3 Phase Noise

[ear5256]

I have attached a 3-phase reading between an MCC and a motor drive. Phase B is causing the ground fault; which is what's causing the thin high peaks on the readout. The drive is on the load side of a reactor. What I can't figure out is why Phase C is almost flat line while Phase A reflects Phase B but inverse. Does anyone have any suggestions?

Thanks

 

[waross]

Have you considered a high resistance phase to phase to ground fault?

Bill
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"Why not the best?"
Jimmy Carter

 

[ear5256]

Hi Bill,

That crossed my mind but I was not sure about that. I'll have someone check that to see if that could be it. Thanks for the suggestion.

Ed

 

[robert122]

The type of starter for a motor depends on the starting current of the motor. for small motors, DOL starter is sufficient as the starting current is not very high. but when rating increases, starting current increases and hence has to use different type starters like star-delta starters, electronic starters etc.