Railway points control and monitor system - has motor control and position signalling via isolation transformers and relays

摘要

The control and monitor system for railway points operation is suitable for use in points installations remotely separated from a central signal box and reduces interference effects due to induced voltages esp. in electrified track layouts. Power supply to the points actuator motor is by cabling interrupted at intervals by isolation transformers. Forward and reverse control of the motors is by means of control contactors and associated relay contacts which complete the circuit to the transformer primary windings. Monitoring of the correctly operated position of the points drive is provided by limit switch contacts and signal lines interrupted by isolation transformers. A relay coincidence detector circuit indicates the operational status of each set of points.