How do ceiling fan capacitors work?
A ceiling fan capacitor is a cylindrical component found at the top of your ceiling fan. Its principal function is to control the speed of your ceiling fan via regulating the amount of voltage being passed through its circuits, which in turn dictates how fast or slow the blades should spin.
There are three different types of capacitors: the aluminum electrolytic capacitor, ceramic disk capacitor, and mica capacitor. The other type is electrolytic, which contains liquid inside while there’s no liquid used in ceramic disk type. A ceramic disk can be identified by its flat shape with two metal leads sticking out from one end, while electrolytic and mica type is cylindrical with two metal terminals at both ends.
These are made up of a dielectric material such as glass chips and epoxy resin binder with conducting plates on each side. One container will have an anodized coating while the other is uncoated. It works by holding an electrical charge when the voltage passes through it.
The non-coated side should always be connected to the negative or grounded side of a circuit, while the other should go to the positive terminal, which will provide more stability for your ceiling fan.
Aluminum electrolytic capacitor
These operate at low frequency (less than 100 Hz) and high capacitance (about 1μF). Thanks to its cylindrical design, it has a remarkable ability to deliver current compared to ceramic disk capacitors. Mica capacitor, on the other hand, is designed with a fragile mica sheet separating two metal terminals; this allows it to hold less charge but handle more current than the aluminum electrolytic type. On the other hand, it has less ability to deliver voltage compared to ceramic disk.
Additionally, an aluminum electrolytic capacitor tends to fail not because of its function but because of its chemical composition. It can lose charge and lower its voltage capacity due to ambient temperature or leakage that damages parts inside the device.
These conditions may induce higher current flow, which can cause overheating. Sometimes, it results in an explosion; hence, if you notice any abnormality with your ceiling fan capacitor, such as a bulging top, then immediately replace it for safety reasons.
Also, note that this type should be replaced by a certified technician only since there’s a danger of electric shock during the installation and replacement process.
Mica capacitors are made of insulating material. They are constructed with two or more layers of mica, a naturally formed silicate mineral that has been used for decades as electrical insulation.
The mica capacitor was invented by Edward Weston in the early 1900s and was quickly adopted for use in radio sets to reduce the microphony effect. Microphony is also known as contact or conduction hum; it occurs when vibrations from sound sources such as fans cause analog meters to deflect briefly, producing erratic readings.
A mica capacitor provides superior insulation by utilizing mica instead of glass between its plates allowing it to function better under vibration than glass interrupters would be able to do. Mica also has an excellent temperature coefficient, which also provides superior insulation.
Mica capacitors are known for high-frequency and high-voltage applications. A typical mica capacitor will operate up to 10MHz and can handle voltage over 100kVrms.
Mica capacitors can easily be identified because they have one transparent plastic plate on one side, while the other has alternating thin black and dark brown plates. The thin plates allow for the maximum surface area inside the capacitor, allowing better performance than larger plates would offer due to higher impedance caused by reactive inductive losses within the capacitor.
These thin alternation color plates also break up current flow through any dielectric material (insulating coating) formed between the plates. This breaks up the potential shorting paths in a capacitor, allowing it to operate more efficiently.