Hi Alehman,
I have attached pdf file of the drawing.
It is a PT of metalclad switchgear so there is no probability of L-L fault. As well if there is line to line fault, third fuse will blow out in less than 0.2s.
I appreciate if you can see the drawing and give your opinion.
Thankx...
jghrist,
I think you are in same line with me.
Thanks for the link. I went through it and now I have developed a opinion that line to neutral rated fuse can be applied under certain circumstances.
Can you look the attach diagram where fuse is for grounded star/grounded star PT. Can you give...
Last Try!
I came to know that BIL is apply to the equipment whose one part is connected to voltage and other part is connected to earth.
Now suppose a star connected PT (grounded) of 25kV system. If all 3 fuses of PT blows out, then one end of fuse will exposed to voltage and other end of fuse...
Hi David,
I have learnt a lot from your response in Eng Tips. But still I am not convinced with your view in this issue.
You are saying that Fuse Holder will take care about over voltage to ground and fuse has nothing to do with voltage. If it is so why fuses are rated for voltage as well...
Dear all,
Still I have confusion.
Transformer, Switchgear (Breaker, Instrument transformer, Insulators) are rated for BIL and they are rated for system voltage as well. As these equipments are seeing voltage so rated for system voltage and BIL.
So Fuse is rated for system voltage because fuse...
Dear All,
Are fuse rated for BIL?
I haven't seen in manufacturer's catalog that it is rated for XXX BIL. I saw fuse is rated for current and system voltage.
So if we are using fuse for 95kV BIL system, the fuse should be rated for 95kV BIL. Am I right?
And there is no BIL declared in fuse...
Dear All,
I have seen during hi pot test of switchgear, PT takes out of circuit. So PT won't subjected to Hi potential test.
But in actual sevice condition, PT will be in circuit and exposed to hi voltage like other component during abnormal condition.
Please reply.
Alehman,
Thank you for reply.
But still I have confusion in No 3.
When there is phase to phase fault, Suppose fault between phase A & B then fuses at phase A and phase B could see more than 15kV because Phase C appears to other end of fuse. Is this what you mean?
But I am thinking as star...
Dear all,
I have few questions related to PT fuses in metalclad switchgear.
1. why fuse is rated for kV like 5A, 15kV. Does kV rating also affect the melting curve of a fuse?
2.As per my knowledge, kV rating of fuse is max. voltage that a fuse can withstand which appers across both end of fuse...
