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Motor fed from xfmr

Motor fed from xfmr

Motor fed from xfmr

(OP)
What problems can I expect if I wanted to energize a 480v-240v transformer to start a 240v motor from a level switch contact?

RE: Motor fed from xfmr

Not enough information.  Motor size, transformer size, starting method?

Three-phase or single phase motor?  Many motors can be connected for either 460 or 230 V.   

David Castor
www.cvoes.com

RE: Motor fed from xfmr

crivitz,
Presume you mean a dedicated trafo supplying to the motor that is switchead on trafo primary side.
Generally speaking, the large voltage drop in the transformer during motor starting poses difficulty in terms of low voltage at the motor terminals (i.e. secondary terminals of trafo) and hence insufficient torque at the motor shaft. This can be overcome by choosing a fairly higher VA rated trafo (in comparison to the motor rating.

RE: Motor fed from xfmr

(OP)
The circuit is 480V to a 2kVA transformer to 230V single phase to power a 1/3HP fuel oil pump.  The level switch contact initiates starter to energize 480V transformer.

RE: Motor fed from xfmr

You'd want a really stout switch or you should consider having the level switch operate a small contactor.  Switching on and off a transformer can be very tough on a switch.

Keith Cress
kcress - http://www.flaminsystems.com

RE: Motor fed from xfmr

I think the OP said the level switch energizes the starter (contactor)which feeds the xfmr.  Don't really see any problems with this setup.  1/3HP motor will start & run just fine on a 2kVA xfmr.

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