Please Help with Transformer feeding one motor!!!

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Jraef said:
I would agree, however I mentioned it because ...
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I saw that as well and that leads me to believe there would be no provision for that frame size breaker. The sub feed spot would be special order and if there were no intended loads for it why would they do that?

One other possibility is if it has feed through lugs on it or if the main breaker has open lugs left for parallels he could easily leave the panel in place and simply continue the feeder into the transformer.

Like you I dislike the idea of doing away with a perfectly good panel. :)
 
iwire said:
In my experiance it would be rare that an existing 225 amp panel would be able to accept a 175 amp breaker.

The panel would have to have an unused subfeed postion.
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Not rare at all in the I-Line series.:happyyes:

In that series you may run into a panel with 800 amp bus that is only intended for a 600 amp max breaker, but I think anything 225 amps or less (and very possibly up to 400 amps) can have full bus rating connected to any single breaker position.
 
kwired said:
Not rare at all in the I-Line series.:happyyes:

In that series you may run into a panel with 800 amp bus that is only intended for a 600 amp max breaker, but I think anything 225 amps or less (and very possibly up to 400 amps) can have full bus rating connected to any single breaker position.
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Yes, I know about I-Line but they are rare.

I also have never seen an I-line rated less than 400 amps.
 
iwire said:
Yes, I know about I-Line but they are rare.

I also have never seen an I-line rated less than 400 amps.
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I installed two last year that were both 800 amps - but only rated for a 600 amp max branch. One of them I installed a 600 amp breaker as the main, the other I installed a main lugs/subfeed kit (which the kit happened to be rated 1200 amps) and had six or less breakers as the mains for that particular service.

I don't install them all the time, but do run into them frequently, majority of them are 400 amp or less. If you get over the 800 amp range you are probably looking at switchboards being used instead in most cases, but I believe there are over 800 amp versions in the catalog. (I guess if I had a 1200 amp lug kit they must go to at least 1200)
 
I guess I'm so used to Siemens now that I was thinking you can add at least one sub feed kit for any breaker frame up to the bus rating of the panel. But now that I look at others, I see that is not the case, you have to have ordered the interior with that capability for some of them (C-H). I should have realized also that it would not be Siemens, they don't have a 225A bus, theirs is 250A. My bad.

Jjmodoc1,
If changing the motor out is too distasteful to you because of how busy the IR compressor package is inside of that housing, I don't blame you. But most decent motor shops would do that for you in a heartbeat, and they would offer to buy that 208V 50HP motor back as well. If it were me, I would tell the owner I would take care of the whole shebang for a fixed price, then load that compressor into the back of my pickup and pay someone else to swap out that motor, bring it back to them and do the rest of the work in 480V.
 
Use table 430.250 to size the circuit required.
50 HP @ 208 = 143 FLA
143 * 1.25 = 179 amps requires 3/0 in the 75 degree column of table 310.15(b)(2)

The maximum inverse time delay circuit breaker form table 430.52
2.5 * 143 = 358 amps. This won't fit in a 225 amp panel.
Maximum dual element fuse from table 430.52
1.75 * 143 = 250 amps. Again this won't fit in the panel.

The wire feeding the panel should be large enough to abandon the panel and replace it with a 400 amp disconnect fused with 250 amp dual element fuses.
 
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