SIEMENS BROTHERS
S15

The S15 System

The S15 system was the precursor of the S16, with Pre-selectors (later Line-finders) First, Second and Final selectors.

The selectors stepping under pulses centrally generated on a pulsing machine.

The switches operated on 60-volt dual battery charged by a motor generator with two batteries on the charge discharge principle.

Notes
L&SWR had three S15 PABX's all installed in 1921 at Southampton (500 line), Eastleigh (60 line) and Waterloo (50 line).

The SR then replaced the S15 at Waterloo, with a much larger (900 line) S16 in 1925.

Last revised: October 08, 2025

FM2