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ITFrequently Asked Questions · AVR
How does an AVR differ from a transformer-based stabilizer?
Almost all voltage stabilizers, AVRs included, use a transformer. The real difference is how they regulate: electronic AVRs switch transformer taps with relays or thyristors, fast but in steps, while servo stabilizers regulate smoothly and more precisely, but more slowly. Only a separate isolation transformer provides galvanic isolation.
Almost all voltage stabilisers use a transformer; the real difference is how they regulate the voltage. In electronic AVRs, relays or thyristors automatically switch between the transformer's taps. Correction is very fast but happens in steps, so the output voltage moves within a band rather than staying at one fixed value.
In servo-motor stabilisers, a small motor moves a carbon brush along a variable transformer. Regulation is smooth and more precise, but slower, and the moving parts need periodic inspection. Galvanic isolation from the mains is provided only by a stabiliser with a separate isolation transformer; ordinary autotransformer-based stabilisers do not isolate.
For computers, electronics and household appliances, an electronic AVR is usually sufficient. For sensitive or large loads, such as medical or industrial equipment, the precision of a servo-motor unit is often preferred. If you need isolation, ask for it explicitly in the specification and do not assume that every stabiliser with a transformer provides it.
