Air compressor 200hp

[kwired]

I like to go NEC I try my best to follow it. But my guess is they will leave it as is. This is the main compressor then there’s a secondary when it can’t keep up

You asked "realistically" and I gave you possible situation where it may last. I still mentioned NEC still requires the conductor to match the actual motor rating, so no what you have still is not NEC compliant even if realistically it may last for some time with no undesired results.

 

[rambojoe]

Sized adequately for the compressor alone.
What would the additional load be? Cooling? Crankcase heat? Obviously I've never worked on one that sized.

Heat is a fundamental issue with a comp of that size.. which sorta overheats everything around it. Ive infrared'd °300f+ on units half that size. You cant even touch the pipe coming out of the head!

 

[Besoeker3]

Heat is a fundamental issue with a comp of that size.. which sorta overheats everything around it. Ive infrared'd °300f+ on units half that size. You cant even touch the pipe coming out of the head!

I disagree. The power rating should be appropriated regardless rated power rating.

 

[rambojoe]

I disagree. The power rating should be appropriated regardless rated power rating.

Are you sure you replied to the right statement?!
I said nothing about power rating...

 

[kwired]

I disagree. The power rating should be appropriated regardless rated power rating.

I think the response was to earlier mentioning that this is a 200 HP machine yet the nameplate has higher current rating than just a 200 amp motor would likely be rated for, so there is probably more loads than just the 200 amp motor. Cooling fans, pumps, maybe even oil pump wouldn't be out of the question on something like this.

 

[retirede]

I think the response was to earlier mentioning that this is a 200 HP machine yet the nameplate has higher current rating than just a 200 amp motor would likely be rated for, so there is probably more loads than just the 200 amp motor. Cooling fans, pumps, maybe even oil pump wouldn't be out of the question on something like this.

If it’s a rotary screw compressor, it likely has a cooling fan that’s either 7.5 or 10 HP. There will be no pumps.

 

[kwired]

If it’s a rotary screw compressor, it likely has a cooling fan that’s either 7.5 or 10 HP. There will be no pumps.

They can be water cooled. One that I know of is only 50 HP, though the cooling water is city water so still no additional pumps, just a solenoid valve on the controls is only additional load for it.

 

[electrofelon]

During a maintenance window a contractor installed a 200hp air compressor. After we got up and running I looked over the install before commissioning and I believe the wire installed is incorrect. Can someone double check me. 3 Cables plus gnd in conduit along beams and wall no other electric.

200hp compressor unit label 293 Fla/ 480 v
My math 293x 125%=366amp 500kcm copper 380 amps @75c.

Contractor ran 4/0 DLO aka NEC RHW-2 flex.
I see that as 230 amp at 75C.
Contractor said that is special high capacity cable and is why it was selected. Am I missing something here??????

Please straighten me out

Wouldn't you use table 430.250 to size the conductors? Or in this case do we use one of the exceptions to 430.6(A)?

 

[retirede]

They can be water cooled. One that I know of is only 50 HP, though the cooling water is city water so still no additional pumps, just a solenoid valve on the controls is only additional load for it.

For water-cooled, the unit nameplate amps likely matches the main motor. In this example, they don’t match.