Abstract: Apparatus consuming heavy electric current, such as an arc furnace, has concentric members (1) and (3) between which the current has to be transferred. The member (3) can rotate around, and/or move axially with respect to, member (1). Interposed, an annular member (2) has helically twisted tufts (11) of copper wire slidably retained by bushes (12) in a hole (10). The copper wires are compressed to fit between the members (1) and (3), and the compression is stored as elastic helical twisting energy, ensuring good contact pressure to transfer current between the members (1) and (3).

Abstract: An induction heater, particularly for heating metal slabs, is constructed in modular form. Two sets of modules are spaced apart to form a gap for reception of a slab. Each module is slotted and is wound with a group of polyphase coils so as to produce a travelling wave magnetic field and each group of coils is connected to a polyphase electrical supply independently of the other groups. The modules of one set are disposed directly opposite modules of the other set so that each pair of confronting modules have their like poles in opposition.

Abstract: An electric contact device for conveying electric current to an article such as a moving billet or wire comprising a current feeder member in a bed of electrically conductive de-oxidized metal particles and the article being placed in contact with the bed. The particles may be copper particles and the bed may be fluidized with a non-oxidizing gas and be maintained in a non-oxidizing atmosphere. Two contact devices may be provided at spaced positions to cause a current flow along the article. The contact device may operate as a switch by providing means to move the article into and out of the bed.