meggering breakers

[electricalperson]

i have an 800 amp large frame GE breaker with an adjustable trip built into it. is it safe to use the megger on that breaker with the 500 volt setting without burning anything out? the feeder off of that breaker is feeding a 480 volt 600 amp 3 phase disconnect about 300 feet away and i want to megger the feeders. the feeder is located in switchgear and its already on the breaker.

 

[zog]

First it depends on what type of breaker and what type of trip unit, GE has only made a bout 1 million different types of 480V breakers in the last 100 years.

That said the breaker should be meggered racked out of the switchgear, or are you asking about meggering the cables? If so you need to disconnect them or your readings will be worthless. PT fuses also need to be pulled in the switchgear of you are meggering that and there always other aux devices that can be damaged or screw up your readings.

 

[electricalperson]

First it depends on what type of breaker and what type of trip unit, GE has only made a bout 1 million different types of 480V breakers in the last 100 years.

That said the breaker should be meggered racked out of the switchgear, or are you asking about meggering the cables? If so you need to disconnect them or your readings will be worthless. PT fuses also need to be pulled in the switchgear of you are meggering that and there always other aux devices that can be damaged or screw up your readings.

its a THKM circuit breaker with the microversa adjustable trip built in. the 600mcm conductors were hooked up without meggering them first. i dont want to flip the switch to energize it without meggering it first. equipment at that high of a voltage and amperage makes me a little nervous when it comes to energizing it without first testing it. if i was able to remove the conductors off of the breaker to test it i would but its located inside of switchgear that cant be turned off and im not going inside of it while its energized

 

[electricalperson]

well lets just say this. will a 1000VDC insulation resistance test damage a circuit breaker containing a microversa adjustable trip built into it? if it didnt have the adjustable trip i wouldnt be confused and just do it. im not sure how those trip devices in the breaker work. any information on them would be helpful

 

[bth0mas20]

If your meggering the 480v circuit your fine. Go phase to phase then each phase to ground at 1000vdc. If your meggering the control power I doubt you will affect the trip unit at 500vdc but im sure theirs a way to disconnect the wires to it and megger the rest of the circuits. The tech manual should tell you this. Look it up on GE industrial website.

 

[electricalperson]

If your meggering the 480v circuit your fine. Go phase to phase then each phase to ground at 1000vdc. If your meggering the control power I doubt you will affect the trip unit at 500vdc but im sure theirs a way to disconnect the wires to it and megger the rest of the circuits. The tech manual should tell you this. Look it up on GE industrial website.

i cant find and manuals on the circuit breaker. if im at the location tommorw ill double check the numbers on it. the microversatrip unit is built into the breaker from the factory. we should of meggered the feeders before we hooked it up but i dont know what im talking about i guess

 

[Packinaglock]

i cant find and manuals on the circuit breaker. if im at the location tommorw ill double check the numbers on it. the microversatrip unit is built into the breaker from the factory. we should of meggered the feeders before we hooked it up but i dont know what im talking about i guess

I've been in that position before

 

[brian john]

You cam megger this CB at 1000 VDC, with the CB closed pole to pole and pole to ground (if applicable) then with the CB open line to load across the poles.