Lighting contactors

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sam34

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Missouri
Please if anyone explain the different between Electrically held and Mechanically held lighting contactors and their different type of application. Thank you,

sam
 
Re: Lighting contactors

The power contacts are driven to both the open and closed positions by a momentary pulse of control power, therefore they are quieter than magnetically-held contactors because there is no continuous AC hum.

Mechanically-held contactors do not "drop out", and switch off the lighting during control power failures. During such failures, magnetically-held contactors usually drop into the "off" position, even though service voltage may still be available.

Ed

[ January 03, 2005, 06:56 PM: Message edited by: Ed MacLaren ]
 
Re: Lighting contactors

The "classic" example of a mechanically-held contactor (latching contactor), is in a library where is is very quiet & you want to eliminate the possibility of hearing the alternating current hum of an energized coil.

There are of course, other applications.
 
Re: Lighting contactors

if changing out bulbs for better designed versions does not fix a problem with humming in a dimmer switch, can contactors help eliminate the loud noise. Note, I've tried 3 types of dimmers now, none help the cause. Just curious if this is something viable or is there another option. I/ve had to use contactors once for a photo cell, but not sure of its application beyond this.
 
Re: Lighting contactors

Don't see why a dimmer would generate audible noise except in the lamp itself unless the RF filter inductor is humming?

And, I wonder if the proximity of the filament to ferrous materials makes the filament vibrate more.

I also speculate that these vibrating filaments might fail prematurely.

But why a contactor, why not just replace the dimmer with a switch?

[ January 07, 2005, 12:45 AM: Message edited by: rattus ]
 
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