Question 230Electricity & Electronics - 1st Asst/Chief

The correct answer is B) conduct a bar to bar test of the armature. In the given scenario, where an open in the armature of a DC motor is suspected but not found through visual inspection of the commutator, the next logical step is to perform a bar to bar test of the armature. This test involves checking the continuity between the individual commutator bars, which can help identify the location of the open circuit within the armature winding. The other options are not the best next steps in this situation. Option A (test the commutator for a ground) would not directly address the suspected open circuit in the armature. Option C (visually inspect the armature windings) has already been attempted without success. Option D (conduct an insulation resistance test of the armature) would not provide information about the specific location of the open circuit.