What is a Synchronous Condenser?

Electronics & ElectricalElectronDigital Electronics

An over-excited synchronous motor running on no-load is called the synchronous condenser. It is also known as synchronous capacitor or synchronous compensator or synchronous phase modifier.

A synchronous motor can deliver or absorb reactive power by changing the DC excitation of its field winding. It can be made to draw a leading current from the supply with over-excitation of its field winding and therefore, it supplies lagging reactive power (or absorbs leading reactive power).

Under-excited Synchronous Motor

When the synchronous motor is under-excited, then it draws a lagging current form the source and hence supplies leading reactive power (or absorbs lagging reactive power). Therefore, the current drawn by a synchronous condenser can be changed from lagging to leading smoothly by varying its field excitation.

Over-excited Synchronous Motor at No Load

When an over-excited synchronous motor is operated at no-load, it takes a leading current and hence, behaves as a capacitor. As the over-excited motor draws a leading current from the supply, it absorbs leading reactive power and delivers the lagging reactive power.

When such a machine connected in parallel with induction motors or other inductive load, i.e., devices that operate at lagging power factor and absorbs the lagging reactive power, this lagging reactive power demand is met by the synchronous condenser. Thus, the inductive load does not take the lagging reactive power from the supply and the power factor of the plant has been improved.

The synchronous capacitors, i.e., over-excited synchronous motors on no-load are installed in electric power systems only for power factor improvement of the system. The synchronous condensers are economical in large sizes than the static capacitors.

Updated on 30-Oct-2021 07:50:51