Frequency and Power Factor

On a purely resistive load - No

On all other loads - Yes

Capacitave loads are designed by their charge and discharge times. Inductive loads ave a specific resistance at each frequency. Both are frequency dependant. A major change in frequency may even destroy these loads.

To change the frequency will delay or advance the power factor of all loads that are not purely resistive.

I assume that's because it puts the voltage and current out of phase, so the power fluctuates with the frequency?

Power factor is a function of Impedance ( R/Z ) and Impedance of pure resistive load is R and PF is Unity where as in Inductive and capacitive load The Impedance of load is a function of Frequency. Hence for such load Power Factor will depend on Inductance/capacitance/frequency .As the frequency approaches zero, the capacitive reactance grows without bound so that a capacitor approaches an open circuit for very low frequency sinusoidal sources. As the frequency increases, the capacitive reactance approaches zero so that a capacitor approaches a short circuit for very high frequency sinusoidal sources and the converse effect for Inductive reactance. So change of frequency affects the Power Factor in Inductive and Capactive loads.

The impedance of an AC circuit is determined by the resistive and reactive loads.

Inductive reactance is the result ofter equation 2 x 3.142 x F x L

where F = frequency (Hz)

and L = inductive component value (Henry's)

Capacitive Reactance XC = 1/(2 x 3.142 x F x C)

where F = frequency (Hz)

and C = capacitive component (micro farads)

But XL and XC oppose each other which results in the final equation

Z = square root of (R + (XL -XC) )

Power factor correction attempts to limit the value of XL - Xc, but XL - Xc must never be allowed to equal zero, the circuit must have either have a liiet inductance or capaitance, or simply be purely resistive. The latter in practice is never achieved

When both inductance and capacitance is present in a power circuit with XL = Xc then circuit is in RESONANCE a dangerous state in power circuits.

So you can see the direct relationship

RESONANCE a dangerous state in power circuits.

Can you explain further why this is dangerous?

It is more understable when you can see the formulae for X and Z calculation. Good job (A-)

One error was found in the formula for XC, The value of C that should be entered in F (farads) not in μF (microFarads) if the result should be in Ω (Ohms). Entering C in μF you will receive Z in MΩ (MegaOhms = million of ohms)

I had to write this errata so the students will not bring this error to the tests or, even worst to lab experiments.

PF (power factor = Active power/Apparent Power = R / Z of the system load)

Thank you southern123. Since frequency and power factor have a direct relationship in reactive power system, how can frequency cause the measurement of energy (KWHr) to speed up or slow down, say; in a 3 phase, 60Hz, 220Volts, 0.8PF, 20KW inductive load system when for example in a 12Hrs total operation, the frequency drops to say 58Hz or 57Hz for a period of 5Hrs, while voltage is maintained at 220? How does it affect the consumer and the supplier of electricity?