Siemens ST950 Handbook page 29

In the Unlikely event that Halogen loads are being used, refer to the ST900 General
Handbook 667/HB/32900/000 for signal power consumptions and permitted load
numbers.
Low power LED signals should only be used on the LED variant of the
Lamp Switch Card because the standard Lamp Switch Card is not designed
to switch the low power levels experienced with LED signals.
Note 1: The ST950LED controller is not intended to be used with Halogen signals. If
Halogen signals are used the main limiting factor is the Supply power available in Dim.
500VA represents just 15 Halogen loads.
The figures quoted for Maximum number of aspects are based on Siemens CLS Heads
consuming 14W in Bright and 4W in Dim (154V). Although the LED variant 8 phase
driver card has the same drive capability as the standard card this maximum drive
capability cannot be reached in an LED configuration with lamp monitoring.
Note 2: The current capability of the Lamp Switch cards depends on whether they are
wired for the UK (not hardware fail flash) or for non UK (with hardware fail flash). For a
Lamp Switch card not wired for hardware fail flash, the two 10A fuses protect four
phases each. For a Lamp Switch card wired for hardware fail flash, one 10A fuse
protects the red and amber supply and the other 10A fuse protects the green supply.
Note 3: Where LED Lamp Switch cards are used the maximum load remains at 4A but
must be reduced to 2A when lamp monitoring is enabled.
Note 4: The supply for LED regulatory sign on the ST950LED has been reduced to a
maximum of 50. This is to allow current taken by other items (such as detection) to
avoid exceeding the rating of the 20A supply fuse on a heavily populated controller. If it
is necessary to exceed 50 LED regulatory signs on a controller Traffic Engineering at
Poole should be contacted for advice.
It is recommended that only LED regulatory signs be used on an ST950LED controller.
Note 5: With an LED Lamp switch card the limit is based on the number of lower power
signals that can be monitored on any single aspect output, this being a maximum of 8
for Siemens LV CLS, but may be lower for other products, please see 667/SU/46000
for full details.
3.6.3 Selection of Dimming Transformer
This section details how to select the correct dimming transformer and estimate the
power consumed by a controller, using the theoretical junction in Figure 5 as an
example.
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Copyright © Siemens plc 2015. All Rights Reserved.
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Paul Cox
ST950 General Handbook
Mobility Division, Traffic Solutions
Sopers Lane, Poole, Dorset, BH17 7ER
Page 29 of 107
Status Issued
Date 16-Jul-2015
Document No. 667/HB/46000/000
Mobility is a division of Siemens Plc