Gain Adjustment Procedure For The Mh 60 - Chauvin Arnoux MH 60 Notice De Fonctionnement

7.2. Gain adjustment procedure for the MH 60

Make sure you are technically qualified to perform this operation.
Warning: Make this adjustment only if the gain coefficient is manifestly outside
tolerances. Check first that nothing interferes with the movements of the jaws
and that the air gap is clean. Make sure that the clamp is adequately charged.
Disconnect the USB charger.

Check of the gain:
Equipment necessary: AC current calibrator accurate to 0.1% capable of delivering least 3A
at 50/60Hz, 10-turn coil, RMS AC multimeter accurate to better than 0.1%, female
BNC/male banana adapter, leads.
Step Action
1
Switch the clamp on and clamp it centred on the coil. Connect the clamp to the
multimeter using the adapter.
2
Optional: Demagnetize the clamp (0...3A....0/50 or 60Hz)
3 Adjust the DC-Zero with no current and do not subsequently move the clamp.
The measurement must be < 0.1mV DC.
4
Establish a current of 3A
5 Measure the output voltage with the multimeter set to AC rms and note this value.
- If 295.1mV ≤ Reading ≤304.9mV
- Otherwise: adjust the gain.

Adjusting the gain:
Step Action
1
Switch the clamp on and clamp it centred on the coil
2
Optional: Demagnetize the clamp (0...3A....0/50 or 60Hz)
3 Adjust the DC-Zero with no current and do not subsequently move the clamp.
4
Press the DC-Zero key and the ON/OFF key for approx. 30s, until all of the indicators
blink. At this point, there is no turning back: the procedure must be completed.
5
Release the keys. The BAT and ON/OFF LEDs blink.
6
Establish a current of
7
Adjust the output by successive presses
1.5mV. Wait for the display to stabilize between presses.
8
Press the ON/OFF key 2s (the ON/OFF LED blinks) to store the gain.
9
Gradually reduce the current from 3A to zero.
10
Check the gain as before.
1
( ) Gradually increase the current starting from zero.
2
( ) Gradually increase the current, starting from zero, up to 3A, then gradually reduce it to zero.
3
( ) The increment is approximately 0.5mV.
1
60Hz in the coil.

Do not adjust.
1
3A 60Hz in the coil.
3
on the DC-Zero key until you reach 300mV 
30
Oscilloscope clamp
2
.
2
.