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transformer selection

transformer selection

transformer selection

(OP)
I have a vacuum pump using a 240v .75KW motor 5 amp I want to use a 110v .75KW  10 amp motor can anyone suggest what transformer I need

RE: transformer selection

Well according to your numbers, you have a 240V machine drawing 5 amps or 240 x 5 = 1200 Volt-Amps.  If it is indeed seeing .75 kW then that means your power factor is a pretty low .625.  If you are changing out the motor to a 110V motor then it will draw about twice the Amperage, 240/110 = 2.2 x 5 = 11 Amps.  If the power factor us unchanged, then the wattage is 11 x 110 x .625 =.756kW.  So all you need is a 240V primary, 120V secondary, single phase, 1.5 kVA transformer.  Very common piece of equipment. Jefferson Transformer makes one rated at 2kVA which will work, it is Catalog number 411-0091-120.  You can see the enclosure and the wiring diagram (#S240A) on their website under "Encapsulated Transformers".  www.jeffersonelectric.com/s3/site/catalog/1phaseEncap.pdf  Hope that helps.

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