Step up transfomer. 240v delta to 480 volt delta. gounding of corner tap???

[dannyt]

Sorry if this is a repeated subject.
Need to install a step up transformer. Its a 240v delta to 480 volt delta. The building has 240 volt 3phase with the high leg. Its a 45 kva transformer that will run two 3 phase machines. Does the one corner of the secondary transformer need to be gounded . What happens if you dont.

 

[raider1]

You either need to ground the secondary of the transformer or if you decide to leave it ungrounded you must comply with 250.21(B) and install ground detectors.

Keep in mind that if the secondary is left ungrounded you would not be able to trip an overcurrent protective device with an initial ground fault.

I would ground the secondary unless there is a very good reason not to.

Chris

 

[dannyt]

Thanks for the input. Does it matter as what corner to ground??

 

[jim dungar]

B-Phase is the preferred one.

 

[dannyt]

Thanks again...