Displacement Power Factor Source voltage waveform is assumed to be an undistorted sinusoid with zero phase angle. Due to reactance of the load, the current waveform may exhibit a “constant” phase shift , with respect to the voltage waveform. = 0 Orthogonal = T/2

cos ( F) is defined as the “Displacement Power Factor” (DPF). The cosine of the phase angle by which the current wave is “displaced” from the voltage wave. Note that DPF > 0 for leading and lagging phase: |  | <  /2 The power company is supplying a currrent equal to I(RMS), but they’re only getting paid for I(RMS)cos(  ). The additional current causes unrecoverable losses due to series resistance in the transmission lines. Customers are required to correct their Power Factor to as close to unity as possible. “Apparent Power”

The Problem: the customer’s load presents an impedance Z L (or an admittance Y L = 1/Z L ) at its utility connection. The customer is required to place a compensating reactance X C (or a susceptance B C = -1/X C ) in parallel with the power input lines to correct the power factor to unity. Z L = 1/Y L Y L = G L + jB L X C = -1/B C = 1/B L B C = -B L + V RMS _ Y in = G L + j0 Z in = 1/ G L R TX Factory

Example: A factory is supplied with 440 VAC, 60 Hz from the utility. It draws 650 amps RMS with a phase lag of 15 degrees (  /12 rad) Determine the Apparent Power, Average (real) Power, required DPF correction circuitry, and RMS utility current after correction.