On what factor does the string efficiency of a string of suspension insulators is dependent. Aug 24, 2011 advantages of suspension type i suspension type insulators are cheaper than pin type insulators for voltages beyond 33 kv. String efficiency of suspension insulator when the voltage is applied across the suspension insulator string, it is unequally distributed across the individual unit. The unique design of our rodurflex suspension insulators and the variations possible on account of our patented modular system permit a combination of different installation lengths with different shed profiles and sizes. The disc near the line conductor is extremely stressed and takes the maximum.
Generally, it is specified as the ratio of the output obtained to the input fed to a device. The conductor is suspended at the bottom end of this string while the top end is secured to the crossarm of the tower. A suspension type string insulator consists of a number of porcelain discs connected in series through metallic links. Evaluation of string efficiency and voltage distribution of 400 kv over a.
Dec 07, 2017 a suspension type string insulator consists of a number of porcelain discs connected in series through metallic links. Suspension insulator article about suspension insulator by. String efficiency is an important factor is transmission line designing. Voltage distribution in a suspension insulator strain. There are two basic types of suspension insulators. First of all thanks for visiting electrical engineering info now let us discuss p otential distribution in a string of suspension insulators. Ssoolluuttiioonn the equivalent circuit of string insulators is the same as shown in fig. Ijsrd international journal for scientific research. The analysis and simulation of voltage distribution over. Sep 25, 2011 string effeciency and methods to improve string effeciency posted on september 25, 2011 by k10blogger the ratio of voltage across the whole string to the product of number of discs and the voltage across the disc nearest to the conductor is known as string efficiency i. Among these are the leakage distance, the 60 hz wet and dry flashover values, and the positive and negative impulse critical values. The disc nearest to the conductor has much higher potential then the other discs. Automotive part high quality suspension rubber bush.
Company profile and product overview lapp insulators. Each unit of suspension insulators insulator disc is designed for comparatively low voltage 11kv and can be increase the insulation strength by connecting these insulator disc modules in series. Aug 01, 2015 methods of improving string efficiency the maximum voltage appears across the insulator nearest to the line conductor and decreases progressively as the crossarm is approached. A new cleaning robot system for suspension insulator strings was developed to prevent a power failure, which can have severe effects on the national industry and economy. Porcelain insulator has a dielectric power is almost 4 10 kvmm. It consists the number of porcelain insulator units connected with each other by metal links to form a flexible string. Suspension insulator for voltages greater than 33 kv, it is a usual practice to use suspension type insulators, consisting of a number of glass or porcelain discs connected in series by metal links in the form of a string. There are many insulator manufacturers using pdf profiles to introduce some information about insulator types, application and definition, such as suspension insulators. Effects of disc insulator type and corona ring on electric field and voltage distribution over 230kv insulator string by numerical method. Typical application areas for different types of insulators. Methods of improving string efficiency string efficiency in power system string efficiency in suspension. The st suspension type classification system was born out of a simple need. Department of physics, princeton university, princeton, nj 08544, usa 2princeton institute for the science and technology of materials.
The most important difference between suspension and strain insulators is the strength, and the strain insulator string strength is higher than the. This zinc sleeve is strongly recommended for insulators which are going to be used in lines with heavy pollution. Suspension insulators consist of the following elements. The string efficiency is defined as the ratio of voltage across the string to the product of the number of strings and the voltage across the. Suspension insulators or string insulators are very widely used in an.
In the high voltage overhead transmission and distribution power line in order that transmission towers or poles support the lines, high voltage insulators are used to insulate the live. In this study, the voltage distribution over an insulator string of suspension insulators and the string efficiency have been investigated with respect to the. Suspension type insulators are cheaper than pin type insulators for voltages beyond 33 kv. In this project, calculate the voltage distribution along a string of 5 suspension insulators, and determine the efficiency of string and we get efficiency equal to 53. Each unit or disc of suspension type insulator is designed for low voltage, usually 11 kv. These capacitances could be made negligibly small by increasing the distance between the insulators and the tower structure which. The insulators prevent the loss of current and make the current more efficient by concentrating the flow.
This paper presents simulations of pollution and their effects on the electrical performance of capandpin glass suspension insulators. The pin insulator is the earliest developed insulator. Suspension insulator pdf can let you know more about suspension insulator. Insulators for overhead lines are considered to be of basic importance to the transmission system, through their ability to insulate the power lines as well as their function in.
The effect of stray capacitance over voltage distribution using kcl at each node it can be found that. Vph the phase voltage across the subsequent units measured from the ground respectively. The capacitances between each cappin junction and the tower and between the cap and pin of each unit determine the voltage distribution. The suspension insulator separates the line conductors and supports them electrically. They are further classified into two types, they are. Potential distribution over suspension insulators the porcelain portion of each disc is in between two metal links. Compared with existing cleaning robots using jets of water or waterair, this robot mechanism is superior in insulation as it uses a porcelainclamping method, and is more useful in mountainous or salt damage areas by. Although it is impossible to achieve 100% string efficiency, yet efforts should be made to improve it as close to this value as possible. More the utilization of discs of insulator more will be the string efficiency. When we include r and g in the model, we have a lossy transmission line.
Glass insulator has a higher dielectric power, but it pull condensation and the thick unequal shapes needed for insulator are difficult to cast without inner strains. We assign numbers starting first on smallest to largest diameter, then least to most number of petticoats, then length of outer skirts and inner petticoats. Potential distribution over a suspension insulator string the figure below shows a 3disc string of suspension insulator. The pollution is modeled by using a partially conductive. Suspension insulators or string insulators are very widely used in electrical overhead transmission system. Calculate the string efficiency of 50 kv string containing insulators. Simulations of pollution and their effects on the electrical. Another way to define string efficiency is in terms of flashover voltage.
Polymer vs porcelain suspension insulator equivalence. In this distribution of voltage, disc nearest to the conductor will be at higher potential than the other discs. String efficiency is a measure of utilization of material in the string and is defined as. Basic formula to calculate string efficiency of insulators. String efficiency in power system in hindi suspension. Structural advantage of using vstrings power line systems. Suspension insulator string has single suspension string, double suspension string, v type suspension string, and so on. As stated above the voltage applied across the string of suspension insulators is not uniformly distributed across various units. Practically it is better to use shorter strings in the insulator than a larger string to get 100% efficiency. The disc near the line conductor is extremely stressed and takes the maximum voltage in the absence of stress. As explained above, voltage is not uniformly distributed over a suspension insulator string. In order to reduce shunt capacitance, the distance of conductor from tower must be increased i.
Strain insulators the strain insulator is a variation of the suspension insulator and is designed to sustain extraordinary pulls. We talked about advantages and disadvantages of each type of insulators. Suspension assembly types are introduced in the following. Types of insulators in transmission lines properties of. String of glass suspensiontype insulator in different atmospheric. Insulator made from porcelain is wealthy in alumina is used where high mechanical power is a standard.
We have the planning to produce insulators for distribution and current transformers, cable boxes, lighting arrestor, insulators for overhead, transmission lines and post and telegraph insulators. Suspension insulators are cheaper in cost compared to pin type insulators for operating voltage above 50kv. The disc nearest to the conductor has maximum voltage across it and, hence, it will be under maximum electrical stress. Suspension and strain insulators are the same thing. The total voltage applied across the string of suspension type insulators is not equally distributed across all discs. Difference between suspension and strain insulatorsorient. The voltage across the various discs of a string of suspension insulator having identical discs is different due to a. Simulation of voltage distribution calculation methods over a. This constitutes a series of connected capacitors, with each ones capacitance being created by two. When our customers think of trouble free transmission insulators with the longevity to outpace life time expectations of the transmission lines supported, they think of porcelain suspension insulators from lapp insulators.
This library is a compilation of section 26 of the ohio brass january 2002 catalog for hilite xl transmission insulators. Simulation of voltage distribution calculation methods over a string of suspension insulators abstract. You will find here lectures, experiments, projects and guidance about electrical engineering. Advantages of suspension insulators and pin type insulators. Suspension insulators transmission line is for high voltage, extra high voltage and ultra high voltage used in suspension insulator string or strain type strings suspension insulators are used to transmit above 33kv. Jul 23, 2017 in the previous article, we have discussed different types of insulators used in an overhead transmission line. The maximum voltage appears across the insulator nearest to the line conductor and decreases progressively as the. Suspension assembly is main hardware used for high voltage applications, and it is used with suspension insulators together like tension assembly. Pdf effects of disc insulator type and corona ring on.
String efficiency is defined as the ration of conductor voltage and the voltage across the disc nearest to conductor multiplied by number of discs. Orientsuspension insulators,voltage distribution in. The second broad category is electrical equivalences. String efficiency of suspension insulators and methods of. In an ideal condition, the efficiency is equal to 100% if the voltage across each disc is equally distributed and in the practical world it is not possible.
Depending upon the working voltage, the desired number of discs can be connected in series. Thus 100% string efficiency is an ideal case for which the volatge across each disc will be exactly the same. String efficiency shows the utilization of suspension insulator. Suspension insulators can be divided into three kinds according to their applications. String efficiency of suspension insulators and methods of improving. Type and construction, grading of cables, capacitance in 3 core cables and dielectric loss in cables. Each disc forms the capacitance c this is known as the mutual capacitance or the self capacitance. The lesser the value of k, the greater is the string efficiency and more uniform is the voltage distribution. Strain insulator string has single strain string and double strain string. In suspension insulator numbers of insulators are connected in series to form a string and the conductor is suspended at the. String efficiency of suspension insulator is defined as the ratio of voltage across the whole string to the product of the number of insulator discs and the voltage across the insulator disc nearest to the line conductor. In this study, the voltage distribution over an insulator string of suspension insulators and the string efficiency have been investigated with respect to the atmospheric conditions such as wind.
Zahid hasan,1,2 suyang xu,1 and madhab neupane1 1joseph henry laboratories. In these topics, it is discussed the voltage distribution over suspension insulator string. How can we achieve the maximum string efficiency across an. If we assume there is no loss, we can reduce the model to an ideal. Find the string efficiency of a 37 kv string containing 20 insulators. In this project, calculate the voltage distribution along a string of 5 suspension insulators, and determine the efficiency of string and we get efficiency equal to. This is because of the capacitances formed between the metal parts of the insulators and tower structure. Thus 100% string efficiency of suspension insulators is an ideal case for which the voltage across each disc will be exactly the same. String effeciency and methods to improve string effeciency. So, the string efficiency of an insulator of n units suppose in. String efficiency of suspension insulators are affected the environments, the numbers of disc insulators, temperature and mechanical strength, especial electrical properties. The function of high voltage insulator is to insulate the electrically charged part of equipment or machine from another charged part or uncharged metal part.
Potential distribution over a string of suspension insulators. Mar 09, 20 suspension type insulators are cheaper than pin type insulators for voltages beyond 33 kv. A suspension insulator consists of a number of porcelain discs connected to each other with metal links in the form of a string. String efficiency is defined as the ration of conductor voltage and the voltage across the disc nearest. Line conductor is suspended at the bottom end of the suspension string which is secured to crossarm of the tower.
Bulk of the production programmed comprises of these special purpose repairers besides standard insulators for transformer manufacturer and repairers. Suspension insulators components verescence insulators. String efficiency of suspension insulator electrical. Physical equivalence the ultimate strength of porcelain suspension insulators is character.
It is important to note that in a string of suspension insulators one or more insulators can be replaced without replacing the whole string. In the ideal case, the value of string efficiency will be 100%, but, in a normal case, it is impossible to achieve 100% string efficiency, yet effort should be made to improve it as close to this value as possible. Hubbell suspension insulator is popular used for the electrical power systems, divided into distribution insulators for 10kv to 69kv, and transmission line insulators for 110kv to 500kv suspension insulator is used on overhead distribution power lines, overhead line to the mechanical design is considered that the important issue of the suspension and the voltage insulator division of the disk. String efficiency problems how to improve string efficiency of suspension type insulator. Find the voltage distribution of an insulator of 3 units, if the maximum voltage of each unit is 17 kv, and the capacitance to ground is 20% of unit capacitance, also find the insulator efficiency. String efficiency of suspension insulators and methods of improving it by kiran daware overhead lines, power system a suspension type string insulator consists of a number of porcelain discs connected in series through metallic links. Sag and stress calculation of overhead conductors, vibration dampers under ground cable. String efficiency of a string of suspension insulators. This paper describes observation and analysis of calculation the voltage distribution over a string of suspension insulators, and compares the efficiency percentage to other methods, which have.
Overhead line to the mechanical design is considered that the important issue of the suspension and the voltage insulator division of the disk. The greater the string efficiency, the more uniform is the voltage distribution in the each disc insulator. For suspension type of insulators, the ratio of voltage across the whole string to the product of number of discs and the voltage across the disc nearest to the conductor is known as string efficiency. Porcelain suspension insulators suspension and tension towers for high voltage transmission lines. Orientsuspension insulators,disc suspension insulators,end. Suspension insulators have been used widely all over the world for high voltage transmission and distribution overhead lines with the voltage ranging from 10kv to kv. String efficiency of suspension insulator electrical concepts.
However, there is a significant thing to be considered in case of these string insulators, known as string efficiency. This unequal potential distribution is undesirable and is usually expressed in terms of string efficiency. Structural advantage of using vstrings when comparing the relative advantages and disadvantages of using suspension insulators vs. The maximum voltage appears across the insulator nearest to the line conductor and decreases progressively as the crossarm is approached. In this article, we will be talking about voltage distribution and string efficiency of suspension insulator. Solved calculation of string efficiency for suspension. Voltage distribution in suspension insulators includes the efficient string, efficient string upgrade, and solved problems on string efficiency and voltage distribution the value of voltage distribution in suspension insulators. Similarly, the pins may be protected using an anticorrosion zinc sleeve sacrificial anode, when requested. Simulation of voltage distribution calculation methods. The most common methods for transfer of electric power are. So, for voltages higher than 33 kv, suspension insulators are used. Voltage distribution over suspension insulator string efficiency.
String efficiency of a suspension insulator youtube. A suspension insulator strain consists of a series of alternately insulators and metal parts, which bind each insulator to the next. It contains information for suspension, post, and braced post insulators. In conventional calculations of the voltage distribution over a string insulator and string efficiency, it is assumed that the insulator surface is clean, dry, and also there is no wind. Electric power transmission uses three types of overhead insulator. Voltage distribution over suspension insulator string. Because above 33kv using of pin type is uneconomical. Let us know how the potential is distributed over each unit of suspension insulator whether is it uniform or nonuniform. A type of insulator used to support a conductor of an overhead transmission line, consisting of one or a string of insulating units suspended from a pole or.
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