Does using Hi-Com TRIAC to drive motor compressor have a weakness?

Why do most (all) refrigerator manufacture use a relay instead of HI-COMM TRIAC to drive the compressor?

Isn't a [Hi-Com TRIAC more reliable than a relay?

NOTE: The motor compressor is induction motor.

  • \$\begingroup\$ Even though you are new here it should be obvious that you need to supply a link to the datasheet for the "HI-COMM TRIAC". Please add it into the question and not in the comments so that all the information required to answer your question is in the one place. \$\endgroup\$
    – Transistor
    Sep 21, 2016 at 6:58
  • \$\begingroup\$ Hi-Com triacs (Specific type of triac) are specifically designed to give superior triac commutation performance in the control of motors for domestic equipment and tools. These devices are suitable for use with a wide variety of motor and inductive loads without the need for a snubber. Conclusion: It must be less expensive to use a relais. \$\endgroup\$
    – Decapod
    Sep 21, 2016 at 8:59

1 Answer 1


Triacs produce a lot of heat when on (which has to be dissipated somehow to keep the semiconductor from failing) and are generally less reliable than relays, especially when the power line contains transients.

Relays have a definite life and will eventually wear out, however within their lifetimes they are very rugged and reliable. The switching rate for A/C equipment is low so the inexpensive and reliable relay is the sensible choice of manufacturers. Manufacturers can live with a definite life (though it means that service has to be accommodated) but they really, really hate infantile failures, especially those that occur during the warranty period.

Even a minuscule percentage of field failures is extremely expensive, both in service costs and in damage to reputation. Even more so today in the age of online reviews and class-action suits.


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