Belated Transformer Differential Protection
Belated Transformer Differential Protection
(OP)
At our federal agency we have at our Main Substation two 69/12.470kV, 15/20MVA, transformers feeding two walkin breaker lineups. Each lineup is fed from one transformer and the two lineups are connected by a NO tie ACB. Presently the transformers are protected by S&C Fuses. Soon S&C Trans-rupters will be installed to provided primary switching. The S&C Trans-rupters were purchased with Basler OC relay system.
Belately, it was decided to also provide transformer differential protection. A Basler system will used.
Can the Basler OC system be used as a backup to the Basler 87T?
Management may decide to forego the 87T system and stick with the 50/51 system. Will it offer sufficient protection for transformers in this size range, considering that the replacement value per transformer is not insignificant.
Thank you!
Belately, it was decided to also provide transformer differential protection. A Basler system will used.
Can the Basler OC system be used as a backup to the Basler 87T?
Management may decide to forego the 87T system and stick with the 50/51 system. Will it offer sufficient protection for transformers in this size range, considering that the replacement value per transformer is not insignificant.
Thank you!






RE: Belated Transformer Differential Protection
RE: Belated Transformer Differential Protection
Overcurrent relays alone would be sufficient, especially if you set the instantaneous element on the relay to pickup for fault current higher than the maximum secondary fault current.
But not as good as the differential protection, of course.
You didn't mention ground fault protection - you will want that in addition to the differential relaying and phase overcurrent.
RE: Belated Transformer Differential Protection
RE: Belated Transformer Differential Protection
Are different things.
87T, 50, 51N, etc. are xfr. electrical protections.
Pressure relief, Bucholtz relay, etc. are xfr. mechnical protections.
You need both of them.
Regards.
Slava