Explanation: It should be remembered that individual phase MMF is not a rotating MMF wave, its amplitude merely pulsates or alternates along its own phase axis. 7. The effect of poly phase currents in poly phase winding can be compared to _______________
A. Mechanical rotation of permanent magnets at synchronous speed
B. Mechanical rotation of DC excited field poles at synchronous speed
C. Mechanical rotation of either permanent magnets or DC excited field poles, at synchronous speed
D. None of the mentioned
Answer:A
Explanation: It should be remembered that individual phase MMF is not a rotating MMF wave, its amplitude merely pulsates or alternates along its own phase axis. 7. The effect of poly phase currents in poly phase winding can be compared to _______________
A. Mechanical rotation of permanent magnets at synchronous speed B. Mechanical rotation of DC excited field poles at synchronous speed C. Mechanical rotation of either permanent magnets or DC excited field poles, at synchronous speed D. None of the mentioned
Explanation: The speed at which rotating magnetic field revolves is called the synchronous speed and this effect is equivalent to mechanical rotation of permanent magnets or DC excited field poles. 8. The magnitude of rotating flux _____________ at all instants of time.