The synchronous motor enables the adjustment of its power factor through the excitation, while activating a mechanical load on its axis providing active power – W, it can also supply or absorb reactive power (VAr) to the system where it is connected. https://www.mrosupply.com/v-belts/v-belts/b-section/178314_b93_gates-rubber/ The synchronous compensator is a synchronous motor connected to the network, operating in a vacuum, that is, without mechanical load on the – W axis, and exchanging only reactive power VAr – both capacitive and inductive with the system.
This possibility of changing the reactive power supplied or absorbed from the synchronous compensator to the network, in the same way as in the synchronous motor, is performed through actuation in the excitation of the machine. This can be used to correct the power factor of this installation. A particular application of the synchronous motor in power generation and distribution systems is the synchronous compensator.
In the synchronous compensator, the machine consumes only a small portion of active power (W), enough to supply its internal losses (friction, ventilation, heating), since there is no mechanical load being driven by the shaft. And through the excitation it exchanges reactive power with the point of the system where it is connected.