What happens to our DC motor if we stop motion of the rotor with our hand while motor is active? Will the motor burn? Why, what is really happening in that situation?
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1\$\begingroup\$ How much current does the motor take in the stall condition and what does the supplier state is the max value for stall current? Read the data sheet. \$\endgroup\$– Andy akaCommented Sep 2, 2015 at 10:44
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1\$\begingroup\$ just be careful with your hand first,if you rotate the motor faster than the actual rate at which it is rotating it might produce reverse current,,dynamo effect \$\endgroup\$– LokanathCommented Sep 2, 2015 at 11:11
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2 Answers
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When you stop rotation there is no back emf generated. This means that the rotor sees the full applied voltage across its (small) resistance (I = V/R). This is the stall current. The result is that this large current flows through the rotor coil and generally burns it out.
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Depends on driver. If you use servo drive, which should be the case, then the current is controlled and will remain at it's highest allowed value. This will allow the controller to detect "rotor stuck" condition.
Working with uncontrolled current is dangerous and is only valid for low current systems, where no damage is caused by overcurrent.
Well, in fact there are high performance systems that omit current loop for faster performance. In such sort of system very tight servo error detection is required to keep things safe.