sec.
→PEAK display
(p. 22)
DC power
e.g.: Solar power
system maintenance
29
Bluetooth® Communications (only for CM4372, CM4374)
HIOKI CM4371A971-00
Bluetooth® Communications (only for CM4372, CM4374)
The CM4372 and CM4374 are clamp-style meters with Bluetooth® (Bluetooth® Low Energy) support. When
the Bluetooth
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
2
3
4
®
function is enabled, you can review measurement data and create measurement reports on
Install the GENNECT Cross on your mobile device. (p. 31)
Enable the Bluetooth® function on the CM4372 or CM4374. (p. 32)
Launch the GENNECT Cross and pair it with the CM4372 or
CM4374. (p. 33)
Select the General Measurement, Logging (Recording), or
Waveform Graph function. (p. 34)
30
Press for
1 sec.
Installing the application software GENNECT Cross
HIOKI CM4371A971-00
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
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.
communications range varies greatly with distance from obstructions (walls, metal obstruction,
Bluetooth® Communications (only for CM4372, CM4374)
31
Bluetooth® Communications (only for CM4372, CM4374)
HIOKI CM4371A971-00
Turning on the Bluetooth® function
Bluetooth® function OFF Bluetooth® function ON
32
Press for 1 sec.
icon will ash when the instrument
is connected to a mobile device.
Bluetooth® Communications (only for CM4372, CM4374)
HIOKI CM4371A971-00
Pairing the app with the CM4372 or CM4374
2
• 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.
1
3
33
Bluetooth® Communications (only for CM4372, CM4374)
HIOKI CM4371A971-00
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
34
Logging (Recording)
Simple logging (up to 24 hours)
Waveform Graph
Simple oscilloscope
(voltage/current)
Power-on Option Table
HIOKI CM4371A971-00
Power-on Option Table
+
Canceling the auto power save
(APS) function
DC current and DC voltage
polarity detection function
(ON/OFF)
Displaying all indicators
(Version of software/Model
number)
Buzzer sound (ON/OFF)
Automatic backlight
deactivation (ON/OFF)
Turn on the power while pressing the operation key.
(Turn the rotary switch from OFF.)
Setting Operating instruction
Factory
setting
ON
(Set each time)
OFF Yes
− −
ON Yes
ON Yes
Setting
retained?
No
35
Power-on Option Table
HIOKI CM4371A971-00
Switching the temperature unit
36
Setting Operating instruction
Press for 1 sec.
To change the
temperature unit:
To save the setting:
Press for 1 sec.
Factory
setting
°C Ye s
Setting
retained?
Repairs, Inspections, and Cleaning
HIOKI CM4371A971-00
Cleaning
To clean the instrument, wipe it gently with a soft cloth moistened with water or mild detergent.
Troubleshooting
Symptom Verication and/or Solution
• The instrument is indicating
an abnormal measured
value for current.
Repairs, Inspections, and Cleaning
• 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
HIOKI CM4371A971-00
Symptom Verication and/or Solution
• When readings from the
instrument are compared
with those of another
clamp-on current meter, the
measured values differ.
• The current value is larger
than expected.
• A current value is displayed
even though there is no
input.
• A sound is being emitted
by the instrument’s clamp
sensor.
• The measured value does
not appear.
• No measured value is
displayed, even when the
test leads are shorted.
• Zero adjustment is
impossible.
38
• 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 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.
• The clamp sensor may emit sound when measuring AC currents in excess
of approx. 500 A, however, there is no effect on the measurement.
• Check the continuity of the test leads. (p. 27)
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.
Error display
HIOKI CM4371A971-00
Error display Description Solution
Err 001
Err 002
Err 005
Err 008
ROM error
Program
ROM error
Adjustment data
ADC error
Hardware malfunction
Bluetooth® error
Hardware malfunction
(only for
CM4372, CM4374)
Repairs, Inspections, and Cleaning
When the error appears in the display, it is
necessary to repair the instrument.
Please contact your authorized Hioki
distributor or reseller.
39
Specications
HIOKI CM4371A971-00
Specications
General Specications
Dimensions CM4371, CM4372: Approx. 65W × 215H × 35D mm (2.56″W × 8.46″H × 1.38″D)
Jaw dimensions CM4371, CM4372: Approx. 69W × 14D mm (2.72″W × 0.55″D)
Maximum measurable
conductor diameter
Mass CM4371, CM4372: Approx. 340 g (12.0 oz.) (excluding batteries)
Product warranty period 3 years
Operating environment Indoors, pollution degree 2, altitude up to 2000 m (6562 ft.)
Operating temperature
and humidity
Storage temperature and
humidity
40
CM4373, CM4374: Approx. 65W × 250H × 35D mm (2.56″W × 9.84″H × 1.38″D)
(excluding protruding parts, operation grip, and jaw)
CM4373, CM4374: Approx. 92W × 18D mm (3.62″W × 0.71″D)
CM4371, CM4372: φ33 mm
CM4373, CM4374: φ55 mm
CM4373, CM4374: Approx. 530 g (18.7 oz.) (excluding batteries)
(Measurement accuracy is dened in terms of a 1-year accuracy and a 3-year
accuracy.) (3 years: reference values)
Number of jaw open/close cycles: 30,000
-25°C to 65°C (-13°F to 149°F), 90% RH or less (no condensation)
-30°C to 70°C (-22°F to 158°F), 90% RH or less (no condensation)
Dustproof and waterproof Jaw, barrier: IP50
HIOKI CM4371A971-00
Electrical Characteristics
Display update rate
(measured value)
Maximum terminal-to-
terminal rated voltage
Maximum rated voltage
to earth
Rated supply voltage 1.5 V DC ×2
Specications
Grip: IP54 (when measuring an insulated conductor only)
Risk of electric shock from the conductor being measured increases when wet.
• 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)
(Dened within the measurement range (excluding range changes)).
1000 V AC (up to 1 kHz) /1700 V DC
1000 V AC (Measurement category III)
600 V AC (Measurement category IV)
Anticipated transient overvoltage: 8000 V
LR03 Alkaline battery ×2
41
Specications
HIOKI CM4371A971-00
Continuous operating
time
Standards
Safety EN61010
EMC EN61326
Specication for Model DT4910 Thermocouples (K)
Sensor type Thermocouples (K)
Tolerance ±2.5°C (Class 2)
Temperature measuring
junction
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
• 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
Exposed type (welding)
CM4372, CM4374 Individual Specications
HIOKI CM4371A971-00
Bluetooth® Function
Bluetooth® communications
function
External Interface Specications
Interface
Antenna power Maximum +0 dBm (1 mW)
Communications range Approx. 10 m (line of sight)
Communications prole GATT (Generic Attribute Prole)
Supported devices Supported iOS terminals: iOS 10 or later
Specications
Display of measured values on a smartphone or a tablet while using
®
Bluetooth
Bluetooth
(models supporting Bluetooth low energy only)
Supported Android terminals: Android 4.3 or later
(models supporting Bluetooth low energy only)
communications.
®
4.0LE ( )
43
Specications
HIOKI CM4371A971-00
Accuracy specications and measurement specications
Guaranteed accuracy period 1 year “Accuracy shown in accuracy table”
Guaranteed accuracy period
after adjustment made by Hioki
Guaranteed accuracy for
temperature and humidity
Temperature characteristic Within the operating temperature range, add “measurement accuracy ×
Other conditions When using the L4931 Extension Cable Set, accuracy is guaranteed for
AC measurement method True RMS measurement
Conditions of AC accuracy
guarantee
44
3 years (reference values) “Accuracy shown in accuracy table ×1.5”
1 year
23°C±5°C (73°F±9°F), 90% RH or less (no condensation)
0.1/°C” (excluding 23°C±5°C (73°F±9°F)).
up to two connected cables (totaling 3 m in length).
Sine wave input
AC current/DC current/AC+DC current common specication
HIOKI CM4371A971-00
Effects of conductor
position
Maximum allowable
input (AC/DC)
CM4371, CM4372: within ±1.5% rdg.
CM4373, CM4374: within ±1.0% rdg.
At all positions around the jaw’s center-point reference
CM4371, CM4372: 600 A continuous
CM4373, CM4374: 2000 A continuous
Frequency derating characteristics with continuous input (See the graph below)
Specications
Frequency derating characteristics
Maximum allowable input current [A]
Input current frequency [Hz]
(CM4371, CM4372)
Frequency derating characteristics
(CM4373, CM4374)
Input current frequency [Hz]
Maximum allowable input current [A]
45
Accuracy Table
HIOKI CM4371A971-00
Accuracy Table
Accuracy
We dene 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)
rdg.
(displayed value)
dgt.
(resolution)
AC current 20.00 A/600.0 A (CM4371, CM4372)
1
Conditions of guaranteed accuracy: After zero adjustment has been performed
Zero-display range:
Coupling type:
Crest factor:
Peak detection time width:
46
The maximum displayable value.
This is usually the name of the currently selected range.
The value currently being measured and displayed on the measuring instrument.
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-signicant digit.
5 counts or less
AC coupling
For the 20.00 A range, 7.5
For the 600.0 A range (300.0 A or less), 3
For the 600.0 A range (greater than 300.0 A and less than or equal
to 600.0 A), 1.5
1 ms or more (Filter off)
AC current (Measurement value/MAX/MIN/AVG)
HIOKI CM4371A971-00
Range
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
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
Auto range movement threshold: 2000 counts or more for upper range, 180 counts or less for lower range.
(Accuracy guarantee
range)
AC current (PEAK MAX/PEAK MIN)
Range
20.00 A (±1.0 A to ±150.0 A) 0.1 A 10 Hz≤f<45 Hz ±1.8% rdg.±0.7 A
600.0 A
Values of up to ±1500 A are displayed, but accuracy is not defined for display values in excess of 9
*
(Accuracy guarantee
range)
(±10 A to ±
(which are provided as reference values).
900
Resolution
Resolution
1 A 10 Hz≤f<45 Hz ±1.8% rdg.±7 A
A)*
Accuracy
guarantee
frequency range
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 -
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 -
Accuracy
guarantee
frequency range
45 Hz≤f≤66 Hz ±1.3% rdg.±0.7 A
66 Hz<f≤1 kHz ±2.0% rdg.±0.7 A
45 Hz≤f≤66 Hz ±1.3% rdg.±7 A
66 Hz<f≤1 kHz ±2.0% rdg.±7 A
Accuracy Table
Measurement accuracy
Filter off Filter on
Measurement accuracy
00
A
47
Accuracy Table
HIOKI CM4371A971-00
DC current and auto A DC detection 20.00 A/600.0 A (CM4371, CM4372)
2
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
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.
(Accuracy guarantee
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 ±900 A)*
* Values of up to ±1500 A are displayed, but accuracy is not defined for display values in excess of 900 A
(which are provided as reference values).
48
Resolution
Measurement accuracy
(Values apply regardless of whether the lter is on or off.)
1 A ±1.3% rdg.±7 A
AC+DC current and auto A AC detection 20.00 A/600.0 A (CM4371, CM4372)
HIOKI CM4371A971-00
3
Conditions of guaranteed accuracy: After zero adjustment has been performed
Zero-display range:
Coupling type:
Crest factor:
Peak detection time width:
AC+DC current (Measurement value/MAX/MIN/AVG)
(Accuracy guarantee
Range
range)
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
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
Auto range movement threshold: 2000 counts or more for upper range, 180 counts or less for lower range.
Accuracy Table
5 counts or less
DC coupling
For the 20.00 A range, 7.5
For the 600.0 A range (300.0 A or less), 3
For the 600.0 A range (greater than 300.0 A and less than or equal
to 600.0 A), 1.5
1 ms or more (Filter off)
Resolution
Accuracy guarantee
frequency range
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 -
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 -
Measurement accuracy
Filter off Filter on
49
Accuracy Table
HIOKI CM4371A971-00
AC+DC current (PEAK MAX/PEAK MIN)
Range
20.00 A (±1.0 A to ±150.0 A) 0.1 A 10 Hz≤f<45 Hz ±1.8% rdg.±0.7 A
600.0 A (±10 A to ±900 A)*
* Values of up to ±1500 A are displayed, but accuracy is not defined for display values in excess of 900 A
(which are provided as reference values).
4
Conditions of guaranteed accuracy: After zero adjustment has been performed
INRUSH trigger level:
Coupling type:
Crest factor:
Peak detection time width:
(Accuracy
guarantee range)
Rush current (INRUSH) 600.0 A (CM4371, CM4372)
50
Resolution
1 A 10 Hz≤f<45 Hz ±1.8% rdg.±7 A
Accuracy guarantee
frequency range
DC, 45 Hz≤f≤66 Hz ±1.3% rdg.±0.7 A
66 Hz<f≤1 kHz ±2.0% rdg.±0.7 A
DC, 45 Hz≤f≤66 Hz ±1.3% rdg.±7 A
66 Hz<f≤1 kHz ±2.0% rdg.±7 A
For 600.0 A range, detection of current of +10 A or more or -10 A or less
DC coupling
For the 600.0 A range (300.0 A or less), 3
For the 600.0 A range (greater than 300.0 A and less than or equal to
600.0 A), 1.5
1 ms or more
Measurement accuracy
Rush Current (INRUSH)
HIOKI CM4371A971-00
(Accuracy
Range
guarantee range)
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
600.0 A (±10 A to ±900 A)*
* Values of up to ±1500 A are displayed, but accuracy is not defined for display values in excess of 900 A
(which are provided as reference values).
5
Conditions of guaranteed accuracy:
Zero-display range:
Coupling type:
Crest factor:
Peak detection time width:
(Accuracy
guarantee range)
AC current 600.0 A/2000 A (CM4373, CM4374)
Resolution
Resolution
1 A DC, 20 Hz≤f≤500 Hz ±6.0% rdg.±10 A
Accuracy guarantee
frequency range
Accuracy guarantee
frequency range
After zero adjustment has been performed
5 counts or less
AC coupling
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
1 ms or more (Filter off)
Measurement accuracy
(Values apply regardless of whether the
lter is on or off.)
Measurement accuracy
Accuracy Table
51
Accuracy Table
HIOKI CM4371A971-00
AC current (Measurement value/MAX/MIN/AVG)
Range
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
2000 A (10 A to 1800 A) 1 A 10 Hz≤f<45 Hz ±1.8% rdg.±5 A ±2.3% rdg.±5 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.
(Accuracy
guarantee range)
(1801 A to 2000 A) 1 A 10 Hz≤f<45 Hz ±2.8% rdg.±5 A ±3.3% rdg.±5 A
52
Resolution
Accuracy guarantee
frequency range
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 -
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 -
45 Hz≤f≤66 Hz ±2.3% rdg.±3 A ±2.8% rdg.±3 A
66 Hz<f≤1 kHz - -
Measurement accuracy
Filter off Filter on
AC current (PEAK MAX/PEAK MIN)
HIOKI CM4371A971-00
Range
600.0 A (±10 A to ±1500 A) 1 A 10 Hz≤f<45 Hz ±1.8% rdg.±7 A
2000 A (±10 A to ±2300 A) 1 A 10 Hz≤f<45 Hz ±1.8% rdg.±7 A
6
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)
(Accuracy guarantee
range)
(±2301 A to ±2840 A) 1 A 10 Hz≤f<45 Hz ±6.5% rdg.±7 A
DC current and auto A DC detection 600.0 A/2000 A (CM4373, CM4374)
Resolution
Accuracy guarantee
frequency range
45 Hz≤f≤66 Hz ±1.3% rdg.±7 A
66 Hz<f≤1 kHz ±2.0% rdg.±7 A
45 Hz≤f≤66 Hz ±1.3% rdg.±7 A
66 Hz<f≤1 kHz ±2.0% rdg.±7 A
45 Hz≤f≤66 Hz ±6.0% rdg.±7 A
66 Hz<f≤1 kHz -
Measurement accuracy
Accuracy Table
53
Accuracy Table
HIOKI CM4371A971-00
DC current (Measurement value/MAX/MIN/AVG)
Range
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.
(Accuracy guarantee
range)
DC current (PEAK MAX/PEAK MIN)
Range
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
(Accuracy guarantee
range)
(±2301 A to ±2840 A) 1 A ±6.0% rdg.±7 A
54
Resolution
Resolution Measurement accuracy
Measurement accuracy
(Values apply regardless of whether the lter is on or off.)
AC+DC current and auto A AC detection 600.0 A/2000 A (CM4373, CM4374)
HIOKI CM4371A971-00
7
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
Peak detection time width: 1 ms or more (Filter off)
AC+DC current (Measurement value/MAX/MIN/AVG)
Range
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
2000 A (10 A to 1800 A) 1 A 10 Hz≤f<45 Hz ±1.8% rdg.±7 A ±2.3% rdg.±7 A
Auto range movement threshold: 6000 counts or more for upper range, 540 counts or less for lower range.
(Accuracy
guarantee range)
(1801 A to 2000 A) 1 A 10 Hz≤f<45 Hz ±2.8% rdg.±7 A ±3.3% rdg.±7 A
Accuracy Table
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
Resolution
Accuracy guarantee
frequency range
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 −
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 −
DC, 45 Hz≤f≤66 Hz ±2.3% rdg.±13 A ±2.8% rdg.±13 A
66 Hz<f≤1 kHz − −
Measurement accuracy
Filter off Filter on
55
Accuracy Table
HIOKI CM4371A971-00
AC+DC current (PEAK MAX/PEAK MIN)
Range
600.0 A (±10 A to ±1500 A) 1 A 10 Hz≤f<45 Hz ±1.8% rdg.±7 A
2000 A (±10 A to ±2300 A) 1 A 10 Hz≤f<45 Hz ±1.8% rdg.±7 A
8
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
Coupling type: DC coupling
Crest factor: For the 2000 A range (1000 A or less), 2.84
Peak detection time width: 1 ms or more
(Accuracy guarantee
range)
(±2301 A to ±2840 A) 1 A 10 Hz≤f<45 Hz ±6.5% rdg.±7 A
Rush Current (INRUSH) 2000 A (CM4373, CM4374)
56
Resolution
less
For the 2000 A range (greater than 1000 A and less than or equal to
2000 A), 1.42
Accuracy guarantee
frequency range
DC, 45 Hz≤f≤66 Hz ±1.3% rdg.±7 A
66 Hz<f≤1 kHz ±2.0% rdg.±7 A
DC, 45 Hz≤f≤66 Hz ±1.3% rdg.±7 A
66 Hz<f≤1 kHz ±2.0% rdg.±7 A
DC, 45 Hz≤f≤66 Hz ±6.0% rdg.±7 A
66 Hz<f≤1 kHz -
Measurement accuracy
Rush Current (INRUSH) of AC+DC current
HIOKI CM4371A971-00
Range (Accuracy guarantee range) Resolution
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
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
AC voltage
9
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
Peak detection time width: 1 ms or more (Filter off)
Overload protection: Lower of 1870 V DC/1100 V AC or 2×10
Transient overvoltage: 8000 V
Accuracy Table
Accuracy guarantee
frequency range
Accuracy guarantee
frequency range
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
7
V • Hz (energized for 1 minute)
Measurement accuracy
Measurement accuracy
57
Accuracy Table
HIOKI CM4371A971-00
AC voltage (Measurement value/MAX/MIN/AVG)
(Accuracy
Range
guarantee
range)
6.000 V (0.000 V to
0.299 V)
6.000 V (0.300 V to
6.000 V)
60.00 V (3.00 V to
60.00 V)
600.0 V (30.0 V to
600.0 V)
1000 V (50 V to
1000 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
Resolution
guarantee
frequency range*
0.001 V 15 Hz≤f<45 Hz ±1.5% rdg.±0.015 V ±2.0% rdg.
45 Hz≤f≤66 Hz ±0.9% rdg.±0.013 V ±1.4% rdg.
Accuracy
0.001 V 15 Hz≤f<45 Hz ±1.5% rdg.±0.005 V ±2.0% rdg.
0.01 V 15 Hz≤f<45 Hz ±1.5% rdg.±0.05 V ±2.0% rdg.±0.05 V 3.1 M
0.1 V 15 Hz≤f<45 Hz ±1.5% rdg.±0.5 V ±2.0% rdg.±0.5 V 3.0 M
1 V 15 Hz≤f<45 Hz ±1.5% rdg.±5 V ±2.0% rdg.±5 V 3.0 M
66 Hz<f≤1 kHz ±1.5% rdg.±0.015 V -
45 Hz≤f≤66 Hz ±0.9% rdg.±0.003 V ±1.4% rdg.
66 Hz<f≤1 kHz ±1.5% rdg.±0.005 V -
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 -
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 -
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 -
Measurement accuracy Input
Filter off Filter on
±0.015 V
±0.013 V
±0.005 V
±0.003 V
impedance
(at AC 50 Hz)
3.2 MΩ±5%
3.2 M
±5%
Ω
±5%
Ω
±5%
Ω
±5%
Ω
.
AC voltage (PEAK MAX/PEAK MIN)
HIOKI CM4371A971-00
Range
6.000 V (0 V to ±12.00 V) 0.01 V 15 Hz≤f<45 Hz ±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
600.0 V (±30 V to ±1000 V)*
1000 V (±50 V to ±1000 V)*
Maximum display count for all ranges: 1200/1700 counts
*1 Frequency range of 15 Hz≤f<20 Hz is designed value.
*2 Values of up to ±1200 V are displayed, but accuracy is not dened for display values in excess of 1000 V
*3 Values of up to ±1700 V are displayed, but accuracy is not dened for display values in excess of 1000 V
(Accuracy guarantee
range)
Within the frequency range of f<45 Hz, the accuracy guarantee assumes a superposed DC voltage of less
than 500 V.
(which are provided as reference values).
(which are provided as reference values).
Resolution
2
1 V 15 Hz≤f<45 Hz ±1.8% rdg.±7 V
3
1 V 15 Hz≤f<45 Hz ±1.8% rdg.±7 V
Accuracy guarantee
frequency range*
45 Hz≤f≤66 Hz ±1.5% rdg.±0.07 V
66 Hz<f≤1 kHz ±1.8% rdg.±0.07 V
45 Hz≤f≤66 Hz ±1.5% rdg.±0.7 V
66 Hz<f≤1 kHz ±1.8% rdg.±0.7 V
45 Hz≤f≤66 Hz ±1.5% rdg.±7 V
66 Hz<f≤1 kHz ±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
Measurement accuracy
1
Accuracy Table
59
Accuracy Table
HIOKI CM4371A971-00
DC voltage and auto V DC detection
10
NMRR: -60 dB or more (50 Hz/60 Hz)
CMRR: -100 dB or more (DC, 50 Hz/60 Hz, 1 k
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
DC voltage (Measurement value/MAX/MIN/AVG)
Range (Accuracy guarantee range) Resolution Measurement accuracy
600.0 mV (0.0 mV to ±600.0 mV) 0.1 mV ±0.5% rdg.±0.5 mV 6.7 M
6.000 V (0.000 V to ±6.000 V) 0.001 V ±0.5% rdg.±0.003 V 6.7 M
60.00 V (0.00 V to ±60.00 V) 0.01 V ±0.5% rdg.±0.03 V 6.1 M
600.0 V (0.0 V to ±600.0 V) 0.1 V ±0.5% rdg.±0.3 V 6.0 M
1500 V* (0 V to ±1000 V) 1 V ±0.5% rdg.±3 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.
(±1001 V to ±1700 V) 1 V ±2.0% rdg.±5 V
60
unbalance)
Ω
7
V • Hz (energized for 1 minute)
Input impedance
(DC input)
Ω
Ω
Ω
Ω
6.0 M
Ω
±5%
±5%
±5%
±5%
±5%
DC voltage (PEAK MAX/PEAK MIN Zero to Peak)
HIOKI CM4371A971-00
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
1500 V (0 V to ±1000 V) 1 V ±1.0% rdg.±7 V
11
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
Peak detection time width: 1 ms or more (Filter off)
Overload protection: Lower of 1870 V DC/1100 V AC or 2×10
Transient overvoltage: 8000 V
(±1001 V to ±1200 V) 1 V ±5.0% rdg.±7 V
(±1001 V to ±1700 V) 1 V ±5.0% rdg.±7 V
AC+DC voltage and auto V AC detection
Accuracy Table
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
7
V • Hz (energized for 1 minute)
61
Accuracy Table
HIOKI CM4371A971-00
AC+DC voltage (Measurement value/MAX/MIN/AVG)
Range
(Accuracy
guarantee range)
6.000 V
(0.000 V
to 0.299 V)
6.000 V
(0.300 V
to 6.000 V)
(3.00 V to
60.00 V
60.00 V)
600.0 V
(30.0 V to
600.0 V)
1000 V
(50 V to
1000 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
Resolution
guarantee
frequency range*
Accuracy
0.001 V 10 Hz≤f<45 Hz ±1.5% rdg.±0.023 V ±2.0% rdg.±0.023 V DC: 6.7 MΩ±5%
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%
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%
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%
1 V 10 Hz≤f<45 Hz ±1.5% rdg.±7 V ±2.0% rdg.±7 V DC: 6.0 MΩ±5%
DC,
45 Hz≤f≤66 Hz
66 Hz<f≤1 kHz ±1.5% rdg.±0.023 V -
DC,
45 Hz≤f≤66 Hz
66 Hz<f≤1 kHz ±1.5% rdg.±0.013 V -
DC,
45 Hz≤f≤66 Hz
66 Hz<f≤1 kHz ±1.5% rdg.±0.13 V -
DC,
45 Hz≤f≤66 Hz
66 Hz<f≤1 kHz ±1.5% rdg.±0.7 V -
DC,
45 Hz≤f≤66 Hz
66 Hz<f≤1 kHz ±1.5% rdg.±7 V -
Measurement accuracy Input impedance
Filter off Filter on
±1.0% rdg.±0.023 V ±1.5% rdg.±0.023 V
±1.0% rdg.±0.013 V ±1.5% rdg.±0.013 V
±1.0% rdg.±0.13 V ±1.5% rdg.±0.13 V
±1.0% rdg.±0.7 V ±1.5% rdg.±0.7 V
±1.0% rdg.±7 V ±1.5% rdg.±7 V
(DC input,
AC 50 Hz input)
AC: 3.2 M
AC: 3.2 M
AC: 3.1 M
AC: 3.0 M
AC: 3.0 M
±5%
Ω
±5%
Ω
±5%
Ω
±5%
Ω
±5%
Ω
AC+DC voltage (PEAK MAX/PEAK MIN)
HIOKI CM4371A971-00
Range
6.000 V (0.00 V to ±12.00 V) 0.01 V 10 Hz≤f<45 Hz ±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
600.0 V*
1000 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 dened 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 dened for display values in excess of 1000 V
(which are provided as reference values).
(Accuracy guarantee
range)
2
(±30 V to ±1000 V) 1 V 10 Hz≤f<45 Hz ±1.5% rdg.±7 V
3
(±50 V to ±1000 V) 1 V 10 Hz≤f<45 Hz ±1.5% rdg.±7 V
Resolution
Accuracy Table
Accuracy guarantee
frequency range*
DC, 45 Hz≤f≤66 Hz ±1.0% rdg.±0.07 V
66 Hz<f≤1 kHz ±1.5% rdg.±0.07 V
DC, 45 Hz≤f≤66 Hz ±1.0% rdg.±0.7 V
66 Hz<f≤1 kHz ±1.5% rdg.±0.7 V
DC, 45 Hz≤f≤66 Hz ±1.0% rdg.±7 V
66 Hz<f≤1 kHz ±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
Measurement accuracy
1
63
Accuracy Table
HIOKI CM4371A971-00
Frequency (same for all models)
12
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
HIOKI CM4371A971-00
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.
Continuity check (same for all models)
13
Continuity on threshold: 25 Ω±10 Ω (continuous buzzer sound, red warning backlight lights up)
Continuity off threshold: 245
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
Overload current: 30 mA or less at steady state, 1.5 A or less at transient state
±10
Ω
Ω
7
V • Hz (energized for 1 minute)
Range
600.0 Ω(0.0 Ω to 600.0 Ω) 0.1
(Accuracy
guarantee range)
Resolution
Ω
Measurement
current
200 µA±20% ±0.7% rdg.±0.5
Measurement
accuracy
Ω
Open terminal
voltage
2.0 V DC or less
65
Accuracy Table
HIOKI CM4371A971-00
Resistance measurement (same for all models)
14
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
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
600.0
6.000 k
60.00 k
600.0 k
Auto range movement threshold: 6000 counts or more for upper range, 540 counts or less for lower range.
(Accuracy guarantee
range)
(0.0 Ω to 600.0 Ω) 0.1
Ω
(0.000 kΩ to 6.000 kΩ) 0.001 kΩ100 µA±20% ±0.7% rdg.±0.005 kΩ2.0 V DC or
Ω
(0.00 kΩ to 60.00 kΩ) 0.01 k
Ω
(0.0 kΩ to 600.0 kΩ) 0.1 k
Ω
66
Resolution
Ω
Ω
Ω
7
V • Hz (energized for 1 minute)
Measurement
current
200 µA±20% ±0.7% rdg.±0.5
10 µA±20% ±0.7% rdg.±0.05 k
1 µA±20% ±0.7% rdg.±0.5 k
Measurement accuracy
Ω
Ω
Ω
Open terminal
voltage
2.0 V DC or
less
less
2.0 V DC or
less
2.0 V DC or
less
Diode (same for all models)
HIOKI CM4371A971-00
15
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
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
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
(Accuracy guarantee
range)
Electrostatic capacity (same for all models)
Resolution Short-circuit current
Measurement
accuracy
Accuracy Table
Open terminal
voltage
67
Accuracy Table
HIOKI CM4371A971-00
Electrostatic capacity (Measurement value/MAX/MIN/AVG)
Range
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
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
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
1000 µF (0 µF to 1100 µF) 1 µF
Auto range movement threshold: 1100 counts or more for upper range, 100 counts or less for lower range.
17
Thermocouple: Use the DT4910 Thermocouples (K).
Instrument reference contact temperature
correction stabilization time:
Overload protection: Lower of 1700 V DC/1000 V AC or 2×10
Overload current: 30 mA or less at steady state, 1.5 A or less at transient state
(Accuracy guarantee
range)
Temperature (same for all models)
68
Resolution Discharge current
10 µ/100 µ/200 µA±20%
Accuracy gures do not include the DT4910 Thermocouples (K)
error component. [DT4910 error: ±2.5°C (Class 2)]
120 minutes (when ambient temperature is varied abruptly from
60°C to 23°C)
minute)
Measurement
accuracy
±1.9% rdg.±5 µF 2.0 V DC
7
V • Hz (energized for 1
Open
terminal
voltage
or less
or less
or less
or less
Temperature (Measurement value/MAX/MIN/AVG)
HIOKI CM4371A971-00
Thermocouple type Range Resolution Accuracy*
K
*1: In an environment where the temperature of the instrument is ±1°C and stable, the accuracy is specied.
*2: Instrument can be made to display readings in Fahrenheit (°F) by means of special operation.
Electric charge detection
18
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
1
-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
2
.
Accuracy Table
69
Accuracy Table
HIOKI CM4371A971-00
DC power 600.0 A (CM4371, CM4372)
19
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.
DC power 2000 A (CM4373, CM4374)
20
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.
70
HIOKI CM4371A971-00
HIOKI CM4371A971-00
HIOKI CM4371A971-00
HIOKI CM4371A971-00
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