scope:

This guidance applies to 'Non vital relays' which includes sealed relay units, relay based storage units for program machines and train describer systems with the exceptions defined in the notes below. This guidance should be used by Asset Stewards when devising maintenance regimes for SERs.

Note: This guidance does not apply to "vital type" relays used in non-vital applications.

Note: Workshop overhaul is not covered by this guidance.

Purpose

The purpose of this document is to provide guidance for the minimum maintenance requirements for non-vital relays used in London Underground (LU) signalling and signal control systems.

Note: This guidance supplements S1199 'Signalling and Signalling Control - Operation and Maintenance'