V-Guard Stabilizer is a relay type voltage stabilizer. This is mostly used for the protection of Air Conditioners, Refrigerators, and similar not-so-precise electrical equipments. However, this type of stabilizer is not really a good choice if you are expecting a constant output voltage.
There are two major types of voltage stabilizers widely used across the world. The simplest one is known as static stabilizer, which consists of transformer and electromagnetic relay. The input supply is given to primary winding of transformer and output is obtained from secondary windings. The output voltage is adjusted by adding or subtracting windings of the transformer coil, through switches (or relays). However, output is not accurate in this type. V Guard stabilizer is of this type.
The second type is Servo Stabilizer, which gives precise output. It works on the same principle of transformer. Servo voltage stabilzer boosts the voltage and provides proper output whether the input supply is low or high or even if the input AC voltage fluctuates. The number of windings are added or subtracted through a moving contact on the coil, which is adjusted by a motor.
To prevent failure of air-conditioners, computers, and such electrical gadgets, and to protect it from fluctuating voltage, you must connect them through servo type voltage stabilizers, and not v-guard stabilizer. In case you need help on this topic, you may subscribe at Excell Voltage Stabilizer.