Explanation: Reluctance motors can work on single excitation, and synchronous motors require double excitation. 11. Electromagnetic torque in rotating electrical machinery is present when ________
A. stator winding alone carries current
B. rotor winding alone carries current
C. air gap is uniform
D. both stator and rotor windings carry current
Answer:A
Explanation: Reluctance motors can work on single excitation, and synchronous motors require double excitation. 11. Electromagnetic torque in rotating electrical machinery is present when ________
A. stator winding alone carries current B. rotor winding alone carries current C. air gap is uniform D. both stator and rotor windings carry current
Explanation: Electromagnetic torque = isirdMsr/dθr and if either is or ir =0, then Te=0. 12. All practical electromechanical energy conversion devices make use of the magnetic field rather than the electric field as the coupling medium.This is because