[TCUG] Re: Lamp Monitoring of Nearside LED signal Heads
- From: "Malcolm Kersey" <malcolm.kersey@xxxxxxxxxx>
- To: <tcug@xxxxxxxxxxxxx>
- Date: Wed, 31 Jul 2002 12:16:59 +0100
Lee Shepherd from AGD was demonstrating their Puffin nearside pedestrian =
signals and push button units to us a couple of weeks ago.
He showed us red lamp monitoring facilities for the pedestrian signals, =
which seemed to rely on the expectation that the red would only be =
switched off for short periods (while the green was showing). It would =
produce an output when it had determined that a failure had occurred - =
depending on the proportion of LEDs that had stopped working. He stressed =
that this had been developed in the absence of a specification and that it =
had no Type-Approval status.
It seemed to us that it might be possible to develop the AGD system to =
monitor the incoming voltage to determine when the aspect or wait lamp =
should be lit, compare that with the sensor determining whether the LED's =
were lit and produce a failure output if appropriate.
Alternatively each LED aspect, including WAIT lamps could be monitored for =
operation in a similar way, opening a "normally closed" a volt-free =
contact for use in the controller when the aspect was "ON". Controller or =
lamp monitoring logic could then be used to determine whether there had =
been a failure.
No doubt these ideas could be developed to use digital outputs which would =
have a reduced demand on cabling and terminations.
Malcolm Kersey
Babtie Group for Kent County Council
>>> "Kinnaird, Dave" <D.Kinnaird@xxxxxxxxxxxxxx> 31-Jul-02 10:16:21 >>>
We now have the ability to lamp monitor LED vehicle signal heads, but not
PUFFIN nearside ped signals and push button units (I have AGD). One could
argue that to the pedestrian the down time due to either LED failure or
other factor is as just as critical.
Does anyone know what developments are in the pipeline or perhaps we could
flex our combined 'muscle' to influence the development of such lamp
monitoring.
Dave
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