Figure 11 – Theoretical Junction (St950 Elv) - Siemens ST950 Handbook

4.10.4 Lamp Supply Transformer and Power Consumption Example
The following sections detail how to select the correct lamp supply transformer and
estimate the power consumed by a controller, using the theoretical junction in Figure
11 as an example:
STAGE 1
B
4.10.5 Selection of Lamp Supply Transformer
In order to select the number of lamp supply transformers, the total average signal
Lamp Power is required. See Table 8 on page 45 for the power taken by the different
types of lamps.
When selecting the lamp supply transformer the peak lamp power is not used as the
transformer can withstand the overload for the 2 second Red / Amber period. Thus for
the average power consumption, it is assumed that only one lamp is illuminated on
each signal head. However, Pedestrian Red signals illuminated at the same time as the
Pedestrian and Wait / Demand Accepted signals must be included.
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Figure 11 – Theoretical Junction (ST950 ELV)
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4
Paul Cox
ST950 General Handbook
Mobility Division, Traffic Solutions
Sopers Lane, Poole, Dorset, BH17 7ER
Key:
Traffic Red / Amber / Green Signal (Main)
Traffic Red / Amber / Green Signal (Secondary)
Pedestrian Red / Green Signal.
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Pedestrian Wait Indicator Box (on pole).
'No Right Turn'
Regulatory Sign
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STAGE 2
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Date
Document No.
Mobility is a division of Siemens Plc
STAGE 3
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49 of 107
Issued
16-Jul-2015
667/HB/46000/000