Electrical (Generator and Electrical Plant)

List of Illustrations

Chapter 1. The Generator


1.1. Introduction


1.2. Design Characteristics and Ratings of Generators


1.2.1. Simple A.C. Generators


1.2.2. Armature Reaction


1.2.3. Short-circuit Ratio (S.C.R.)


1.2.4. Synchronous Reactance


1.2.5. Machine Reactances under Short-circuit Conditions


1.2.6. The Rating of Generators


1.3. Development of Large Generators


1.3.1. Electrical Developments


1.3.2. Mechanical Developments


1.3.3. Ventilation System Developments


1.3.4. Excitation System Developments


1.3.5. Future Developments


1.4. Design of Large Generators


1.4.1. Flux and Voltage Calculations


1.4.2. The Magnetic Circuit


1.4.3. Stator and Rotor Windings


1.4.4. Leakage Reactance


1.4.5. Gap Length and Short-circuit Ratio


1.4.6. Voltage Wave-Form


1.4.7. Inertia Constant


1.4.8. Mechanical Design


1.4.9. The Ventilation Systems


1.4.10. Excitation System Design


1.4.11. An Introduction to Computer Applications in Design


1.5. Turbo-Generator Construction


1.5.1. Stator Frame


1.5.2. Stator Core


1.5.3. Stator Windings


1.5.4. Rotor Construction


1.6. Operation of Turbo-Generators


1.6.1. Charging and Discharging Hydrogen Systems


1.6.2. Single Generator Supplying an Isolated Load


1.6.3. Power Angle Equation


1.6.4. Operation of Generators in Parallel


1.6.5. Generator on Infinite Bus-Bars


1.6.6. Transient Stability


1.6.7. Asynchronous Operation of Generators


1.6.8. Generators used as Synchronous Compensators

Some of the British Standards Applicable to the Generator

References

Exercises

Appendix

Chapter 2. Main Switchgear


2.1. Introduction


2.2. Design Principles and Short-circuit Requirements


2.2.1. Principles of Current Interruption


2.2.2. Short-circuit Requirements


2.3. Circuit-breakers and Associated Equipment


2.3.1. Oil Circuit-breakers


2.3.2. Air-Blast Circuit-breakers


2.3.3. Sulfur Hexafluoride Circuit-breakers


2.3.4. Insulation


2.3.5. Contacts


2.3.6. Circuit-breaker Mechanisms


2.3.7. Compressed Air Systems


2.3.8. Application of Auto-reclose


2.3.9. Isolators and Earth Switches


2.4. Performance Requirements and Proving


2.4.1. Ratings Employed


2.4.2. Insulation Level


2.4.3. Normal Current-Carrying Capacity


2.4.4. Short-circuit Capacity


2.4.5. Low-Temperature Tests


2.4.6. Mechanical Tests


2.4.7. Circuit Arrangements


2.4.8. Calculation of Short-circuit Currents


2.5. Switchgear Assemblies


2.5.1. Metal-Clad Switchgear


2.5.2. Open-Type Switchgear


2.5.3. Selection of Type of Switchgear


2.6. Maintenance and Operation


2.6.1. Earthing for Maintenance


2.6.2. Interlocks


2.6.3. Operational Limitations


2.6.4. Safety Rules and Safety Clearances


2.6.5. Oil Treatment


2.6.6. Sampling and Testing of Switchgear Insulating Oil


2.6.7. Routine Testing and Maintenance


2.7. Future Trends

References

Exercises

Chapter 3. Electrical Auxiliary System and Equipment


3.1. Introduction


3.2. The System


3.2.1. General


3.2.2. Description of a 4X500 MW Station Electrical System


3.2.3. Method of Operation


3.2.4. Difficulties of Paralleling and Connection to the Grid


3.2.5. Classification of Auxiliaries


3.2.6. Unit Auxiliary Loads and Unit Transformer Rating


3.2.7. Service Loads and Station Transformer Rating


3.2.8. Choice of Voltages and Motor Ratings


3.2.9. Switchgear Ratings and Transformer Reactances


3.2.10. Voltage Regulation


3.2.11. Protection and Interlocking


3.3. Gas Turbines


3.3.1. General


3.3.2. Description of Plant


3.3.3. Application on Large Steam Generating Stations


3.4. Switchgear


3.4.1. General


3.4.2. Type and Rating


3.4.3. Duty of Switchgear


3.4.4. Operating Mechanism


3.4.5. Safety and Interlocking


3.4.6. Testing


3.4.7. Air-break Circuit-breakers—3.3 kV-150 MVA


3.4.8. Air-break Circuit-breakers—6.6 kV and 11 kV


3.4.9. Oil Circuit-breakers—3.3 kV- 6.6 kV and 11 kV


3.4.10. Air Break Circuit-breakers—415 volt


3.4.11. Metal-Clad Fuse-Switches—415 volt and 240 volt


3.4.12. Contactor Gear—415 volts


3.4.13. Switchgear Maintenance


3.5. Electric Motors


3.5.1 General


3.5.2 Performance


3.5.3 Enclosure


3.5.4 Windings and Insulation


3.5.5 Bearings


3.5.6 Terminal Boxes


3.5.7 Squirrel Cage Induction Motors


3.5.8 Slip-Ring Induction Motors


3.5.9 Variable Speed A.C. Motors


3.5.10 Direct Current Motors


3.6. Protection—Relays and Fuses


3.6.1. General


3.6.2. Relays


3.6.3. Fuses


3.7. Interlocking and Sequencing


3.7.1. Interlocking


3.7.2. Sequencing


3.8. Converting Machinery


3.8.1. General


3.8.2. Motor Generator Sets


3.8.3. Rotary Converter


3.8.4. Mercury Arc Rectifier


3.9. Earthing Resistances


3.9.1. General


3.9.2. Liquid Earthing Resistances


3.9.3. Metal Earthing Resistances


3.10. Future Trends


3.10.1. The System


3.10.2. Switchgear


3.10.3. Motors


3.10.4. Automation and Computer Control

Exercises

Chapter 4. Transformers, Reactors and Power Cables


4.1. Transformers


4.1.1. Introduction


4.1.2. Characteristics


4.2. Power Transformers


4.3. Construction and Assembly of Transformers


4.3.1. The Core


4.3.2. The Windings


4.3.3. On-Load Tap Changer


4.3.4. Tanks


4.3.5. Bushings


4.3.6. Auxiliary Equipment


4.3.7. Insulating Oil


4.3.8. Cooling Systems


4.4. Testing


4.4.1. Factory Assembly Tests


4.4.2. Iron and Copper Losses


4.4.3. Overpotential and High-voltage Impulse Test


4.4.4. Temperature-Rise Tests


4.4.5. Short-circuit Equivalent Run


4.4.6. The Back-to-Back Test


4.5. Commissioning


4.5.1. Phasing Out


4.5.2. Oil Filling


4.5.3. Drying Out


4.6. Operation and Maintenance


4.6.1. Parallel Operation


4.6.2. Overloads


4.6.3. Tap Changers


4.6.4. Cooling Tubes


4.6.5. Oil Pumps


4.6.6. Oil


4.6.7. Silica-gel Breathers


4.7. Reactors


4.7.1. Introduction


4.7.2. Types of Series Reactor


4.8. Aspects of the Design of High-voltage Power Transformers


4.8.1. General Procedure


4.8.2. Limited Variables


4.8.3. Calculation Variables


4.8.4. Considerations of Maximum Efficiency


4.8.5. Considerations of Minimum Prime Cost


4.8.6. Significance of Derived Criteria


4.8.7. The Resultant Characteristics


4.8.8. Surge Response and Its Impact on Design


4.9. Power Cables


4.9.1. Introduction


4.9.2. Types of Cables


4.10. Development of Power Cables


4.10.1. Generating Board's Usage and Comparative Costs


4.10.2. Cable Developments


4.11. Water Cooling of Buried E.H.V. Cable Circuits


4.12. Other Types of Cables


4.12.1. Heavy Flexible Cables


4.12.2. Cables to Use Where There is Risk of Fire or Overheating


4.12.3. Submarine Cables


4.13. Design Characteristics of Cables


4.13.1. General Considerations


4.13.2. Determination of Insulation Thickness


4.14. Testing


4.14.1. Type Tests


4.14.2. Loading Cycle Test


4.14.3. Hot Impulse Voltage Test


4.15. Installation


4.16. Commissioning Tests


4.17. Maintenance


4.18. Present Trends and Future Possibilities

References

Exercises

Chapter 5. Protective Gear and Voltage Regulators


5.1. Introduction


5.2. Protective Gear Development and Practice


5.2.1. Development


5.2.2. Practice


5.2.3. Main and Back-up Protection


5.3. Protective Relays


5.3.1. Induction Overcurrent and Earth-Leakage Relays


5.3.2. Balanced-beam (Electromagnetic) Relays


5.3.3. Permanent-Magnet Moving-Coil Relays


5.3.4. Attracted Armature Relays


5.3.5. Gas- and Oil-Operated Relays


5.3.6. Over-Temperature Relays


5.4. Feeder Protection


5.4.1. Pilot-Wire Schemes


5.4.2. Carrier Current Protection


5.4.3. Distance Protection


5.5. Bus-Bar Protection


5.5.1. The Simple Merz-Price Balanced Current (or Circulating-Current) System


5.5.2. Application of Bus-Bar Protection to C.E.G.B. Transmission Systems


5.5.3. 400 kV Bus-Bar Protection


5.5.4. 275 kV and 132 kV Bus-Bar Protection


5.5.5. H.V. and L.V. Connection Protection


5.6. Generator, Transformer and Motor Protection


5.6.1. Typical Methods of Neutral Earthing


5.6.2. Characteristics of Generators


5.6.3. Types of Faults and Appropriate Protective Gear


5.6.4. Transformer Protection


5.6.5. Current Practice


5.6.6. Testing Procedure


5.6.7. Motor Protection


5.7. Automatic Voltage Regulators


5.7.1. The Duty of the Automatic Voltage Regulator


5.7.2. Electromechanical Regulators—The Direct Acting Rheostat Regulator


5.7.3. Electromechanical Regulators—The Direct Acting Vibrator Regulator


5.7.4. Electromechanical Regulators—The Indirect Acting Rheostatic Type


5.7.5. The Reference of Electromechanical Regulators


5.7.6. Limitations of Electromechanical Voltage Regulators


5.7.7. Modern Regulator Developments


5.7.8. Thermionic Amplifier Type Regulator


5.7.9. Disadvantages of Thermionic Amplifier Type Regulators


5.7.10. Magnetic Amplifier Type Regulators


5.7.11. Modern Voltage Regulator in Relation to System Stability and Operation at Leading Power Factors

References

Exercises