I want to use a triac controlled by a suitable optoisolator such as a MOC3020 to switch a single phase AC motor on and off, like the ones you'd find in a typical desk fan or a blender or similar.

I don't want speed control... just on or off.

I've used triacs in the past to switch resistive loads, which have worked with no problems.

Is there anything special or different I need to do to switch an inductive load? Do I need to include any kind of protection or noise suppression? If so what additional components are needed, and how are they implemented?

  • \$\begingroup\$ This issue has been dealt with before here. Pages 6 & 7 of the fairchild datasheet refer to inductive loads. \$\endgroup\$
    – MikeJ-UK
    May 25, 2011 at 14:55

1 Answer 1


A 3-quadrant triac is well-suited for inductive loads like a motor. It is resistant to spurious turn-on caused by sudden \$\frac{dv}{dt}\$ - like the inductive kick from a motor.


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