The Impact on Lighting of Ripple Injection Signals
Electricity suppliers use ‘ripple injection load control signals’ to control off-peak loads such as hot water heaters and street lights. These signals can be amplified to relatively high levels through electricity network characteristics such as resonance. Amplified signals can impact lighting and other customer equipment resulting in flickering lights (traditional and LED), racing clocks, audible noise from speakers and ceiling fans, bumping compressors, ovens being turned on/off, etc. Lighting is particularly susceptible when dimmed.  Lighting Council Australia, the Commonwealth Department of Environment and Energy and the Australian Power Quality and Reliability Centre are working together on the development of a voluntary test specification that may assist the market to determine combinations of dimmers and lamps that are immune or less susceptible to the amplified signals. However, wide differences in dimming and lamp technology, the use of different ripple injection signal frequencies and very different characteristics across the electricity network means that this problem is not easy to solve. Mitigation strategies identified so far include:
  • When the effects of ripple control signals on lights are significant, the electricity distributor may be able to measure the amplitude of the ripple signal voltage and reconfigure the network to reduce amplification effects. At least some electricity distributors have highlighted they are willing to take this action when high signal voltages are measured.
  • Using combinations of quality lighting equipment recommended by reputable suppliers and performing tests with small numbers of new lamps/dimmers before bulk installation. Tests should continue over multiple days due to the variability in the network conditions at different times and on different days.
  • Careful selection of dimming technology can provide more consistent supply of power to lighting equipment minimising the impact of mains supply instabilities and ripple control signals. Some dimming systems can require additional wiring so involve your lighting supplier and electrician early in the selection process. Alternatively, wireless dimmable lamps and fittings may be available.
  • Filters are available to mitigate the effects of ripple control signals. These need to be installed by an electrician. The widespread roll-out of smart meters will ultimately solve this issue. However, the existing ripple injection signalling equipment may be maintained for another ten years or more.
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