Expert Solutions

Voltage Stabilizers: working, sizing and power consumption


Power supply is erratic at most places in India, with voltage fluctuating in both directions (up and down) at many places frequently. These voltage fluctuations can damage appliances, thereby causing them to end much before their normal useful life. When voltage goes down, electric current in the appliance increase, which can result in burning of the appliance. Voltage Stabilizers have thus found place in many homes and offices in India. In this article we will talk about voltage stabilizers: what they do, how much power do they consume and how to select one for your setup.

What are voltage stabilizers and how do they work?


As the name suggests, voltage stabilizers stabilize the voltage, which means if the supply voltage fluctuates or varies, it brings it to the desired range. It does so by using electromagnetic regulators that use tap changers with autotransformers. If the output voltage is not in range a mechanism switches the tap, to change the transformer to move the voltage in acceptable range. It does not give a constant voltage output, but operates the system in a safe voltage range.

How to choose a right sized stabilizer?


Sizing of a stabilizer is very similar to sizing of a UPS or Inverter (power backup). The most important thing is to know the load connected to the stabilizer. First you must note down the power (or watts) for all the appliances that will be connected to a stabilizer. The sum total of the power consumption (or watts) will give you the load on stabilizer in watts. But most stabilizer sizes are in VA (Volt Ampere) or kVA (kilo Volt Ampere which is equal to 1000 Volt Ampere). Although to get to actual VA (or Volt Ampere) from Watts (W) you will have to do some measurements, but to give a rough approximation, you can increase the Watts value by 20% to get the approximate VA size that you may need.
So for e.g. if sum of watts connected to your stabilizer is 1000 then you can take a 1200 VA or 1.2 kVA stabilizer. (Please note that 20% is suitable for residential systems and may not work in industries if your power factor is bad).

How much electricity do voltage stabilizers consume?


Electricity consumption of voltage stabilizers depends on the efficiency of the stabilizer. Typically they are 95-98% efficient. Which means, they consume about 2-5% of the maximum load? So if you have a 1 kVA (or 1000 VA) stabilizer, it would consume about 50 Watts (on peak load). Which means if a 1kVA stabilizer is left on for 10 hours, it would consume about 0.5 unit of electricity. Thus leaving it on for 24 hours can lead to a lot of electricity consumption.

Do modern refrigerators/air conditioners come with in-built voltage stabilization?
Modern appliances (mostly refrigerators and air conditioners) do come with a bigger voltage range for operation, i.e. if in past refrigerators worked well only between 200-240V, now they have a bigger range of 170-290V. But they do not come with in-built voltage stabilizers. Using voltage stabilizer with such appliances may not be necessary unless voltage in your area shoots up or down much above or below the limit in which the appliance can operate.



Always choose a right sized voltage stabilizer and also try to get them for individual appliances rather than for the whole electricity connection. Leaving them on for longer duration can result in higher electricity bills.