What are Variable Shunt Reactors ? Where are they used ?

In power systems, reactive power stability is extremely important.  Reactive power is dependent on the nature of the load, the line capacitances and the line reactances.  Large power lines which are lightly loaded may need reactors to balance the line capacitances.  Hence accurate control of the reactors in line is one of the requirement for the proper maintenance of reactive power.

This Variable Shunt Reactors are used in applications where the range of the reactive power to be adjusted is large but the regulation is not dynamic, that is, the change in the reactive loading is gradual.

Dynamic regulation will require Static VAr compensators with thyristorised controls.

Variable Shunt Reactors are fitted with reactors whose values can be adjusted through tappings.  These tappings are selected using motorised controls.  These adjustments can be made on load.