8.3 EPATR B Curve 131
8.4 Directional Element 131
8.4.1 Wattmetric Characteristic 132
8.4.2 Icos phi / Isin phi characteristic 133
8.4.3 Directional SEF Logic 134
8.5 Application Notes 135
8.5.1 Insulated Systems 135
8.5.2 Setting Guidelines (Insulated Systems) 136
9 Cold Load Pickup 138
9.1 Implementation 138
9.2 CLP Logic 139
9.3 Application Notes 139
9.3.1 CLP for Resistive Loads 139
9.3.2 CLP for Motor Feeders 139
9.3.3 CLP for Switch Onto Fault Conditions 140
10 Selective Logic 141
10.1 Selective Logic Implementation 141
10.2 Selective Logic Diagram 141
11 Timer Setting Selection 142
12 Blocked Overcurrent Protection 143
12.1 Blocked Overcurrent Implementation 143
12.2 Blocked Overcurrent Logic 143
12.3 Blocked Earth Fault Logic 143
12.4 Application Notes 144
12.4.1 Busbar Blocking Scheme 144
13 Second Harmonic Blocking 146
13.1 Second Harmonic Blocking Implementation 146
13.2 Second Harmonic Blocking Logic (POC Input) 147
13.3 Application Notes 147
13.3.1 Setting Guidelines 147
14 Stall protection 148
14.1 Prolonged start 148
14.2 Locked rotor during starting – (stall time < start time) 149
14.3 Stall during running 150
14.4 Momentary reduction in system voltage during running 150
14.5 Reacceleration after a reduction in system voltage 150
14.6 Low voltage ride through authorization 151
14.7 Auto re-start authorization restoration sequence 152
14.8 Application Notes 154
14.8.1 Start/stall protection 154
14.8.2 Excessive start time/locked rotor protection - stall time > start time 155
14.8.3 Stall protection (Stall while running) 155
14.8.4 Excessive start time/locked rotor protection - stall time < start time 156
14.8.5 Momentary reduction in system voltage during running of the motor 156
14.8.6 Low voltage protection (reacceleration authorization) 157
14.8.7 AUTO RE-START authorization 157
15 Number of Starts 158
15.1 Time between starts 160
15.2 Number of starts limitation 161
16 Anti-Backspin Protection 162
16.1 Application Notes 163
16.1.1 Anti-Backspin protection 163
Chapter 7 Restricted Earth Fault Protection 165
1 Chapter Overview 167
2 REF Protection Principles 168
Contents P24xM
iv P24xM-TM-EN-2.1
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