Automatic voltage stabilizer

It was a time when dealing with fluctuated or inconsistent power supply was a cumbersome task. To handle this Voltage stabilizers are being used from the early days of technological evolution. In conventional or old modeled voltage stabilizer one mechanical rotary was being used with an autotransformer to control the output voltage of mains power. As time changes, many of the manufacturers changed their voltage stabilizer design to provide a more efficient and stable supply. In those several designs Microcontroller based voltage stabilizer is one of them. Several models are present in the market based on their load handling capacity. Here we are mainly focused on the voltage stabilizer for home appliances. Let’s get into this to know more.

What is this?

These stabilizers are also known as an automatic voltage stabilizers. A voltage stabilizer is a device that stabilizes the inconsistent AC power and keeps it between stable ranges (200 to 230 volts AC). Sometimes a variation of voltage or spikes appear on mains power (AC line), if we use this gadget then the variation can cause no problem to the appliances. It protects any electronic appliance like Air-Conditioner, Refrigerator, Washing machine, and much more.

In this gadget, microcontroller generates the control signals automatically by sensing this input power. Earlier versions of this gadget were using several timers and counter IC’s. These older versions are also performing automatic operations but their designs are not efficient. To solve this problem preprogrammed microcontrollers are introduced in the technical industries.

Engineering inside:

Based on its load handling capacity its internal circuit units are changing. But few of them remain in every design and those are given below:

  1. Transformer
  2. Relays
  3. Control board
  4. MCBs
  5. LED display
Internal units of automatic voltage stabilizer

Internal units of automatic voltage stabilizer


We know that transformer works based on mutual induction. In voltage stabilizer step down transformer is being used that works in two modes. The first one is Buck or step-down mode when mains or input AC power is higher than the defined value. And the second one is Boost or strep-up mode when mains power is lower than the desired value.

Buck mode:

In this mode, the secondary winding of the transformer is connected in such a way that secondary output voltage is deducted from incoming AC voltage. In case of a rise in mains power, the electronic circuit in the stabilizer switches the relay that switches deducted output voltage.

Boost mode:

In this configuration mode, the mains voltage is given to the transformer and this voltage is normally stepped down. The secondary winding of the transformer is connected in such a way that the secondary output is added to the primary or mains supply voltage. In case of low mains power, the elec