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ITFrequently Asked Questions · AVR
What is an automatic voltage stabilizer (AVR)? How does it differ from a UPS?
An AVR keeps the voltage stable by filtering out fluctuations and noise, but because it has no batteries it provides no runtime during a power outage.
An AVR continuously measures the mains voltage and corrects it, so that the output stays close to 230 V even when the input drops or rises, for example on a rural line where the voltage falls noticeably in the evening. Depending on the type, correction is done with relays and an autotransformer, with a servo mechanism or electronically. During a power cut, however, the output goes off together with the mains.
A UPS has batteries and an inverter, so it keeps powering your devices when the power goes out. Line-interactive UPS units usually include an AVR function as well, while OnLine units regenerate the voltage entirely.
An AVR is the right fit when the problem is low or unstable voltage rather than outages, and when the loads are too large for a UPS: refrigerators, air conditioners, pumps, a home's electrical appliances or laboratory machines. Choose a rating with headroom for motor inrush current and check the input voltage range it covers.
A common mistake is expecting an AVR to protect against outages or to provide full lightning protection. For outages you need a UPS, while for surges suitable surge protection at the electrical panel is recommended.
