Radio
Frequency Interferance
Chopping the mains sine wave causes fast voltage and current changes. Unless
there is suitable radio interference suppression. high frequency interference
would be caused in the mains wiring. The interference consists of the 50/60Hz
frequency plus varying amounts of multiples and divisions of the frequency. The
multiples can typically range from 30Khz to 1.5Mhz, and the divisions can be
down to 20 harmonics of the original. The house or building wiring acts as an
aerial and transmits the signals into the air. Earth connections that are insufficiently
grounded and form earth loops can also act as aerials. Cheap, poor quality dimmers
without sufficient filtering will cause RF interference. Quality dimmers use
RF choke based suppression circuits to limit the rate of rise of current di/dt
and capacitors to suppress the higher frequencies.Read more on
Buzzing problems
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