scope:

This standard shall apply to LU's 22kV, 11kV, 600V and 400V AC distribution systems and any assets that form part of the Operation and Maintenance responsibilities. The Standard also lays down specific protection requirements associated with the Bulk Supply Points and LU's Emergency Generation Facility.

This Standard includes the requirements for:

a) protection systems

b) protection relays

c) direct acting protectives

d) electronic protection within circuit breakers; including Moulded Case Circuit Breaker

e) fuses

f) protection current and voltage transformers, (including Non-Conventional Instrument Transformers)

g) protection communications and intertripping.

This standard specifically excludes any requirements for protective equipment onboard rolling stock and within SER, IMR and CER rooms, station switch rooms and switchboards that are not the responsibility of Head of Profession, Power.

Purpose

This standard:

a) describes the minimum performance levels required of electrical protection on London Underground's alternating current power distribution system

b) gives details of protection systems in terms of design principles and methods

c) defines the requirements for all electrical protection equipment for power system circuits operating normally at or above 400V AC between conductors

d) provides the underlying principles applicable to protection systems in achieving minimum levels of safety, supply continuity and stability for AC power systems on the LU Power Distribution Network.