scope:

This guidance applies to all equipment and power supply wiring, from the point where it enters the room or apparatus case up to the point of supply for individual circuits, which is usually in the form of a feed fuse or circuit breaker. It should be used by Asset Stewards when preparing maintenance regimes.

Note 1: The following list is a guide to the scope of this engineering guidance:

a) all wiring, transformers, switching equipment and protecting equipment from the 600V AC signal main links or isolators to the feed busbars, and to other power supply units;

b) low voltage supply units, and feeds from these to busbars, including rectifiers for DC supplies;

c) uninterruptible power supplies;

d) 230V wiring from the room consumer unit to any signalling apparatus;

e) power supply units for any computer apparatus;

f) batteries.

Note 2: Workshop overhaul of signalling power supply equipment is not covered by this guidance.

Note 3: The maintenance of Jointless Track Circuit power supplies is not within the scope of this guidance. This is covered by engineering guidance document G199K.

Note 4: The maintenance of cable runs is covered by engineering guidance document G199T.

Purpose

The purpose of this document is to provide guidance for the minimum maintenance requirements for signalling power supplies used on London Underground (LU).

Note: It is not normally intended to define methods of maintenance, but where the guidance does so it is for particular reasons and the Asset Steward should adhere to those methods. Workshop overhaul is not covered by this guidance.

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