64) Calculate slip of an induction motor if it has 4 poles, 50Hz, rotor speed is 1400 rpm.

65) in a 3-phase motor the rotating magnetic field is displaced at an angle of

66) Which one of the following 3-phase motors is NOT self starting ?

67) The motor suitable for loads where constant speed is required is

68) The magnetic field produced in the stator of a three phase induction motor travels at