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

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    \$\begingroup\$ If you have done any research on the subject then explain what part of it you don't understand. If you haven't then please do some rather than ask someone to write an article for you when there are already many on the Internet. \$\endgroup\$
    – Transistor
    Jul 24, 2016 at 14:19
  • \$\begingroup\$ I don't know the run capacitor part \$\endgroup\$ Aug 14, 2016 at 17:06

1 Answer 1


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.

A complete explanation requires at least a half dozen pages and as many diagrams in a text book. There are sources on the internet that can provide an explanation in that depth. This site is designed for a single question and answer in each post. Detailed explanations of complex issues are not suited to this format.


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