NR NR/SIN/100 ISSUE 2 PDF

Relays that have a direct replacement available with the same pin code and contact configuration shall be replaced under the provisions of this SIN.

This Special Inspection Notice is limited to:

• AEI-General Signals Z Type relays bearing the AEI-GS manufacturer's badge (manufactured between late 1960's and 1971) which are installed at automatic level crossings.

Note: Z type relays outside this date range manufactured by anyone other than AEI-GS are not affected.

• M Type relays which are installed in any signalling control circuitry.

For the purpose of this SIN, automatic level crossings means: Automatic Half Barrier Crossings (AHBC), Miniature Warning Light (MWL) and Miniature Stop Light (MSL) crossings and all control circuitry directly responsible for the integrity of the level crossing including the status alarms to the signaller. This scope includes all track relays within the strike-in and their repeats but not relays associated with controls for the protecting signals. Where ‘Another Train Coming' (ATC) facilities are provided, track relays, repeats and other relays associated with this function are also to be included.

Purpose

Two types of relay, which have not been manufactured for some 30 years, are known to exhibit failure conditions which may lead to a Wrong Side Failure and hence less restrictive outputs of the signalling control system. This Special Inspection Notice (SIN) defines actions to be taken to remove the affected types of relay from the infrastructure.