Motor Start Capacitor Polarity

Both types possess two terminals.

Motor start capacitor polarity.

A start capacitor is only used in the motor circuit for a second or two when it first starts to turn. If the start capacitor fails the motor will most likely not turn on. Start capacitors have ratings above 70 µf with four major voltage classifications. The start capacitor gives a fan motor the torque it needs to start spinning then stops.

A start capacitor is used to give a motor an extra electrical push to start it turning. Motor start and motor run capacitors start capacitors. These capacitors usually have capacitance values of over 70 µf. 125 v 165 v 250 v and 330 v 1 start capacitors above 20 µf are always non polarized aluminium electrolytic capacitors 4 with non solid electrolyte and therefore they are only applicable for the short motor starting time.

Once the motor is up to speed the start capacitor disconnects and is not used again until the next time the motor starts. Capacitor start induction run motors we know about the activity of a capacitor in a pure a c. 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. The difference between these two types of capacitors is very simple.

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. There are various capacitors some of them are polarized and some are classified under the category of non polarized. While the run capacitor stays on giving the motor extra torque when needed. 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.

When a capacitor is so introduced the voltage lags the current by some phase angle. In these motors the necessary phase difference between the is and im is obtained by introducing a capacitor in series with the starter winding. Capacitor polarity is an important point to be considered during the connections.