Military generator

[ceb58]

Have been ask to connect a 60 Kw 3 phase military generator to a rural fire department building with a manual transfer switch. The name plate has it at 208 amps at 120/208v. I will be connecting it single phase since the building is 120/240 v 1 ph. My question is because I am using only 2 of the phases, that beats out to 138 amps. So do I size the wire and over current to that or will I have to size per the name plate even though I am not using all 3 phases? The generator doesn't have OC protection so I know I will have to size the wire at 115% to the disconnect per 445.13. So by this my conductors from the generator to the disco. would have to be 2/0 with 160 amps fuses. Or am I going to have to size 115% of the name plate 208 amps?

 

[don_resqcapt19]

Most of the military generators I have seen were 12 lead and could be reconnected for 120/240 single phase at 2/3s the rated KVA. The connection is called a zig-zag connection at I recall. So at 40kw, 120/240, the current would be 166.6.

That being said, I think the answer to your question is that the conductors are sized based on the current that the generator can supply to the conductors.

 

[ceb58]

Most of the military generators I have seen were 12 lead and could be reconnected for 120/240 single phase at 2/3s the rated KVA. The connection is called a zig-zag connection at I recall. So at 40kw, 120/240, the current would be 166.6.

That being said, I think the answer to your question is that the conductors are sized based on the current that the generator can supply to the conductors.

Looked at it, only 2 voltages available 120/208 or 240/316

 

[don_resqcapt19]

Looked at it, only 2 voltages available 120/208 or 240/316

Is that from the nameplate? Some of the ones I worked on only had a couple of voltages on the nameplate, but they were 12 lead generators, and the manual gave the connections for the other voltages. If it is only a 9 lead machine, you are stuck with the two nameplate voltages.

 

[ceb58]

Is that from the nameplate? Some of the ones I worked on only had a couple of voltages on the nameplate, but they were 12 lead generators, and the manual gave the connections for the other voltages. If it is only a 9 lead machine, you are stuck with the two nameplate voltages.

Nine lead. Looked at the lead connection board. So it looks as if I'm at 192 amps @ 208

 

[kwired]

Looked at it, only 2 voltages available 120/208 or 240/316

240/316 or 240/416? 240/416 is possible with a wye connection 240/316 is not.


add: 120/208 to 240/416 change is possible with a nine lead generator, low voltage connection is two parallel wye sets, high voltage puts three outer sections of the wye in series with the inner 7-8-9 leads. To be able to get 277/480 out of this you need to do some tweaking of the regulation methods when switching voltages.

 

[ceb58]

240/316 or 240/416? 240/416 is possible with a wye connection 240/316 is not.


add: 120/208 to 240/416 change is possible with a nine lead generator, low voltage connection is two parallel wye sets, high voltage puts three outer sections of the wye in series with the inner 7-8-9 leads. To be able to get 277/480 out of this you need to do some tweaking of the regulation methods when switching voltages.

316 was a type o . Will be going with the 120/208 voltage just using 2 legs instead of 3.