new dimmer

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aliasghar

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February 08, 2005 01:05 PM
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refer to my question "dimmer".does new dimmer consume power? does new dimmer drop voltage to reduce the amount of light?how does it?it has azener diod?the new dimmer has aheat radiator to reduce the heat ,that heat comes from using the power ?or not?how much does it reduce?
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Re: new dimmer

Electronic dimmers work by chopping part of the sine wave, turning off and on as the actual time the voltage is at peak varies. The heat is created from the operation of the solid state circuits controlling part of the load, not from resisting the load. That is why an electronic dimmer is hotter when full bright than when dimmed all the way. At full bright, it is controlling peak voltage.
 
Re: new dimmer

As Rick has stated, the heat is generated by the Triac. The "heat sink" referred to in the diagram below is actually the dimmer's aluminum mounting strap.

Dimmer.gif



The sketch below shows typical voltage and current waveforms with the dimmer set at about half brightness.

Harmonics5.gif


Ed

[ February 08, 2005, 04:59 PM: Message edited by: Ed MacLaren ]
 
Re: new dimmer

The triac is an electronic switch and it exhibits a significant resistance when ON--much more than does a conventional switch. The current then creates I squared R losses which make the unit get warm. The heat sink tab should be in close contact with the metal portion of the case to let the heat out.
 
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