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We use your LinkedIn profile and activity data to personalize ads and to show you more relevant ads. You can change your ad preferences anytime. Fundamentals of Power System protection by Y. Paithankar and S. Upcoming SlideShare. Like this document? Why not share! Fundamentals of power system protec Embed Size px. Start on. Show related SlideShares at end. WordPress Shortcode. Published in: Engineering. Full Name Comment goes here. Are you sure you want to Yes No. Virgie Mcdowell What if I told you, you've been lied to for nearly all of your life?

Sharon Ramsey Show More. Alex Thu. No Downloads. Views Total views. Actions Shares. Embeds 0 No embeds. No notes for slide. Bhide 1. Fundamentals of Power System Protection Y. Power System Protection is a fascinating subject.

A protection scheme in a power system is designed to continuously monitor the power system to ensure maximum continuity of electrical supply with minimum damage to hfe, equipment, and property.

While designing the protective schemes, one has to understand the fault characteristics of the individual power system elements.

One should also be knowledgeable about the tripping characteristics of various protective relays. The job of the protection engineer is to devise such schemes where closest possible match between the fault characteristics and the tripping characteristics is obtained. The design has to ensure that relays will detect undesirable conditions and then trip to disconnect the area affected, but remain restrained at all other times However, there is statistical evidence that a large number of relay trippings are due to improper or inadequate settings than due to genulne faults.

It is therefore necessary that students should be equipped with sound concepts of power system protection to enable them to handle unforeseen circumstances in real life.

Whenever a tripping takes place it has all the elements of intrigue, drama, and suspense. A lot of detective work is usually undertaken to understand the reason behind the tripping. It needs to be established why the relay has tripped.

Whether it should have tripped at all. What and where was the fault? These are some of the questions required to be answered. This is because a power system is a highly complex and dynamic entity. It is always in a state of flux. Generators may be in or out of sewice. New loads are added all the time. A single malfunction at a seemingly unimportant location has the potential to trigger a system-wide disturbance. In view of such possible consequences, a protective system with surgical accuracy is the only insurance against potentially large losses due to electrical faults.

Protective relays are meant to mitigate the effects of faults. This text treats the entire spectrum of relays, from electromechanical to the state-of-the-art numerical relays, for protection of transmission lines, turbo-alternators, transformers, busbars, and motors. However, it is ironic that every additional protective relay also increases the possibility of disturbance by way of its relay's own malfunction.

This is possibly an area where protection tends to become an art. The protection engineer has to strike a balance between the threat perception and the security offered by the protective scheme. Written in a simple, clear and down-to-earth style, this state-of-the-art text offers students of electrical engineering a stimulating presentation that is both friendly and refreshingly simple.

The text contains a wealth of figures, block diagrams, and tables to illustrate the concepts discussed. The graphics are extensively annotated. The students are urged to spend some time to read the annotations on the figures, so that learning becomes easy and concepts are reinforced.

Though the book's audience consists mainly of final year electrical engineering students, the practising engineers, interested in learning the fundamental concepts of power system protection, will also find it useful. The authors will gratefully receive suggestions and comments from the readers for improvement of the book.

BHIDE And add to this, the mind-boggling number of domestic users of electricity whose life is thrown out of gear, in case the electric supply is disrupted.

Thus, the importance of maintaining continuous supply of electricity round the clock cannot be overemphasized. No power system can be designed in such a way that it would never fail. So, one has to live with the failures. In the language of protection engineers, these failures are called faults. There is no negative connotation to the word fault in this context.

The insulation can break down for a variety of reasons, some of which are listed in Section 1. Figure 1. Such faults due to insulation flashover are many times temporary, i.

I-In low-voltage systems up 1 yC. The repeated attempts at reclosure, at times, help in burning out the object which is causing the breakdown of insulation. The reclosure may also be done automatically In EHV systems, At times the short circuit may be total sometimes called a dead short circuit , or it may be a partial short circuit. A fault which bypasses the entire load current through itself, is called a metallic fault. A metallic fault presents a very low, practically zero, fault resistance.

A partial short circuit can be modelled as a non-zero resistance or impedance in parallel with the intended path of the current. Most of the times, the fault resistance is nothing but the resistance of the arc that is formed as a result of the flashover. The arc resistance is highly nonlinear in nature. Early researchers have developed models of the arc resistance. One such widely used model is due to Warrington, which gives the arc resistance as: a where S is the spacing in feet u is the velocity of air in mph t is the time in seconds I is the fault current in amperes.

The insulation may fail because of its own weakening, or it may fail due to overvoltage. The weakening of insulation may be due to one or more of the following factors: - Ageing - 'i. Rain, hail, snow ' Chemical pollution Foreign objects Other causes The overvoltage may be either internal due to switching or external due to lightening. Consider an isolated turboalternator with a three-phase short circuit on its terminals as shown in Figure 1.

Assuming the internal voltage to be 1 p. We must not, however, forget that in an Faults, thus, cause heavy currents to flow. If these fault currents persist even for a short time, they will cause extensive damage to the equipment that carry these currents.

Over-currents, in general, cause overheating and attendant danger of fire. Overheating also causes deterioration of the insulation, thus weakening it further. Not SO apparent is the mechanical damage due to excessive mechanlcal forces developed during a over-current. Transformers are known to have suffered rnechanlcal damage to their windings, due to faults. This is due to the fact that any two current-carrying conductors experience a force. This force goes out of bounds during faults, causing mechanical distortion and damage.


Fundamentals of Power System Protection

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[PDF] Fundamentals of Power System Protection By Y.G. Paithankar, S.R. Bhide Book Free Download

The electric power system is a highly complex and dynamic entity. One malfunction or a carelessly set relay can jeopardize the entire grid. Power system protection as a subject offers all the elements of intrigue, drama, and suspense while handling fault conditions in real life. The book reflects many years of experience of the authors in teaching this subject matter to undergraduate electrical engineering students. The book, now in its second edition, continues to provide the most relevant concepts and techniques in power system protection.

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