What's the different between measured resistance values of IM400 and IFL12

Issue
The user found a big difference between the measured resistance values of IM400 and IFL12 on site,
please explain the measurement principle of IFL's insulation resistance R.
And the difference between insulation resistance R measured by IM400 and IFL12.

Product Line
IM400
IFL12

Cause
The test observations like IM400 measured high value than IFL12. Normally the IM400 will be average of all IFL12 feeder, so the R value in IM400 will be less than or equal to any low value of IFL12 feeder.
The root cause for this behavior can be following:
1. There are 2 IM400 injecting the signals at same time.
2.IFL12 monitoring network signal not connected properly. (example: N/HV is connected and ground terminal is open.

Resolution
In such conditions, the IFL12 will not measure properly. Verify and correct the conditions to get actual R value in IFL12.

Released for:Schneider Electric Malaysia