15.3 Second Harmonic Blocking Logic (SEF Input) 15115.4 Application Notes 15115.4.1 Setting Guidelines 15116 Load Blinders 15216.1 Load Blinder Implementation 15216.2 Load Blinder Logic 15317 Neutral Admittance Protection 15617.1 Neutral Admittance Operation 15617.2 Conductance Operation 15617.3 Susceptance Operation 15718 Busbar Protection 15918.1 Buswire Supervision 160Chapter 7 Restricted Earth Fault Protection 1611 Chapter Overview 1632 REF Protection Principles 1642.1 Resistance-Earthed Star Windings 1652.2 Solidly-Earthed Star Windings 1652.3 Through Fault Stability 1662.4 Restricted Earth Fault Types 1662.4.1 Low Impedance REF Principle 1672.4.2 High Impedance REF Principle 1683 Restricted Earth Fault Protection Implementation 1713.1 Restricted Earth Fault Protection Implementation 1713.2 Low Impedance REF 1713.2.1 Setting the Bias Characteristic 1713.2.2 Delayed Bias 1723.2.3 Transient Bias 1723.3 High Impedance REF 1723.3.1 High Impedance REF Calculation Principles 1734 Application Notes 1744.1 Star Winding Resistance Earthed 1744.2 Low Impedance REF Protection Application 1754.2.1 Setting Guidelines for Biased Operation 1754.2.2 Low Impedance REF Scaling Factor 1754.2.3 Parameter Calculations 1764.3 High Impedance REF Protection Application 1774.3.1 High Impedance REF Operating Modes 1774.3.2 Setting Guidelines for High Impedance Operation 178Chapter 8 CB Fail Protection 1811 Chapter Overview 1832 Circuit Breaker Fail Protection 1843 Circuit Breaker Fail Implementation 1853.1 Circuit Breaker Fail Timers 1853.2 Zero Crossing Detection 1854 Circuit Breaker Fail Logic 1875 Undercurrent and ZCD Logic for CB Fail 1906 CB Fail SEF Protection Logic 1917 CB Fail Non Current Protection Logic 1928 Circuit Breaker Mapping 1939 Application Notes 1949.1 Reset Mechanisms for CB Fail Timers 1949.2 Setting Guidelines (CB fail Timer) 1949.3 Setting Guidelines (Undercurrent) 195P14x ContentsP14xEd1-TM-EN-1 v
