Dimming control panel noise...

[ultramegabob]

I installed a dimming control panel for a school auditorium recently, the equipment was supplied by another contractor, I got a call today of a complaint of the system making a humming noise when dimming a certain levels. All I did was extend existing circuits, mount the panel on the wall, and make terminations on the neutral buss and the terminals for the dimming modules. They are asking me to look at it because it will take over a week before the dimming system people can look at it, and they want to rule out any other possible issues. Any thoughts?

 

[wiigelec]

Solid state dimmers work by clipping the AC on the time scale similar to a SCR. This creates harmonics that at certain dimming levels can resonate and create noise.

I installed a solid state dimmer for a ceiling fan once and at certain dimming levels the incandescent lamps buzzed quite loudly. I was able to minimize the noise by replacing the lamps with "garage door opener" lamps that have a heavier duty filament...

 

[ultramegabob]

Solid state dimmers work by clipping the AC on the time scale similar to a SCR. This creates harmonics that at certain dimming levels can resonate and create noise.

I installed a solid state dimmer for a ceiling fan once and at certain dimming levels the incandescent lamps buzzed quite loudly. I was able to minimize the noise by replacing the lamps with "garage door opener" lamps that have a heavier duty filament...

Thanks for your quick response, so hopefully this is the person who supplied the dimming equipments baby...

 

[G._S._Ohm]

There are surface coatings that can damp out resonances.
Also, try pushing on panels in places to see if you can kill it. Large panels can act as diaphragms and amplify small vibrations.