Question 119Electricity & Electronics - QMED

70% to pass

An open in the armature of a DC motor is suspected, but is not found by visual inspection of the commutator. What would be the next step in troubleshooting this problem?

Aconduct an insulation resistance test of the armature
Bvisually inspect the armature windings
Ctest the commutator for a ground
Dconduct a bar to bar test of the armature
AI Explanation

The correct answer is D) conduct a bar to bar test of the armature. The reasoning for this is that if a visual inspection of the commutator does not reveal an open circuit in the armature, the next logical step is to perform a more detailed test of the armature windings themselves. A bar to bar test involves checking the resistance between each commutator segment to identify any discontinuities in the armature winding, which would indicate an open circuit. This is a more thorough diagnostic test compared to the other options, which would not directly test the armature winding for an open. The other answer choices are not the correct next step in this situation. Option A, an insulation resistance test, would not specifically identify an open circuit. Option B, visually inspecting the armature windings, has already been ruled out as ineffective. Option C, testing for a ground, is not relevant to diagnosing an open circuit.

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