In repulsion motor, zero torque is developed when___________?
Correct answer: D. both B. and (c)Electricity
- A. brush axis is 45° electrical to field axis
- B. brush axis coincides with the field axis
- C. brush axis is 90° electrical to field axis
- D. both B. and (c)Electricity
Explanation
Repulsion torque varies with the sine of twice the angle between the brush and field axes, so it becomes zero when the axes coincide or are 90 electrical degrees apart. Thus both the coincident-axis and perpendicular-axis conditions apply.
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