What for start and run capacitor used in induction motor why it is not replaced for compensated winding in the motor and why run capacitor is different from start capacitor
A start capacitor, a run capacitor or both are used in single-phase motor designs to provide alternative performance characteristics. Textbooks provide diagrams of the different torque vs. speed characteristics. Various types of loads and duty cycles have different requirements. The objective of motor designs is to satisfy the load-driving requirements at the minimum manufacturing cost. Energy efficiency and motor noise and vibration must also be considered.
Single-phase motors can also be designed without capacitors, using only coil resistance and inductance to achieve the required phase difference between two coils. The shaded-pole motor is the most common design of that type. Other designs have been used, but shaded-pole and capacitor motors have proven to be the most competitive designs and other types are rarely used.
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