Transformer sizing for elevator

[Grouch1980]

What's the correct way to size a step-up transformer for an elevator? (208 - 480 volts)

To determine the transformer KVA, do you use the elevator full load amps, locked rotor amps, or should the size be provided by the elevator vendor?

Thanks!

 

[Grouch1980]

Do I size the transformer at 125% of the elevator motor FLA?

 

[jim dungar]

Do I size the transformer at 125% of the elevator motor FLA?

Maybe.

Transformer are 100% continuous rated. A transformer sized closely to a motor FLA may not be able to handle motor inrush current without causing a significant voltage drop.
Elevator motors often have VFDs as part of their control, so the transformer would need to be sized for the VFD input requirements.

 

[Grouch1980]

Maybe.

Transformer are 100% continuous rated. A transformer sized closely to a motor FLA may not be able to handle motor inrush current without causing a significant voltage drop.
Elevator motors often have VFDs as part of their control, so the transformer would need to be sized for the VFD input requirements.

Sounds like this is something the elevator manufacturer should give.