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ITGlossary · Electrical units
Transformer
An electrical component that changes voltage levels or isolates circuits.
Technical level:Intermediate
A transformer consists of two or more windings around a shared magnetic core and transfers energy through a magnetic field. Depending on the turns ratio, it steps the voltage up or down, and it only works with alternating current. When the windings are separate, there is no conductive connection between input and output.
In power supply it appears in many forms: isolation transformers for medical rooms or sensitive equipment, autotransformers, with a shared winding and no isolation, inside AVR stabilizers and line-interactive UPS units, and output transformers in traditional UPS designs. Isolation reduces noise and can create a new, separate neutral.
Transformers have losses and produce heat. Make sure there is adequate ventilation and do not load them beyond their rated power in kVA.
Questions that mention it
All frequently asked questionsHow 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.
Related terms
- IsolationSeparation of input and output with no conductive connection, usually through a transformer, to protect against faults and noise.
- Noise (Electrical)Unwanted high-frequency disturbances on the supply voltage, e.g. from motors or power supplies, which UPS systems and line conditioners filter out.
- Static BypassAn electronic path inside the UPS that instantly and automatically transfers the load to the mains on overload or internal fault.
- Transformer-Based UPSTraditional UPS design using internal transformers to regulate voltage and provide isolation.
- Dry ContactA passive relay contact used to transmit status signals without applying voltage.
- Offline (Standby) UPSA UPS that leaves the load on the mains and switches to battery only when the mains fails, with a short transfer time; the simplest and cheapest topology.