Muuntin

Muuntin, or transformer, is a passive electrical device that transfers energy between circuits through mutual inductance, enabling voltage and current to be transformed without direct electrical connection. In an ideal case, the output voltage to input voltage equals the turns ratio, and output power closely matches input power, minus losses.

A transformer consists of windings of insulated conductor around a magnetic core, usually laminated steel or ferrite, to guide flux and reduce energy losses. The primary winding connects to the source, the secondary to the load. The turns ratio (Np:Ns) determines voltage transformation; current handles inversely.

Common types include step-up transformers that raise voltage, step-down transformers for lower voltage, isolation transformers for safety, and autotransformers that share windings. Instrument transformers, including current and voltage transformers, provide scaled signals for meters and protection equipment.

Transformers are highly efficient, especially larger units, with typical efficiencies in the 97–99% range. Losses come from core (hysteresis and eddy currents) and windings (copper losses). Cooling and insulation are important for reliability, with oil-filled and dry-type designs used in different settings.

The concept emerged in the late 19th century with foundational work on electromagnetic induction; practical transformers were demonstrated by inventors such as Gaulard, Gibbs, and William Stanley. Widespread use followed with the expansion of electrical grids in the 1890s and early 1900s.