If F1 is the constant amplitude of fundamental rotating MMF wave, the space harmonics of order 6K+1 (where K=1,2,3….), the harmonic MMF wave is of _____________(a) Constant amplitude and stationary in space(b) Constant amplitude and rotates along F1(c) Varying amplitude and rotates along F1(d) Constant amplitude and rotates against F1I had been asked this question during an online interview.The doubt is from Rotating Magnetic Field topic in portion Basic Concepts in Rotating Machines of Electrical Machines

If F1 is the constant amplitude of fundamental rotating MMF wave, the

1.	If F1 is the constant amplitude of fundamental rotating MMF wave, the space harmonics of order 6K+1 (where K=1,2,3….), the harmonic MMF wave is of _____________(a) Constant amplitude and stationary in space(b) Constant amplitude and rotates along F1(c) Varying amplitude and rotates along F1(d) Constant amplitude and rotates against F1I had been asked this question during an online interview.The doubt is from Rotating Magnetic Field topic in portion Basic Concepts in Rotating Machines of Electrical Machines
Answer» Right OPTION is (b) Constant amplitude and rotates ALONG F1 Easiest explanation: Space harmonics of the order of 6K+1(7,13,19,…) have their constant amplitude equal to 1/(6K+1)F1 and ROTATE in the direction of fundamental component F1 at a SPEED of 1/(6K+1) of the fundamental synchronous speed.

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