Siemens Traffic Controls Ltd.

Technical Services Dept.

Technical Bulletin No: / TB 41-0041
Status
Issue Date / 26/3/01
Issued by / W Rogers
Approved by / J Burgess
Title: / ST800, ST700, TC12 and 3U/5U OMU Dim/Bright Monitoring
Introduction / Due to bright street lighting, the photocell does not detect a sufficient change of light level during the hours of darkness. The Signals therefore remain on bright throughout the night.
This subsequently causes the lamp monitoring facilities within several different products to report the fault “No dim/bright changes in 24 hours.”
This document details the action to be taken should this situation occur on different lamp monitoring facilities.
Scope / ST800, ST700, TC12 and 3U/5U OMU
Related Documents / None
Background / Apparent failures on lamp monitoring facilities can be reported due to bright street lighting causing the photocell not to see changes in light level at night.
Procedure / The work-around for each lamp monitor product is as follows:
ST800 and ST700 Traffic Controllers (built in lamp monitor)
Available from PB800 issue 11 onwards, the dimming present setting has a new option, KDP=2. This allows the controller to perform dim/bright changes (as for KDP=1) but removes the checking of the dim/bright changes (as for KDP=0).
TC12-OTU Lamp Monitor and T400 Integral Red Lamp Monitor
The dimming present setting can be set to 'no dimming' using KDP=0 so that the lamp monitor does not check for dim/bright changes.
RMS 3U or 5U OMU
The OMU should be reconfigured with 'N' against "Has the controller got dimming?" on screen 90 so that the lamp monitor does not check for dim/bright changes.
Also note that if the mains is high and the dimming transformer is set to 230V and/or there is a small load, the OMU may report Dimming failures. This may be overcome as above, or by change of the tapping to 240V. (The new issue of 3U software, issue 13, will cure this.)