How to stop Dimmable Lights Flashing because of the Ripple Control in NSW and QLD

Dimmable LED Lights flickering in parts of NSW and QLD. What is ripple control?

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Throughout Australia, but in particular in NSW and South East Queensland, electricity distributors use a remote control switching system that is commonly called 'ripple control'. Ripple control has existed for many years and is used for controlling demand and implementing different customer tariffs, for example switching a site between its on-peak and off-peak meter in the days before smart meters.


In Australia, our electricity supply is 230 volts AC at 50 hertz. AC means alternating current, a type of electrical energy that flows in one direction for half a cycle, and then in the opposite direction for the other half a cycle. 50 hertz means there are fifty cycles per second. Ripple control superimpose higher frequency signals on the 50 hertz mains supply so they can be distributed throughout a local power grid. These signals are understood by specific hardware that then turns on or off, such as off peak hot water heaters. Unfortunately many electrical devices including toasters, fridges, fans, fluorescent, halogen, and LED lighting can be sensitive to these frequencies. This may lead to buzzing sounds or other side effects from affected devices. In the case of LED lights, there can be a perceptible flicker, especially if connected to a dimming device or driver.


Electricity suppliers can use different frequencies at different times and therefore devices in one area/suburb may be affected whilst the same device in another area/suburb may not. Why does the ripple frequency affect my devices? Not all devices will show symptoms of ripple frequency interference, however it will affect all devices on the circuits. Humming in devices is caused because the ripple frequency is within the ranges of human hearing and is amplified when running through the coils in the device. You can hearing humming from any device with a power supply but some are much more obvious than others such as heaters. Devices that rely on zero cross detection, the point that the AC sine wave crosses the 0 volt point, such as dimmers are very susceptible to ripple frequency as it causes the detection to fail. When this fails it causes the components that handle dimming, such as the triac, to switch at the wrong time causing damage to the device components and potentially the load connected as well.

What can I do if I am affected? Several companies produce ripple frequency filters that can be installed either at the device you wish to protect or on the entire circuit to protect many devices. These filters MUST be installed by a licensed electrician and the filter has to be matched to the particular signals in your area (i.e.: 750Hz/1050Hz etc.).

For more information, see here: Zellweger Tone Filter Unit

Gayrad tone filters

This is the unit that we recommend:

Because signals vary significantly between providers and areas it isn't possible to build frequency filtering into every device, especially not small devices. If you are affected by ripple control, please contact your local dealer to purchase the appropriate filter.

Occasionally, the ripple control signals are so strong they cannot be sufficiently filtered.

In some cases additional sine wave correcting devices may also be required for optimal performance

References  Page 108 of Service and Installation Rules of New South Wales - Zellweger off-peak

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1 comment

hi, great article. Have you had experience dealing with AusGrid on this topic? They don’t seem to be very helpful. My electrician tried another brand of 750Hz filter but it had close to zero effect reducing flicker of dimmable LED downlights. Thx. Paul


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