Reactive Power in Inductive Loads

Inductive loads such as chokes, motors, inductive heating equipment, generators, transformers, and arc welding equipment produce an electrical lag that is commonly referred to as inductance. This inductance causes a phase difference between current and voltage.

As a result of phase shift due to inductance, there are times when current and voltage have different signs. During such times, negative energy is generated and fed back into the power supply network. When the two regain same sign, a similar amount of energy is required to generate the magnetic fields. The energy that is lost due to magnetic reversals in inductive loads is commonly referred to as reactive power.

Power Factor

The efficiency with which electrical devices or installations consume AC power varies. Some loads utilize power efficiently, while others waste a significant portion of the power that they consume. Power factor is used to describe the efficiency with which loads consume AC power. This dimensionless quantity ranges between 0 and 1.

Power Factor Correction (Compensation)

Electrical loads that have a low power factor consume more power that it is needed to perform a task. This can result in a considerable power loss in a network and high transformer losses. Such increases in energy consumption increase the cost of running equipment or installations. Poor power factors also cause a power distribution network to have increased voltage drops. It is common for power suppliers to penalize industries whose power factor is below a specified value.

Electricity suppliers encourage industrial consumers to improve their power factor for various reasons. To start with, improving power factor can help to cut the electricity bill by a significant margin. Secondly, a high power factor helps to minimize efficiency losses in a consumer’s transformers. Thirdly, adding power factor correction system helps to boost the effective capacity of a consumer’s electricity network. Lastly, a high power factor helps to increase the service life of electrical equipment.

A power factor compensation network lessens the power demanded by a load thus improving the overall power factor. The compensation network enables electrical loads to achieve a good power factor, typically between 0.95 and 0.98. A power factor of 0.85 and below is usually considered by utility companies as a poor power factor.

Capacitor Banks and Static Var Generator

Capacitor Bank is a combination of numerous capacitors of similar rating that are joined in parallel or series with one another to collect electrical energy. The resulting bank is then used to counteract or correct a power factor lag or phase shift in an AC power supply.

Static VAR Generators are high performance, compact, flexible, modular and cost-effective Active Power Factor Correction (APFC) systems that provide an instantaneous and effective response to power quality problems in low or high voltage electric power systems.

Connected in parallel with the load to be compensated, SVG units act as a controlled current source, providing a current waveform in real time.

SVGs enable longer equipment lifetime, higher process reliability, improved power system capacity and stability, and reduced energy losses, complying with most demanding power quality standards and grid codes.