Originally Posted by
Kev Williams
Have you ever noticed your electric stove, be it a cal-rod or ceramic coils, that the burners don't work at 60 or 80% power? What they do is cycle on and off at 100% power. I'm not electrically inclined enough to know why, but I figure that if a simple rheostat would work, they'd use them on stoves... but they don't!
Only other way I can think of to vary the power output of a heating element is via a variable voltage transformer to vary the input voltage...
The problem with a simple rheostat is that quite a bit of power is dissipated in the rheostat when you turn the burner down. What most modern controls do is change the waveform - that is, it blocks the power for part of the cycle. But those controls are probably somewhat expensive for the amount of power needed by a stove burner, so they go with a simple off/on control, as you described.
Mike
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