NR NR/SP/ELP/21021 ISSUE 2 PDF

This specification applies to all new step-down transformers installed on the d.c. electrified lines.

Purpose

This specification states the requirements for the design, manufacture and testing of stepdown three phase transformers and their associated earthing resistors in the range:

33/11 kV up to 10 MVA

33/22 kV up to 15 MVA

They are used for power distribution in d.c. traction systems where incoming supplies are at 33 kV and distribution to traction substations is at 11 kV or 22 kV.

The document is to be read in conjunction with the relevant procurement specification.