ERICSSON, Type B
P.A.B.X.

Used by other telephone administrations

The company manufactures two types of P.A.B.X., both of which include the requirements of the Post Office.

Both systems operate from a 50 volt power supply.

This equipment employs forward hunting uniselectors individual to each extension and the connecting circuits contain two-motion switches of standard Strowger type throughout.

The sizes of the installations depend upon the capacity required and are divided mainly into three; viz.:- 50 lines (2 digit), 150 lines (3 digit) and over 200 lines (3 digits or more).

Racks. All the above are mounted on G.P.O. type single-sided racks.

The equipment consists of a line finder group and final selector rack and two line apparatus racks which are of the single-sided type 4' 6" wide and 8' 6" high. The line apparatus racks are similar to those used for "type A" equipment.

Other features. All relays are fitted with twin contacts, thus reducing dirty contact faults to a minimum.

If the assigner employed in "type A" equipment is operated and fails to find a line finder the release alarm is brought in after 9-18 seconds.

P.G. conditions are provided if dialling fails to take place within 30-60 seconds of a line finder being connected with an extension line either due to a fault or due to delayed dialling.

Direct access can be provided on the 9th level and restricted service can be introduced, if required, on any extension.

The manual boards supplied provide through signalling and dialling conditions when necessary.

Alarms. The usual alarms are provided and can be extended to the manual board when required.

The power plant generally consists of two batteries of 25 cells each and motor generator charging plant, but can be arranged to suit any type of main supply.

Automatic charging and disconnecting devices can be supplied if required.

Taken from a paper by the IPOEE dated 1932 (No. 142)

Last revised: June 18, 2022