The hot spot rise simulator

THE NEED FOR accurate indicaton of hot spot temperatures under both steady-state and transient conditions is well known. This applies to rotating machines and cables as well as to transformers. The deficiences of the available hot spot indicators led to the development of the Hot Spot Rise Simulator. The goal was the production of a reliable instrument which could be tested and adjusted in the field by the relay engineer in the same way that he tests and adjusts an ordinary protective relay. Work was begun in 1946, and the first installations were made early in 1947 at two stations in the Niagara region of The Hydro-Electric Power Commission of Ontario. All major power transformers purchased by this authority since early 1950 are being equipped with these devices.