60 hp roto phase

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ptonsparky

ptonsparky

Tom
Location
NE (9.06 miles @5.9 Degrees from Winged Horses)
Occupation
EC - retired
Customer called about wire size for a rotophase , 230 volt that would handle a 60hp. I did.a.SEWAG of 350 kcmil al minimum for the distance he gave. His anyone used a rotophase of that size? I checked the ARCO website this evening and did not find details for one that size. Actual current draw would be helpful.
 
120825-1314 EDT

Wild ball park figure.

Assume the end load is 60 HP 3 phase induction motor. More information is needed.

Assume 1KVA per HP or 60 KVA. This should take care of the motor inefficiency. Maybe not the power factor effect.

Assume the rotary phase converter has an efficiency of 75%. Then input KVA is about 60/0.75 = 80 . Not all the energy passes thru the rotary converter. Something under 33% goes directly to the load motor. This would be 33% but there are losses in the rotary converter that is supplying energy to the other two phases.

Thus, input single phase current from the line is about 80,000/230 = 350 A, or maybe more.

If the load could be a big single phase capacitor run motor, then the whole system would be more efficient and a better power factor. The line current might be about 260 A.

Alternatively a smaller DC motor might do what is needed and not require high inrush energy for start-up with the correct control.

.
 
120826-0931 EDT

ptonsparky:

My wild guess is probably on the high side. The 1 KVA per HP sort of includes motor efficiency and power factor as a ball park figure. So probably as a multiplier there should not be an additional contribution relative to power factor when the phase converter is included. Actually the phase converter may look more like a single phase capacitor run motor which has good power factor at full load. Thus, possibly the added system input over the motor load alone may be more like the actual power losses in the phase converter added to the 1 KVA estimate per HP.

.
 
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