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6 F 2 S 0 8 5 7
Contents
Safety Precautions 1
1. Introduction 8
2. Application Notes 10
2.1 Protection Scheme 10
2.2 Current Differential Protection 12
2.2.1 Differential Scheme 12
2.2.2 Stability for CT Saturation during Through-fault Conditions 16
2.2.3 Matching of CT Secondary Currents 18
2.2.4 Connection between CT Secondary Circuit and the GRT100 22
2.2.5 Setting 23
2.3 Restricted Earth Fault Protection 34
2.4 Overcurrent Protection 38
2.5 Thermal Overload Protection 43
2.6 Frequency Protection 44
2.7 Overexcitation Protection 46
2.8 Trip by External Devices 48
2.9 Tripping Output 49
2.10 Characteristics of Measuring Elements 51
2.10.1 Percentage Current Differential Element DIF 51
2.10.2 High-set Overcurrent Element HOC 52
2.10.3 Restricted Earth Fault Element REF 52
2.10.4 Inverse Time Overcurrent Element OCI and EFI 54
2.10.5 Definite Time Overcurrent element OC and EF 55
2.10.6 Thermal Overload Element THR 55
2.10.7 Frequency Element FRQ 57
2.10.8 Overexcitation Element V/F 57
3. Technical Description 58
3.1 Hardware Description 58
3.1.1 Outline of Hardware Modules 58
3.1.2 Transformer Module 61
3.1.3 Signal Processing Module 62
3.1.4 Binary Input and Output Module 63
3.1.5 Human Machine Interface (HMI) Module 67
3.2 Input and Output Signals 69
3.2.1 Input Signals 69
3.2.2 Binary Output Signals 70
3.2.3 PLC (Programmable Logic Controller) Function 71
3.3 Automatic Supervision 72
3.3.1 Basic Concept of Supervision 72
3.3.2 Relay Monitoring and Testing 72
3.3.3 PLC Data and IEC61850 Mapping Data Monitoring 73