Week 10: Power Factor Improvement by using Static Capacitors.

Power Factor: The power factor of an AC electrical power system is defined as the ratio of the real power flowing to the load, to the apparent power in the circuit, and is a dimensionless number between -1 and 1.

Real Power is the capacity of the circuit for performing work in a particular time.

Apparent Power is the product of the current and voltage of the circuit.

Apparent Power is always greater than Real Power: Due to energy stored in the load and returned to the source, or due to a non-linear load that distorts the wave shape of the current drawn from the source, the apparent power will be greater than the real power.

Negative Power Factor: It occurs when the device which is normally the load generates power which then flows back towards the device which is normally considered the generator.

Low Power Factor: In low power factor system draws more current. The higher currents increase the energy lost in the distribution system, and require larger wires and other equipment. Because of the costs of larger equipment and wasted energy, electrical utilities will usually charge a higher cost to industrial or commercial customers where there is a low power factor.

High Power Factor: In high power factor system draws less current.

Linear loads with low power factor (such as induction motors) can be corrected with a passive network of capacitors or inductors. Non-linear loads, such as rectifiers, distort the current drawn from the system. In such cases, active or passive power factor correction may be used to counteract the distortion and raise the power factor. The devices for correction of the power factor may be at a central substation, spread out over a distribution system, or built into power-consuming equipment.

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