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Is the short circuit level setting of the Current limiter site adjustable?

Is the short circuit level setting of the Current limiter site adjustable?

We have a 11kV, 2500A Current Limiter (Is Limiter) application. The current limiter is originally designed for 40kA. But the project is in two phases. Phase-1 (i.e. present) requirement is to limit the short circuit level to 20kA. Later, i.e. in Phase-2 the current limiter should limit the current to 40kA.

I want to know whether the current limiters have fixed setting or it can be changed based on the requirement at later date.

Thanks in advance.

RE: Is the short circuit level setting of the Current limiter site adjustable?

Depends on type of device used to limit the current:

Current Limiting Fuse- You would have to change the fuse. Finding a fuse that could do the current limiting at that voltage level for all faults and system configurations would be unusual, but possible. Unless the fuse has been actually tested with some of the downstream devices it may not be acceptable.

Reactor- Change reactor.

Power Assisted Fuse - This "fuse" has a separate current measuring CT and control that triggers the fuse by using explosives to cut a bus bar shorting the fuse. The fuse trip level can be adjusted, but it may have to be done by factory technicians. (G&W used to sell these, I think that product line is owned by someone else).

There are issues in using any of these items: cost of the fuse, the extended outage when a fuse blows, system changes affecting the let-through current, etc.

RE: Is the short circuit level setting of the Current limiter site adjustable?


Thanks for your input.

Here I am talking about the ABB Make Is Limiter.
[ABB Is Limiter]

This has a very complex electronic circuit and some small amount of explosive substance inside the panel. Not the same as you have mentioned in your post. This is 11kV, 2500A rated.

Anyone in this forum who can shed some more light on this?

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