I've been asked to find an IEEE or equivalent test procedure for meggering from the T-leads in an MCC cubicle to the motor in the field. Any help would be much appreciated.
This is what I refer to when asked. There may be changes (Rev's) but pretty standard for Rotating Equipment and Cables. Corrections welcome.
IEEE STANDARD 43-1974 (29) ACCEPTANCE CRITERION FOR INSULATION
For Rotating Equipment
•IR is equal to or greater than 1 Megohm plus rated equipment KV.
MEGGER
IEE STANDARD NO. 43.1974
ACCEPTANCE CRITERION:
•IR IS EQUAL TO OR GREATER THAN 1 MEGOHM + RATED KV.
MOTOR RATING VOLTAGE DC MEGOHMETER (Test Voltage)
460/575 500 or 1000
2300/2400 1000 or 2500
4000/41602 2500
6600/6900 5000
POLARIZATION INDEX
PI = IR Measurement at 10 minutes
(Divided by)IR Measurement at 1 minute
Again, I do not completely understand the application. However, I will give a warning that the IEEE standards noted are not applicable for shielded MV cables with extruded insulation. Per IEEE 400-2001 DC should not be used as it can damage aged cable and will not detect most defects. I recommend at least a AC withstand or, better yet, a PD stress test. Let me know if you have any questions.
Kind regards,
-Ben
Benjamin Lanz
Vice Chair of IEEE 400
Sr. Application Engineer
IMCORP- Power Cable Reliability Consultants