scope:

This document gives requirements for direct current relays intended for safety-related applications in railway signalling installations.

This document is applicable to non-proved signalling monostable relays of the spring type, whose return force is generated by elasticity of spring.

The return force can be provided either from a separate spring and/or from the contact springs themselves.

NOTE "Non-proved" means the feature of relays fulfilling all the safety conditions without the aid of other relays or without control of operations in the circuit.