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Phase Dimmer Control using Triac


Aug 29, 2019
Aug 29, 2019
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



  • Phase_Dimmer_Schematic.pdf
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  • Phase_Dimmer_Schematic.png
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