Diverter isolating switch between mains conductors and earth - is activated by excessive temp. detected by sensors in close thermal contact with supporting circuit board

摘要

In each current path an overvoltage diverter (44-47) is provided with a contact set so that the earthward sections of all current paths are connected in parallel and taken through the toroidal core of a currrent transformer, whose sec. winding energises a relay for isolation. The diverters (44-47) are fixed to a circuit board (35) in the transformer compartment and soldered through insulating gaps (37-39) in mutually isolated Cu coating regions. The switch is tripped by temp. sensors (57a-57d) in thermal contact. ADVANTAGE - Simplified assembly more easily repairable if fault arises.