Originally Posted by Landmark
I replaced two old 3-speed 5 amp fan controls that controlled 5 ceiling fans each in a small retail store. My supply house ordered me infinitely variable speed switches ( 5 amp Lutron ). The old ones were slide switches with off-lo-med-hi.
Now when the fans are on high they work fine. When you adjust the speed a little lower the fans start to make a humming or slight buzzing sound.
Anyone else had this problem?
Yeah but it isn't a problem, per se. It is the result of the PWM electronics that control the fan speed. The frequency that is used to regulate the motor speed is at the mid to high end of the sound spectrum, so instead of the regular 60 Hz hum, we can hear the higher pitched buzz from the motor. Kinda like a speaker.