Fig. 1,629.—Richmond three phase induction motor on base fitted with screw adjusting gear for shifting the position of the motor on the base to take up slack of belt.
Ques. Why is a single phase induction motor not self-starting?
Ans. When the armature is at the rest, the currents induced therein are at a maximum in a plane at right angles to the magnetic field, hence there is no initial torque to start the motor.
Ques. What provision is made for starting single phase induction motors?
Ans. Apparatus is supplied for "splitting the phase" (later described in detail) of the single phase current furnished, converting it temporarily into a two phase current, so as to obtain a rotating field which is maintained till the motor is brought up to speed. The phase splitting device is then cut out and the motor operated with the oscillating field produced by the single phase current.
Figs. 1,630 to 1,641.—Terminals for General Electric polyphase induction motors. In order to prevent any mechanical strain on the leads being transmitted to the motor windings, the terminal cables are clamped in insulated bushings with a connector for each cable.