Delta:wye 480v:12,470v for a generator on a campus med power loop.

[fj40dan]

Is the best solution to feed a delta:wye step-up with the 480v generator? Where the H0 on the secondary (12,470v) is grounded/bonded to prevent a floating neutral and also to allow any phase to trip the med volt breaker?

Or are am I missing a big pitfall?

I've never done step up transformers for generators. I'm primarily low voltage (<1000v) in my day to day. On this project I'm feeding 12,470 switch gear and another group does that medium voltage switchgear. This low volt guy wants to make sure that I'm not messing it up.

 

[jim dungar]

Are you using protective relays on the primary and secondary?
This is a pretty straight forward application as far as hardware goes.
Is the secondary equipment close coupled?

 

[fj40dan]

Are you using protective relays on the primary and secondary?

Primary - no, secondary - yes in med volt gear. The genset primary has the typical shunt-trip (LSIG) breaker controlled by the alternator protection plc, among other things.

Is the secondary equipment close coupled?

No the transformers are separate from the med volt gear. They're just commodity pad-mounts. Unless you mean something else by that.

 

[jim dungar]

Primary - no, secondary - yes in med volt gear. The genset primary has the typical shunt-trip (LSIG) breaker controlled by the alternator protection plc, among other things.

Is there a dedicated transformer primary device, or are you expecting the generator breaker to do double duty?
Not a big deal, stepping up voltage is stepping up, you don't have to worry about single phasing on the primary side.