Benning CM7 Service Information

BENNING

CM7 Electrical Tester

Service Information

TABLE OF CONTENTS Page

Introduction 1

Precautions and Safety Information 1

Symbols 1

Safety 2

Specifications 3

General Specification 3

Voltage Specification 4

Resistance & Continuity Specification 4

Current Specification 5

Frequency Specification 5

Physical and environment characteristics 7

Certification and compliance 7

Required Equipment 8

Basic Maintenance 9

Opening the Meter Case 9

Replacing the Battery 9

Performance Tests 10

Testing the Voltage Function 10

Testing the Resistance Function 11

Testing the AC Current Function 12

Testing the DC Current Function 12

Testing the Hz Function 13

Calibration 14

Calibrating DCV, ACV, ACA Functions 14

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Introduction

Warning

To avoid shock or injury, do not perform the verification tests or calibration procedures

described in the manual unless you are qualified to do so.

The information provided in this document is for the use of qualified personnel only.

Caution

The CM7 contain parts that can be damaged by static discharge.

Follow the standard practices for handling static sensitive devices.

For additional information about BENNING GMBH & CO. KG. and its products, and

services, visit BENNING GMBH & CO. KG. web site at:

www.benning.de

Precautions and Safety Information

Use the Meter only as described in the Service Manual. If you do not do so, the protection provided

by the Meter may be impaired. Read the “Safety Information” page before servicing this product.

In this manual, a Warning identifies conditions and actions that pose hazard (s) to the user; a

Caution identifies conditions and actions that may damage the Meter or the test instruments.

The Symbols

The symbols used on the Meter and in this manual are explained in Table 1.

Table A. The Symbols

 Risk of electric shock
 See instruction card
 DC measurement

Equipment protected by double or reinforced



insulation

 Battery

 Earth
 AC measurement
 Conforms to EU directives

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SAFETY

Review the following safety precautions to avoid injury and prevent damage to this product or

products connected to it. To avoid potential hazards, use the product only as specified.

 CAUTION: These statements identify conditions or practices that could result in damage to

the equipment or other property.

 WARNING: These statements identify conditions or practices that could result in personal

injury or loss of life.

Specific precautions

Do not operate without covers. To avoid personal injury, do not apply any voltage or current to

the product without covers in place.

Electric overload. Never apply a voltage to a connector on the product that is outside the range

specified for that connector.

Avoid electric shock. To avoid injury or loss of life, do not connect or disconnect probes or test

leads while they are connected to a voltage source.

Do not operate in wet/damp conditions. To avoid electric shock, do not operate this product in

wet or damp conditions.

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SPECIFICATIONS

All specifications are warranted unless noted typical and apply to the CM7.

Stated accuracies are at 23°C±5°C at than 80% relative humidity and without the battery

indicator displayed.

General specifications

Characteristics Description

Display count 3 3/4

Numeric update rate 1.5 times / sec

Polarity display Automatic

Overrange display “OL” is display

Low voltage indicator  is indicated

Automatic power-off time Automatic backslit off = 30 minutes

Power source One 9V battery

Maximum input voltage 600V CAT Ⅳ between V and COM

Maximum floating voltage

V connector V, V, , 

Temperature Coefficient 0.2×(Spec. Accuracy) / °C, <18°C or >28°C

Battery Life 100 hours typical (Alkaline)

600V CAT Ⅳ between any terminal and earth

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Measurement Characteristics

Accuracy is ±(% reading + number of digits) at 23°C ± 5°C, less than 80% R.H.

Temperature coefficient: 0.2 × (Specified accuracy) /°C, <18°C, >28°C
Operating temperature: 0°C ～ 30°C (≦ 80% RH)

30°C ～ 40°C (≦ 75% RH)
40°C ～ 50°C (≦ 45% RH)

(1) AC Volts: Auto-ranging

Range Resolution Accuracy

400.0V 100mV

±(1.0% reading + 5 digits) 50Hz ～ 500Hz 750V rms

750V 1V

Input Impedance：≧1M// less than 100pF.
AC Conversion Type: Reading less Full Scale 15% add 4 dgt.

AC Conversions are ac-coupled, true rms responding, calibrated to the rms
value of a sine wave input. Accuracies are given for sine wave at full scale and
non-sine wave below half scale. For non-sine wave add the following Crest
Factor corrections:
For Crest Factor of 1.4 to 2.0, add 1.0% to accuracy.
For Crest Factor of 2.0 to 2.5, add 2.5% to accuracy.
For Crest Factor of 2.5 to 3.0, add 4.0% to accuracy.
CF 2 @ 600V

1.5 @ 750V

(2) DC Volts: Auto-ranging

Range Resolution Accuracy

Over voltage

protection

Over voltage

protection

400.0V 100mV
±(0.7% reading + 2 digits) 1000V rms

1000V 1V

Input Impedance：≧1M

(3) Resistance Auto-ranging

Range Resolution Accuracy

Over voltage

protection

400.0 100m ±(1.0% reading + 3 digits) 600V rms

Continuity: Built-in buzzer sound when resistance is less than 30 approximately.

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(4) Frequency: Hz

Range Resolution Accuracy

20Hz ～ 400Hz 1Hz ±(0.1% reading + 2 digits)

Min. Input Frequency：20Hz
Sensitivity: 3A rms for ACA (A～)(>400Hz Unspecified)

(5) ACA: Auto-ranging

Over voltage

protection

AC/DC 1000A

for 1 min.

Range Resolution Accuracy

Frequency

Response

0A ～ 200.0A 0.1A ±(1.9% reading + 3 Amp)

50Hz ～ 400Hz

200.0A ～ 400.0A 0.1A ±(1.9% reading + 2 Amp)

400A ～ 1000A 1A ±(2.9% reading + 5 Amp) 50Hz ～ 200Hz

Operating Temperature: 0℃ to 30℃(≦80%RH), 30℃ to 50℃(≦75%RH)
AC Conversion Type: Reading less Full Scale 15% add 4 dgt.

AC Conversions are ac-coupled, true rms responding, calibrated to the rms
value of a sine wave input. Accuracies are given for sine wave at full scale and
non-sine wave below half scale. For non-sine wave add the following Crest
Factor corrections:
For Crest Factor of 1.4 to 2.0, add 1.0% to accuracy.
For Crest Factor of 2.0 to 2.5, add 2.5% to accuracy.
For Crest Factor of 2.5 to 3.0, add 4.0% to accuracy.
CF 2 @ 600V

1.5 @ 750V

(6) DCA:

Range Resolution Accuracy

Over voltage

protection

0A ～ 200.0A ±(2.9% reading + 3 Amp)

200A ～ 400.0A

0.1A
±(1.9% reading + 2 Amp)

AC 1000A

for 1 min.

400A ～ 1000A 1A ±(2.9% reading + 5 Amp)

Overload

protection

1000A rms

Additional error according to remanence: 1% max. of current crest.

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(7) Auto Power Off (APO)

The meter will automatically shut itself off after approximately 30 minutes after power on.

(8) Peak Hold: ±(3% reading +20 digits)

* >750V Unspecified.

* >800A Unspecified.

(9) Min/Max Hold: Add ± 15 dgt to accuracy for ACA.

Add ± 15 dgt and add remanence to accuracy for DCA.

* Automatically switch to the low resolution range at Peak Hold and Min/Max Hold.

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