This requires a motor with two windings spaced apart 90 This type of motor suffers increased current magnitude and backward time shift as the motor comes up to speed, with torque pulsations at full speed.
The solution is to keep the capacitor (impedance) small to minimize losses. This motor configuration works well up to 1/4 horsepower (200watt), though, usually applied to smaller motors.
The current density in the auxiliary winding is so high during starting that the consequent rapid temperature rise precludes frequent restarting or slow starting loads.Single phase induction motors have a copper or aluminum squirrel cage embedded in a cylinder of steel laminations, typical of poly-phase induction motors. kontaktbörse One way to solve the single phase problem is to build a 2-phase motor, deriving 2-phase power from single phase.(figure c) they are partially additive along the x axis and cancel along the y axis. The sum of these two phasors is a phasor stationary in space, but alternating polarity in time. However, if the rotor is rotated forward at a bit less than the synchronous speed, It will develop maximum torque at 10% slip with respect to the forward rotating phasor.Less torque will be developed above or below 10% slip.
Applications of capacitor start single phase induction motor
It could be reduced by decreasing the applied voltage, improving the power factor and efficiency.The power factor corrector senses power factor, and decreases motor voltage, thus restoring a higher power factor and decreasing losses.A capacitor for motor running must not be of electrolytic construction, but a lower loss polymer type. If an auxiliary winding of much fewer turns of smaller wire is placed at 90 electrical to the main winding, it can start a single phase induction motor.Frank Nola of NASA proposed a power factor corrector for improving the efficiency of AC induction motors in the mid 1970’s.
It is based on the premise that induction motors are inefficient at less than full load.A three phase motor may be run from a single phase power source. It may be hand started in either direction, coming up to speed in a few seconds.It will only develop 2/3 of the 3-φ power rating because one winding is not used.In Figure below a larger capacitor may be used to start a single phase induction motor via the auxiliary winding if it is switched out by a centrifugal switch once the motor is up to speed.Moreover, the auxiliary winding may be many more turns of heavier wire than used in a resistance split-phase motor to mitigate excessive temperature rise.