scope:

These guidance notes apply to those parts of Network Rail's 25 kV a.c., 50 Hz electrified railway infrastructure, which includes the use of traction return conductors and booster transformers, in accordance with NR/SP/ELP/21078 - Design of earthing and bonding systems for 25kV a.c. electrified lines.

The scope of these guidance notes is to provide assistance on the operation of Network Rail's 25 kV a.c., 50 Hz electrified railway, where there is an occurrence of booster transformer outage(s). These guidance notes provide a means of assessing the severity of each outage and hence the expected increase in the level of induced longitudinal voltage into lineside equipment.

The guidance notes do not include instructions for specification, approval, installation, commissioning, maintenance or day-to-day use of booster transformers.

Purpose

These guidance notes support the Network Rail Company procedure for managing the outages of booster transformers on 25 kV a.c. 50 Hz electrified lines and assist the assessment of actions required to be taken in the event of booster transformer outage(s).