Switchgear Protection And Power Systems by Sunil S. Rao Download. Posted by Ishtiaq ur Rehman. Switchgear Protection And Power Systems by Sunil S. Reliability based design of utility pole structures pdf merge, Organic chemicals in food additives pdf, Afterlife knowledge guidebook pdf, Mind value and.

Latest Material Links Link – Link – Link – Link – Link – Link – Old Material Links UNIT – I Circuit Breakers-1 Circuit Breakers: Elementary principles of arc interruption, Recovery, Restriking Voltage and Recovery voltages.- Restriking Phenomenon, Average and Max. Maquetas De Arquitectura Libro Descargar Gratis Libros Y Sus. RRRV, Numerical Problems – Current Chopping and Resistance Switching – CB ratings and Specifications: Types and Numerical Problems.

– Auto reclosures UNIT – II Circuit Breakers-2 Description and Operation of following types of circuit breakers: Minimum Oil Circuit breakers, Air Blast Circuit Breakers, Vacuum and SF6 circuit breakers. UNIT – III Electromagnetic and Static Relays Principle of Operation and Construction of Attracted armature, Balanced Beam, induction Disc and Induction Cup relays.

Relays Classification: Instantaneous, DMT and IDMT types. Application of relays: Over current/ Under voltage relays, Direction relays, Differential Relays and Percentage Differential Relays.

Universal torque equation, Distance relays: Impedance, Reactance and Mho and Off-Set Mho relays, Characteristics of Distance Relays and Comparison. Static Relays: Static Relays verses Electromagnetic Relays UNIT – IV Generator Protection Protection of generators against Stator faults, Rotor faults, and Abnormal Conditions. Restricted Earth fault and Inter-turn fault Protection.

Numerical Problems on% Winding Unprotected. UNIT – V Transformer Protection Protection of transformers: Percentage Differential Protection, Numerical Problem on Design of CT s Ratio, Buchholtz relay Protection. UNIT – VI Feeder and Bus-Bar Protection Protection of Lines: Over Current, Carrier Current and Three-zone distance relay protection using Impedance relays. Translay Relay. Protection of Bus bars – Differential protection. UNIT – VII Neutral Grounding Grounded and Ungrounded Neutral Systems.- Effects of Ungrounded Neutral on system performance.

Methods of Neutral Grounding: Solid, Resistance, Reactance – Arcing Grounds and Grounding Practices. UNIT – VIII Protection against over voltages Generation of Over Voltages in Power Systems.-Protection against Lightning Over Voltages – Valve type and Zinc-Oxide Lighting Arresters – Insulation Coordination -BIL, Impulse Ratio, Standard Impulse Test Wave, Volt-Time Characteristics. TEXT BOOKS: Switchgear and Protection Notes – SGP Notes – SGP Pdf Notes • Switchgear and Protection – by Sunil S Rao, Khanna Publlishers • Power System Protection and Switchgear by Badari Ram, D.N Viswakarma, TMH Publications REFERENCE BOOKS: Switchgear and Protection Notes – SGP Notes – SGP Pdf Notes • Fundamentals of Power System Protection by Paithankar and S.R.Bhide.,PHI, 2003 • Art & Science of Protective Relaying – by C R Mason, Wiley Eastern Ltd. • Electrical Power Systems – by C.L.Wadhwa, New Age international (P) Limited, Publishers, 3nd editon • A Text book on Power System Engineering by B.L.Soni, Gupta, Bhatnagar, Chakrabarthy, Dhanpat Rai & Co. Note:- These notes are according to the r09 Syllabus book of.In R13,8-units of R09 syllabus are combined into 5-units in r13 syllabus.

Every phase has inherent distributed capacitance with respect to earth. If earth fault occurs on phase B, the distributed capacitance discharges through the fault. The capacitance again gets charged and gets discharged. Because of this sever voltage oscillation is reached in healthy phases. These voltage oscillation causes stress on insulation of connected equipment.

Figure 1 – Ungrounded neutral or ungrounded system Ic2 = jCwv2 Ic3 = jCwv3 Ic = jCwv2 + jCwv3 Ic = jCw(v2 + v3) // Equation-01 Now by drawing the phaser diagram as shown below wecan write: VN + V2 = v2 // Equation-02 VN + V3 = v3 // Equation-03 Substituting equation -02 and equation-03 in equation-01: Ic = jCw(VN + V2 + VN + V3) Ic = jCw(2VN + V2 + V3) // Equation-04 Figure 2 – Ungrounded neutral or ungrounded system Voltage phasers V3 can be resolved in the direction of V N and in direction perpendicular to V N as V3Cosθ and V3Sinθ. Similarly voltage phaser V2 can be resolved as V2Cosθand – V2Sinθ Hence: V2 + V3 = V3Cosθ + V3Sinθ + V2Cosθ – V2Sinθ // Equation-05 V3 = V2 V3Cosθ + V2Cosθ = V N Substituting in equation-05 we get: V2 + V3 = VN = V1 (Since V1 is shorted to soVN = V1) // Equation-06 Substituting equation-06 in equation- 04 we get: Ic = jCw(2VN + VN). As seen from equation -07, in unearthed system ground fault current is totally dependent on capacitive current returning via the network phase-earth capacitances. This is the reason for sever voltage stress in healthy phases of ungrounded system.

Since there is no return path available for fault current in ungrounded system so detection of earth fault current is difficult. This is other disadvantage of ungrounded system. Advantages of Ungrounded System There are some advantages of ungrounded system: • Ungrounded system has • Some continuous process or system and essential auxiliaries where single phase to ground fault should not trip the system. Disadvantages of Ungrounded System However below listed disadvantages of ungrounded system are more adverse than advantages: • Unearthed system experience repeated arcing grounds. • Insulation failure occurs during single phase to ground faults. • Earth fault protection for unearthed system is difficult. • Voltage due to lightning surges do not find path to earth. In order to overcome the above mentioned technical and operation issues the concept of system grounding was introduced.

System grounding is connecting the neutral of system to earth. Coefficient of earthing is the ratio which is measured during single phase to ground fault: Ce = Highest phase to ground voltage of healthy phase / Phase to phase voltage In a system without neutral earth ( refer Figure 1), phase to earth voltage phase-1 and phase-2 rises to 3times phase to phase voltage Vrms during single phase to earth fault on phase 3. In a neutral earthed system the voltage ofhealthy phase rises to Ce times Vrms. Therefore value of Ce: • For non-effectively earthed system Ce = 1 • For effectively earthed system Ce 0.8 V rms Surge voltage kV instantaneous is taken as 2.5 times of critical flashover voltage (CFOV) of line insulation. Thus discharge current is given as: I = (2.5(CFOV) –Residual voltage of arrester) / Surge impedance of line. Earth fault factor is a ratio calculated at selected point of the power system for a given system. Earth fault factor = V1/V2 • V1 = Highest RMS phase to phase voltage of healthy phases ( phase 2 and 3 refer to Figure 1) during earth faulton pahse-1 • V2 = RMS value of phase to earth voltage at same location with fault on faulty phases removed References: • Industrial electrical network design guide By Schneider electric • Switchgear protection & power system By Sunil S Rao, Khanna publications • EARTHING: Your questions answered By Geoff Cronshaw • IEEE Recommended Practice for Electric Power Distribution for Industrial Plants.

About Author Asif Eqbal Asif Eqbal - Bachelor of Engineering in Electrical & Electronics engineering, from Manipal University, (Karnataka), India in 2006. Presently involved in the design of EHV outdoor substation and coal fired thermal power plants for more than seven years. Motto of joining EEP as a contributor is to share my little engineering experience and help the budding engineers in bridging the conspicuous gap between academics and Industrial practice. “If you have knowledge, let others light their candles with it, so that people who are genuinely interested in helping one another develop new capacities for action; it is about creating timeless learning processes”.