autotransformointeihin

Autotransformointi, or autotransformer, is a type of electrical transformer where the primary and secondary windings are connected in series, sharing a common portion of the winding. This design differs from a conventional transformer, which has two separate windings. Autotransformers are typically smaller, lighter, and more efficient than comparable two-winding transformers, especially when the voltage transformation ratio is close to one. They also exhibit lower leakage reactance.

The primary application of autotransformers is in voltage regulation and stepping up or down voltages where a significant voltage change is not required. They are commonly used in power distribution systems, particularly for starting large electric motors, as they can provide a reduced voltage to the motor during startup, thereby limiting inrush current. Autotransformers are also employed in audio equipment and in certain high-voltage applications where their size and cost advantages are significant.

However, autotransformers have a drawback: there is no electrical isolation between the primary and secondary circuits. This means that a fault in one circuit can directly affect the other, which is a significant safety consideration in some applications. Due to the direct electrical connection, they are not suitable for situations where galvanic isolation is essential. The efficiency and size benefits are most pronounced when the voltage ratio is close to unity; as the ratio deviates further, the advantages diminish, and a two-winding transformer may become more appropriate.