Automatic Voltage Regulation (AVR) is a term commonly associated with electrical devices such as UPSs, stabilizers, and generators that use voltage regulators. But what does it mean and how important is it?
What is voltage?
Before getting into the nitty-gritty, it’s important to understand voltage, the very unit that the AVR is based on. Voltage or electromotive force (EMF) is measured in volts (V). It is the pressure of a power source in an electrical circuit that pushes charged electrons (current) through a conducting loop.
In simpler terms, voltage means the work or energy required to move a unit charge between two points. For example, if you connect a light bulb to the negative and positive terminals of a battery using wires, the voltage will be the energy that pushes current from the negative terminal through the battery and to the positive terminal.
Now that you know what voltage is all about, let’s get into AVR properly.
What is AVR and why is it important?
An automatic voltage regulator is a device that keeps the voltage supply to electrical equipment constant. It serves as a buffer for voltage fluctuations, delivering a reliable flow of power at all times. In other words, it converts fluctuating input voltage levels from a power source into a constant output for the connected load. Without AVR, your appliances would be susceptible to damage from brownouts, spikes, or surges, shortening the life of your appliances.
Voltage regulators are found in systems such as automobile alternators, central power plants, stabilizers, computer power supplies such as UPSs, and just about anywhere electricity is needed. In a UPS, for example, the AVR monitors high and low voltages and stabilizes incoming AC signals to maintain a set output without drawing on battery power. This reduces the chance of data loss, system failure, or total equipment damage. It also significantly increases the battery life of the UPS.
What to know when buying devices with AVR
When buying a device with an AVR, whether it’s a UPS, stabilizer, or generator, there are just a few things to consider. This is because most specifications (impedance, load compatibility, and voltage accuracy) are primarily relevant to manufacturers of UPSs, stabilizers, and generators, or to companies purchasing custom devices.
As an everyday consumer who buys a simple power supply device for personal use, you should look at the input voltage range, which should be wide enough to accommodate high and low voltage fluctuations. Many regulators will have a wider low-voltage range than high-voltage, since line voltages tend to drop more than they rise. For example, a regulator could correct voltages as low as 125V – 165V (40V difference) and as high as 250V – 270V (20V difference) to optimum values of 200-230V.
This will allow more low correction than high correction. The wide range also makes the regulator better able to protect your devices in cases of extremely low or high input voltages. Also, a good AVR should be able to cut off the power supply automatically when needed, such as when voltage values drop below or above the UPS’s correction range.
Note that while the range examples above show numbers that are common in Europe, most people in the US will be looking for much smaller numbers. This is thanks to the 120V system used in North America compared to 240V in Europe. Therefore, an AVR with an input range of 90V to 140V would be ideal for a 120V output. However, as a general rule of thumb, a wider input range is usually better as long as the output is within the normal values for your location.
Another feature to consider when purchasing would be the ability to delay the output power supply for a few minutes. Commonly called time delay, it is essential in areas prone to power failures, as a sudden restoration could damage connected appliances due to excessive voltage. Or, in the case of refrigerators, air conditioners, and other devices with compressors, it can prevent the gases from the compressor from being neutralized, leading to failure of the device. While most consumer AVRs have a built-in time delay, check with your dealer if you’re not sure.
Now you can put your knowledge to work choosing the right electronics to keep your devices up and running. Be sure to check out our buying guides to take advantage of the research we’ve done for you.