Circuit arrangement for the monitored operation of two AC loads via a common supply line

摘要

A circuit arrangement is specified which enables the supply and monitoring of two AC loads (rtH, rtN), of which the second comes into operation automatically in the event of the first failing, from an actuating mechanism via a common two-wire supply line. The two loads are supplied asymmetrically with respect to the polarity of the AC half-cycles. The actuating mechanism tests for the presence and the orientation of the asymmetry in the supply current. The asymmetry is achieved by means of devices in separate current paths for positive and negative AC half-cycles and by different attenuation or different transmission factors in these current paths. When the loads are switched over, the assignment of the AC half-cycle polarities to the current paths is also interchanged.