Differential operation on transformer 1

[111ggg]

For a 230/13.8 transformer in a substation feeding five feeder rows,what is the general operation sequence after a differential transformer operation? The control house contains SEL 487E relays and SEL 451 relays in the feeder rows.

 

[davidbeach]

The 487E trips the transformer lockout relay, which in turn trips all the breakers around the transformer.

 

[Madman4q]

umm...agree with David... I'll also have the 487E intiate BF...

 

[pwrtran]

A differential indicates an internal fault, so you need to isolate the transformer. Trip the low side breaker(s) is NOT enough. You also need to open the primary side switch or breaker if installed at the same time when tripping the low side breaker(s).