Q&A for How to Calculate Power Factor Correction

The power factor is calculated to reduce loading on the source and the physical requirements of the conductors that carry that current. By calculating the power factor, you determine how inefficient your circuit is. This gives you the information you need to make it more efficient by adding in components that will yield power factor correction.

You can get an ammeter and voltmeter and attach them to the lamp wires. If you don't want to do that much work, you can read the instructions in the lamp's package.

If the circuit is inductive, by adding in a cap bank. If the circuit is capacitive, by adding in inductive loads.

In step four, the user has a right triangle. In the case of a right triangle, the tangent of the angle theta is the opposite (reactive power) divided by the adjacent (real power). Taking the inverse tangent of this ratio gives you the angle (make sure your calculator is in degrees). This angle is the phase difference between your voltage and current.

The resistance is calculated from the real component of the power triangle (a value in watts) and your knowledge of the voltage. R = V^2 / P. R is in ohms, V is in volts and P is in watts.

PF = P/S which means S=P/PF. S = 230/0.23 = 1000 VA. P = IE which means I = P/E = 1000/120 = 8.33 A.

You need to know the source voltage and frequency, reactive power, real power and power factor goal (for example, 0.93) of the circuit in question then you need to calculate the following: Apparent Power (S) = real power (W) / PF goal. Total Reactive Power (QT) = sqrt(real power ^ 2 apparent power ^ 2. Capacitive Reactive Power (QC) = total reactive power - inductive reactive power. Capactive Reactance (XC) = source voltage ^ 2 / Capacitive Reactive Power. Capacitance (C) = 1 / (2 *pi * frequency * Capacitive Reactance). From this you will have to find the next higher standard capacitor to install.

There are many available online. Google "power factor calculator."