Is there a way to stop a DC motor when its motion be blocked ? For example if it rotates in a free motion raising a load and the load reached a blocking part making the shaft not rotating while the current is on, ( without using a micro limiting switch).

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    \$\begingroup\$ Yes, I think there is a way \$\endgroup\$
    – PlasmaHH
    Nov 19 '16 at 18:39
  • \$\begingroup\$ I'd fully agree with @PlasmaHH. But it's unnecessary. If the motion is blocked, your motor stops automatically, unless the axis breaks. \$\endgroup\$ Nov 19 '16 at 19:09
  • \$\begingroup\$ Do you want to stop powering the motor if the rotor is blocked? \$\endgroup\$
    – c-a
    Nov 19 '16 at 19:14
  • \$\begingroup\$ Yeah, that's what I want.. I think the motor will be blocked while current is running in its coils which will not be effective and may increase heat, consume useless power.. I need to stop current when it's being blocked. \$\endgroup\$
    – m sayed
    Nov 19 '16 at 19:38

Monitoring the motor current would appear to be a viable way of detecting suddenly increased load (like blockage, etc.) If you are controlling the motor from a microcontroller, you could make it adaptive to avoid false triggering.

  • \$\begingroup\$ Yeah, I'm going to control it from a microcontroller via H-bridge IC.. Could you please explain how your idea can be applicable? If the motor been blocked, will be there any change in current to be detected ? \$\endgroup\$
    – m sayed
    Nov 19 '16 at 19:43
  • \$\begingroup\$ Typically, the current through the motor is directly proportional to how much "work" it is doing. Try measuring the current with no load, and then start loading it down and see how much the current rises. You have not revealed what your motor control circuit looks like, otherwise we could suggest methods of sensing the motor current. \$\endgroup\$ Nov 19 '16 at 20:07
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    \$\begingroup\$ @msayed This can work, but there's a "gotcha"...when you first start the motor, its current is very high (close to stall current), and your current monitor is tripped, stopping the motor. At start, a delay is required allowing the motor to speed up, before acting on current measurement. \$\endgroup\$
    – glen_geek
    Nov 19 '16 at 21:33

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