Ground Fault Protection to 480v Delta transformer

[metallica5]

I have a 225 kva harmonic suppression transformer with 480volt delta primary and 208/120 Wye secondary. Feed is coming from 350 Amp breaker in 1000 amp main distribution service board. Specification calls for ground fault protection on all branches over 225 amps. My question is how to provide ground fault protection to this 480 volt delta primary?

 

[jim dungar]

Use an electronic trip breaker with built in GF protection.
The GF can be set almost any where you want, as there is nothing that would occur on the secondary side of the transformer that would appear as a GF on the primary side.

 

[templdl]

I have a 225 kva harmonic suppression transformer with 480volt delta primary and 208/120 Wye secondary. Feed is coming from 350 Amp breaker in 1000 amp main distribution service board. Specification calls for ground fault protection on all branches over 225 amps. My question is how to provide ground fault protection to this 480 volt delta primary?

I'm always intrigued by information that is omitted in the OP. You stated that you are feeding a 480D-208Y/120 transformers. The 208Y/120 is not relevant, the 480D provides a hint but missing what the source voltage is. From that one has to assume that it is a 480Y/277 with the X0 grounded. As such Jim suggested a MCCB with and electronic trip that includes a GF option which is the way to go. Because there is no neutral loads when feeding a 480vD 3ph3w transformer primary, the neutral CT for the breaker is not required as would be common for a 480Y/277 load.
Also, if the GF option is not feasible then a breaker with a shunt trip that can be tripped by an external GF device would be a possibility.
On additional question is what GF pickup does the application require? Most devices of this category have an adjustable pickup and some may even have a short delay. What should the pickup be set at?

 

[metallica5]

Source voltage is 480/277. I included the 208/120 in case there was some relevance that I am not aware of. This particular switch board came to us with GF monitoring sensor donuts for neutrals on all feeders 225 amps and higher. This one particular circuit being a three phase delta has no neutral to monitor. My question was how I could provide GF protection to meet this spec since gear designers at manufacturer missed this.

 

[templdl]

Source voltage is 480/277. I included the 208/120 in case there was some relevance that I am not aware of. This particular switch board came to us with GF monitoring sensor donuts for neutrals on all feeders 225 amps and higher. This one particular circuit being a three phase delta has no neutral to monitor. My question was how I could provide GF protection to meet this spec since gear designers at manufacturer missed this.

If your GF has a neutral sensor already it's no big deal. Normally you would run your neutral from the load through the window but since you will have no neutral that isn't going to happen.
As far as the GF pickup setting you are going to have to hit on the manufacturer to advise you of that. It's fairly difficult for you to guess at what that may be as then you become liable. I would ask them what they recomment in writing.