SUMMER TRAINING

A SUMMER TRAININGPRESENTATION ON INSULATORS FROM BHEL JAGDISHPUR(SULTANPUR)

Presented by- ANU GUPTA B.TECH AE VII SEM 1218748004

BHARAT HEAVY ELECTRICALS LTD.1st unit set up in Bhopal in August 1956.

B.H.E.L. is the largest engineering and manufacturing enterprise in India in the energy/infrastructure sector with strong man force of 82000 people.

B.H.E.L. manufacture over 180 products under thirty major product groups and caters to core sectors of the Indian Economy viz., Power Generation and Transmission, Industry, Transportation, Telecommunication, Renewable Energy, etc.

MANUFACTURING UNITS OF BHELFirst Generation Units

BHOPAL Heavy Electrical Plant HARDWAR Heavy Electrical Equipment Plant HYDERABAD Heavy Electrical Power Equipment Plant TIRUCHY High Pressure Boiler PlantSecond Generation Units

JHANSI Transformer and Locomotive Plant HARDWAR Central Foundry and Forge Plant TIRUCHY Seamless Steel Tube PlantUnit Through Acquisition and Merger

BANGALORE Electronic Division Electro Porcelain DivisionNew Manufacturing Units RANIPAT Boiler Auxiliaries Plant JAGDISHPUR Insulator and Csu-Plant RUDRAPUR Component and Fabrication Plant BANGALORE Industrial System Group

INSULATORS

CONTENTS

1.Introduction5.Need of insulators3.Types of insulators3.Dielectric strength4.Breakdown in insulator6.Applications

INSULATOR A perfect insulator is a material that

does not respond to electric field and resist the flow of electric charge through it.

Perfect insulator do not exist.

Dielectric material with high dielectric constant are considered as insulator.

NEED OF INSULATORSInsulators are required for following

purposes:-

Between coils and earth. Phase to phase insulation Inter turn insulation

TYPES OF INSULATOR Gas or vacuum Liquid dielectric Solid dielectric

The solid dielectric insulators are further classified as follows:-

1. Pin type Insulators 2. Suspension or string type 3. Strain insulators

DIELECTRIC STRENGTH

The dielectric strength of an insulating material is defined as maximum dielectric stress which the material can withstand without any conduction.

The electric stress to which an insulating material is subjected is numerically equal to voltage gradient and which is equal to electric field intensity.

Voltage at which current starts flowing through the dielectric is known as breakdown voltage.

GAS INSULATOR Air at atmospheric pressure is the

most common gaseous insulation. Breakdown strength of air is 3okv/cm. other gases such as nitrogen (N2),

carbon dioxide (CO2), Freon (CCl2F2) and sulphur hexafluoride (SF6) are also .

Breakdown strength can be increased by operating gases at higher pressure.

LIQUID INSULATOR Liquids are usually 103 times denser than

gases. So, they possess much higher dielectric

strength of the order of 107 V/cm. Petroleum oils are the commonest insulating

liquids Fluorocarbons ,silicones, esters are also used

as insulating oil.

SOLID INSULATOR Solid dielectrics have higher breakdown

strength compared to liquids and gases. Many inorganic and organic materials are

used as insulator. Inorganic insulators used are ceramic

and glasses Organic insulator commonly used are

PVC, polythene,cross linked polythene etc.

Dielectric strength can be up to 10MV/cm

.

There are several types of solid insulators but the most commonly used are pin type, suspension type, strain insulator and shackle insulator.

1. PIN TYPE INSULATORS

• As the name suggests, the pin type insulator is secured to the cross-arm on the pole. There is a groove on the upper end of the insulator for housing the conductor. 

• Pin type insulators are used for transmission and distribution of electric power at voltages upto 33 kV.

• Beyond operating voltage of 33 kV, the pin type insulators become too bulky and hence uneconomical.

2 . Suspension Type• For high voltages (>33 kV), it is a usual practice to use

suspension type insulators shown in Figure. consist of a number of porcelain discs connected in series by metal links in the form of a string.

• The conductor is suspended at the bottom end of this string while the other end of the string is secured to the cross-arm of the tower. Each unit or disc is designed for low voltage, say 11 kV. The number of discs in series would obviously depend upon the working voltage. For instance, if the working voltage is 66 kV, then six discs in series will be provided on the string.

3 . Strain Insulators• When there is a dead end of the line or there is corner or sharp curve,

the line is subjected to greater tension. In order to relieve the line of excessive tension, strain insulators are used. For low voltage lines (< 11 kV), shackle insulators are used as strain insulators.

• However, for high voltage transmission lines, strain insulator consists of an assembly of suspension insulators as shown in Figure. The discs of strain insulators are used in the vertical plane. When the tension in lines is exceedingly high, at long river spans, two or more strings are used in parallel.

ELECTRICAL BREAKDOWN Gaseous dielectric ionization leads to breakdown of gases. Ionization may occur due to…. A) collision B)photo ionization C)thermal ionizationLiquids dielectrics Presence of any solid impurity lead to

breakdown Formation of gaseous product

Solid dielectrics Electronic breakdown Structural imperfection also leads to

breakdown. Chemical reaction such as oxidation ,

hydrolysis also leads to breakdown.

APPLICATION

Insulators are employed in:- Power transformer Generators Circuit breaker Cables

CONCLUSION Engineers need to develop knowledge and

skills necessary to evaluate and compare suppliers and products from many different countries

An understanding of the basics of insulator manufacturing, design and application is more essential than ever before

REFERENCES High voltage engineering by M S Naidu Wikipedia Power system by Asfaque Husain

.

THANK YOU!!