Transformer inrush
Transformer inrush
(OP)
We have the 2 units Interbus transformers (IBT) 90MVA, 275/150KV, 2 winding at the substation where the substation is supplied from hydro power plant with a 275KV transmission distance of 200km.
While IBT-1 was energized with voltage at HV side is 265 KV, voltage at LV side is 155KV and load 51 MW at LV side, when we energize IBT-2 by closing HV side CB the diff protection relay IBT-2 trip with Id=0.98Ie and at the same time Uninterruptible power supply (UPS) at Power plant fail.
whether when we energize HV side IBT-2 occur inrush that could cause diff protection trip and UPS at Power plant fail ?
While IBT-1 was energized with voltage at HV side is 265 KV, voltage at LV side is 155KV and load 51 MW at LV side, when we energize IBT-2 by closing HV side CB the diff protection relay IBT-2 trip with Id=0.98Ie and at the same time Uninterruptible power supply (UPS) at Power plant fail.
whether when we energize HV side IBT-2 occur inrush that could cause diff protection trip and UPS at Power plant fail ?






RE: Transformer inrush
Without more info. this is a puzzle. The UPS failure* sounds like a ground voltage transient resulting from the switching. Some details about the transformer connections, grounding, surge protection, relay types and the connection of the station service (where the UPS is fed from) might help.
*Could be a bad UPS that just crapped out when it had to pick up load during transformer switching. Or not.
RE: Transformer inrush
Could you, please, give more detail about differential protection operation, i.e., supply the "oscilograms" from the relays?
Best Regards,
Herivelto S. Bronzeado
Ministério da Integração Nacional - MI
Brasília, Brazil
RE: Transformer inrush
Thanks mr. PHovnanian
UPS feed from the station service transformer (Please find the attached file of single line diagram).
RE: Transformer inrush
Thanks mr. PHovnanian & Bronzeado
UPS feed from the station service transformer (Please find the attached file of single line diagram. Actually the UPS not totally fail the UPS just blink, after we change the source using diesel generator set the UPS become normal.
we had difficulty to copying oscillograms from the relay, we hope that we can copy oscilogram later
RE: Transformer inrush
RE: Transformer inrush