Protection of tapped windings
Protection of tapped windings
(OP)
For power transformer with no load tap changer +/- 10% of HV voltage, liniar; the value of overvoltage which apear on tapped winding is too high. What kind a protection for tapped windings it is necessary to use?






RE: Protection of tapped windings
Standard protective devices for tap changer tank.
it's base on the oil flow, pressure.
RE: Protection of tapped windings
Thank you for your support.
RE: Protection of tapped windings
RE: Protection of tapped windings
'OLTC' is universally accepted to mean On-Load Tap Changer; true off load tapchangers which allow a tap to be changed with the circuit energised but carrying no load are a rare device. Off circuit tap selectors require the transformer to be dead and isolated before any attmept is made to change tap. Which type are we talking about here?
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If we learn from our mistakes I'm getting a great education!
RE: Protection of tapped windings
The transformer is 50 MVA; 132 kV star connection; off load tap changer is provided on the neutral +/-10%. During the impulse test on HV (BIL 550 kV) on the tapped windings apear more than 950 kV. The transformer is already manufactured and I ask for a solution without any changes inside of the windins.
RE: Protection of tapped windings
I think also is a kind of resonance. The medium voltage motors are provided with an arrestor beside a capacitor-both grounded- in order to break the resonance.
If it is compulsive to test the transformer, an arrestor provided inside the transformer housing will reduce the BIL to the arrestor residual voltage that means part of the transformer winding will not be tested at the required BIL.
If it is so critic to limit the possible overvoltage from the network a suitable arrestor connected with the transformer terminals may protect entire winding [including tap-changer].
RE: Protection of tapped windings
Eric Kench, P.E.
RE: Protection of tapped windings
RE: Protection of tapped windings
RE: Protection of tapped windings
I already put ZnO elements on the tapped windings. I tried to get another solution that I didn't know.
RE: Protection of tapped windings
We have some installation with arresters mounting over transformer tank.