Switch Point Control Circuits with Small-size Safety Relays

Relay-based railway signalling systems are constructed with safety relays, which are produced by the main signalling manufacturers. Such safety relays are hard to fi nd on the market. Th erefore signalling contractors frequently use small-sized, easily-available relays of the SF4 and H-464 type, which conform with the UIC736 normative requirements. Th e paper presents safety relays of the H-464 type as well as three-phase switch point control circuits, which are based on such relays cooperating with switch point transducers and utilized in centralised mechanical signalling systems with electrical switch-over of the switch points.