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Davidbeach, the polarity of the CT is marked so as for the first half cycle the current flows from the ground to the neutral point. this CT is a zero sequence current transformer with only the neutral conductor going through it. My question is why would charge flow from ground potential to the...

hmmm let me try again. i was testing the CT ratio of the ground CT on the neutral of a 2MVA 4160V/600v delta-wye transformer. this CT in integral to the XFMRs assembly so I have no access to it except to the secondary terminals through the XFMRs control cabinet. so my setup was to inject current...

is there a season why the polarity of a GF detection CT on the neutral is setup as if the flow of current is from ground , through the NGR to the neutral point?

I found some explanation in NEMA ICS 2.4 which explains the difference between NEMA and IEC motor control devices. NEMA has no numbering convension for control terminals IEC NC Contact 11 12 first digit designate sequence of control terminal second designals NC contact 23 24 first digit...

is there a standard for the numbering convention for motor starters? like NO/NC contacts, 11-14,12-13, or coil ,A1-A2? thanks in advance

NETA is fine for North American operation, but you need to consult with your XFMR vendor on specific testing and procedures required before energization.

if you have a current inbalance, disconnect the motor, the test the winding resistance ,A-B,B-C,C-A, if one of these tests is different then your motor winding insulation is degraded and you need a new motor. hope this helps. also if your motor starts fine , then the current increases over...