Noise: Ripple Control

WHAT IS RIPPLE CONTROL

Ripple control is a way of controlling utilities by using a superimposed frequency on the standard 50Hz AC power supply.  It has been used for many years by power companies to control and manage peak power load on their distribution networks. The ripple control frequency is interpreted by a remote receiver unit at the point of power usage to switch on and off systems such as off-peak hot water heaters, street lights and water pumps.  Ripple control may also be used to signal high network load periods for major customers to allow them to reduce power consumption.

WHAT ARE ITS EFFECTS

A noise from electrical appliances is the most common complaint arising from ripple control, which is generated when a transformer or motor windings in a switched-on appliance resonate with the ripple control frequency, usually between 300Hz and 1300Hz.  The noise is often, but not always, intermittent depending on when ripple control signals are being transmitted.  People often notice it most acutely in the night when off-peak hot water systems are turned on.

WILL I BE AFFECTED

Ripple control frequencies are commonly used in NSW, south east Queensland and New Zealand, although other areas also use this technology.  This does not mean you will have a problem if you live in one of these areas or conversely that you will not have an issue outside of these areas because not all properties will be affected and not all appliances will react in the same way.

The easiest and sometimes the only way to confirm if there is a ripple control frequency acting in your area is to call your power company and ask.  If you have a system that uses ripple control signalling you might also see a ripple control receiver wired into the fuse box and a dual tariff meter or dual meters.  Note the presence of a ripple control signal does not necessarily mean you will experience ripple control noise in ceiling fans.

WHAT CAN BE DONE ABOUT RIPPLE CONTROL NOISE

Ripple control signal filters are available to manage the noise generated by affected electrical appliances.  The ripple control filter has to be matched to the local signal, usually 750Hz or 1050Hz, and must be installed by a licensed electrician. There may be extreme cases where the ripple control frequency is so strong it requires two filters to be installed to reduce the noise sufficiently and in some locations multiple ripple control frequencies are used also requiring multiple filters.

WHY AREN’T RIPPLE CONTROL FILTERS BUILT INTO CEILING FANS

Ripple control noise is not the norm and in many environments where it does occur it is not a problem because the noise generated is not audible.  While we sympathise with the few customers who do experience a problem, it is not cost effective to build an AC electric motor that rejects all ripple control frequencies given the small proportion of people affected, a cost that would have to ultimately be borne by all consumers.

IF IT’S NOT RIPPLE CONTROL NOISE, IT COULD BE ELECTRICAL HARMONICS AT PLAY

If you are hearing the tones at random times of the day, your electrical supply may be affected by harmonics; a power fluctuation that is not part of the normal electricity supply or ripple control signal output. Harmonics is caused by an interference created by other equipment on the network, such as inverter type air conditioners and switch mode power supplies for computers. The offending appliances may be in your home or other premises on the local power grid. If you are being affected by network harmonics, it may be of benefit to transfer the electricity supply to your premises to a different phase in the street. This is something you will need to discuss with your power supplier.

IS RIPPLE CONTROL AND ELECTRICAL HARMONICS NOISE COVERED BY MY WARRANTY

Ripple control and electrical harmonics noise is not the result of a fault with your ceiling fan.  As such we do not cover them under our warranty.  Where ripple control noise is found to be at fault, the customer will have to acquire a filter and have it installed by their electrician at their expense.  If you make a warranty based service call and ripple control or electrical harmonics noise is diagnosed as the problem you may be charged the call-out fee for the electrician.

FOR MORE INFORMATION ON CEILING FAN NOISE: