The synchronous electric motor, because it allows the adjustment of its power factor through the excitation, simultaneously activates a mechanical load on its axis (granting active power – W), it can also grant or absorb reactive power (VAr) to the system where it is connected . And with this can be applied to the correction of the power factor of this installation. A specific application of the synchronous motor in power generation and distribution systems is the Synchronous Compensator.

The Synchronous Compensator is a synchronous, grid – connected, synchronous motor (no mechanical load on the W – axis), replacing only reactive power (VAr – both capacitive and inductive) with the system.

This probability of variation of the reactive power transferred or absorbed from the Synchronous Compensator to the network, in the same way as in the synchronous motor, is also performed by means of actuation in the motor excitation.

In the Synchronous Compensator, the motor only consumes a small portion of the active power (W), the minimum to supply its internal losses (friction, ventilation, heating, etc.), since there is no mechanical load being driven by the shaft. And by means of the excitation it changes reactive power with the point of the system where it is connected.