Electrolytic capacitor, Physics

Assignment Help:

In this type of capacitors the dielectric consists of an extremely thin film of aluminium oxide formed on one of its aluminium foil plates. Intimate contact with the other plates is achieved by impregnating the paper between the foils between electrolytes in the form of viscous substance, such as ammonium borate. The sandwich is then rolled into cylindrical element and housed in either plastic or ceramic, metallic cardboard, protective tube. It is divided into:

(a)          Plain foil type electrolytic capacitors

(b)         Etched foil type capacitor

(c)           Tantalum electrolytic capacitor

Plain foil type electrolytic capacitor: A thin film of aluminium oxide is deposited on the surface of aluminium plate. Aluminium electrode is placed in a solution of ammonium borate and a constant voltage is applied. Initially current is large. It drops gradually as the film grows. The thickness of the film depends upon the forming voltage. Working voltage is about 90% of forming voltage. A thickness film is formed at about 600V. Thus maximum working is 550V.

Construction: Film of aluminium oxide 0.01 cm thick is coated on both sides of aluminium foil. Two strips of aluminium foil are used separated by two layers of porous paper soaked with electrolyte. It is rolled; ends closed with wax and sealed in a container.

 Etched foil type capacitors: The construction is similar to plain foil type capacitor but anode is mildly etched before forming. This increases the anode surface area.

Specifications:

Range of capacitance                                                                       up to 6μf/cm2 for aluminium foil capacitors 50μf/cm2                        

                                                                    For capacitors for etched foil capacitors

Power factor                                                                     2 to 4%

Working voltage                                                                     max 550V

Variation in capacitance                                                                     20 to + 50% of nominal value

Advantages: High capacitance volume ratio with reasonably low cost.

Disadvantages: High power factor, large variation in capacitance, small safety factor, and high leakage current.

Application: Filtering, decoupling and bypass.

Tantalum electrolytic capacitor: Pellet type tantalum powder is pressed in vacuum and then mounted inside silver cup containing sulphuric acid as electrolyte.

Foil type: Construction is similar to that of aluminium foil type capacitors. These capacitors do not need reforming. They are made in polarized and non-polarized types.

Solid electrolyte type: this uses solid semiconductor in place of a liquid electrolyte. The pellets are pressed and sintered. They are then impregnated with aqueous solution of Magnus salt. A carbon compound is applied to allow metal cathode to be formed.

Specifications

Range of capacitance                                                                      200μf

Working voltage                                                                     6V to 150V

Tolerance                                                                     0.25μf

Power factor at 50 Hz                                                                    3 to 12%

Maximum operating temperature                                                    700C

Leakage current                                                                    < 10μf

Applications: These are used as decoupling capacitors with transistors, and integrated circuits.


Related Discussions:- Electrolytic capacitor

Metallised paper capacitors, One side of impregnated paper capacitors is sp...

One side of impregnated paper capacitors is sprayed with metal.  When such paper is rolled, its gives higher capacitance for a given value. This capacitor has a self healing proper

Ratio of the frequency of fourth overtone, What do you mean by the ratio of...

What do you mean by the ratio of the frequency of fourth overtone to the fundamental frequency of a stretched string?

Explain the energy, Explain the Energy Again, we have all heard about e...

Explain the Energy Again, we have all heard about energy. When the alarm clock rings in the morning we roll over and say, “I do not want to get up, I have no energy this mornin

Determine concept of pressure, A woman wearing high heels briefly supports ...

A woman wearing high heels briefly supports all her weight on the heels. If her mass is 45 kg and each heel has an area of 1.2 cm 2 , what pressure does she exert on the floor

Broadcast, composition of mosfet .

composition of mosfet .

What will be effect on newtons rings, What will be effect on Newton's rings...

What will be effect on Newton's rings if: (a) A little oil (μ=1.65) is introduced between the lens (μ=1.5) and the glass plate (μ=1.75) (b) A plane mirror is placed instead o

Define ultimate strength , The stress at which the specimen breaks or reptu...

The stress at which the specimen breaks or reptures ultimately is known as ultimate strength. We also called this TENSILE STRENGTH .

Logic gate, how to prepare for logic gate project?

how to prepare for logic gate project?

Classes of magnetic materials: diamagnetism, Diamagnetism is a basic proper...

Diamagnetism is a basic property of all matter, though it is generally very weak. It is due to the no cooperative behaviour of oepenrbiting electrons when exposed to an applied mag

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd