NR NR/L2/ELP/23003/MOD B ISSUE 1 PDF

The scope of this document (Module B) covers requirements related to Network Rail High Voltage (HV) transformers and transformer rectifier units which are derived from the HV traction power network in d.c. electrification areas. This includes those used in d.c. traction substations, for railway signalling power applications, and for supplies to other Distribution & fixed Plant (D&P) loads which are for operational infrastructure purposes.

In addition to the general requirements of BS EN 50327, BS EN 50328, and BS EN 50329 this module covers specific requirements for the following equipment types:

a) Auxiliary transformers

11, 22, and 33kV alternating current (a.c.) three-phase and single-phase auxiliary transformers with ratings up to and including 800kVA are used in d.c. traction substations to provide low voltage domestic supplies, for railway signalling power applications, and to supply other D&P loads for electrical power operational infrastructure purposes.

b) Transformer rectifier units

Transformer rectifier units are used in d.c. traction substations for the conversion of HV three-phase a.c. supply to d.c. having a nominal output voltage in the range 650 to 750V d.c. They consist of a traction transformer coupled to a traction rectifier.

c) Distribution transformers

Step-down three phase distribution transformers with a rating not more than 15MVA and their associated neutral earthing resistors used for distribution to d.c. traction substations at 11 or 22kV a.c. and the input supply is at 22 or 33kV a.c.

A procurement specification should be produced by the client/client’s representative when placing an order on any of the units covered by this module. This document is to be read in conjunction with the relevant procurement specification.

Purpose

Module B states the requirements for the design, manufacture, and testing of auxiliary transformers, transformer rectifier units, and distribution transformers in direct current (d.c.) traction applications.

This module is aimed to mitigate the following risks:

• Unclear requirements leading to difficulties in procuring equipment components;

• Increased costs from different routes and projects working to different sets of requirements;

• Non-compliance of procured components to BS EN 50327, BS EN 50328, and BS EN 50329.