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I am developing a heating application where temperature need to be constant. I am planning to set the temperature @ 200 degree C. when my sensor find the temperature exceeding the set temperature how can i reduce the temperature of the heating element. I currently plan to cut the supply to heating element but is there any other method which i can reduce the temperature.

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    \$\begingroup\$ Can you regulate the power of the heating element? \$\endgroup\$ – Eugene Sh. Mar 23 '15 at 16:43
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    \$\begingroup\$ What kind of heating element is this and how do you control it? A lot of them are fine with bang bang pwming. \$\endgroup\$ – PlasmaHH Mar 23 '15 at 16:55
  • \$\begingroup\$ I am hopping to regulate the power of heating element with a relay switch...the element I use is heat seal machine heating element. It's an ceramic type heater element \$\endgroup\$ – romy mathew Mar 23 '15 at 18:11
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Practically you have two main choices involving i) on/off control; ii) average control.

i) Hysteretic control turns the heater on at a lower limit and turns it off at an upper limit. (i.e. on/off).

ii) Drive the heater with a fast switching PWM signal (via Switches and a switch-driver) so that the average value of the temperature is your desired setpoint value. This usually involves feedback and a controller such as a PID.

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  • \$\begingroup\$ Does power off and on bring down the life of the Heating element ...? \$\endgroup\$ – romy mathew Mar 24 '15 at 10:53
  • \$\begingroup\$ Most heating wires have a positive tempco so they draw more current when cold so current surges may (in theory) reduce lifetime. In your case the element should stay at a fairly constant temperature so On/Off pulsing shouldn't be a problem. \$\endgroup\$ – akellyirl Mar 24 '15 at 11:10

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