TTR on K type transformer

[tallyson71]

Using a 3 phase TTR on a K type two winding transformer and getting very poor results. Error on some taps ranged from -2% to +2.5%. Also noticed a much higher excitation on first winding tested than second two. Using test set in single phase mode worked a little better but still didn't produce satisfactory results. Any tips or tricks for K type XFMR?

[Jay Knight]

Sounds like you might have a bad transformer. High exciting current usually indicates a shorted winding. Is this an acceptance test or maintenance? Are there similar units you could compare readings to? I have never had issues with doing TTR on K transformers but maybe you could try ungrounding the shield? Also be mindful of your test leads, are you making good contact with the windings? If there is varnish where your leads are connected you will not produce the proper voltages.