Keithley 2450 Constant power source

Good day,&#160;<br> <br> <span style="font-size:11pt;"><span style="font-family:Calibri,sans-serif;"><span style="color:#1f497d;">I want to create a constant power source to measure the thermal properties in a resistive element using a Sourcemeter 2450.&#160;</span></span></span><br> <br> <span style="font-size:11pt;"><span style="font-family:Calibri,sans-serif;"><span style="color:#1f497d;">A typical test would be for say 10 milli seconds to 1 second, &#160;supply a nominal 10R element with constant 100mW and log the resistance.</span></span></span><br> <br> <span style="font-size:11pt;"><span style="font-family:Calibri,sans-serif;"><span style="color:#1f497d;">For this one would need to control the current to </span></span></span><br> <span style="font-size:11pt;"><span style="font-family:Calibri,sans-serif;"><span style="color:#1f497d;">(i^2)R = 10</span></span></span><br> <span style="font-size:11pt;"><span style="font-family:Calibri,sans-serif;"><span style="color:#1f497d;">But since R is a function of temperature the resistance would need to be measured and i adjusted similar to an active load. </span></span></span><br> <br> <span style="font-size:11pt;"><span style="font-family:Calibri,sans-serif;"><span style="color:#1f497d;">Would this be possible? </span></span></span><br> <br> <span style="font-size:11pt;"><span style="font-family:Calibri,sans-serif;"><span style="color:#1f497d;">Your input will be greatly appreciated. </span></span></span><br> <br> <span style="font-size:11pt;"><span style="font-family:Calibri,sans-serif;"><span style="color:#1f497d;">Kind regards, </span></span></span><br> <span style="font-size:11pt;"><span style="font-family:Calibri,sans-serif;"><span style="color:#1f497d;">Gerhard </span></span></span><br> &#160;

Hello Gerhard,<br> You will not be able to get the 2450 to operate in a constant power mode as your resistance changes over time.<br> The closest that you could achieve with this instrument is to set a source value and compliance value and have those variables remain fixed throughout your test, as Power (P) is equal to your current (I) multiplied by voltage (V) P=I*V, this would imply a constant I and constant V. If you expect your resistance to change this would violate Ohm's Law, V=I*R.<br> If your resistance is expected to change, your I or V would need to adjust accordingly throughout your test. With the 2450 you can choose to set one of these functions as the constant source function, and the other would adjust according to your resistance, then you could measure your resistance.