NR TI 120 ISSUE 1 PDF

This TI applies to all applications of TI21 track circuit receiver ends.

Purpos

This Technical Instruction relaxes the constraint on the selection of TR styles stated in § 3.1.2 and § 4.9 of NR/L2/SIG/11761.

§ 3.1.2 shall be modified and § 4.9 shall be replaced by:

"A 50V line relay to BR 930, BR 931, BR 960 or BR 961 shall be used as the Track Relay; the choice may be made to match other local applications and spares holding. The contact configuration shall be selected to meet circuit requirements. The relay shall be positioned in the same apparatus case as the receiver. Note that if a BR 961 relay is used, its biased feature is not a safety requirement, so the exemption from routine servicing of TI21 TRs still applies."