JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD

Prerequisite

Power Systems and Electrical & Electronics Instrumentation

Course Objectives:

• To distinguish the Gaseous, liquid and solid dielectric behavior under High Voltage.
• To understand the generation methods of High A.C, DC & Impulse Voltages required for various application.
• To apply the measuring techniques of High A.C., D.C & Impulse voltages and currents.
• To identify the testing techniques for High Voltage Equipment.

Course Outcomes

Upon the completion of the subject, the student will be able to

• Know conduction and breakdown will occur in gases, liquids and solids dielectrics, and different applications of the insulating materials in electrical power apparatus.
• Explain the insulation testing of various components in power systems for different types of voltages, namely power frequency A.C, high frequency, switching or lightning impulses, for which generation of high voltages in laboratories is essential
• Interpret the necessity to measure the voltages and currents accurately, ensuring perfect safety to the personnel and equipment.
• Detect the necessary condition for all the electrical equipment which are capable of withstanding the over voltages which met in service like natural causes lightning or system originated ones switching or power frequency transient voltages.

UNIT - I

Introduction To High Voltage Engineering: Electric Field Stresses, Gas / Vacuum as Insulator, Liquid Dielectrics, Solids and Composites, Estimation and Control of Electric Stress, Numerical methods for electric field computation, Surge voltages, their distribution and control, Applications of insulating materials in transformers, rotating machines, circuit breakers, cable power capacitors and bushings.

UNIT - II

Break Down In Dielectric Materials: Gases as insulating media, collision process, Ionization process, Townsend’s criteria of breakdown in gases, Paschen’s law. Liquid as Insulator, pure and commercial liquids, breakdown in pure and commercial liquids. Intrinsic breakdown, electromechanical breakdown, thermal breakdown, breakdown of solid dielectrics in practice, Breakdown in composite dielectrics, solid dielectrics used in practice.

UNIT - III

Generation & Measurement of High Voltages & Currents : Generation of High Direct Current Voltages, Generation of High alternating voltages, Generation of Impulse Voltages, Generation of Impulse currents, Tripping and control of impulse generators. Measurement of High Direct Current voltages, Measurement of High Voltages alternating and impulse, Measurement of High Currents- direct, alternating and Impulse, Oscilloscope for impulse voltage and current measurements.

UNIT - IV

Over Voltages & Insulation Co-Ordination: Natural causes for over voltages – Lightning phenomenon, Overvoltage due to switching surges, system faults and other abnormal conditions, Principles of Insulation Coordination on High voltage and Extra High Voltage power systems.

UNIT - V

Testing of Materials & Electrical Apparatus: Measurement of D.C Resistivity, Measurement of Dielectric Constant and loss factor, Partial discharge measurements. Testing of Insulators and bushings, Testing of Isolators and circuit breakers, testing of cables, Testing of Transformers, Testing of Surge Arresters, and Radio Interference measurements.

TEXT BOOKS:

• 1. High Voltage Engineering by M.S. Naidu and V. Kamaraju – TMH Publications, 3rd Edition
• 2. High Voltage Engineering: Fundamentals by E. Kuffel, W.S. Zaengl, J.Kuffel by Elsevier, 2nd Edition.

REFERENCES:

• 1. High Voltage Engineering by C.L. Wadhwa, New Age Internationals (P) Limited, 1997.
• 2. High Voltage Insulation Engineering by Ravindra Arora, Wolfgang Mosch, New Age International (P) Limited, 1995.
• 3. High Voltage Engineering, Theory and Practice by Mazen Abdel Salam, Hussein Anis, Ahdan El-Morshedy, Roshdy Radwan , Marcel Dekker