| 摘要 |
In a push-button and track-diagram railway signal box, the storage relays of the element groups for identifying start loading, destination loading, direction loading and position loading of the respective groups are not switched directly but rather via connecting relays which are acted on during the approval test. The approval test takes place after the route search has been successfully completed; this requires separate switching levels for the route search and the approval test. As a result of this separation it is possible to use long-life, quickly-switching switching means, for the route search, preferably electronic switching means. In the approval test, only the connecting relays (FA2, DA, FA2<*>, ZK2, DK) of the element groups (ES2, ED) which are actually involved in a route, and thus also only the associated storage relays, are activated. The connecting relays are fault current-excited, as soon as the acceptability of the entire route has been established, and only switched after further approval conditions have been tested. They are mainly of low-impedance design so that a greater number of them can be switched simultaneously in series. <IMAGE>
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