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I am looking for a bit of advice (or corrections). I need to turn on a 600W AC motor (220V 50Hz), just ON-OFF control.

I plan to use the following circuit which AFAIK it should work well for resistive loads (I will be using it for a heater as you can see below). However, the motor as we all know, is an inductive load.

I think in terms of just turning ON the motor, there will be no big problems. However, I worry about noise or long term performance of the circuit.

Is there any advice or better practices I should take into account?

schematic

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    \$\begingroup\$ Why not use a motor-rated relay and skip all the trouble? \$\endgroup\$
    – Hearth
    Commented Jul 11 at 3:43
  • \$\begingroup\$ Relay will work great. I am trying to do it this way to learn some stuff along the way. \$\endgroup\$
    – b1063n
    Commented Jul 11 at 5:25

2 Answers 2

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If the BTA26 isn't getting hot it should preform well. Make sure you adjust the snubber for the inductive load, because inductive loads can change the zeroing point and cause issues for the triac.

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It won't work very well with the driver returned to device common (MT1, BTA26 pin 1). The MOC has to source power from MT2 (pin 2) into G (pin 3).

Give or take exact snubber values, this is fine for switching a motor. If you find the TRIACs tend to remain on without enable, or get destroyed after some cycles, consider increasing the snubber capacitance, or choosing a more robust (e.g. "Snubberless") type.

You can also choose AC type SSRs which integrate all this and are rated for various types of loads; choose one suitable for inductive load.

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  • \$\begingroup\$ Oh you are right about MT2 and MT1 my bad. I have switched MT2 and MT1. Got it. \$\endgroup\$
    – b1063n
    Commented yesterday

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