An Introduction to High-Voltage Experimental Technique

High-voltage technology is a field of electrical engineering the scientific principles of which are essentially found in Physics and which, by its application, is intimately linked with industrial practice. It is concerned with the physical phenomena and technical problems associated with high voltages. The properties of gases and plasmas, as well as liquid and solid insulating materials, are of fundamental significance to high-voltage technology. However, despite all progress, the physical phenomena observed in these media can only be incompletely explained by theoretical treatment, and so experiment constitutes the foreground of scientific research in this field. Teaching and research in high-voltage technology thus rely mainly upon experimental techniques when dealing with problems. Recognition of this fact is the conceptual basis for the present book. It is primarily intended for students of electrical engineering and aims to provide the reader with the most important tools for the experimental approach to problems in high-voltage technology. An attempt has been made here to indicate important practical problems of testing stations and laboratories, and to suggest solutions. The book should therefore also prove to be a help to the work of the practising engineer. The theoretical considerations are correlated with the experiments of a high-voltage practical course, which are described in great detail. The treatment assumes as much familiarity with the subject as may be expected from 3rd year students of electrical engineering.

1 Fundamental Principles of High-Voltage Experimental Techniques.- 1.1 Generation and Measurement of High Alternating Voltages.- 1.1.1 Characteristic Parameters of High Alternating Voltages.- 1.1.2 Test Transformer Circuits.- 1.1.3 Construction of Test Transformers.- 1.1.4 Performance of Test Transformers.- 1.1.5 High Voltage Generation with Resonant Circuits.- 1.1.6 Peak Voltage Measurement with Sphere Gaps.- 1.1.7 Peak Voltage Measurement Using Measuring Capacitors.- 1.1.8 Peak Value Measurement with Capacitive Voltage Dividers.- 1.1.9 Measurement of r.m.s. Values by Means of Electrostatic Voltmeters.- 1.1.10 Measurements with Voltage Transformers.- 1.2 Generation and Measurement of High Direct Voltages.- 1.2.1 Characteristic Parameters of High Direct Voltages.- 1.2.2 Properties of High-Voltage Rectifiers.- 1.2.3 The Half-Period Rectifier Circuit.- 1.2.4 Voltage Multiplier Circuits.- 1.2.5 Electrostatic Generators.- 1.2.6 Measurements with High-Voltage Resistors.- 1.2.7 Measurement of r.m.s. Values by Means of Electrostatic Voltmeters.- 1.2.8 Voltmeter and Field Strength Meter Based upon the Generator Principle.- 1.2.9 Other Methods for the Measurement of High Direct Voltages.- 1.2.10 Measurement of Ripple Voltages.- 1.3 Generation and Measurement of Impulse Voltages.- 1.3.1 Characteristic Parameters of Impulse Voltages.- 1.3.2 Capacitive Circuits for Impulse Voltage Generation.- 1.3.3 Calculation of Single-Stage Impulse Voltage Circuits.- 1.3.4 Further Means of Generating Impulse Voltages.- 1.3.5 Peak Value Measurement Using a Sphere Gap.- 1.3.6 Circuit and Transient Response of Impulse Voltage Dividers.- 1.3.7 Experimental Determination of the Response Characteristics of Impulse Voltage Measuring Circuits.- 1.4 Generation and Measurement of Impulse Currents.- 1.4.1 Characteristic Parameters of Impulse Currents.- 1.4.2 Energy Storage Systems.- 1.4.3 Discharge Circuits for the Generation of Impulse Currents.- 1.4.4 Current Measurement with Measuring Resistors.- 1.4.5 Current Measurement Using Induction Effects.- 1.4.6 Other Methods of Measuring Rapidly Varying Transient Currents.- 1.5 Non-Destructive High-Voltage Tests.- 1.5.1 Loss in a Dielectric.- 1.5.2 Measurement of the Conduction Current for Direct Voltage.- 1.5.3 Measurement of the Dissipation Factor for Alternating Voltage.- 1.5.4 Measurement of Partial Discharges at Alternating Voltages.- 2 Layout and Operation of High-Voltage Laboratories.- 2.1 Dimensions and Technical Equipment of the Laboratories.- 2.1.1 Stands for High-Voltage Practicals.- 2.1.2 High-Voltage Testing Bays.- 2.1.3 High-Voltage Research Laboratories.- 2.1.4 Auxiliary Facilities for Large Laboratories.- 2.2 Fencing, Earthing and Shielding of Experimental Setups.- 2.2.1 Fencing.- 2.2.2 Earthing Equipment.- 2.2.3 Shielding.- 2.3 Circuits for High-Voltage Experiments.- 2.3.1 Power Supply and Safety Circuits.- 2.3.2 Setting up High-Voltage Circuits.- 2.4 Construction Elements for High-Voltage Circuits.- 2.4.1 High-Voltage Resistors.- 2.4.2 High-Voltage Capacitors.- 2.4.3 Gaps.- 2.4.4 High-Voltage Construction Kit.- 3 High-Voltage Practicals.- 3.1 Experiment “Alternating Voltages”.- 3.1.1 Fundamentals: Safety Arrangements ― Testing Transformers ― Peak Value Measurement ― r.m.s. Value Measurement ― Sphere Gaps.- 3.1.2 Experiment.- 3.1.3 Evaluation.- 3.2 Experiment “Direct Voltages”.- 3.2.1 Fundamentals: Rectifier Characteristics ― Ripple Factor ― Greinacher Doubler-Circuit ― Polarity Effect ― Insulating Barriers.- 3.2.2 Experiment.- 3.2.3 Evaluation.- 3.3 Experiment “Impulse Voltages”.- 3.3.1 Fundamentals: Lightning Impulse Voltages ― Single Stage Impulse Voltage Circuits ― Peak Value Measurement with Sphere Gaps ― Breakdown Probability.- 3.3.2 Experiment.- 3.3.3 Evaluation.- 3.4 Experiment “Electric Field”.- 3.4.1 Fundamentals: Graphical Field Determination ― Model Measurements in Electric Fields ― Field Measurements at High Voltages.- 3.4.2 Experiment.- 3.4.3 Evaluation.- 3.5 Experiment “Liquid and Solid Insulating Materials”.- 3.5.1 Fundamentals: Insulating Oil and Solid Insulating Material ― Conductivity Measurement ― Dissipation Factor Measurement ― Fibre-Bridge Breakdown ― Thermal Breakdown ― Breakdown Test.- 3.5.2 Experiment.- 3.5.3 Evaluation.- 3.6 Experiment “Partial Discharges”.- 3.6.1 Fundamentals: External Partial Discharges (Corona) ― Internal Partial Discharges ― Gliding Discharges.- 3.6.2 Experiment.- 3.6.3 Evaluation.- 3.7 Experiment “Breakdown of Gases”.- 3.7.1 Fundamentals: Townsend Mechanism ― Streamer Mechanism ― Insulating Gases.- 3.7.2 Experiment.- 3.7.3 Evaluation.- 3.8 Experiment “Impulse Voltage Measuring Technique”.- 3.8.1 Fundamentals: Multiplier Circuit after Marx ― Impulse Voltage Divider ― Impulse Voltage-Time Curves.- 3.8.2 Experiment.- 3.8.3 Evaluation.- 3.9 Experiment “Transformer Test”.- 3.9.1 Fundamentals: Specifications for High-Voltage Tests ― Insulation Coordination ― Breakdown Test of Insulating Oil ― Transformer Test with Alternating Voltage ― Transformer Test with Lightning Impulse Voltage.- 3.9.2 Experiment.- 3.9.3 Evaluation.- 3.10 Experiment “Internal Overvoltages”.- 3.10.1 Fundamentals: Neutral Shift ― Earthing Coefficient ― Magnetization Characteristic ― Jump Resonance ― Subharmonic Oscillations.- 3.10.2 Experiment.- 3.10.3 Evaluation.- 3.11 Experiment “Travelling Waves”.- 3.11.1 Fundamentals: Lightning Overvoltages ― Switching Overvoltages ― Surge Diverter ― Protective Range ― Waves in Windings ― Impulse Voltage Distribution.- 3.11.2 Experiment.- 3.11.3 Evaluation.- 3.12 Experiment “Impulse Currents and Arcs”.- 3.12.1 Fundamentals: Discharge Circuit with Capacitive Energy Storage ― Impulse Current Measurement ― Forces in a Magnetic Field ― Alternating Current Arc ― Arc Quenching.- 3.12.2 Experiment.- 3.12.3 Evaluation.- Appendix 1 Safety Regulations for High-Voltage Experiments.- Appendix 2 Calculation of the Short-Circuit Impedance of Transformers in Cascade Connection.- Appendix 3 Calculation of Single-Stage Impulse Voltage Circuits.- Appendix 4 Calculation of the Impedance of Plane Conductors.- Appendix 5 Statistical Evaluation of Measured Results.- References.