Transformer Primary Protection - Relay vs Fuse
Transformer Primary Protection - Relay vs Fuse
(OP)
When considering transformer primary protection on a 13.8kV or 4.16kV transformer can better protection be achieved with a fuse or a relay?
From what I've heard and read the fuse provides better short circuit protection but does not provide good overload protection while the relay provides better overload protection but does not provide good short circuit protection.
Is there a better or preferred method for how transformer is protected on primary or does it come down to cost and system topology? A lot of times I see them protected on the primary with both fuse and relay with the relay located at the switchgear feeder and the fuse located at a MV switch at the transformer location. I'm assuming using this fuse and relay combination protection provides the best protection but the fuse may cause coordination issues with upstream relays?
From an overload perspective I have always viewed this as being provided by the secondary protection, so any overload protection on the primary is just backup protection for the secondary protection.
From what I've heard and read the fuse provides better short circuit protection but does not provide good overload protection while the relay provides better overload protection but does not provide good short circuit protection.
Is there a better or preferred method for how transformer is protected on primary or does it come down to cost and system topology? A lot of times I see them protected on the primary with both fuse and relay with the relay located at the switchgear feeder and the fuse located at a MV switch at the transformer location. I'm assuming using this fuse and relay combination protection provides the best protection but the fuse may cause coordination issues with upstream relays?
From an overload perspective I have always viewed this as being provided by the secondary protection, so any overload protection on the primary is just backup protection for the secondary protection.






RE: Transformer Primary Protection - Relay vs Fuse
RE: Transformer Primary Protection - Relay vs Fuse
RE: Transformer Primary Protection - Relay vs Fuse
Should a lot of emphasis be put on the primary protective device in terms of overload protection or is this primarily the role of the secondary protection?
If the relay or curve or fuse curve sits under the transformer through-fault damage curve then it appears that they would both provide the same level of protection for through faults. I suppose the only difference would be a currently limiting fuse may be able to react quicker for internal transformer faults and perhaps minimize the damage that may otherwise occur with relay 50/51 protection?
RE: Transformer Primary Protection - Relay vs Fuse