Metering-Unit No. 3A and 3B

These Metering-Units were used on P.M.B.X.'s when subscriber metering was required. The unit was powered from the P.M.B.X.'s power supply. On large P.M.B.X. installations a separate power supply would be fitted.

Much smaller than the Unit, Metering No. 1, which they superseded and they could also house a totals meter (Meter No. 150) which was visible through a hole in the case.

A resettable meter would have been fitted on the switchboard (Meter No. 21).

Metering-Unit No. 3A - 20-30volts DC.
Metering-Unit No. 3B - 45-55volts DC.

Click her for a detailed description - Telephones, PBX, A1003.

Click here for metering schemes and apparatus required - Telephones, PBX, B3104.

Click here for a POEEJ article - 1959