Switchgear and protection notes pdf
EE8602 PS Notes, PROTECTION AND SWITCHGEAR Notes – EEE 6th Sem
Mho relay: In the impedance relay a separate unit is required to make it directional while the same unit can not be used to make a reactance relay with directional feature. With the loss of this gradient, local distortion of the electrical field distribution is caused by the TRV appearing across the open account when designing the geometry of the contact arrangement. However, the streamer stops without reaching to the earth. Such faults are uncommon because the insulation used between the coils of different phases in a slot is large.The circuit breakers can be operated manually as when required and it can also be operated autometically during over current and short circuit or any other faults in the system by sensing the abnormality of system parameters. Download Offline. Pages: 2 Topic 7 Blased beam relay. The contacts are separated and the blast of air will take ionized gases with it and pritection in extinguishing the arc.
With the second's y winding of non directional element Non directional element: The current coil of the directional element is connected in series with the primary winding of non directional element. Applications :The air blast circuit breakers are preferred for arc furnace duty and traction system. Hence generally backup protection is located at different stations from the primary protection. All these factors make the design of protection scheme for the generator very much complex.
Title: Lecture notes on switchgear and protection devices for students – VEER SURENDRA SAI UNIVERSITY OF TECHNOLOGY. Format: PDF. Size: MB.
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Definition of Switchgear
Also to describe the phenomena of current interruption to study the various switchgears. To discuss the causes of abnormal operating conditions faults, lightning and switching surges of the apparatus and system. To understand the characteristics and functions of relays and protection schemes. To understand the problems associated with circuit interruption by a circuit breaker. Qualitative review of faults and fault currents - relay terminology — definitions - and essential qualities of protection.
These methods will be discussed in detail later in this chapter. Switch gear and Protection Purpose of circuit breakers switchgear The main purpose of a circuit breaker is to: Switch load currents Make onto a fault Break normal and fault currents. If this dielectric strength of the medium between the contacts does not build up faster than the rate of rise of the transient recovery voltage then the breakdown takes place which will cause restriking of arc Thus it is very important that the dielectric strength of the contact space must build very rapidly that rate of rise Page This is post arc phase in which hot gases are removed and fresh dielectric medium is introduced.
Ravindranath, and N. The purpose of an Electric Power System is to. The clearing I2t is proportional to the total energy let through by the fuse when clearing a fault. The production of arc delays the current interruption and in addition to this it produces large amount of switchyear which may damage the system or the breaker.