The benefits of a CEPS (Centralised Emergency Power Supply) system for a modern metro

From Royal Oak Portal in the west, to Pudding Mill Lane and Plumstead in the east, Crossrail makes provision for its emergency power supplies via localised UPS (Uninterruptible Power Supply) systems. With autonomies of 3hrs for lighting and 4hrs for communications systems, a required 10 year battery life, and the ability to provide adequate fault current to discriminate faults when the batteries are almost life expired has created many challenges for the design teams, not least of all, for the architect who was tasked with creating adequate space within the station, shaft & portal designs to accommodate such large pieces of equipment, and the mechanical engineer to cool & vent these spaces.

Based on experiences of Crossrail, there are alternatives to providing large standalone UPS systems. The purpose of this document is to consider one of these alternatives and the benefits of receiving a Centralised Emergency Power Supply (CEPS) connection.