| 摘要 |
The d.c. circuit consists of a plurality of adjacent track sections (A1 to An) which are fed cyclically with a.c. signals of different frequencies from a common transmitter (S) and which transmit a.c. signals extracted from them to a common track-release device (E). By means of the arrangement of relatively short track sections, a high response-sensitivity with respect to axle shunts is achieved, the d.c. circuit having in total the same response-sensitivity as the individual sections. A single double line (L) is sufficient to feed the individual track sections and monitor them. For the track-release indication it is tested whether the monitoring indications output by the individual track sections occur exclusively in the sequence which is specified by the cyclical call-up of the sections. Track current influences lead to a reliable track-occupied indication of the d.c. circuit. <IMAGE>
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