Transformer sizing for elevator

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JAMAN

Member
Building has a 208Y/120volt 3-phase service. A 25HP 480volt 3-phase elevator was purchased and is already on the site. The elevator can't obviously be returned, so I need to size a step-up transformer. The elevator specs indicate that on an intermittant bases 29.4HP can be developed at full car capacity for 4 seconds.

Should i base the calc off of the 25HP or 30HP? I was always told to take the worst case scenario, so it would be 30HP. Based on table 430.148, my calcs are as follows:

40amp x 460volt x 1.732 = 31869VA
31869VA x 125% = 39836VA therefore next standard size is 45KVA

Is this calc correct?
 

nakulak

Senior Member
sounds like that is plenty big, however, why isn't the engineer providiing you with the size for the tranformer ? (someone else screwed up already, tell them to give you the size they want and if its wrong its not on you)
 
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