Off-Peak Ripple Control Signal on Mains Supply
What is the signal and why is it used?
Electricity suppliers in particular areas of Australia are injecting an off-peak ripple control signal onto their distribution networks at specific times. It is done in order to remotely control devices like off-peak hot water heaters, space heaters, car park lighting, public lighting and others. Therefore, this high frequency signal is often described as ripple control signal, since electricity suppliers are using it to manage peak electricity demand. It is mainly applied in NSW, parts of QLD and less common in other states.
How does it affect electrical appliances?
Ripple control adds a high frequency signal on top of the standard Australian 240V AC 50Hz power supply. Basically for standard alternating current (AC), electricity flows in one direction for a particular time and then into the other for the same amount of time. This cycle is alternated 50 times per second, hence the nominal specification of 50Hz. The general 50Hz is relatively slow for electrical devices, whereas the ripple is commonly at 492Hz, 750Hz or 1050Hz. Therefore, it is much faster and some electrical appliances can be sensitive to this high frequency signal. It is mainly devices like fans, toasters and non-dimmed or dimmed lights that can potentially be affected by the ripple control signal.
Examples of symptoms could be buzzing noises from fans or flickering lights at set times during the day. Different ripple control signals may be used in the same area for the various remotely controlled devices. Each can start at different times and have an individual repeating interval of commonly 60 or 30 minutes.
How do I know if my area is affected?
High frequency signal injection is most commonly used in NSW and parts of QLD. The best and easiest way to find out if there is a ripple control signal injected onto the power grid in your area is to call your local electricity supplier and ask. Additionally, there may be a dual tariff meter installed in your meter box that allows for switching from high to off peak tariff. A special ‘Zellweger’ meter might also be installed close to the dual meter and it generally shows the specific frequency of the ripple control signal at your property. It is possible that certain areas have more than one ripple signal present and they are operated at different times.
However, even if there is a ripple control signal present in your power grid, it doesn’t necessarily mean that you will see its symptoms because not all properties will be affected in the same way.
Why do I suddenly experience this issue, while it was fine before?
There can be a strong amplification of the signal in certain areas of the grid, caused by various factors related to the impedance of the supply grid itself.
Energy efficient lighting like LED can be very susceptible to any variations in the power supply. Therefore, these lights will be much more affected by the ripple signal than other lighting loads. Experience shows that certain LEDs can cope better with the high frequency signal depending on the quality of the design.
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