Use of A Voltage Stabiliser

A typical voltage stabiliser is able to respond to changes in the voltage level called sags (voltage drops) and surges (voltage peaks) on the input line. Sags might be due to undersized distribution lines, connection of large loads to the network, ground faults. Surges might be generated by disconnection of large loads, increased voltage at the generating plant, atmospheric  events.
The duration of such phenomena depends on the cause and is not easily predictable.

Sags are generally more common especially where the distribution is not wide and efficient. Other disturbances like spikes, transients, high frequency noise and harmonic distortion have to be treated with the addition of specific filtering systems. The good functioning of the majority of electrical and electronic equipment depends on the supply voltage correctness and steadiness. Nowadays, many industrial and private users are subject to long-lasting fluctuations that can be inconvenient or even dangerous.