Specifications

ST900 Family General Handbook
667/HB/32900/000 Issue 12 Page 37 of 265
2.11.3.4 Total Average Junction Power
For the total average junction power to aid local authorities with running cost
estimates, the total average lamp power must be added to the controller average
power.
Total average Junction power is calculated as follows:
Total average lamp power
946W
Controller power 53W
Total Average Junction Power is: 999W
If it is required to make an estimate of running costs which include the period of time
that the signals are dimmed this can be approximated as follows:
Total Average Junction Power (Dimmed) is:
Total Average
Signal Power
x
Dimmed
Mains Voltage
+
Total
Reg. Signs
+
Total Average
Controller Power
Nominal
Mains Voltage
Therefore, for the theoretical junction:
(946W – 30W)
x
160V
+ 30W + 53W
230V
Total average Junction Power (Dimmed) = 693W
Note 1: The power used by the regulatory signs (which are not dimmed) for
estimation of running costs is approximately 30W. For fusing purposes the
regulatory signs are rated at 76 VA due to the inductive nature of the load
they present to the supply.
Note 2: The controller power should also include any additional equipment
supplied by the controller. This may include, for example, OTU, OMU or
Auxiliary detector power supply.
Note 3: Many customers may now prefer to use the Elexon codes for each individual
device within the site to determine power consumption for Billing purposes
when using an un-metered supply. Some older devices may not have an
Elexon code in which case there is a Genetic code. The Elexon Home
page can be found here : http://www.elexon.co.uk/Pages/home.aspx
2.11.4 Detector Power Supplies
The Loop Detectors in the ST900 are all powered from 24V AC provided from either
2A or 6A transformer depending on the number and type of Detectors fitted. The