As there is no back e.m.f. at the instant of starting a D.C. motor, in order to prevent a heavy current from flowing though the armature circuit____________________?
Correct answer: A. a resistance is connected in series with armature
- A. a resistance is connected in series with armature
- B. a resistance is connected parallel to the armature
- C. armature is temporarily open circuited
- D. a high value resistor is connected across the field winding
Explanation
At starting, back e.m.f. is zero, so the armature would draw an excessive current limited only by its very small resistance. A starting resistance is therefore connected in series with the armature and gradually removed as speed builds.
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