transformerna

Transformers are static electrical devices that transfer electrical energy between circuits through electromagnetic induction. They typically consist of two or more windings of conductor wrapped around a common magnetic core. By varying the turns ratio, transformers increase or decrease voltage while conserving most of the input power, with losses limited to core and winding losses.

Construction and operation: The primary winding is connected to the source and induces a magnetic flux in the core. The secondary winding, coupled to that flux, develops a voltage proportional to the turns ratio. The core is usually made of laminated steel to reduce eddy currents, and the windings are insulated copper or aluminum conductors. There are no moving parts, and energy transfer occurs via the magnetic field.

Types and configurations: Transformers are categorized by function and construction. Power transformers handle large voltages for transmission and distribution, and can step up or step down voltage. Distribution transformers operate at lower voltages for local networks. Instrument transformers, including current transformers and potential transformers, provide scaled readings for meters and protection equipment. Autotransformers share a common winding for efficiency at high voltage changes. Core-type and shell-type constructions describe how windings are arranged around the core.

Efficiency and losses: Modern transformers are highly efficient, often exceeding 98% for large units. Losses are mainly core losses (hysteresis and eddy currents) and copper losses in windings. Performance is affected by temperature, insulation, and loading.

Cooling and insulation: Transformers use oil-immersed, dry-type, or gas-filled cooling. Common cooling classifications include ONAN and ONAF for oil-filled units. Insulation levels determine voltage ratings and longevity.

Applications: Transformers are essential in electrical grids, industrial equipment, and electronic devices. They enable efficient transmission over long distances, voltage adaptation at various stages, and safe measurement and protection in power systems.

History and development: The concept arose in the 19th century with experiments in electromagnetic induction. Practical transformers were developed in the late 1800s and have since evolved into highly reliable components for modern electricity networks and electronic systems.