I have 3 phase 480/208-120 delta/zig-zag transformer that gave me bad ratio when tested with a Vanguard TTR test set. Any ideas how to ratio this transformer using a voltage source on the primary and a voltmeter on the secondary?
potteryshard...
Yes! 47 V consistent on all of them.
Only one transformer was loaded.
Today I am planning on verify neutral grounding and recheck everything again.
I am also going to measure phase voltages to ground and check what kind of load we have on the one that is loaded.
Test equipment...
Thanks for your help dpc.
I went back to rechecked everything and still the same.
Another piece of information about the scheme: This is an ungrounded wye system with a ground fault detection scheme. Neutral is connected to ground through a 28 ohm resistor bank and a CT to measure ground...
I have two identical 3 phase dry type transformers I am trying to parallel:
1.5 MVA 15kv/480v Z=7.2% Dy11
They are being fed from the same source. I measured voltage across A-A B-B and C-C before closing the tie breaker and they measured 47 V. Voltages between phases are all the same, 480v. Is...
