Ripple Control

Wow I hadn’t heard that phrase in a long time. About 20 years now.

Ripple Control - all but history

I first learnt about Ripple Control as an intern at Landis & Gyr. It was a power control strategy by which Singapore could control switching of public (street and park) lighting. At that time, it was deemed necessary to turn off public lighting in case of a bombing raid – so as not to give enemy pilots ground-based points of reference.

On a daily basis, it was used to turn on and off the street lights at dusk and dawn. It was also used to turn on park and playground lighting at sunset, and off again when children were meant to go to bed – at 11pm.

I remember spending many afternoons programming the ripple control receivers’ chips that would be delivered to the clients. 3 street lighting lamp-posts shared a receiver.

It was also used to control street lighting in inclement weather, when ambient light had fallen below a certain threshold. This was achieved by means of lux-meters installed at various parts of the island.

I was told that if power ever failed to the meter that it was “tedious” to have to send a man up to the roof of the building to perform recalibration. As part of my internship assignment, I was tasked to design and build an uninterruptible power supply for it. It contained a step-down transformer, a rectifier circuit, voltage regulator, nickel cadmium batteries and a charging circuit.

I built 4 units of those and delivered them to my mentor at the end of my 2 month stint. He still works there.

I have been told that the Ripple Control system has since been decommissioned. Night vision made the defence requirement moot. All street lamps now run off a timer, instead of varied sunrise / sunset times in the course of the year.

In the words of Obi-Wan, “So uncivilised!”

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