Hi
I used circuit below. it seems simple. it works properly but after some while the BT136 born.
I guess it's lead by dI/dT limitation.
let me know about your ideas? how can I solve the problem?

 

What is the wattage of the bulb?
Is the triac on a heatsink?

 

What is the wattage of the bulb?
Is the triac on a heatsink?

100w and 60w. I saw it in both powers.
heatsink, no but it's not warm.

 

The opto-coupler has to connect G to MT2 for the triac to operate, and a 4K7 resistor between MT1 and Gate to prevent false triggering.

 

The opto-coupler has to connect G to MT2 for the triac to operate, and a 4K7 resistor between MT1 and Gate to prevent false triggering.

I drive an AC motor perfectly. 40w and 60w single phase AC motor. I have Snobber and it's complete.
but TRIAC born after several months when I use bulb lamps.

 

100w and 60w. I saw it in both powers.
heatsink, no but it's not warm.

A 100watt 20 volt bulb will draw 5amps. The current handling limit for this TRIAC is 5amps.

Also the bulb will have a very low resistance (1/10 to 1/100th cold vs warm) as it turns on.

It could demand over 1KW initially. This would be limited by your power source, but it easily could exceed the 25Amp for 20msec max spec stated on the data sheet.

Is this a aircraft landing light?

No wonder the triac is failing.

 

A triac in TO-220 operating at 5 amperes would be very hot if operated without a heatsink. Even 2 A of average current would raise the package temperature to around 100 °C.

 

dears
a mistake happened.
the source voltage is 220V AC.