What is Fan Capacitor : Working & Its Applications

Electric Fans are used everywhere like in our homes, industries, offices, cars, computers, factories, trains, etc. These fans are classified into three types based on the power supply type AC fans, DC fans, and AC/DC fans. And also there are different models of electric fans are available like ceiling fans, table fans, pedestal fans, and exhaust fans. Generally, a ceiling fan is used by hanging from the ceiling in our bedrooms, living rooms, kitchens, etc. These fans are generally specified through the blade span size where the standard sizes of ceiling fans are 36 inches (900mm), 48 inches (1200mm) & 52 inches (1300mm) being the popular options. To make the fan rotate smoothly a capacitor is required, which is called as a FAN Capacitor. This article discusses on what is fan capacitor and its role and applications.

What is Fan Capacitor?

A capacitor that is used to operate a ceiling fan is known as a fan capacitor. The capacitor used in a ceiling fan is a non-polarized electrolytic AC capacitor. The electrical parts of the ceiling fan include a stator, capacitor, rotor, and regulator where a capacitor plays a key role to make the fan work properly. The main function of a capacitor in a fan is not only to operate but also it makes to rotate.

Fan Capacitor
Fan Capacitor


Fan capacitor specifications include the following.

  • Through-hole mounting type.
  • Capacitance ranges from 1.5 MFD to 4 MFD (micro-Farad).
  • The voltage rating is 440 VAC.
  • The diameter is 27 mm.
  • Tolerance is 5%.
  • Cylindrical shape.
  • The frequency is 50Hz.
  • The number of phases – 1 phase.
  • Temperature ranges from -25 to +85 Deg C
  • Wire terminals.
  • The size of the capacitor is 27 x 52.

Working of a Fan Capacitor

Let understand the working of a Capacitor with an example like When we turn on a ceiling fan, an electric current will flow through the circuit, causing it to rotate. However, if we want the  fan to operate at different speeds, we need a way to regulate its energy output. This is where a capacitor comes in. A capacitor allows you to vary the amount of energy flowing into the motor, which in turn determines its rotational speed.

Most ceiling fans contain two capacitors: a starting capacitor and a running capacitor. Both are called as Fan Capacitors.  The start capacitor is used to give the motor an initial push while the run capacitor is used to maintain speed. However, some capacitors may have both functions.

Start capacitors are generally large, cylindrical aluminum or oil-filled cans with two leads coming out of the top. Run capacitors are smaller than start capacitors and may be either cylindrical or flat in shape. They are generally rated for continuous duty and offer no over-voltage protection. The capacitance range for single phase run capacitors is from 1.0 µF up to 50 µF, with voltage ratings from 120V up to 450V (250VAC for 50/60 Hz).

A run capacitor is self-healing, which means that it can recover after being overloaded as long as it is not overheated. Run capacitors are designed to stay energized at all times and therefore do not have any polarity markings on them; they can be connected in either direction without affecting performance. Let’s see

How does fan capacitor controls the speed of the FAN?

 When we switch on the fan the capacitor starts charging slowly stores energy and release it in an electric arc to give a boost of energy at the start up of the FAN by increasing the current through the windings of the motor. This causes a high torque which makes the motor to rotate. The rotation of the motor increases, thus increasing its speed.

Fan Capacitor Polarity

The ceiling fan capacitor doesn’t have a polarity so they are non-polarized capacitors. The connection of this capacitor can be done at the outside metal layer of the fan. The direction of fan rotation will remain the same, in the first positive half cycle of supply, the phase will be positive whereas, in the negative half cycle, neutral will be positive.

Please refer to this link to know more about capacitor polarity.

Fan Capacitor Connection Diagram

The circuit diagram of the ceiling fan with a capacitor is shown below. This circuit provides the proper connection of the ceiling fan with a switch, capacitor, and regulator. So we can get an idea about how to connect a capacitor with a ceiling fan.

Fan Capacitor Connection Diagram
Fan Capacitor Connection Diagram

Generally, in the ceiling fan, there are two windings running winding & starting winding. A capacitor must be connected to the starting winding in series after that, it must be connected across the power supply. Alternatively, the running winding is directly connected to the power supply.

For that initially, we have to recognize both the windings in the fan. When you observe in the above diagram, the ceiling fan includes three wires blue, black and red located outside.

Usually, most of these fans include three wires outside and in the winding connection also you can also observe, that one terminal of every winding is connected jointly & it is brought outside like a regular wire. Here, the winding terminals can be observed by measuring their resistance. Suppose we measure the three terminals’ resistance as;

  • The resistance of Red & Black color wire is 200 ohm.
  • The resistance of Red & Blue color wire is 210 ohm.
  • The resistance of Blue & Black color wire is 500 ohm.

If the resistance between black & blue color wires have higher so these are the starting and running winding terminals. Thus the red terminal wire is common and is connected through both windings.
We know that starting winding the resistance is higher as compared to running winding. So when the resistance between Red & blue color wire is higher as compared to red & black color wires, then the blue color wire is the starting winding terminal & black color wire is the running winding terminal.

When you recognized the ceiling fans terminals, and the capacitor must be connected in between both windings like running & starting as shown in the diagram.

How Does Fan Capacitor Work?

If a ceiling fan is used without a capacitor then the two windings starting & running winding will be connected in parallel. Once the power supply is given to the ceiling fan, then both windings will generate fluxes which will be in phase, so the fan will not turn, so the capacitor is simply connected in series through the starting winding to perform some phase shifting, Once the capacitor is connected to a fan, then phase leads with 90 degrees & the ceiling fan will start to revolve. So this capacitor is used to perform the phase shift within the ceiling fan.

Types of Fan Capacitor

There are different types of capacitors used in ceiling fans which are discussed below.

Non-polarized Electrolytic Capacitor

In-ceiling fans, a nonpolarized electrolytic capacitor is used and it is non-polarized which means it has no polarity, so it can be connected in any way within a circuit. Other applications of this capacitor mainly involve feedback, coupling, compensation, oscillation, and decoupling circuits.

Non-polarized Electrolytic Capacitor
Non-polarized Electrolytic Capacitor

Please refer to this link to know more about Non-polarized Capacitor.

Fixed Capacitors

A fixed capacitor is used to store a fixed amount of electric charge. This electric charge is not changeable because while manufacturing, these values are fixed. This capacitor helps in maintaining a fixed charge & energy output within electric devices or appliances. So these are applicable to ceiling fans.

Fixed Fan Capacitor
Fixed Fan Capacitor

Oil Filled Fan Capacitor

Oil-filled capacitors are applicable in different high-voltage or high-current-based applications like motor-run, fan-run, power factor correction & energy storage. In these capacitors, the oil will help to cool down the large capacitors, so it moves air to avoid corrosion & decrease the destructive corona chances.

Oil Filled Fan Capacitor
Oil Filled Fan Capacitor

These capacitors have been used for many years without losing capacitance Value. So they play a major role while maintaining the ceiling Fan speed. These capacitors have a leak-proof design and they are the most frequently used capacitors in many countries.


The features of the fan capacitor include the following.

  • There is no capacitance loss.
  • It works with the same efficiency over a wide range of humidity and extreme temperatures.
  • It gives long life service.
  • The dissipation factor is low.
  • Self-healing properties.
  • High insulation resistance.
  • No leakage.

Fan Capacitor Uses

The applications of a fan capacitor include the following.

  • This capacitor is connected to the ceiling fan to make it self-starting.
  • It provides a phase shift within the fan windings.
  • It creates torque to make the ceiling fan revolve.

Thus, this is all about an overview of a fan capacitor and its working in fans. These capacitors are composed of two conductors which are separated through a dielectric material. Once the voltage is noticed through the two conductors, then electrical energy can be stored within the capacitor, so this energy provides an increase in mechanical force. Every ceiling fan generally requires different capacitors as they change energy from electrical to mechanical to turn the blades. Here is a question for you, what are different fans available in the market?

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