Coils
Coils
(OP)
I am doing part sizing and selection for a circuit of mine. Was curious to how much current if any a motor starter coil will pull. It controls 480V 3 phase squirrel cage but is 120v controlled
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS Come Join Us!Are you an
Engineering professional? Join Eng-Tips Forums!
*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail. Posting GuidelinesJobs |
|
RE: Coils
Keith Cress
kcress - http://www.flaminsystems.com
RE: Coils
RE: Coils
Keith Cress
kcress - http://www.flaminsystems.com
RE: Coils
my fault - 3HP motor
full load current 3.9A
Loacked rotor 30.8A
No load - 1.75A
All based on 480V numbers
RE: Coils
Those little control transformers have a rather bad "voltage regulation".
That means that voltage drops a lot when loaded with unexpectedly high current. The contactor coil usually does just that. So it starts closing the contacts, coil voltage drops and contacxts start opening. Not good.
Make the transformer at least five times nominal coil power. Ten times is even better.
Gunnar Englund
www.gke.org
--------------------------------------
100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...
RE: Coils
You can buy packaged "Motor starters". You should consider it.
Keith Cress
kcress - http://www.flaminsystems.com
RE: Coils
Bill
--------------------
"Why not the best?"
Jimmy Carter
RE: Coils
Starters have a horsepower rating which would have to correspond with the motor hp. You must find a starter that matches the horse power rating for your motor otherwise use the FLC values as determined from the NEC.
Eric Kench, P.E.