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SWITCH, GEAR & PROTECTION
1 Introduction
Need for protective systems
Nature and causes of faults
Types of faults
Effects of faults
Fault statistics
Evolution of protective relays
Zones of protection
Primary and back-up-protection
Essential qualities of protection
Performance of protective relays
Classification of protection system
Classification of protective schemes
Automatic reclosing
Current transformers for protection
Voltage transformers
Basic relay terminology
Exercise
2 Relay construction and operating principles
Introduction
Electromechanical relays
Static relays
Numerical relays
Comparison between electromechanical relays
And numerical relays
Exercises
3 Current and voltage transformers
Introduction
Current transformers
Voltage transformers
Summation transformer
Phase-sequence current-segregating network
Exercises
4 Fault analysis
Introduction
Per-unit system
One-line diagram
Impedance and reactance diagrams
Symmetrical fault analysis
Symmetrical components
Unsymmetrical fault analysis
Grounding earthling
Exercises
5 Over current protection
Introduction
Time-current characteristics
Current setting
Time setting
Over current protective schemes
Reverse power or directional relay
Protection of parallel feeders
Protection of ring mains
Earth fault and phase fault protection
Combined earth fault and phase fault
Protective scheme
Phase fault protective scheme
Directional earth fault relay
Static over current relays
Numerical over current relays
Exercises
6 Distance protection
Introduction
Impedance relay
Reactance relay
MHO
Angle impedance relay
Input quantities for various types of
Distance relays
Sampling comparator
Effect of arc resistance on the performance of
Distance relays
Sampling comparator
Effect of arc resistance on the performance of distance relays
Reach of distance relays
Effect of power surges on the performance of distance relays
Effect of line length and source impedance on
Distance relays
Selection of distance relays
MHO relay with blinders
Quadrilateral relay
Elliptical relay
Restricted MHO relay
Restricted impedance relay
Restricted directional relay
Restricted reactance relay
Some other distance relay characteristics
Swiveling characteristics
Choice of characteristics for different zones of
Protection
Compensation for correct distance measurement
Reduction of measuring units
Switched schemes
Auto-reclosing
Appendix
Exercises
7 Pilot relaying schemes
Introduction
Wire pilot protection
Carrier current protection
Exercises
8 Differential protection
Introduction
Differential relays
Simple differential protection
Percentage or biased differential relay
Differential protection of 3-phase circuits
Balanced voltage differential
Protection
Exercises
9 Rotating machines protection
Introduction
Protection
Protection of generators
Exercises
10 Transformer and buzzone protection
Introduction
Transformer protection
Buszone protection
Frame leakage protection
Exercises
11 Numerical protections
Introduction
Numerical relay
Data acquisition system
Numerical relaying algorithms
Mann-Morrison technique
Differential equation technique
Discrete fourier transform technique
Walsh-hadamard transforms technique
Block pulse functions technique
Wavelet transforms technique
Block pulse functions technique
Wavelet transform technique
Removal of the dc offset
Numerical over current protection
Numerical distance protection
Numerical differential protection
Exercises
12 Microprocessor-based numerical protective relays
Introduction
IC elements and circuits for interfaces
A/D converter, analog multiplexer, S/H circuit
Over current relays
Impedance relay
Directional relay
Reactance relay
Generalized mathematical expression for
Distance relays
Measurement of R and X
Mho and offset Mho Relays
Quadrilateral relay
Generalized relay
Generalized interface for distance relays
Microprocessor implementation of digital distance
Relaying algorithms
Exercises
13 Artificial intelligence based numerical protection
Introduction
Artificial neural network
Fuzzy logic
Application of ANN to over current protection
Application of ANN to transmission line
Protection
Neural network based directional relay
ANN modular approach for fault detection
Classification and location
Wavelet fuzzy combined approach for fault detection
Classification and location
Application of ANN to power transformer
Protection
Power transformer protection based on neural network and fuzzy logic
Network and fuzzy logic
Power transformer protection based upon combined
Wavelet transform and neural network
Application of ANN to generator protection
Exercises
14 circuits breakers
Introduction
Fault clearing time of a circuit breaker
Arc voltage
Arc interruption
Restriking voltage and recovery voltage
Resistance switching
Current chopping
Interruption of capacitive current
Classification of circuit breakers
Air-break circuits breakers
Oil circuit breakers
Air blast circuit breakers
SF6 circuit breakers
Vacuum circuit breakers
Operating mechanism
Testing of circuits breakers
Exercises
15 Fuses
Introduction
Definitions
Fuse characteristics
Types of fuses
Applications of HRC fuses
Selection of fuses
Discrimination
Exercises
16 protection against overvoltage’s
Causes of overvoltages
Lightning phenomena
Wave shape of voltage due to lightning overvoltages due to lighting
Klydonograph and magnetic link
Protection of transmission lines against direct
Lighting strokes
Protection of stations and sub-stations from
Direct strokes
Protection against travelling waves
Peterson coil
Insulation coordination
Basic impulse insulation level
Exercises
17 Modern trends in power system protection
Introduction
Gas insulated substation/switchgear
Frequency relays and load-shedding
Field programmable gate arrays based relays
Adaptive protection and control
Relay reliability advantages of fast fault clearing
Exercises