Explanation: A uniform current sheet produces trapezoidal MMF wave and sinusoidal current sheet produces sinusoidal MMF wave leading by 90°. 9. A uniformly distributed winding on the stator has three full pitched coils, each coil having N turns and each turn carrying a current i. The MMF produced by the winding is
A. sinusoidal in waveform with an amplitude 3Ni
B. sinusoidal in waveform with an amplitude 3Ni/2
C. trapezoidal in waveform with an amplitude of 3Ni
D. trapezoidal in waveform with an amplitude of 3Ni/2
Answer:A
Explanation: A uniform current sheet produces trapezoidal MMF wave and sinusoidal current sheet produces sinusoidal MMF wave leading by 90°. 9. A uniformly distributed winding on the stator has three full pitched coils, each coil having N turns and each turn carrying a current i. The MMF produced by the winding is
A. sinusoidal in waveform with an amplitude 3Ni B. sinusoidal in waveform with an amplitude 3Ni/2 C. trapezoidal in waveform with an amplitude of 3Ni D. trapezoidal in waveform with an amplitude of 3Ni/2
Explanation: When the machine has more than 3 slots per pole per phase, the steps in the MMF wave are neglected and MMF variation is taken as smooth over these slots and as a consequence, stepped MMf wave changes to trapezoidal MMF wave.