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A motor capacitor,〔〔 such as a start capacitor or run capacitor (including a dual run capacitor)〔 is an electrical capacitor that alters the current to one or more windings of a single phase AC induction motor to create a rotating magnetic field. There are two common types of motor capacitors, ''run capacitors'' and ''start capacitors''. The units of capacitance are labeled in microfarads (µF or uF). Older capacitors may be labeled with the obsolete terms "mfd" or "MFD", which means microfarad. Motor capacitors are used with air conditioners, hot tub/jacuzzi spa pumps, or forced air heat furnaces for example. A "dual run capacitor" is used in some air conditioner compressor units, to boost both the fan and compressor motors.〔 ==Run capacitors== Some single-phase AC electric motors require a "run capacitor" to energize the second-phase winding (auxiliary coil) to create a rotating magnetic field while the motor is running.〔 Run capacitors are designed for continuous duty while the motor is powered, which is why electrolytic capacitors are avoided, and low-loss polymer capacitors are used instead. Run capacitors are mostly polypropylene film capacitors and are designed for continuous duty; they are energized the entire time the motor is running.〔 Run capacitors are rated in a range of 1.5 to 100 microfarads, with voltage classifications of 370 V or 440 V.〔 If a wrong capacitance value is installed, it will cause an uneven magnetic field around the rotor. This causes the rotor to hesitate at the uneven spots, resulting in irregular rotation, especially under load. This hesitation can cause the motor to become noisy, increase energy consumption, cause performance to drop and the motor to overheat.〔 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Motor capacitor」の詳細全文を読む スポンサード リンク
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