SWITCHBOARD No. N116
Lamp Signalling with Automatic or C.B. exchange lines
This private manual branch exchange switchboard with capacity for three exchange lines, twelve extensions and five connecting circuits has been designed in accordance with modern needs. Compared with earlier types of switchboard, it offers the attractive combination of improved facilities and compact design, both features having been obtained largely through the use of miniature keys and 4-wire extension lines. The switchboard operates from a 50V supply and its physical design features are similar to the 2 + 6 and 4 + 18 types in the cordless PMBX range.
Up to half the extension line circuits can be converted to 2-wire working by the use of wall mounted auxiliary relay units of which there are five types for:
Construction and Finish
The switchboard is fully tropicalised and uses p.v.c.-insulated wire throughout.
Relays are Types N45000 (BPO 600) and N30000 (BPO 3000), protected by strip covers. An internal terminal field permits direct termination of incoming lines. Alternatively, for plug-in switchboard connection, a 6ft (1 .83m) flexible cord with matching plug can be supplied, together with an associated line jack.
At installations where no source of power ringing exists, a wall mounted ringing converter, operating from 200-250V, 50Hz a.c. mains, can be supplied. Alternatively, an in-built or wall mounted transistor ringing unit can be supplied.
The separate two-tone grey table type Etelphone provided for the switchboard operator can be arranged for use in conjunction with an operator's lightweight headset, if required.
Plessey Publication No. 7129 (1970)
Last revised: October 12, 2019