Power Factor and Induction Motor

i do not believe that there is a "utility power factor". You just get a voltage at your incomer. When you put loads on it - motors, lights, furnaces, etc, that decides your plant power factor. If it is too low, the utility may ask you to put some capacitors to improve it. In some areas, there may be penalties for low pf. The motor, once you connect it and start, will run at its inherent designed pf, nothing external will affect it. However, depending on the voltage and the load on it, pf will vary slightly. For more details, you can check out this thread:http://cr4.globalspec.com/thread/56346#newcomments

kind courtesy - msamad.

You are right. The graph shows the relation with respect to voltage variation. What my question is that

Yesterday our PFC was not working. Its shows the power factor 0.72 instead of 0.95. Now in that scenario this P.F 0.72 have what kind of influence on the performance of the induction motors in the area?

This Low P.F 0.72 does affect the P.F of the motor or not? Let a motor of 4 KW, 400 V, 50 Hz, 7.8A, P.F 0.87, 2850 RPM. Does its P.F (0.87) remain same or will change?

Look at it this way ... the incoming voltage applied to the motor is seeing the impedance of the motor only, nothing else. So, the motor will draw whatever current it needs to deliver the mechanical power it is asked to deliver. If you measure only the motor's pf, it will be close to what the nameplate says. The plant pf is another story. It will take ALL your loads including the motor, and the meter will show that.

You seem to have some high-inductance loads..maybe an induction furnace? You wouldn't need a PFC otherwise. If it is not working, you may need to manually cut in some capacitors while watching the pf meter.

Please rest assured that the motor is unaffected. Even if you shut down everything else, it will work as usual