NR RT/SIN/081 ISSUE 1 PDF

This Special Inspection Notice applies to:

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

• All AEI-GRS Type M relays which are installed in all signalling control circuitry.

• A separate note is required to be made of those AEI-GRS Type M relays which are installed at automatic level crossings. (A column is provided on the results sheet).

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 un-safe failure of the relay and hence less restrictive outputs of the signalling control system.

This Special Inspection Notice (SIN) defines actions to be taken to identify the variants of these types of relay still in use and identify the functions which they perform. The aim of collecting this information is to permit the definition and prioritisation of any action required to remove them from signalling control systems.

This SIN is aimed at collecting information to assist with the production of ‘equivalents' lists and the prioritisation of removal of these types of relay from high risk signalling control circuitry.