Wall-mounted heating element with metal resistance sheets - has narrow slots forming broad zig-zag current paths coupled in parallel

摘要

The wall-mounted heating element consists of sheets of metal (1, 2, 3) mounted on flexible insulators and connected electrically in parallel to the a.c. supply input transformer (7). Each metal sheet has a slot cut up its centre to form a U-shaped resistance element whose electrical contacts are situated at the ends of the arms of the U. Further slots may be cut into the broad, flat arms of the U to give a rectangular zig-zag current path through the sheet. All the slots are narrow so that the largest possible area of metal is retained. The zig-zag may extend over part of both arms or over the whole of one arm.