I have a 540 ton 480VAC 3 PH Y-D closed transistion starter fed from a Y solidly grounded transformer secondary.
The complaint is that the chiller may experience a ground fault trip on the first start-up after not running for a long period of time. The gfi is reset and the chiller starts and runs. This problem has been happening for years.
When I took a first look at the starter I found that there is a zero sequence (core balance) CT on the line side of the main mold case non automatic breaker. This main is fitted with a shunt trip operated by the GFI relay.
The issue that I want to get your opinion on is this:
The installing contractor ran the the phase conductors and the Ground conductor through the CT. There is no Neutral conductor.
I am thinking that the ground conductor is not to be running through the ct and could be causing the problem.
Exactly, no ground conductor should run through the CT.
Above is a snippet.