Electrical Protection

[GILLARN MUTALE]

Why is it that some feeders they have sensitive protection when others don't.

 

[davidbeach]

Because that’s what somebody decided to do. There needs to be a lot more context around the question to get a real answer. Detailed descriptions of the characteristics of the feeders in question would help.

 

[GILLARN MUTALE]

Have seen on the Same 11KV Board with three feeders. two they have both Earth Fault and Sensitive Earth fault protection. the third feeder only with Earth faulty protection. is there any explanation to that

 

[waross]

Reread and ponder the answer given by davidbeach.

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[Padlock01]

Waross & Davidbeach are correct more info required.
Check the design drawings SLD
a)Transformer feeder protection depends on the size of the transformer?
b)Feeder to another Substation?
c)Feeder to an OHL ?
d)Feeder to a Generator?

 

[Prot123]

If your question is about Sensitive earth fault(SEF) then, yes some feeders have SEF and some don't; depends on whether its overhead conductor or a cable its protecting. For cable, SEF protection is not needed whereas for overhead conductor SEF is needed as it can be faulted through high impedance(tree branch) which will lower the fault current(3Io) to go below the normal earth fault protection pickup. To protect at these times a SEF protection is enabled which will have pickup current way below the Earth fault pickup.

 

[RRaghunath]

Agree with Prot123. To add, SEF protection is recommended for motor feeders as well.

Rompicherla Raghunath

 

[veritas]

Careful, motor feeders do not necessarily warrant SEF. It depends on the voltage for one. Many motor systems use core balance rather than SEF.

 

[davidbeach]

OP has never describe how SEF feeders differ from non-SEF feeders. So many possibilities that we're left to merely guess.