My question is 1) around how much force these micro solenoids provide, given that they are sub 2 watts, and 2) how long can they run before starting to overheat? Some seller say not to run them for over 5 seconds, but others claim that they can run 8 hours continuously(not really sure I believe that one).
0.22 A x 5 V is essentially 1 Watt. Spread over the entire winding, this sounds plausible for continuous operation though the innermost part of the winding will retain heat.
If nothing else, leaving them on for a minute or so and then off for a number of minutes should be quite safe.
Of course, I'm working on short of Braille display, but instead of the normal "binary" on and off, I want to be able to change the height of each of the "rods" in the display.
Thank you for your insight. Would adding a small PC fan be useful for cooling and reducing the cooling period/extending the continuous operation period?
The steel frame of the solenoids conducts the heat away from the windings. What you have the solenoids mounted to will also sink the heat away. The question remains, however, is how fast the heat in the copper wire of the windings can be conducted to the frame. If not fast enough, smoke will eventually appear. Fan cannot aid in the heat movement.
Paul
What is the duty cycle, is it really 100%? I have seen similar work energized around the clock no problems. Hint: once you energize the solenoid you can reduce the current to what is required for holding, this will reduce the heat a lot. Is this a one time thing or will it go into production? Try to contact the solenoid manufacturer for a data sheet.
Both questions for a datasheet - otherwise you'll have to characterize them yourself really. Its quite normal for solenoids to be rated for something like a 10--20% duty cycle or thereabouts, though continuous duty are of course available.
Note that solenoid force varies over the stroke, so its not just a question of a single number either.
