Phil Corso
Senior Member
- Location
- Boca Raton, Fl, USA
RaiderUM...
I should have asked for Hp or voltage!
Phil
I should have asked for Hp or voltage!
Phil
RaiderUM...
I should have asked for Hp or voltage!
Phil
RaiderUM...
Using a time honored R-O-T (Rule of Thumb) PF correction should offset about 80% of the no-load kvA of a 2-pole, TEFC, induction motor.
Presuming full-load kVA is about equal to rated Hp, and no-load kVA is, say, 15% of full-load,then the "safest" capacitive reactance, kVAr(c), should not exceed some 60 kVAr!
Thus, the value you detrmined is much too high!
Regards, Phil
PS: what are the approximate bus-voltages used in your facility?
Typically, the no load current of a cage induction motor is about 30% of full load current.Presuming full-load kVA is about equal to rated Hp, and no-load kVA is, say, 15% of full-load
Typically, the no load current of a cage induction motor is about 30% of full load current.
On that basis, your 15% is much too low.
As I said in my note, 12 kv primary capacitors are easy to install. You can get then in 1000 kvar and smaller if needed. You can leave these on line until you feel it is time to take them off line. You use load-break fused disconnects and a hot stick. This would be much simpler that what you had proposed. Pay back maybe 1 year.
Since you're correcting the supply power factor, motor efficiency doesn't have a direct bearing on the correction required.Voltage is 460V
Full load Amps is 465
PF is around .8
I dont know what %eff is?? I'm guessing 92.4?
Of course it varies.Boeseker...
I never said, in my example, that I used a "typical" value. In fact, the no-load current is a funtcion of construction, speed (# poles), and voltage.
See post #54.Besoeker,
Your saying that my Kvar should be 116 Kvar then?
140*1.732*480=116390
Care to supply actual drive motor name plate data?Besoeker...
Tit-For-Tat, huh :happyyes:
How about an 11,400 kW (15,300 Hp) ethelene compressor-drive, having a no-load current of 135A and a full-load current of 750A. NL/FL ratio is 18%. Closer to 15% than 30%.
Regards, Phil