Therefore, it is important to know the characteristics of the specific capacitor-start motor to make certain it is suitable for the application.
Single-phase motors have appreciable rotor current and rotor losses at no load. For a given breakdown torque, the single-phase motor requires considerably more flux and more active material than the equivalent three-phase motor. A comparison of the losses between single-phase and three-phase motors is shown in Fig. Note the significantly higher losses in the single-phase motor.
The general characteristics of these types of single-phase induction motors are as follows.
The running capacitor is usually a metallized polypropylene unit rated for continuous operation.
Figure 1.15 shows one method of mounting both capacitors on the motor.
Comparison of this performance with the performance shown in Table 1.6 for capacitor-start motors shows the improvement in both efficiency and the power factor.