Contents
Preface to the second edition
Preface to the first edition
Simple protection devices
Direct-acting trip
Thermal trip
Time-limit fuses
Thermal overload devices
Oil dashpots
Fuses
Moulded-case circuit-breakers
Relays
Induction relays
Typical applications
Attracted-armature relays
Typical applications
Moving-coil relays
Thermal relays
Timing relays
Design
Static relays
Current and voltage transformers for protection
Current transformers
Construction
Design
Burden
Operation
Open-circuited current transformer
Short-time factor
Accuracy limit factor
Specification of current transformers
Rated secondary current
Secondary winding impedance
Primary windings
Application
Effect of CT magnetising current on relay setting
Residual connection
Quadrature or air-gap current transformers
Summation current transformer
Voltage transformers
Accuracy
Protection
Residual connection
Capacitor voltage transformers
Fault calculations
Impedance
Fault level
Generators
Cables
Source impedance
Motors
Practical example
Current distribution
Earth faults
Time-graded overcurrent protection
Settings
Time-multiplier setting
Application
Discrimination with fuses
Typical calculation
Earth-fault protection
Directional protection
Directional relays
Very inverse characteristic
Extremely inverse characteristic
High multiples of setting
Unit protection
Relays
Application
Protection of a motor
CT knee-point voltage
Overall setting
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