Hi,
I've got a brushless DC motor that I am using that I need to automatically trigger off whenever the current draw exceeds 1.8A at the power source (DC 12V).
The problem that I am running into is that I cannot use a fuse (I tried a few different PTC's models and brands) and they're basically all the same in the sense that you need to chose one with a value that is "far" enough from the nominal power draw.
In this project, my motor would typically draw 1.5A (nominal) and I need it turned off if the current goes above 1.8A which is pretty close to it.
I tried using a 1.8, even 2.0A PTC's and while they would do the job at opening the circuit at 1.8A, they would also trigger at 1.5 or 1.6A after hours, sometimes days of operation. Yes, that's another thing in this project, I will leave the motor run for days/weeks, and I don't want it to stop unless the current really goes above 1.8A, not less.
Using a fuse would have simple and perfect except it won't work in this case...
Anyway, I was redirected to this forum (new here!) when I found this link: http://forum.allaboutcircuits.com/showthread.php?t=30383
it doesn't exactly fit my needs but I found the responses very helpful and thought that maybe would be able to help me out with some pointers...
Any idea?
thanks
Steve
I've got a brushless DC motor that I am using that I need to automatically trigger off whenever the current draw exceeds 1.8A at the power source (DC 12V).
The problem that I am running into is that I cannot use a fuse (I tried a few different PTC's models and brands) and they're basically all the same in the sense that you need to chose one with a value that is "far" enough from the nominal power draw.
In this project, my motor would typically draw 1.5A (nominal) and I need it turned off if the current goes above 1.8A which is pretty close to it.
I tried using a 1.8, even 2.0A PTC's and while they would do the job at opening the circuit at 1.8A, they would also trigger at 1.5 or 1.6A after hours, sometimes days of operation. Yes, that's another thing in this project, I will leave the motor run for days/weeks, and I don't want it to stop unless the current really goes above 1.8A, not less.
Using a fuse would have simple and perfect except it won't work in this case...
Anyway, I was redirected to this forum (new here!) when I found this link: http://forum.allaboutcircuits.com/showthread.php?t=30383
it doesn't exactly fit my needs but I found the responses very helpful and thought that maybe would be able to help me out with some pointers...
Any idea?
thanks
Steve