Megger Reading in Low Voltage Switch Gear

The same, before and after. Obtaining the same reading will indicate "no damage".

required specific value

I have come accross many times, that client ask me to give standard magger values. I have searched a lot but could not find any standard for that. (Otherwise, it would have mentioned in magger user manual also)

None of the standard mention about Magger value. Standards indicate only BIL of the insulation of equipment. Hence, equipment must withstand Power Frequency withstand voltage for 1 minute. For MV or HV, BIL also indicates PIV but for low voltage PIV is not mentioned.

Maggger is used to check the insulation level of the equipment before & after HV test. By comparing the values before & after HV test, we can make out that after HV test there is no deteriaotion of insulation.

If we are looking for standard magger value. I will say it should ne be Zero, means there shuold not be short circuit. Many times, I have seen that maintenance people starts motors at 1 M-Ohm magger value.

For cables, magger value depends on cable lenght also. If lenght is long, you will not get high magger value. (Means, how to establish, standard magger value? )

Thank you very much for your kind information

1000 ohms per volt-