Transformer for elevator

[brianthejabroni2]

Can someone help me understand why this 20kva transformer is saying primary input 80A (see attached nameplate)

I feel it should be the following
20,000/240v=83.33/1.73=48.16

 

[jim dungar]

Can someone help me understand why this 20kva transformer is saying primary input 80A (see attached nameplate)

I feel it should be the following
20,000/240v=83.33/1.73=48.16

You are correct with the formula for the primary side full load current. But the nameplate shows the protective device rating.
The NEC suggests the primary side protection should be 125% of FLA. However, it allows up to 250%, when a 125% maximum secondary side protection is provided. These differences allow the protective device to handle the start up/in rush currents of the transformer.

 

[Tulsa Electrician]

I did notice it's an auto transformer.

 

[jim dungar]

I did notice it's an auto transformer.

That does not make much difference, except it probably has a high inrush.

 

[Tulsa Electrician]

Thank you