Pilot-wire relaying on a metropolitan system

ANUMBER of papers have been written which discuss individual pilot-wire relaying schemes. A recent paper presented by the relay subcommittee of the committee on protective devices¹ analyzed the pilot-wire circuit used in these relaying schemes. The present paper is a discussion of pilot-wire systems on a large metropolitan system where they have been in successful use for many years. The paper brings out the fact that pilot-wire relaying has many advantages over other forms of relaying because of selectivity and high-speed operation. It has also been found that the reliability of a complete relaying scheme is substantially better than would be expected from the record of the pilot-wire circuit as reported in the subcommittee paper at the 1943 winter technical meeting.