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Discussion Starter · #1 · (Edited)


The above is the schematic of a control cabinet feed for a 25Hp hydraulic motor.

To upgrade this machine to 75HP motor, I need to do the following:

1. Get rid of the fusible 60A and change it to a 150A breaker.
2. Change 1L's to 1/0.
3. PDB can stay, as it is rated 175A already
4. Change 1CB to 125A.
5. Change 1M and overloads to size 96FLA.


Everything is Cutler-Hammer.

What frame CH breaker would you use, and does this sound plausible?
Thanks,


edit: Hoffman 24x24 enclosure, no outside handle option.
 

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View attachment 34961

The above is the schematic of a control cabinet feed for a 25Hp hydraulic motor.

To upgrade this machine to 75HP motor, I need to do the following:

1. Get rid of the fusible 60A and change it to a 150A breaker.
2. Change 1L's to 1/0.
3. PDB can stay, as it is rated 175A already
4. Change 1CB to 125A.
5. Change 1M and overloads to size 96FLA.


Everything is Cutler-Hammer.

What frame CH breaker would you use, and does this sound plausible?
Thanks,


edit: Hoffman 24x24 enclosure, no outside handle option.
So first off, you likely have a NEMA size 2 starter for a 20HP motor, you will need a NEMA Size 4 starter. Whole different animal.

Second, it's entirely possible that because of the larger conductors and larger components, you will not longer have the required wire bending space for both line and load.

Third, it would likely be a lot less expensive to just go buy a NEMA size 4 combination starter and be done with it.
 

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A 75hp starter/overload will not fit in a 24x24. Been there done that. You need 36" of panel height to do a reasonable job.
 

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A 75hp starter/overload will not fit in a 24x24. Been there done that. You need 36" of panel height to do a reasonable job.
UL wire bending space for cables necessary for 1/0 cable is 5" minimum on the line and load sides. Add another 8-10" for the breaker and wires to a contactor and you have very little left for the contactor and overload, which like I said is going to be much larger now. You might be able to move the starter off to the left and up in order to make room, but that assumes there is nothing else in that box and making tight S curves in 1/0 cable without putting a lot of strain on the breaker and contactor lugs is not easy.
 

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Discussion Starter · #5 ·
I see what both of you are saying. The starter size is much bigger....

Maybe an option for them might be a control cabinet for controls, and a complete CH motor starter unit, mounted somewhere close and convenient...

That might work...
 
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