Transformaattori

Transformaattori, or transformers, are electrical devices that transfer electrical energy between circuits through electromagnetic induction. They consist of one or more windings, typically a primary and a secondary, wrapped around a magnetic core. When an alternating current flows in the primary winding, it creates a time-varying magnetic flux in the core, which links to the secondary winding and induces a voltage proportional to the turns ratio between windings. In an ideal transformer, power input equals power output (minus losses), and the output frequency matches the input.

Construction and components: The core is usually made from laminated ferromagnetic material to minimize energy losses from hysteresis and eddy currents. Windings are insulated conductors, often copper, with insulation between windings and the core. Many transformers are enclosed in casings and equipped with cooling systems for heat dissipation.

Types and applications: Transformers are used in power distribution and electrical grids (step-up and step-down transformers), in power supplies, audio equipment, and signal processing. Autotransformers share a common winding and can be more compact for certain voltage changes. Special forms include isolation transformers, impedance-matching transformers, and ferrite-core transformers for high-frequency applications.

Performance and safety: Key performance metrics include efficiency, regulation, and thermal performance. Core losses (hysteresis and eddy current losses) and copper losses determine efficiency. Safety standards require proper insulation, grounding, and protection against overheating and magnetic leakage. Standards bodies such as IEC and IEEE publish specifications for transformer design and testing.