Benning CM 8 Operating Manual page 27

See figure 3:
8.3 Current measurements (frequency measurements, THD-harmonic distortion)
8.3.1 Preparing the measurement
Operate and store the BENNING CM 8 at the specified storage and operating
temperatures only! Do not permanently expose the device to sunlight.
- Strong sources of interference in the vicinity of the BENNING CM 8 might
involve unstable readings and measuring errors.
Do not apply any voltage to the output contacts of the

BENNING CM 8! Any possibly connected safety measuring
leads have to be removed.
8.3.2 Current measurements
- Select the desired function (A AC/ DC) by means of the rotary switch 8 of
the BENNING CM 8.
- Select the current type (direct current DC or alternating current AC) to be
measured by means of the blue key 5 of the BENNING CM 8 and perform
a null balance N, if necessary.
- Operate the opening lever K and clamp the single-wire live conductor cen-
trally by means of the clamp M of the BENNING CM 8.
- Read the value indicated on the digital display 1.
- In the AC range, it is possible to switch over to the frequency measuring mode
by pressing the „PEAK / Hz-THD" key 7 for approx. 2 seconds. You can
switch back by pressing the key for another 2 seconds. Normal pressing of
the key switches the device into the THD mode (%harmonic distortion).
See figure 4:
8.4 Inrush current measurements (AC)
- Select the function (A) by means of the rotary switch 8 of the
BENNING CM 8.
- Select the current type AC current by means of the blue key 5 of the
BENNING CM 8.
- Briefly press the „INRUSH" key 6.
- Operate the opening lever K and clamp the single-wire live conductor cen-
trally by means of the clamp M of the BENNING CM 8.
- Switch on the load.
- Read the value indicated on the digital display 1.
See figure 4:
8.5 Resistance measurements
- Select the function (Ω) by means of the rotary switch 8 of the
BENNING CM 8.
- Connect the black safety measuring lead to the COM jack J of the
BENNING CM 8.
- Connect the red safety measuring lead to the jack for V and Ω 9 of the
BENNING CM 8.
- Bring the safety measuring leads into contact with the measuring points and
read the measured value on the digital display 1 of the BENNING CM 8.
See figure 5:
8.6 Diode tests
- Select the function (
BENNING CM 8.
- Connect the black safety measuring lead to the COM jack J of the
BENNING CM 8.
- Connect the red safety measuring lead to the jack for V, Ω 9 of the
BENNING CM 8.
- Bring the safety measuring leads into contact with the diode connections and
read the measured value on the digital display 1 of the BENNING CM 8.
- For a standard Si diode applied in conduction direction, a conduction volt-
age between 0.400 V and 0.900 V is displayed. „000" indicates a short-
circuit inside the diode, „OL" indicates an interruption inside the diode.
- For a diode applied in reverse direction, „OL" is indicated. If the diode is
defective, „000" or other values are indicated.
See figure 5:
02/ 2019
AC voltage measurement/ frequency measurement
DC/ AC current measurement
(frequency, inrush current measurement)
DC/ AC current measurement
(frequency, inrush current measurement)
Resistance measurement/ diode test/
continuity test with buzzer
) by means of the rotary switch 8 of the
Resistance measurement/ diode test/
continuity test with buzzer
BENNING CM 8
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