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Co generation & fault mitigation

Co generation & fault mitigation

Co generation & fault mitigation

(OP)
thread238-296351: Cogeneration and Fault Mitigation

With reference to the above closed thread I'd be very interested to know what solution the original poster finally went with and any other experiences from other forum members for similar projects.

Issues with Is limiters and CCLs: aren't they explosive devices, creating safety hazards? And after every fault event, don't these need to be replaced, thus increasing costs?

Issues with series reactors: voltage drops and fluctuations affecting power quality?

Many thanks

RE: Co generation & fault mitigation

We just came from a project with three 45 MVA generators paralleled on a 11 kV bus with switchgear rated 50 kA.  ETAP gave initial fault levels of 102 kA.  The two tie breakers between the three generators had current limiting explosive fuses (G&W CLiPS) that triggered at 18 kV to limit fault current on any bus to within the ratings. (ETAP can't account for the current limiters).

I was skeptical at first, but after looking at it in detail, it seems like a good economical solution.  Fault currents through the ties will only exceed 18 kA for close-in 11 kV faults. Contribution to faults out in the refinery is less than 18 kA, greatly reducing the chance of a current limiting fuse actuation.

The associated tie breakers also trip as soon as the current limiting fuse is activated to isolate systems and prevent single-phasing problems.

If a fault occurs close in, fuse replacemnt is required and spares are expensive.  But they should seldom be required.  

The explosive fuse technology is very safe, especially compared to arc flash dangers.

The explosive fuses were a good solution in this case.

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