Twilight astronomical clock Accessory for SEC STPi power controllers
astronomical twilight clock public for lighting plants with remote control reverberi

The correct switching of outdoor lighting is a neglected source of savings. The correct switching can save between 7% and 10% of energy in average.

The correct switching of outdoor lighting is a neglected source of savings. The correct switching can save between 7% and 10% of energy in average. Depending on the location and the time of the year, the lighting should be switched on and off when the sun has reached an angle of around 6° below the horizon (-6°) or around 24 minutes after sunset/24 minutes before sun rise. The topography and the use of the public space may influence this time.

The on/off function of outdoor lighting can be done with a clock. Clocks however need periodical maintenance. They have to be calibrated at least once per year. This is very costly and human error can lead to wrong switching cycles.
As an alternative an LDR based photo cell can be used measuring the residual daylight. This works well when the photocell is new and placed in the right position. However because of the aging of the glass /acrylic cover and the accumulation of dust aged photocells will always switch on early and switch off late. This will waste a lot of energy. Another disadvantage is that the photocells cannot be synchronised. The on and off seems to be more of a random function.

A more advanced solution is the use of a remotely synchronised and intelligent astrological time clock, as we offer it as an option in the DIM module. This time clock allows for maximum flexibility. The on / off timings can be adjusted differently for each season or for four period defined by the user and the remote control makes sure that your clock is “on time”.
Since all the clocks are synchronised an “organised” switching of the public lighting will take place. Because of the high accuracy of the system a considerable percentage of energy will be saved.

In case of remote control, all the functions of the astronomical twilight clock can be managed by a remote PC.