Motor Start Capacitor Polarity

Capacitor start induction run motors we know about the activity of a capacitor in a pure a c.

Motor start capacitor polarity. A start capacitor is used to give a motor an extra electrical push to start it turning. If the start capacitor fails the motor will most likely not turn on. When a capacitor is so introduced the voltage lags the current by some phase angle. Motor start capacitors are used during the motor startup phase and are disconnected from the circuit once the rotor reaches a predetermined speed which is usually about 75 of the maximum speed for that motor type.

While the run capacitor stays on giving the motor extra torque when needed. When the electrolytic capacitors are polarized the voltage or potential on the positive terminal is greater that of the negative one allowing charge to flow freely throughout the capacitor. The starting capacitor is a simple electrical device which can give an extra voltage jolt or boost to get the hard starting motor spinning. These capacitors usually have capacitance values of over 70 µf.

In these motors the necessary phase difference between the is and im is obtained by introducing a capacitor in series with the starter winding. Motor start and motor run capacitors start capacitors. There are various capacitors some of them are polarized and some are classified under the category of non polarized. Both types possess two terminals.

When the capacitor is polarized it s generally marked with a minus or plus to indicate the negative and positive ends. If a run capacitor goes bad then a motor can turn on but the running amperage will be higher than normal causing. The difference between these two types of capacitors is very simple. Once the motor is up to speed the start capacitor disconnects and is not used again until the next time the motor starts.

The start capacitor gives a fan motor the torque it needs to start spinning then stops. A start capacitor is only used in the motor circuit for a second or two when it first starts to turn. The capacitor in our page top photo is oval in cross section but most replacement and many newer air conditioner motor starting capacitors are simply cylindrical in shape photo at left.