meggering a 3 phase motor controller
meggering a 3 phase motor controller
(OP)
I have a marine 440 volt motor controller I meggered and all 3 phases went to 0 when meggered. I megged the motor leads with them seperated from the power leads and the motor is god and there is no aparent electric cable damage from the controller to the actual motor.I have never seen this and appreciate any suggestions from the group.I just started an account and this looks good.Thanks everyone....






RE: meggering a 3 phase motor controller
RE: meggering a 3 phase motor controller
RE: meggering a 3 phase motor controller
Any chance you are meggering something in the starter that doesn't like being meggered?
Surge arresters are a possible culprit.
RE: meggering a 3 phase motor controller
RE: meggering a 3 phase motor controller
Some meggers have several scales and one of the scales may be a 6 volt scale for continuity tests. The 6 volt scale is often reversed so an open circuit looks like a short on the higher voltage ranges if the 6 volt scale is mistakenly used for insulation testing.
Some meggers start their scale at about 200,000 ohms. A motor may be below this value and still work, but the megger will indicate zero.
If you have had a flash over, you may have carbon tracking on your starter.
Check the starter and the leads seperately.
respectfully
RE: meggering a 3 phase motor controller
RE: meggering a 3 phase motor controller
Even if the system is grounded on "B" phase, the starter should be isolated from the system before grounding and should ring clear.
If there has been a flash over in the starter there may be carbon tracking to ground. Do you get ground on the load side terminals or the line side terminals?
respecfully