I already asked this question Triac BT 136 getting shorted when load is given to T1.
When I referred this link, I understood rate effect is the root cause for our problem. To avoid this either we could use RC snubber or high power triac. Such as BTA316B-800E and BTA316B-800B.
Now I got confused which one to select from these.
My application is to dimmer control incandescent bulb or fan.
Switching ON/OFF LED lamps(all appliances with 240V/50Hz) or any other alternative step I could make in the circuit.