General :

Originally the only junctions out of Parkend to Norchard were two level 5 outgoing junctions which used auto-auto relay sets at Parkend and terminated directly onto incoming final selectors at Norchard. This meant that no other level than 5 could be connected to Norchard. This relay set overcomes that difficulty.

The relay set can be accessed from up to five levels ie 4, 5, 6, 7, and 0 in the case of Parkend. The relay set will remember which level the call came in on. There are five L relays for this purpose.

The relay set then generates a digit equal to the level that originated the call. It will transmit this digit to Norchard. At Norchard the call is received on an incoming first selector which will step to this generated digit. This will allow access to up to five first selector levels.

This call is made via a junction made available by recovering the second level 5 junction to Norchard and the reuse of the cable pair. This means that there are still two junctions available for level 5 calls from Parkend to Norchard but the second junction also carries calls for levels 4 (Asterisk), 6 (Lydney Signal Box exchange), 7 (proposed Whitecroft exchange), and 0 (assistance telephone).

Whilst the relay set is generating and transmitting the initial digit to Norchard the Parkend caller is dialling two further digits into the relay set. These are stored on a mechanical regenerator and are transmitted to Norchard after the initial digit has been generated and sent.

Show Relay Set Circuit as a PDF (476Kb 4 Pages)

Page provided by John Bathgate This page was last updated on 12th March 2015