Definition: Reactive Power
The portion of electricity that establishes and sustains the electric and magnetic fields of alternating-current equipment. Reactive power must be supplied to most types of magnetic equipment, such as motors and transformers. It also must supply the reactive losses on transmission facilities. Reactive power is provided by generators, synchronous condensers, or electrostatic equipment such as capacitors and directly influences electric system voltage. It is usually expressed in kilovars (kvar) or megavars (Mvar).
- In electric power transmission and distribution, volt-ampere reactive (var) is a unit of measurement of reactive power. Reactive power exists in an AC circuit when the current and voltage are not in phase. The term var was proposed by the Romanian electrical engineer Constantin Budeanu and introduced in 1930 by the IEC in Stockholm, which has adopted it as the unit for reactive power. Special instruments called varmeters are available to measure the reactive power in a circuit. The unit "var" is allowed by the International System of Units (SI) even though the unit var is representative of a form of power. SI allows one to specify units to indicate common sense physical considerations. Per EU directive 80/181/EEC (the "metric directive"), the correct symbol is lower-case "var", although the spellings "Var" and "VAr" are commonly seen, and "VAR" is widely used throughout the power industry.
- Also Known As
- volt-ampere reactive (var)