Transmission or Distribution Voltage phase angle disparity
Transmission or Distribution Voltage phase angle disparity
(OP)
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.
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.






RE: Transmission or Distribution Voltage phase angle disparity
RE: Transmission or Distribution Voltage phase angle disparity
I have no info on the transposes (yet) but transmission distances are "long" at about 200 - 250 km depending on how transmission is routed.
RE: Transmission or Distribution Voltage phase angle disparity