Motor IR testing
Motor IR testing
(OP)
I have been searching the web for some "basic" guide lines to follow on doing a insulation resistance test on motors.
I seem to be getting inconsistent procedures on test voltage range and in particularly "lead placement".
For insistence:
I have read test voltage range <1000v = 500vdc range and also read test voltage range is set at 2x motor voltage.
Lead placement is all over the place from; to ground, across winding, connect the motor leads, I'm confused!
I am looking for some old school, rule of thumb advice on testing a WRIM, 3 phase, Wye - 480v, 76kw (in the field)
Regards
I seem to be getting inconsistent procedures on test voltage range and in particularly "lead placement".
For insistence:
I have read test voltage range <1000v = 500vdc range and also read test voltage range is set at 2x motor voltage.
Lead placement is all over the place from; to ground, across winding, connect the motor leads, I'm confused!
I am looking for some old school, rule of thumb advice on testing a WRIM, 3 phase, Wye - 480v, 76kw (in the field)
Regards





RE: Motor IR testing
Some free info on-line here:
http://www.usbr.gov/power/data/fist_pub.html
(see item 3-1: "Testing Solid Insulation of Electrical Equipment, December 1991")
=====================================
Eng-tips forums: The best place on the web for engineering discussions.
RE: Motor IR testing
2x voltage is not correct for an insulations test... it is is roughly related to hi-pot test - factor ac-hi-pot done at 2*E+1. Maintenance level dc test in the same ballpark.
Your acceptance criteria is a 1-minute temperature-corrected insulation resistance value of 100 megaohms. (Older windings were kv+1).
Test voltage should be applied to the machine winding (checking insulations resistance to ground). Which of three phases doesn't matter although I believe the standard might suggest to connect all three phase terminals together.
=====================================
Eng-tips forums: The best place on the web for engineering discussions.
RE: Motor IR testing
Make sure you hook the motor back up correctly.
JTK
RE: Motor IR testing
What about the rotor ( 3 wire )
Would you need to ground them while megging the stator
THANKS : jtkirb and electricpete