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Phase Dimmer Control using Triac


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Hello Sir/Madam,
I am engineering student making phase dimmer control using triac
The schematic is as attached
What I have observed that many times attached circuit stop working due to failure of triac
I am not sure is it because of di/dt or dv/dt failure. In order to avoid this I have used triac of much higher rating (10A) even though current needed can be as low as 1A.
However the problem continues.
I have observed that the failure is for transformer powered halogen lamp (inductive load?) and for ceiling fans.
It works satisfactorily for incandescent lamps.
Also I am sharing one more observation that if I connect glass tube fuse link in series with the load then the fuse blows.
From the various information available I realized that I need to use choke / inductor to overcome this problem. Is that right?
I need help to
    1. To find out the value of the inductor for 0.5A, 1A and 2A
    2. Is this a special type of inductor? if yeswish to know make
Thank you in advance



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  • 1 month later...

Hi... a light dimmer like that, which switches power on part way through each half cycle, can only work well with a direct filament lamp load.
To dim any other type of lamp, a different circuit has to be used where the power is on from the zero crossing of the AC supply and turned off at some point through each half cycle.
pcb assembly

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