summenstromwandler for a two - or vierpoligen with fehlerstromauslösung circuit breaker for use in a one - or three-phase low-voltage distribution network containing a nulleiter, and processes for the

摘要

In a core-balance transformer for a two-pole or four-pole circuit-breaker with leakage-current tripping, whose toroidal core (10) is made of high-quality magnetic material such as, in particular, an iron-nickel alloy, the primary winding conductors (141, 142, 143) made of solid copper wire are insulated with thermally curable epoxy resin, and the toroidal core (10) is formed as an elongated hollow body coated on all sides with curable epoxy resin (12), which hollow body has an essentially constant cross-section over its length and has the smallest possible internal diameter. As a result, the dimensions of the transformer and the material costs thereof can be considerably reduced, and insulating the primary winding can be considerably simplified. Such a core-balance transformer is expediently manufactured by the primary winding conductors, after they have been cut to their final length and bent into their final shape, being coated with the epoxy resin in a conventional fluidized-bed coating process, whereupon all the primary-winding conductors are drawn into the toroidal core which has likewise previously been coated by the fluidized-bed coating process. IMAGE