Ground current

[Jett]

I am trouble shooting a site with 6- large motors thathas a large unbalance of the phase current draw. The motors range from 250 hpto 700hp, they are all 3ph 480v wired to soft starters connected inside thedelta. The motors are also fed delta from a wye system. The call from my sitesays they checked the ground also and had current on the ground wire. There areno substantial single phase loads on this system. Any thoughts would beappreciated.

 

[ActionDave]

The motors don't care if the power system is wye.

Current on the ground wire needs some more details. Which "ground wire"? The earth ground? How much current?

How good is the utility power?

 

[Jett]

I actually have not been on site yet. Maintenance is telling me they
are seeing end rush current and then it is maintaining 22 amps
. The power is questionable the sub is 12 miles away
utility is building a new sub next year. Feeders are underground to the motors and are 15
years old.