Gen./Transformer Differential Prot.
Gen./Transformer Differential Prot.
(OP)
Can anyone suggest a differential relay for a Generator and its step up transformer. One set of differential CTs are on the neutral side of the 13.8kV generator and the other set is on 115kV Bus of a step-up transformer. So the zone of protection includes both Gen. and Transformer. Which relay (Make and Model) will be best suited for this application?






RE: Gen./Transformer Differential Prot.
RE: Gen./Transformer Differential Prot.
SEL 700G
RE: Gen./Transformer Differential Prot.
http://www2.schneider-electric.com/sites/corporate...
RE: Gen./Transformer Differential Prot.
RE: Gen./Transformer Differential Prot.
RE: Gen./Transformer Differential Prot.
In my application, there is a tap changer on 115kV side for GSU transformer. Does it makes difference for Differential Protection? Because I believe the tap changer variation will be compensated in the relay settings for differential protection.
RE: Gen./Transformer Differential Prot.
If you use a biased scheme I don't think you will be able to achieve as low a setting and the protection afforded to the machine will be reduced. The cost of an additional relay is likely to be a few thousand pounds or dollars, to protect a machine worth perhaps 1000 times as much.
RE: Gen./Transformer Differential Prot.
I see this as added protection as back up to the primary units. If you can live with lower sensitivity if it is a back up unit (high slope / second slope) settings most modern relays will satisfy your initial requirements. You will want to also pay attention to the CT's for matching performance and lead length / burden issues for a run that long. What you don't want is your back up protection to nuisance trip for a through fault, due to saturation issues. On a 160 MVA unit that could be quite a distance between the Gen Neutral CTs and the Transformer HV side or HV breaker, if you choose to further extend the back up protection to cover the breaker.
RE: Gen./Transformer Differential Prot.
RE: Gen./Transformer Differential Prot.
If you need also back-up protection to generator protection, a good style for such application use protective terminals like to ABB REG670/REG650, Alstom P34x, Siemens 7UMx.
In your case, a best way use same terminal as exist transformer differential, less spare parts :).