240V to 480V

[slect]

Client to adding a machine for his cabinet building shop.. shop is located at rear of property about 250 feet away from existing service location..
Have a 200 amp single phase disconnect available at service not being used…
Installing a 45 KVA 240V TO 480V single phase transformer to get power back to the shop, reducing wire size, cost, VD , etc..
once at the shop I will install disconnect and then feed a Digital phase converter to provide 3-phase 480V.. Delta.. to the new machine.. no other loads..
Question 1 .. I will not be using the neutral from the transformer to the shop as I don’t think I need the neutral for the primary feed to the digital phase converter, so for cost sake is there any code issues in not installing it ? Will confirm with manufacturer of converter ..
Thanks for any comments

 

[augie47]

I don't beliebe your 240 to 480 transformer will have a neutral on the hi voltage side, will it ??

 

[electrofelon]

I don't beliebe your 240 to 480 transformer will have a neutral on the hi voltage side, will it ??

Often these will be two winding transformers so I think it could be center tapped. However, the most economical way to do it is probably to ground one of the 480 "ends" and use 250.30(A)(1) exception #2 so only two conductors will be required (grounded conductor also serves as EGC).

OP, Watch out for the transformer trap. Thats a lot of capital cost and $175 in no load losses per year (then there is load losses). Aluminum wire is cheap. How big is the motor? It sounds like the motor is 480 and I admit finding a single phase 240 in to 480 three phase out VFD may be difficult. This may be an option worth looking into:

https://www.phasetechnologies.com/explore/solutions/voltage-doubling

Also, it may be best to change the motor (depending on size).