I have a microcentrifuge which has a DC motor rated 24V, 10 Watt and 7000 rpm.
I have attached one 5W, 500 Ohm potentiometer with it to control the speed and it works fine without heating up.
This microcentrifuge is supposed to be used with a light weight part. But as I need to use it with some large tubes I have 3D printed some parts and attached on the rotor part.
This time with this extra weight my potentiometer becomes very warm within 1 minute.
Is it because of the extra mechanical load or it is something wrong with my potentiometer rating?
Best Answer
My guess: When you want to use the extra tubes, you are probably changing the potentiometer setting.
If you have 500 ohm and 24 V, nothing happens. If you reduce the value to 50 ohm, though, Joule losses become 10 times as large and at 10 ohm 50 times:
$$ \begin{equation} P(R) = \frac{V^2}{R} \end{equation} $$
If you can, you should measure the potentiometer voltage and current.