Hi!
I have a board with the basic triac driver circuits as described at page 8 (fig. 14) of MOC3052:
https://www.fairchildsemi.com/datasheets/MO/MOC3052M.pdf
The triac is a BTA204S-600D (600V 4A).
The load is a small electric motor (less than 250W) but there are no snubbers because the leakage is not acceptable for the customer.
I tested a resistive load up to 750W with no problems. The circuits works well also with lighter inductive loads, about 100W.
With the original one (250W) after few commutations the triac goes in short-circuit - I guess due to the back-EMF when disabling the triac.
I tried with a very big triac (25A, 250A peak) and there are no problems, but of course it's not a good solution.
I also tried with a TVS (275V) to clamp the VAC across the line (between L and N, and between T1 and T2) with no chance.
Also a snubber between L and N does nothing.
Any idea?
