Page 12 - Industrial_Technology_EXTRA_May_4th_2020

SENSORS...

Sensors provide reliable

detection for pantrograph tram

When a tram reaches a road junction, wire-switches, installed on the overhead

conductor cables, control its direction of travel, with switches in either the default
‘straight-through’ or ‘turnout’ positions. As the tram passes a switch in the turnout
position, photoelectric sensors mounted on the overhead cables detect the presence
of the pantograph current collector so that the control system can then reset the
switch to the default position. Contrinex sensors provide a reliable solution

n urban tram transportation systems, wire- If a triggered switch reverts to the straight-
switches installed on the overhead conductor through position prematurely, the pantagraph
cables at road junctions, control the direction current collector may become disengaged,
Iof travel for the trams. The switches default to damaging the switch. Therefore tram operators
the straight-through position so that when a bus install safety systems to prevent premature
approaches a turn, the driver uses a remote trigger switching. Typically, these utilise timer circuits and
to change the switch to the turnout position. After a predetermined delay or mechanical sensors that
the bus completes the turn, the switch reverts to the rely on physical contact with the current collector,
straight-through position. but neither system is reliable.
A Swiss manufacturer of trolley-bus control
systems required a highly reliable, rugged
sensor system that will detect the presence
of a current collector as it passes a switch.
The system had to operate with minimal
maintenance and withstand the varied
weather conditions of an outdoor
environment in Switzerland and so the
company selected Contrinex sensors.
Contrinex’s C23 through-beam
photoelectric sensors offer high-
performance, small size and high-stability. A
purpose-designed metal bracket, mounted
above the conductor cable, holds the

May 2020 • INDUSTRIAL TECHNOLOGY EXTRA! • p12