transformatorens

Transformatoren, commonly referred to in English as transformers, are electrical devices that transfer electrical energy between circuits through electromagnetic induction. They consist of one or more windings of insulated conductor wrapped around a magnetic core. When alternating current flows in the primary winding, it produces a time-varying magnetic flux in the core, which induces voltage in the secondary winding. The voltage ratio approximately equals the turns ratio N1:N2, while the currents adjust so that input power roughly equals output power, minus losses.

Construction and losses: Cores are typically laminated iron or ferrite to guide flux and minimize losses; windings are copper (or aluminum) conductors insulated from the core. Real transformers have copper losses in the windings, core losses from hysteresis and eddy currents, and stray losses. Efficiency for power transformers is high, often above 95% to 99% for large units. Cooling and insulation are important for safety and reliability.

Types and uses: Step-up transformers increase voltage (N2 > N1); step-down transformers decrease voltage (N2 < N1). Isolation transformers provide galvanic isolation between circuits. Auto-transformers share a portion of winding for compact designs. High-frequency transformers (in switching power supplies) use ferrite cores and operate at high frequencies. Transformers are used in power transmission, distribution, consumer power supplies, audio equipment, and instrumentations for impedance matching and isolation.

History: The principle was discovered by Michael Faraday in the 1830s, with practical transformers developed in the late 19th century as electrification expanded. Modern laminated-core transformers became standard for efficient mains systems.