Safety relay for monitoring heating in electrical connection, comprises sprung piston normally restrained by fusible ring which melts on excessive heating to allow piston to contact earth connection

摘要

A plastic box (1) has internal housings (3,5) which receive conductors (12,39). The first conductor (12) has a terminal (14) with a radial spade (15). The spade has an axial hole penetrated by a piston (25) which is under spring pressure (27) but secured by a fusible ring (31). When the first conductor overheats the fusible element melts and the piston makes contact with the terminal (35) of an earthing conductor (39) to operate normal protection.