Transformer Excitation
Transformer Excitation
(OP)
I've got a question concerning XFMR ratios and excitation. Assume a Wye/Delta 138kV to 13.2kV GSU (138kV/13.2kV = 10.455 turns). Are there any issues with using a Wye/Delta 138kV to 13.8kV GSU, if I adjust the taps to closely match the 10.455 (set tap at 144,900kV to yield 144.9kV/13.8kV=10.5 turns). Matching ratios seems the obvious thing to watch for, but are there any possible issues with under exciting the core, operating it at 13.2kV instead of the designed 13.8kV? Losses may change?






RE: Transformer Excitation
Your transformer nameplate is 138kV/13.2kV.
You have high side taps but no low side taps.
You want low side system voltage around 13.8 and high side around 145kv.
You want turns ratio to be 145/13.8
So your high side voltage tap Hshould be set so that
H/13.2 = 145/13.8
That means H = 145 *13.2/13.8
You should adjust your high side tap down (not up) shouldn't you?
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(2B)+(2B)' ?
RE: Transformer Excitation
H = 145 *13.2/13.8 = 138.7
Isn't that (138.7) where you want to set your tap?
Maybe there is transformer voltage drop to consider as well.
Better to wait for someone else to weigh in.
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(2B)+(2B)' ?
RE: Transformer Excitation
RE: Transformer Excitation
RE: Transformer Excitation
From factory test data on 378 MVA GSU, 18 kV, Voltage and No Load Losses:
90% V 111 kW
100% V 146 kW
110% V 207 kW
115% V 256 kW.
RE: Transformer Excitation
RE: Transformer Excitation
Bill
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"Why not the best?"
Jimmy Carter
RE: Transformer Excitation
Is what I stated above correct?
If so, why isn't the high-side tap set to:
H = 145 *13.2/13.8 = 138.7
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(2B)+(2B)' ?
RE: Transformer Excitation
(at middle tap of high winding). Correct?
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(2B)+(2B)' ?
RE: Transformer Excitation
I had it all wrong.
Never mind.
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(2B)+(2B)' ?