Overview
IEC 62912-2:2019 - "Railway applications - Direct current signalling monostable relays - Part 2: Spring type relays" is an IEC International Standard that defines requirements for direct current (DC) spring-type monostable relays used in safety‑related railway signalling installations. It applies to non‑proved signalling relays whose return force is produced by spring elasticity (either a separate return spring and/or the contact springs). IEC 62912-2 complements IEC 62912:2015 and coordinates with safety requirements in IEC 62425:2007.
Key topics and technical requirements
The standard sets out generic and specific technical requirements covering:
- Generic construction and behaviour
- Requirements for spring‑type signalling relays and definitions of “non‑proved” operation.
- Forcibly guided contacts and operation; degradation during service.
- Contact performance
- Non‑welding characteristics, opening of make contacts, contact spacing (gap), contact force, bounce, contact resistance and self‑cleaning.
- Limits for contact heating and service life expectations.
- Mechanical and spring design
- Mechanical construction, connecting devices, materials, prevention of spring breakage and screw loosening.
- Annex A includes a Modified Goodman diagram and methods to calculate maximum stress of the return spring.
- Magnetic and insulation systems
- Anti‑residual magnetism design, functional magnetic requirements.
- Insulation coordination: overvoltage, test voltages, pollution and required clearances.
- Environmental and application conditions
- Environmental classes, vibration and shock requirements relevant to signalling equipment.
- Measurement and test methods
- Specified tests and measurement procedures; Annex B (service life agreement) and Annex C (method to measure contact opening force).
Practical applications and users
IEC 62912-2:2019 is intended for use by:
- Relay manufacturers designing and certifying DC spring‑type monostable relays for railway signalling.
- Signalling system integrators and designers who specify components for interlocking, block systems and other safety circuits.
- Test engineers and maintenance teams responsible for qualification, routine testing and lifecycle agreements.
- Procurement and conformity assessors verifying that relay products meet safety‑related signalling requirements.
Using IEC 62912-2 helps ensure reliability, predictable contact behaviour, and conformity with safety principles used in railway signalling equipment.
Related standards
Relevant normative references and related documents include:
- IEC 62425:2007 (Safety‑related electronic systems for signalling)
- IEC 62912:2015 (DC signalling monostable relays - types N and C)
- IEC 62497-1 (Insulation coordination - clearances and creepage)
- IEC 62498-3:2010 (Environmental conditions for signalling equipment)
Keywords: IEC 62912-2:2019, railway signalling, direct current relays, spring type relays, monostable relays, non‑proved relays, relay standards, contact performance, insulation coordination.