Transmission or Distribution Voltage phase angle disparity

[purplepete]

I've worked on the outskirts of a major city in Australia and have found at times the line currents of three phase motors installed across a wide area in the same region run out of balance, but only slightly, maybe one to two percent.
When run on a local generator they always come back into perfect pitch. Recently I had an elaborate electricity meter installed in a large plant on the secondaries of 22kV/110V metering VTs. The meter can do voltage phase angle measurement. It reads he following:

V A-B 126.9 degrees
V A-C 123.7 degrees
by inference the
V B-C is 109.4 degrees.

What am I seeing please? I think it's a stretch to say the VT's are out, they're calibrated and certificates read OK. I'm starting to wonder if this is what causes the current out of balances in a number of installations I've worked in at 415 Volts and also at 22 kV. The currents here are also out of balance at the 22 kV level incoming through the meter. Is this phase shift (if real) a result of a displacement somewhere in transmission? A phase-shift winding somewhere with shorted turns or the wrong tap position for one phase?
Any suggestions please.

 

[magoo2]

I'd be looking at your transmission voltages, 132 kV and above. If the lines aren't transposed, you could expect unbalances of 1 or 2%.

 

[purplepete]

magoo2, thanks. We have 500 kV and 220 kV in transmission then 66 kV in local sub-transmission.
I have no info on the transposes (yet) but transmission distances are "long" at about 200 - 250 km depending on how transmission is routed.

 

[davidbeach]

You're seeing the real world, as opposed to the text book world. In theory there is 120 degrees between phases, but the weaker the system the more variation there will be.