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. Reactive power is provided by generators, synchronous condensers, or electrostatic equipment such as capacitors and directly influences electric system voltage. It is a derived value equal to the vector difference between the apparent power and the real power.  It is usually expressed as kilovolt-amperes reactive (kVAR) or megavolt-ampere reactive (MVAR).  See Apparent Power, Power, Real Power