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I am using a triac to drive am AC contactor.
the contactor coil is 1.25H & 385ohm
The problem is that the snubber circuit burns when I turn on the supply "220V"
What should be the R & C values and rating for the snubber circuit to drive such load?
If you are saying the snubber burns out when voltage is applied at R1, either it isn't DC or the triac is faulty.
If you are saying it burns out as soon as the 220V is applied, even if DC is not fed to the optocoupler, the snubber components are faulty or under-rated. The snubber does very little when the triac is conducting because the voltage across it is very small. When the triac is not conducting it will have 220V RMS across it so the capacitor must be rated at no less than 220V AC and preferably higher to add a safety margin. My guess is you are not using one with sufficient voltage rating.
Probably your snubber cap is not 10nF, more like 100nF or bigger and too low a voltage so it just fails short straight away and over heats the resistor? it needs to be a 630V DC type at least, or 310Vac.
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