What would happen if the field of a D.C. shunt motor is opened?
- A. Speed will be reduced
- B. Continue to run normally
- C. Speed will enormously increase damaging the motor
- D. None of the above
Answer: C. Speed will enormously increase damaging the motor
Explanation: For a DC shunt motor, speed N ∝ Eb/Φ. If the field circuit is opened, the flux Φ drops to the residual value (near zero), causing the speed to increase dangerously to destructive levels.