Specifications

ST900 Family General Handbook
667/HB/32900/000 Issue 12 Page 33 of 265
(which are limited to 10A). The total controller load (including regulatory
signs and the maintenance socket) is limited to 45A. This option also uses
a 3kVA dimming transformer, see section 2.11.3.
Note 2: The ST900LED 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 3: 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) – see section 34. 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 4: Where “LED Lamp Switch” PCB (667/1/33905/3xx) are used to lamp
monitor Helios LV CLS (NLM) LED Signals, refer to 667/HB/32921/007
because the number of signals that can be lamp monitored is reduced
(even though the drive capability remains the same).
Note 5: The supply for LED regulatory sign on the ST900LED 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
ST900LED controller.
The following sections detail how to select the correct dimming transformer and
estimate the power consumed by a controller, using the theoretical junction in Figure
6 as an example.