The opto coupler fails frequently in the circuit below.
hello.
I am using bta16-800-bw for 400v 3 phase motor phase control.
In triac control, the optocoupler frequently fails in the circuit below.
For couplers, use moc3071sm, il4208-x007, etc.
Please see photos for symptoms.
I'm thinking of changing to BTA16-800CW.
I'm asking for advice.
and!
bta16-800-bw Snubless type.
Should I install another snubber circuit like the circuit?
Or is it okay not to use a snubber circuit in the triac?
C14, C15, R8, and R9 you pointed out are snubber circuits, and C is the X-cap.
There were cases where this snubber resistor was damaged or burned.
I would like to ask for advice on two phenomena.


The picture on the oscilloscope shows line T + fan W of the circuit tested with a differential probe.
