⎯4⎯
6F2S0846
Contents
Safety Precautions 1
1. Introduction 9
2. Application Notes 12
2.1 Power System Protection - Basic Concepts 12
2.1.1 The Function of The Protection Relay 12
2.1.2 Protection Relay Requirements 12
2.1.4 Distance Relay - General Performance 14
2.1.5 Power Swing and Out-of-Step 15
2.1.6 Redundant Configuration of Protection Relay and Improvement of
Reliability 16
2.2 Principle of Distance Measurement 17
2.2.1 Phase Fault 17
2.2.2 Earth Fault 18
2.3 Multi-Terminal Line Protection 20
2.3.1 Increased Use of Multi-Terminal Lines 20
2.3.2 Protection Problems on Three-Terminal Application 20
2.3.3 Three-Terminal Line Protection 22
2.4 Protection Scheme 24
2.4.1 Time-Stepped Distance Protection 24
2.4.2 Zone 1 Extension Protection 40
2.4.3 Command Protection 43
2.4.4 Directional Earth Fault Protection 60
2.4.5 Overcurrent Backup Protection 65
2.4.6 Thermal Overload Protection 69
2.4.7 Switch-Onto-Fault Protection 72
2.4.8 Stub Protection 73
2.4.9 Overvoltage and Undervoltage Protection 74
2.4.10 Broken Conductor Protection 81
2.4.11 Breaker Failure Protection 84
2.4.12 Out-of-Step Protection 87
2.4.13 Voltage Transformer Failure Supervision 89
2.4.14 Power Swing Blocking 91
2.4.15 Tripping Output Signals 95
2.4.16 Fault Detector 97
2.5 Characteristics of Measuring Elements 100
2.5.1 Distance Measuring Elements Z1, Z1X, Z2, ZF, Z3, Z4, ZR1, ZR2, ZND
and PSB 100
2.5.2 Phase Selection Element UVC 109
2.5.3 Directional Earth Fault Elements DEFF and DEFR 109
2.5.4 Inverse Definite Minimum Time (IDMT) OC, EF, DEF Elements 111
2.5.5 Out-of-Step Element OST 112
