Phase Dimmer Control using Triac

[dinesh4761]

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 yes wish to know make

Thank you in advance

Dinesh

 

[rjenkinsgb]

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.

eg. A basic triac dimmer gives an output waveform like this:

https://sound-au.com/lamps/dim-f3.gif

To control the type of thing you are trying to drive, the waveform must be like this:
**broken link removed**

That presumably needs something like a GTO thyristor or IGBT to enable switching off under load in each half cycle?


Edit - this article gives an example of a dimmer circuit of that type, with "trailing edge" switching:

Project 157

ESP Audio Projects - 3-wire trailing edge dimmer

sound-au.com