Sizing of Transformer

[kencoel]

What is the best way or formula to size a transformer? Lets say the primary voltage is 480V 3PH, the secondary 240/120 3PH and aprox. 800amp load.

 

[coulter]

240 x 800 x sqrt(3) = 333kva

However, now for the "I don't know part".


1. 240/120, 3ph xfmrs are usually really limited in the single phase 120V loads. With out knowing the loading, and the transformer specs, this could easily be the limiting factor.

2. What does "about 800A" mean? 10% more maybe?

3. Is there any chance of additions? Is there any inclination that the customer would want to pay for possible or probable additions?

The formula is at the top, but I wouldn't use just that to pick the xfm.

carl

 

[kencoel]

The projected total load is aprox. 800 Amps or less.

240 x 800 x sqrt(3) = 333kva

However, now for the "I don't know part".


1. 240/120, 3ph xfmrs are usually really limited in the single phase 120V loads. With out knowing the loading, and the transformer specs, this could easily be the limiting factor.

2. What does "about 800A" mean? 10% more maybe?

3. Is there any chance of additions? Is there any inclination that the customer would want to pay for possible or probable additions?

The formula is at the top, but I wouldn't use just that to pick the xfm.

carl[/QUOTE]

 

[bob]

What is the best way or formula to size a transformer? Lets say the primary voltage is 480V 3PH, the secondary 240/120 3PH and aprox. 800amp load.

With that much load, I would consider a service at 277/480 volts. You would not need 800 amps.

 

[bob]

What is the best way or formula to size a transformer? Lets say the primary voltage is 480V 3PH, the secondary 240/120 3PH and aprox. 800amp load.

With that much load, I would consider a service at 480/277 volts. You would not need 800 amps.