we had caps installed on our large motors with a contactor that comes in on up to speed. They were installed on the load side of the softstart, the other day we had to bump the motor a few times and ended up shorting an ser at the same time a contact burned up on the same phasein the breaker protecting it. If the caps were installed on the line side and we had to bump the motor would it have heated the SERs.
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power correction
- Thread starter dshelley
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gar
Senior Member
- Location
- Ann Arbor, Michigan
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- EE
101130-1354 EST
What is an SER? Are you referring to an SCR or some other kind of solid-state device?
I am not experienced with what is done with soft start controls. My guess is that you would not want to put power factor correction capacitors on the output of a soft start even if not connected to the motor during soft start.
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What is an SER? Are you referring to an SCR or some other kind of solid-state device?
I am not experienced with what is done with soft start controls. My guess is that you would not want to put power factor correction capacitors on the output of a soft start even if not connected to the motor during soft start.
.
we had caps installed on our large motors with a contactor that comes in on up to speed. They were installed on the load side of the softstart, the other day we had to bump the motor a few times and ended up shorting an ser at the same time a contact burned up on the same phasein the breaker protecting it. If the caps were installed on the line side and we had to bump the motor would it have heated the SERs.
I'm assuming that instead of SER you are meaning to say SCR (Silocon Controlled Rectifier) which are used to contol the voltage applied to the ouput of the softstarter.
With the caps on the load side of the softstarter they will have a charging current associated with them that may cause excess current through the softstarter in combination with the starting current of the motor. I believe this is why it it recommended that for softstarters and VFD's that have caps on the load side that there is a switch to isolate the caps until the motor is brought up to speed.
I'm sure other experts will chime in with a better explanation.
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