In simple words, the capacitor having no fixed polarity can work with alternating current or alternating voltage is called AC Capacitor. The capacitor is a passive electrical or electronic device. The main function of a capacitor is to store the electrical energy in form of an electric charge. According to the polarity and application of the type of power supply capacitors are divided into two types - 1. AC Capacitor and 2. DC Capacitor
AC capacitor is also known as a non-polarized capacitor and the DC capacitor is also known as a polarized capacitor.

Characteristics or Properties of AC Capacitor

1. AC capacitors are having no polarity, they can work with any polarity. That is why it can be called as a Non-Polarized Capacitor.

2. The charging and discharging rate of the of the AC capacitor is very fast than a DC capacitor. Even they can be charged in any direction of polarity.

3. The reactance property of the AC capacitor changes with the changing of frequency of the applied power supply. The capacitive reactance decreases with the increase of frequency and capacitive reactance increases with the decreasing of frequency.

4. Most of the AC capacitors can work with both AC and DC power supplies, but DC capacitors cannot work with AC supplies. Of course, an AC capacitor cannot give high frequency when it used with DC Supply like an DC capacitor.

5. The thickness of the dielectric material of the AC capacitor is much more thicker than DC capacitors. Sometimes solid material used in some AC Capacitors.

AC Capacitor Ratings

Generally, an AC Capacitor rated like AC 450V, 50Hz, 50.00 MFD

AC - when a capacitor marked with 'AC' means it is designed for AC supply.

450V - it is the operating voltage rating.

50Hz - it is the frequency rating. All the AC capacitors come with a frequency rating. The frequency rating of a capacitor is very important and it should be kept in mind when connecting in a circuit. If a capacitor is operated with a different frequency than its rating, it will be damaged. AC capacitors come with 50HZ, 60Hz, 70Hz, 40Hz, 30Hz, and many other frequency ratings.

50.00 MFD - it is the capacitance rating of the capacitor. Ac capacitors are comes with microfarad(MF), nano farad(nF), Farad(F) ratings.

Symbol and Marking - As we know the AC capacitor has not any polarity, so there is no marking on the capacitor for positive or negative like a DC Capacitor.

Example of AC Capacitor or Non-Polarized Capacitor

Motor capacitors, ceiling fan capacitors, capacitor bank capacitors, inverter output filtration capacitors are examples of AC capacitors or non-polarized capacitors. Small ceramic capacitors are also non polarized capacitors so they also be usd in AC supply.

AC Capacitor Applications

1. AC capacitors are used for power factor improvements. Capacitor banks are made of multiple numbers of capacitors and they are consumed reactive power. When inductive loads are connected in a power system, the power factor of the system goes low or lagging. So, the capacitor bank is connected in parallel to the system. As the capacitor bank causes the leading power factor so the total power factor of the system is balanced.

2. AC capacitor is used in single phase induction motor or ceiling fans. We know that the single-phase induction motor is not self-starting. To provide starting torque to the motor capacitor is used.

3. AC capacitors or non-polarized capacitors are used in rectifier input circuits as an EMI( Electromagnetic Interference) Filter to reduce or eliminate electromagnetic interference.

4. AC capacitors are used in inverter output for the filtration of the output power supply of the inverter. Here, they used as filter capacitors.

5. AC capacitor is also used to step down the voltage or voltage drop by its reactance property. You can see in low-cost led driver circuits, transformerless power supply circuits AC capacitors are used for voltage step down purposes.