BIL rating of fuse.
BIL rating of fuse.
(OP)
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 manufacture's catalog. how I know that fuse is rated for which BIL ?
Please reply.
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 manufacture's catalog. how I know that fuse is rated for which BIL ?
Please reply.






RE: BIL rating of fuse.
RE: BIL rating of fuse.
However, there are deratings for both for tempeture, and alitutude.
RE: BIL rating of fuse.
BIL is used to determine voltage spikes.
AIC is used to determine amperage spikes.
Voltage spikes dont matter too much to fuses as they are designed as a current limiting device.
RE: BIL rating of fuse.
Anywhoo, ignore the part where I say BIL and instantaneous time curves, I havent had my coffee this morning, and that statement is completely wrong.
RE: BIL rating of fuse.
If you really regret a post, you can red-flag it and ask that it be removed or corrected.
RE: BIL rating of fuse.
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 will see the system voltage. Now when fuse see the system voltage and rated for system voltage then why it is not rated for BIL ?
Please give your view.
Thankx.
RE: BIL rating of fuse.
RE: BIL rating of fuse.
With regard to BIL, I agree with davidbeach - is not relevant for fuse as it is an in-circuit element and not connected between phase and earth.
RE: BIL rating of fuse.
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, like 5kV,5A 15kV,5A 25kV,5A. And we can't use 5kV,5A fuse for 15kV system.
Since either end of fuse will exposed to system voltage when there is L-L or L-G faults so we need to put rated kV fuse.
So there is no doubt that fuse has to takecare of voltage indepndently of fuse holder. So why it shouldn't takecare of BIL.
Please give your opinion.
RE: BIL rating of fuse.
RE: BIL rating of fuse.
RE: BIL rating of fuse.
RE: BIL rating of fuse.
Rafiq Bulsara
http://www.srengineersct.com
RE: BIL rating of fuse.
Rafiq Bulsara
http://www.srengineersct.com
RE: BIL rating of fuse.
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 will exposed to ground through star point.
Suppose now voltage spike come in the system due to lighting. is there chance of flashover across the fuse? As other part of switchgear is propery BIL rated and air gap between two points of melted fuse is not sufficient for BIL withstand.
RE: BIL rating of fuse.
BUT, that is not how BIL is measured or tested. It is measured to ground.
In your example, if the PT had a proper BIL rating before the fuse failed it would still have the same rating after the fuse failed.
The same argument could be applied to every distribution transformer on some four wire distribution systems. The argument would still be invalid.
Yes, a transient approaching BIL levels may jump across an open fuse or across a fuse holder with the fuse removed. That is one of several reasons that many utilities will allow their crews to commence work on any transformers before the primary safety grounds are installed.
Bill
--------------------
"Why not the best?"
Jimmy Carter
RE: BIL rating of fuse.
RE: BIL rating of fuse.
RE: BIL rating of fuse.
It's not very likely that you will pass the BIL test with a line to neutral connected transformer but say the transformer does pass with a good fuse. Then, what difference does it make if the blown fuse will isolate the 60kV or not? If the blown fuse passes the voltage to the tranformer then the transformer will still pass the test just like it did with a good fuse.
RE: BIL rating of fuse.
If you look at most cutouts, the air distance from jaw to jaw is usually greater than the air distance from jaw to ground.
It sounds like someone needs some field experence.