NR RT/E/C/19004 ISSUE 1 PDF

This document applies to Type SJ821 I relay units used in the GEC-GS Geographical unit

This code of practice does not address the general personnel and system safety measures necessary for working on the track with signalling equipment

PURPOSE

A number of track circuit indication failures have occurred due to high resistance contacts in the sub-miniature relays of Type SJ821I relay units. These relays (type A43 T21/4CA 2500L'2 or A43 21/4CA 2500L'2) have contacts rated at I A. However, at certain installations this rating may be exceeded where a large number of lamps are driven over a single contact, resulting in reduced dependability. This document provides advice on the procedure necessary to:

• identify relays incorrectly rated for their application

• obtain correctly rated relays

• fit higher rated relays into the units