75 kva 3 phase transformer

[domnic]

I have a 75 kva transformer 3 phase delta/Y 480 PRI 208 SEC CAN I FEED IT WITH #3 THHN AND #000 THHN TO MY 208 V PANEL?

 

[raider1]

What is the calculated load and what size is the transformer secondary conductor overcurrent protective device?

Chris

 

[don_resqcapt19]

Also what size is the OCPD for the primary conductors?

 

[domnic]

3 phase 480/208 75kw

3 phase 480/208 75kw

Calculated load 50 kw might be a little more in the future. secondary protection 200 amps primary 100 amps

 

[raider1]

With the additional information you have provided I would say that you would be OK to use #3 copper for the primary conductors and 3/0 copper for the secondary conductors.

Make sure that you comply with one of the rules in 240.21(C) for overcurrent protection of the secondary conductors.

Chris

 

[don_resqcapt19]

You may have a problem with the inrush tripping the 100 amp primary breaker.

 

[iMuse97]

I have a 75 kva transformer 3 phase delta/Y 480 PRI 208 SEC CAN I FEED IT WITH #3 THHN AND #000 THHN TO MY 208 V PANEL?

Just did one like this, fed from an MDP with the setup you mention here. No troubles.