In Rush

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jbolen

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Will a 350 amp Bussman fuse, Class aR be able to handle a 500 amp in rush for chiller compressor under high load.
 
jbolen said:
Will a 350 amp Bussman fuse, Class aR be able to handle a 500 amp in rush for chiller compressor under high load.
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I would think so but look at the fuse curves.
What is high load? How long?

What is the MCA of the unit? MOP? FLA? LRA?
In general, motors easily pull 6 times their FLA. Your 500 amp starting current is about an 83 amp load. Typically a fuse would be no bigger than 250% of that, or about 200. The 200 should work. The 350 is oversized.
 
jbolen said:
Will a 350 amp Bussman fuse, Class aR be able to handle a 500 amp in rush for chiller compressor under high load.
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As far as I know, Class aR fuses are for short-circuit protection only and should be relied upon for overload protection! These types of fuses should not be used to operate above the fuses' A-A line.
 
aR fuses would typically only be used if there are semiconductors used in a controller, i.e. a VFD or a Soft Starter. If that is the case, "inrush" current would not be a factor in their sizing.

But ALSO, if there is a controller involved, that controller's listing is likely dependent upon using the EXACT fuse it is listed with, you are usually not allowed to substitute.

You have some more investigating to do here.
 
Jraef said:
aR fuses would typically only be used if there are semiconductors used in a controller, i.e. a VFD or a Soft Starter. If that is the case, "inrush" current would not be a factor in their sizing.

But ALSO, if there is a controller involved, that controller's listing is likely dependent upon using the EXACT fuse it is listed with, you are usually not allowed to substitute.

You have some more investigating to do here.
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Insert slaphead emoji...I thought the 'a' was a typo
 
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