Encapsulated current transformer

Abstract

A current transformer encapsulated in an injection molded layer of insulating material. The current transformer includes a secondary winding which is disposed around a winding spool having side flanges thereon. Permanent spacers extend across the length of the winding spool and rest on the side flanges such that the permanent spacers are spaced from the secondary winding. A primary winding is wound around the spacers so as to be spaced from the secondary winding before the encapsulating material is injection molded around the magnetic core and windings and into the space between the primary and secondary windings. The winding spool and permanent spacers are formed of a material which softens within the processing temperature range of the encapsulating material to form an amalgamation without a distinct interface between the encapsulating material and the winding spool and spacers. In another embodiment, a 'through-type' current transformer has a toroidal-shaped magnetic core enclosed in a rigid sheath of solid material. A tubular member is disposed within the central opening of the magnetic core and secondary winding and is formed of a material which softens in the processing temperature range of the encapsulating material to form an amalgamation without a distinct interface therebetween such that a fluid-type seal is formed between the tubular member and the encapsulating material.