Thermal overload protection cct for polyphase transformer - has electromagnetic relay actuated by bimetal strip sensitive to transformer oil temp

摘要

The thermal relay is designed for the protection of a polyphase transformer which is housed in a container which may be refilled with a dielectric liquid. An electromagnetic probe is immersed in the liquid and connected with a transformer. A thermally sensitive element is also connected with the coils of the transformer, and includes a bithermal strip which makes a short circuit connection when a particular temperature is reached. The circuit arrangement prevents the transformer oil from exceeding a given temperature. The arrangement is designed mainly for the protection of apparatus in rural environments.