Power factor

Hello, if I have a 240v 60hz supply connected to a load of 200 amps with a power factor of 75% lagging, what capacitance would i require to reduce the power factor to 90% lagging?

I have to check my numbers but a quick calculation gives 422 uF.

I came up with a result of 498uF. Fairly close to your quick calculation.



Apparent Power, S = (Irms) * (Vrms) = (200A)(240V) = 48kVA
Existing Load True Power, P = S * pf = (48 kVA) (0.75) = 36 kW
Existing Load Reactive Power, Q = sqrt (S^2 – P^2) = sqrt((48 kVA)^2 – (36 kW)^2) = 31.75 kVAR

Target Load True Power, P = S * pf = (48kVA)(0.90) = 43.2 kW
Target Load Reactive Power, Q = sqrt (S^2 – P^2) = sqrt((48 kVA)^2 – (43.2 kW)^2) = 20.92 kVAR

Capacitor Reactive Power Required = 31.75 kVAR - 20.92 kVAR = 10.83 kVAR
Capacitive Reactance Required, Xc = V^2 / Q = (240V)^2 / 10.83kVA = 5.32 ohms
Capacitor Size Required, C = 1/(2 * pi * f * Xc) = 1 / (2*pi*(60Hz) * (5.32 ohms)) = 489uF

Member of "StrykerTECH":http://www.stryker-tech.com/ Engineering Staff

thanks for you help David / Stryker. Much appreciated!