<P> Start capacitors briefly increase motor starting torque and allow a motor to be cycled on and off rapidly . A start capacitor stays in the circuit long enough to rapidly bring the motor up to a predetermined speed, which is usually about 75% of the full speed, and is then taken out of the circuit, often by a centrifugal switch that releases at that speed . Afterward the motor works more efficiently with a run capacitor . </P> <P> Start capacitors have ratings above 70 μF, with four major voltage classifications: 125 V, 165 V, 250 V, and 330 V. Examples of motor capacitors are: a 35 μF, at 370 V, run capacitor, or an 88--108 μF at 250 V start capacitor . </P> <P> Start capacitors above 20 μF are always non-polarized aluminium electrolytic capacitors with non solid electrolyte and therefore they are only applicable for the short motor starting time . </P> <P> The motor will not work properly if the centrifugal switch is broken . If the switch is always "open", the start capacitor is not part of the circuit thus preventing startup of the motor . If the switch is always "closed", the start capacitor is always enabled, thus likely destroying the capacitor . If a motor does not start, the capacitor is far more likely the problem than the switch . </P>

Capacitor start and capacitor run single phase motors