| 摘要 |
Electronic switching elements having a tripping behaviour which are connected to the proportional voltage of a voltage divider which carries the operating voltage control grouping devices on the output side. The proportional voltage occurring on the voltage divider (1/2) is split into different connected selection stages (4, 5, 6) on the basis of frequencies which can be expected, including zero frequency, that is to say DC voltage, and the grouping devices are controlled via the frequency determined. In the case of the multi-voltage selection device, tuned-frequency tuned circuits are provided as selection stages (4,5) for AC voltages, an RC element being used as the selection stage (6) for zero frequency. Each selection stage (4, 5, 6) is connected to a number (corresponding to the number of voltages which can be expected in the frequency band) of triggering stages (7-10) which respond in a voltage-stepped manner. It is thus possible to differentiate in a simple manner and irrespective of voltage tolerances precisely between the railway frequencies, including zero frequency, and to make correct groupings for inductive loads. <IMAGE> |
