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An Introduction to Capacitor, Capacitance, Types and Real life applications

Updated: Jan 18


What is a capacitor?


A capacitor is a passive, two-terminal electronic component. A capacitor has the ability to store electrical energy. A capacitor is otherwise called an electric condenser. Because it stores electrical energy in an electrical field when we bring two conductors close but insulated from each other.


Capacitor
Capacitor

While designing an electrical and electronic circuit, the capacitor is predominantly used. It plays a crucial role in different kinds of embedded applications. There is a wide range of capacitors available on the market, distinguished mainly by the type of dielectric material used in the plates.


This is the symbol of capacitor
Capacitor Symbol

What is capacitance?


Capacitance is the electrical capacity of the capacitor. Capacitance is a measure of the amount of electrical energy stored in a capacitor when it is charged to a voltage of 1 volt. It is typically measured in units of Farad (F).


What are all the factors that affect capacitance?


Surface area of the plates


  • The higher the surface area, the higher the capacitance value.


Distance between the plates


  • The lower the distance, the higher the capacitance value.


Dielectric Medium


  • Dielectric is the type of material that separates the two plates.

  • The higher the dielectric's permittivity, the higher the capacitance value


C = ε A/d


C = capacitance of the capacitor

ε = permittivity of the material between two plates

A = surface area of each plate

d = distance between two plates


Construction of a Capacitor


A parallel-plate capacitor is considered one of the simplest forms of a capacitor. It is constructed by placing two metal plates parallel to each other, separated by a distance.


Let's say a voltage source is connected across a capacitor. The positive terminal of the voltage source is connected to the positive terminal of the capacitor, and the negative terminal of the voltage source is connected to the negative terminal of the capacitor. Then the amount of energy stored in the capacitor is directly proportional to the voltage that is applied.


Q = CV


Where Q =charge, C = capacitance, and V = voltage.


Classification of capacitors


Based on the structure, the capacitors are classified as

  • Fixed Capacitors

  • Variable capacitors

  • Trimmer Capacitors


Based on the polarization, the capacitors are classified as

  • Polarized capacitors

  • Non-polarized capacitors


Polarized capacitors


  • Polarized capacitors are electrolytic capacitors. This type of capacitor is a crucial part of an electronic circuit.

  • It is responsible for providing high capacitive density.


Non-polarized capacitors


  • Non-polarized capacitors are used in pure AC circuits.

  • As these are non-polarized capacitors, they find applications in DC circuits.

  • The spillage current is low in this capacitor.


Series & Parallel Connection


Capacitors connected in series


When capacitors are connected in series, the amount of charge stored is the same on each plate, but their plates contain different voltages.


Total capacitance in series 1/C = 1/C1 +1/C2+ 1/C3+.....+1/Cn



Capacitors connected in series
Capacitors connected in series

Capacitors connected in parallel


When capacitors are connected in parallel, the voltage across the plates is the same, but on each plate, the charge is different.


Total capacitance in parallel C  = C1 + C2 + C3 + .....+Cn



Capacitors connected in parallel
Capacitors connected in parallel


Types of Capacitors


  • Ceramic capacitors

  • Film capacitors

  • power film capacitors

  • electrolytic capacitors

  • paper capacitors


Ceramic Capacitors


  • These are the most commonly used capacitors and consist of dielectric material.

  • As these are non-polar, they can be used in any path of the circuit.



Ceramic Capacitors mounted on PCB
Ceramic Capacitors mounted on PCB

Types of Ceramic Capacitors


  • Leaded-plate ceramic capacitors

  • microwave-exposed lead-less plate ceramic capacitors

  • surface-mount multi-layered ceramic capacitors


Based on resistance, temperature float, and temperature range, ceramic capacitors are classified as

  • Class 1 ceramic capacitors

  • Class 2 ceramic capacitors

  • Class 3 ceramic capacitors


Class 1 ceramic capacitors

  • These are considered to be some of the steadiest capacitors.


Class 2 ceramic capacitors

  • Used for coupling and decoupling.

  • Has better volumetric effectiveness.

  • The precision and dependability of these capacitors are questionable.


Class 3 ceramic capacitors

  • Used for de-coupling.

  • Has high volumetric effectiveness.

  • Has low precision and scattering factors.


Applications of ceramic capacitors


  • Used in printed circuit sheets (high-density apps)

  • Used in DC engines to diminish RF noise

  • Useful in transmitter stations in full circuits


Film Capacitors


  • This capacitor is a polymer, plastic film, or film dielectric.

  • The voltage scope of the film capacitor is 50V to 2KV.

  • It is modest, reliable, and durable.

  • It uses a slight dielectric material, and the opposite side of the capacitor is metalized.


Film Capacitor
Film Capacitor

Types of Film capacitors


A film capacitor is classified into four types based on the dielectric material used:

  • Heavy-duty snubber film capacitor

  • SMD-style film capacitor

  • Axial-style film capacitor

  • Radial-style film capacitor


Applications of Film Capacitors


  • Used in force hardware

  • Used to avoid unexpected voltage spikes in gadgets

  • The power factor can be improved for the gadget.

  • Used in electromagnetic impedance


Power-film capacitors


  • Power film capacitors are made up of materials and developed by methods that are similar to those of standard film capacitors.

  • It consists of polypropylene film as a dielectric material.


Electrolytic Capacitors


The dielectric material used in this capacitor is a metallic anode covered with an oxidized layer.


Depending on the dielectric used, they are classified as follows:

  • Aluminum Electrolytic Capacitor: Aluminum oxide is used as the dielectric material.

  • Tantalum Electrolytic Capacitor: Tantalum pent-oxide is used as the dielectric material.

  • Niobium Electrolytic Capacitor: Niobium pent-oxide is used as the dielectric material.



Electrolytic Capacitor
Electrolytic Capacitor

Applications of Electrolytic Capacitors


  • It is used when enormous capacitance is required as a prerequisite.

  • To bring down the wave voltage, it is used as a sifting gadget.

  • Sound speakers are used to reduce electrical noise.

  • It is also used to smooth the information and produce DC signals, which have a powerless AC segment.


Paper Capacitor


These are the fixed capacitors, and the dielectric material used here is paper.


Applications of Paper Capacitor


  • Noise-sifting, coupling, and decoupling frameworks

  • Stickiness sensors, fuel level sensors

  • In vehicles, it is used in sound frameworks to provide additional capacity to the speakers.


To know more about the properties and functions of capacitor, refer to Properties and Functions of Capacitor


Real-life Applications of Capacitor


Tuned Circuits


  • To select information in particular frequency bands in tuned circuits, capacitors and inductors are applied together.


Power factor correction


  • When three capacitors are connected as a 3-phase load, it can be used for power factor correction.

  • These capacitor values will not be given as Farad but as VAR (i.e., reactive power in volt-amperes).


Filtering


Single-De Coupling


  • Capacitors allow only AC and block DC signals.

  • Capacitors are used to separate the DC and AC components of a signal by a method called AC decoupling.


Energy Storage


  • In a charging circuit, when a capacitor is disconnected, it can store electric energy and would be used like a temporary battery.

  • In electronic devices, capacitors are most commonly used to maintain the power supply when the batteries are being charged.


Pulsed power


  • For many pulsed power applications, capacitor banks are used to supply huge pulses of current.


Sensing


  • The structure of the capacitor can be affected or changed by various factors, and the capacitance of the capacitors resulting from this change is used to sense various parameters.


Power Conditioning


  • In power suppliers, capacitors are used to smooth the output of a full-wave rectifier or a half-wave rectifier.


Signal Processing


  • As we all know, a capacitor is used to store energy. It is used to represent information in binary form or in analog form.

  • Capacitors are used to integrate a current signal into signal processing circuits.


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