Scotttransformatorer

Scotttransformatorer, commonly known as Scott-T transformers, are a pair of single‑phase transformers arranged to convert between three‑phase and two‑phase power. They were developed in the early 20th century by Charles F. Scott of General Electric to provide an economical method for supplying two‑phase equipment from a three‑phase network, or vice versa. The arrangement can operate in either direction, allowing three‑phase power to feed two‑phase machinery or two‑phase power to supply three‑phase loads under suitable conditions.

In operation, the two single‑phase transformers are connected to two of the phases of a three‑phase system, with the secondary windings arranged to produce two outputs that are approximately 90 degrees apart. A specific turns ratio is used, including a tap on one secondary winding (often about 0.866 of full secondary voltage), to balance voltages and establish the required phase displacement. When the loads on the two outputs are balanced, the two phases produced by the Scotttransformatorer closely approximate a true two‑phase, 90‑degree phase shift.

Historically, Scotttransformatorer found use in early electric installations that required two‑phase drives for motors or equipment such as rotary converters and certain industrial machinery. With the expansion of standardized three‑phase systems and modern power electronics, their use declined, though they remain of historical interest and may appear in retrofits or specialized applications where a two‑phase interface is needed or preferred. Design and application require attention to load balance and voltage regulation to maintain the intended phase relationship and power delivery.