Controller reccomendation

[JoeM3]

Good Morning,
I have a not-normal application. We are heating something, but they want to use wattage as a setpoint rather than temperature in a closed loop configuration. (Im not going to divulge more due to IP constraints.) Is there a off-the-shelf system I can buy that does this?

Thanks

 

[joseph_e2]

Not done this before, but here's my thought.


You need to control the power going in, which is V*A (or I^2 * R) of the heating element. Look for an appropriately ranged current transducer with a mA or voltage output (Here's one Google found for me). If you know the resistance of the heater, you now also know the actual watts. Then, you'd use just about any process controller that's compatible with your current transducer and whatever you're using to control the power to the heater.

 

[drbitboy]

+1 for what @joseph_e2 wrote.

Power is also V² R^-1, so voltage could also be controlled, assuming you know the resistance of the heating element or material.

If the resistance is changing or unknown a priori, then volts and amps together might be necessary.

For an off-the-shelf, turnkey control system, PWM might be another option, assuming some thermal inertia to filter the Btu's. google

turnkey process control heating "pwm"
​

those look like some possible hits.