Contactless DC indicator for communication cable - has wiegand wire with asymmetrical control giving large amplitude

摘要

The galvanically decoupled direct current indicator is used for monitoring subscriber cables in communication systems. It is more efficient and more conveniently assembled than conventional arrangements. The indication point consists of a module contg. a ferromagnetic wire (1) shaped into an approximately rectangular magnetising loop. The loop is directly enclosed by one winding (2) and is placed in the magnetic field of a coil with two windings (3,4) so that the magnetic flux of the winding adjacent to the module opposes that of the outer winding. The wire forming the rectangular loop has a weakly mangetic core and an outer region of magnetically harder material, e.g. it is a Wiegand wire. The induction coil produces a higher magnitude signal using asymmetrical control than could be achieved using symmetrical control.