3 HP Cyclone dust collector trips breaker on startup

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  #1  
Old 09-24-14, 06:47 PM
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3 HP Cyclone dust collector trips breaker on startup

I have a Penn State 3 HP cyclone shop dust collector, wired for 240V, 14 amp motor, 20 amp circuit. Upon startup it often trips the breaker. An electrician was called, and he put the meter on it at the panel. On startup each leg surges to about 100 amps for a fraction of a second, and sometimes it immediately trips the breaker and sometimes not, but it always surges on startup. The 3 HP motor was built in 2000. Electrician is having a hard time finding out what the problem might be. Could a bad capacitor be causing the spike? Would a soft start kit solve the problem?
Thank you!
 
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Old 09-24-14, 07:41 PM
Tolyn Ironhand's Avatar
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Welcome to the forums!

First I have to ask, is this a licensed electrician, or just a handyman?

There is nothing wrong with your dust collector. It is normal for a motor to draw 3 times (or more in your case) during start up, especially if it is spinning a heavy impeller like you would find on a cyclone system.

Motor circuit have a totally separate set of rules in the NEC. According to here: electrician2.com Motor Circuit calculator you can go as high as a 45 amp circuit breaker for that circuit for a FLA of 14 amps. Circuit breakers are not for protection of the motor, they are for protection of the circuit wiring, so make sure the motor is thermally protected.

I would not go as high as 45 amp breaker. I would go the next size up and see if that holds. A 25 or 30 amp should be fine.
 
  #3  
Old 09-24-14, 08:17 PM
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The motor data calculator I use calls for either a 35 amp thermal breaker or 25 amp dual element time delay fuse with #12 wire. I think a 30 amp breaker would work just fine.

Single Phase Motor Data
 
  #4  
Old 09-25-14, 07:54 PM
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I went by the FLA of 14 while Joe went with the HP rating. This is why our info differs, however our advice is the same.
 
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