transformátor

Transformátor, or transformer, is an electrical device that transfers alternating-current energy between circuits through electromagnetic induction. It typically comprises one or more windings—primary and secondary—wound around a common magnetic core. The device relies on a changing magnetic flux produced by alternating current in the primary to induce a voltage in the secondary.

In operation, an ideal transformer maintains a voltage ratio equal to the turns ratio: Vp/Vs = Np/Ns, while the current ratio is the inverse: Ip/Is = Ns/Np. Power transfer is approximately conserved, with real devices exhibiting losses due to magnetizing current, core (hysteresis and eddy current) losses, and winding (copper) losses. The magnetic core concentrates flux and minimizes leakage.

Construction and design vary. The core is commonly laminated steel to reduce eddy currents; windings are copper or aluminum insulated conductors. Transformers can be oil-immersed or dry-type and are categorized by core configuration (core-type or shell-type) and cooling method. They are designed for specific voltage, current, and frequency ratings, with typical mains operation at 50 or 60 Hz.

Applications and types. Step-up transformers increase voltage for long-distance transmission, while step-down units reduce voltage for distribution and end-use equipment. Instrument transformers, including current transformers and potential transformers, provide scaled measurements for protection and metering. Transformers are essential in power systems, electronics, and industry, enabling efficient voltage conversion and electrical isolation.

Performance and safety. High efficiency, commonly 95%–99%, depends on design and load. Core losses and winding losses limit efficiency and determine heat generation. Proper insulation, cooling, grounding, and adherence to standards are necessary to ensure safe operation. Transformers do not work with direct current and are sensitive to frequency and operating conditions.