Primary fuse for VT
Primary fuse for VT
(OP)
Is it recommended to protect Voltage transformer by Primary fuses?
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RE: Primary fuse for VT
99NEC450-3(c) Voltage transformers installed indoors or enclosed shall be protected with primary fuses.
RE: Primary fuse for VT
The transformer must be protected on the primary side (though it need not be on the secondary side)either by a fuse or a circuit breaker. The modern practice is to use a circuit breakers for units 1MVA and above.
RE: Primary fuse for VT
It is not mandatory (as per IEC anyway)to have a fuse on the primary side on VT if the VT is of a cast resin type design and located in a fault free deemed zone and some switchgear manufacturers have adopted this practice. The secondary side is fused in the usual manner.
Mnufacturers who have a oil filled (often withdrawable ) design would offer a fused primary design.
Therefore it is more of a question of choice.
RE: Primary fuse for VT
For HV, primary protection gets a lot more expensive and you will almost always have instantaneous bus protection. Generally, I would not provide primary fusing on HV VT's.
RE: Primary fuse for VT
Thanks for your expert comments.
HiSet