Transformadors

Transformadors, or transformadores, are electrical devices that transfer alternating current (AC) energy from one circuit to another through electromagnetic induction. They consist of a magnetic core and two or more windings of insulated conductive material. When an AC voltage is applied to one winding (the primary), a changing magnetic flux induces voltages in the other winding(s) (the secondary). The voltage ratio between windings approximates the turns ratio, allowing a step-up or step-down of voltage while transferring most of the power, subject to losses.

Key characteristics include the requirement for AC operation, the dependence on frequency, and the presence of a magnetic core that concentrates flux. The core is usually laminated to reduce eddy currents, and windings are insulated copper or aluminum conductors. Transformers can be oil-immersed or dry-type, with cooling systems sized for their rated load. Insulation and clearances are designed for high voltages and environmental conditions.

Common types and uses:

- Power transformers: large units for transmission and distribution, stepping voltage up or down in substations.

- Distribution transformers: smaller units near consumers that supply final voltage levels.

- Instrument transformers: voltage transformers (potential transformers) and current transformers used for metering and protection.

- Autotransformers: share part of their winding to reduce weight and cost, with limited isolation.

- Isolation transformers: provide galvanic isolation between circuits.

Efficiency and losses: core losses (hysteresis and eddy currents) and copper losses in windings determine overall efficiency, typically high for large units (often above 98% under nominal load). Safety and maintenance focus on insulation integrity, cooling, and environmental containment for oil-filled devices.