Power Factor Correction

[Chris30559]

Hi Everyone,

So I've read a few threads about this already, but most seem to just ignore it since they are grid tied, and the power company doesn't care. My Setup is off Grid, So I am my own power company and waisted power is not ideal.
So anyway, I am running 2 well pumps with my XW6048 inverter. I noticed that I was drawing much more current from my solar/batteries than I expected. So I looked at my inverter meters and found that my apparent power "VA" is 4593 va, while my real power is 3458 watts. That works out to a Power Factor of 0.75. I run these pumps for a couple of hours each day, so this waist in power is significant. Is there anything that can be done to "fix" this, or at least improve it.

Thanks,
Chris

 

[RCinFLA]

You can put shunt foil capacitor, like run capacitors used on air conditioners, to correct inductive power factor from a single phase induction motor.

You should not correct it too close to a power factor of 1. This is resonance and can creating some voltage ringing when turning off or on.

You need to know the pump motor power factor (relatively accurately), pump applied AC voltage, and pump current to figure the inductive reactive load of motor.

Convert series impedance of motor from above calculation to parallel equivalent impedance. Correcting shunt capacitor will be the mfd's to cancel out the parallel inductive reactance. (should stay a little less than full correction).

Good to put a NTC power thermistor in series with correction capacitor, like used to reduce surge current on a simple rectifier/capacitance filter power supply. This reduces surge current the motor contactor sees hitting a totally discharged compensation capacitor with AC voltage.

Here is an example of my air conditioner compressor. It reduces AC run current by about 15% on the inverter. Keep in mind the power factor will change with motor loading. It gets worse the lighter the motor is mechanically loaded.

Most pump motors only use starter capacitor. With no run capacitor to start winding of motor the run power factor of water pump is usually worse, in the 0.7 range.