stuartdmc
Senior Member
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- Newport Beach, Irvine, CA
We are designing power for a UPS system and are providing primary fuse protection for it after the transformer, is there a specific type of fuse that should be used for the UPS system?
What Fuse Types to UPS ?
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iceworm
Curmudgeon still using printed IEEE Color Books
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- North of the 65 parallel
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- EE (Field - as little design as possible)
The few that I have done had internal fuses where special protection was needed - such as semiconductor fuses. So my designs were just thermal-mag cbs feeding the UPS. However this does not apply to your case because I don't know anyting about your equipment specs or this transformer in the feeder, or anything about your system available SCC.
The first place I would check is the manufacturer's literature, followed by a call to the mfg if there was any doubt.
ice
The purpose of fuse protection on a UPS input is to clear faults in the input stage semiconductors very quickly. With high speed fuses a failed diode or IGBT will have a burn mark on the side of it, with slow protection the IGBT or diode will be destroyed and adjacent components will also likely be damaged.
For this reason any high quality UPS will already have the proper fuses designed into the UPS, there is no reason to provide anything other than a thermal magnetic breaker or standard branch circuit fuses on the UPS feeder.
Standard 6 pulse diode input VFDs on the other hand do not typicially include fuses, but high speed Class J or similar fuses are recommended by drive manufacturers for the same reason - to prevent collateral damage when an input diode fails, which minimizes repair cost.
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