Transformatoare

Transformatoare, in electrical engineering, are devices that transfer electrical energy between circuits through electromagnetic induction, changing voltage and current levels while ideally conserving power. They typically consist of a magnetic core and two or more windings wound around it, with the primary winding connected to the source and the secondary winding delivering power to the load.

The operating principle is based on Faraday’s law of induction. When alternating current flows in the primary, it creates a changing magnetic flux in the core, which induces voltages in the secondary windings. The turns ratio between primary and secondary windings determines the voltage transformation: a higher turns count on the secondary yields a step-up transformation, while fewer secondary turns yield a step-down transformation. Proper magnetic coupling and core design minimize losses and maximize efficiency.

Construction and variants vary by application. Most power and distribution transformers use laminated iron or steel cores to reduce eddy currents, with windings made of copper or aluminum and insulated to withstand operating voltages. Variants include isolation transformers (galvanic isolation), autotransformers (single winding with taps), and three-phase transformers for large-scale power systems. Dry-type transformers use air cooling, while oil-immersed units provide higher insulation and cooling capacity.

Performance characteristics include voltage ratio, efficiency, and regulation. Large transformers routinely reach efficiencies of 98–99% under full load, while losses arise from core (hysteresis and eddy currents) and copper resistance. Regulation describes how output voltage changes with load. Applications span electricity generation and distribution, power supplies, audio and RF equipment, and impedance matching.

Safety and standards are governed by organizations such as IEC and IEEE, with attention to insulation, cooling, grounding, and environmental considerations for oil-filled designs.