Capacitor or Condenser is an insulating medium that can separate two operating surfaces. Insulating medium is called dielectric constant or relative permittivity of the material. The most commonly used dielectric materials in capacitors are air, mica, paper, ceramic and plastic.
The insulating medium does not allow DC current to pass whereas, in an AC circuit, current flows through the capacitor have little and no resistance. Capacitor is an electrical component that can store energy in the form of electrical charge.
Types of Capacitor
- Dielectric – It is of variable type and is required for tuning transmitters, receivers, and transistor radios. These are multi-plate capacitors consisting of a set of both fixed plates and movable plates. movable plates move between fixed plates.
- Film – They are most commonly available among all types of Capacitor. Film capacitors have a family of capacitors, but their dielectric properties are different. The dielectric material may include polyester, Teflon, metabolized paper.
- Ceramic – Ceramic capacitors are made from both sides by silver coating and then stacked together to form capacitors. Ceramic capacitors are also known as disk capacitors.
- Electrolytic – This type of capacitor is used when considerable capacitance is required. They are used in DC power supply circuits, there are two forms of electrolytic capacitors:
- Aluminum Electrolytic – These capacitors are of two types: Plain foil type and etched foil type. The DC current is anodized to the foil plates of the capacitors, and due to this anodizing process, the polarity of the poles can be established, and this contradiction tells us which side of the plate is positive or negative.
In addition, they have the ability to re-anodize the foil plate. If the layer of aluminum oxide is destroyed, the electrolytic Capacitor will allow it to pass through the condenser and destroy the Capacitor.
- Tantalum Electrolytic – This type of Capacitor is available in both wet and dry electrolytic types. dry electrolytic Capacitor is most commonly used. They are mostly used in circuits where the AC voltage is smaller than the DC voltage.
The capacitance of a conductor depends on the following factors:
- Plates Size : If the plates are larger than the size, they can charge more than the given potential.
- Distance between plates : The capacitance of the capacitor depends on the distance between the plates. If the distance is less then the capacitance will be more.
- Relative permittivity : The capacitance depends on the relative permittivity of the insulating medium. The capacitance is high when the relative permittivity is high.
- Common Capacitance (C) : The standard values of capacitance are measured in picofarads (pF), nano-Farads (nF) or micro-Farads. It’s value can change according to the frequency of the capacitance circuit.
- Working voltage : The working voltage is the maximum voltage, whether AC or DC, that can be applied to the circuit without breaking its entire working life.
- Tolerance (+ -%) : It has a tolerance rating, which is a plus or minus value in Pico-farads for capacitors, the most common tolerance variation being 5% or 10%.
- Leakage current : The dielectric medium that we used to separate the capacitor plates had leakage in the current, so the dielectric medium cannot be called correct. This small leakage of current is known as Leakage Current.
- Working temperature : As we know, a change in temperature allows a change in dielectric properties, the difference in temperature also affects the capacitance. The average working range for most Capacitor is -30°c to + 125°c.
- Temperature coefficient : The temperature coefficient of the capacitor tells us the maximum change in the value of the capacitance for a specific temperature in the form of million degrees per centigrade.
- Polarization : Polarization tells us about electrolytic type capacitors, but they must have the correct polarity as we know the wrong polarization that can damage the circuit.
- Equivalent series resistance : This is the AC impedance of the Capacitor. This tells us about the energy loss of equivalent series resistance of Capacitor.
Applications of Capacitor
- It is used for storing energy.
- In Capacitor, energy storage is used to create dynamic digital memories.
- Reservoir capacitors are used in power supply.
- It is also used for many pulsed power applications such as lasers, radar, pulse forming networks.
- It is also used for power factor correction.
- It is used to separate the AC and DC components because the capacitor passes the AC and blocks the DC.
- The energy stored in it is used to represent the information.
- Radio receivers use the variable Capacitor for tuning frequency.