IEC 62912-2-2019 pdf download.Railway applications – Direct current signalling monostable relays of type N and type C.
This International Standard gives requirements for direct current relays intended for safety- related applications in railway signalling installations.
This International Standard is applicable to monostable relays of type N and type C.
2 Normative references
The following documents, in whole or in part, are normatively referenced in this document and are indispensable for its application. For dated references, only the edition cited applies.
For undated references, the latest edition of the referenced document (including any amendments) applies.
IEC 60664-1 , Insulation coordination for equipment within low-voltage systems – Part 1:
Principles, requirements and tests
IEC 61 81 0-3:201 5, Electromechanical elementary relays − Part 3: Relays with forcibly guided (mechanically linked) contacts
IEC 62497-1 , Railway applications – Insulation coordination – Part 1: Basic requirements – Clearances and creepage distances for all electrical and electronic equipment
IEC 62498-3: 201 0, Railway applications – Environmental conditions for equipment – Part 3:
Equipment for signalling and telecommunications
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1 all-or-nothing relay
electrical relay, which is intended to be energised by a quantity, the value of which is either within its operative range or effectively zero
Note 1 to entry: “All-or-nothing relays” include both “elementary relays” and “time relays”.
[SOURCE: IEC 60050-444:2002, 444-01 -02]
3.2 armature
moveable part of a relay that controls contact members
3.3 bistable relay
electrical relay which, having responded to an energising quantity and having changed its condition, remains in that condition after the quantity has been removed; a further appropriate energisation is required to make it change its condition
3.4 bounce time
for a contact which is closing/opening its circuit, time interval between the instant when the contact circuit first closes/opens and the instant when the circuit is finally closed/opened
[SOURCE: IEC 60050-444:2002, 444-05-04]
3.5 break contact <for elementary relays>
contact which is open when the relay is in its operate condition and which is closed when the relay is in its release condition
[SOURCE: IEC 60050-444:2002, 444-04-1 8]
3.6 change-over contact
combination of two contact circuits with three contact members, one of which is common to the two contact circuits; such that when one of these contact circuits is open, the other is closed
[SOURCE: IEC 60050-444:2002, 444-04-1 9]
3.7 contact gap
gap between the contact points when the contact circuit is open [SOURCE: IEC 60050-444:2002, 444-04-09]
3.8 contact member <for elementary relays>
conductive part designed to co-act with another to close or open the output circuit [SOURCE: IEC 60050-444:2002, 444-04-05]
4 Classification
The requirements of the various categories of signalling relays required to guarantee installation with the degree of reliability and safety desirable for operating purposes, depend on the functions to be fulfilled by the relays and the type of circuit with which they are to be used.
Bearing in mind these characteristics, a distinction may be made between the following types of signalling relays:
• Type N (non-proved relays)
Relays themselves fulfilling all the safety conditions without the aid of other relays or without control of operations in the circuit.
• Type C (proved relays)
Relays for which the safety conditions are guaranteed by control of operations in the circuit.
5 Essential requirements of the relays and their construction
5.1 Generic requirements for signalling relays
5.1 .1 Forcibly guided (mechanically linked) contacts
Signalling relays shall be equipped with forcibly guided (mechanically linked) contacts. The
forcibly guided (mechanically linked) contacts shall be designed in such a way that it is
ensured by mechanical means that make and break contacts can never be in the closed
position simultaneously.
If one of the make contacts is closed, none of the break contacts is closed. If one of the break contacts remains closed, none of the make contacts closes (assuming that nominal power conditions apply – see also 5.6.2). Operation of forcibly guided (linked) contacts means that if, for example, any given make contact fails to open and the relay is de- energised, none of the break contacts closes. The same principle applies to the failure-to-open of a break contact with energisation of the relay, i.e. in this case, no make contact shall close (IEC 61 81 0-3).IEC 62912-2 pdf download.