Siemens 7SA511 manual Method of Operation

7SA511 Line Protection RelayReference A

Method of Operation

Table of Contents
A. Method of Operation	A-5
A.1 Overview of Hardware and Protection Functions	A-5
A.2 Distance Protection Overview	A-7
A.2.1 Ground Fault Detection and Processing	A-8
A.2.2 Overcurrent Fault Detection	A-9
A.2.3 Polygonal Impedance Fault Detection (Optional)	A-10
A.2.4 Voltage Controlled Overcurrent Fault Detection (Optional)	A-12
A.3 Determination of the Faulted Loops	A-15
A.3.1 Verification of the Faulted Loop(s)	A-15
A.3.2 Fault Loop Determination in Grounded Systems	A-17
A.3.3 Fault Loop Determination in Ungrounded Systems (Optional)	A-19
A.4 Fault Impedance Calculation	A-24
A.4.1 Impedance Calculation on the Protected Line	A-24
A.4.2 Correction for Parallel Lines (Optional)	A-26
A.5 Directional Determination	A-27
A.5.1 Directional Characteristics	A-27
A.5.2 Directional Characteristics without Load	A-28
A.5.3 Directional Characteristics with Load	A-30
A.6 Tripping Characteristics and Logic	A-32
A.6.1 Tripping Characteristics	A-32
A.6.2 Tripping Logic	A-33
A.7 Switch-Onto-Fault Protection	A-36
A.8 Emergency Overcurrent Protection	A-36
A.9 Power Swing Function	A-37
A.9.1 Detection of Power Swings	A-38
A.9.2 Power Swing Blocking	A-40
A.9.3 Power Swing (Out-of-Step) Trip	A-40
A.10 Pilot Protection	A-41
A.10.1 Permissive Underreach Transfer Trip With Fault Detection	A-45
A.10.2 Permissive Underreach Transfer Trip With Zone Z1B	A-46
A.10.3 Permissive Overreach Transfer Trip With Zone Z1B	A-47
A.10.4 Permissive Overreach Transfer Trip With Fault Detection Zone	A-48
A.10.5 Permissive Overreach Transfer Trip Unblock Scheme with Zone Z1B	A-50
A.10.6 Permissive Overreach Transfer Trip Unblock Scheme With Fault Detection	A-53
A.10.7 Blocking Scheme With Zone Z1B	A-54
A.10.8 Z1B Blocking via Pilot Wires	A-56
A.10.9 Reverse Interlocking	A-58
A.10.10 Echo Keying Function (Weak-Feed Compensation)	A-59
A.10.11 Transient Blocking	A-60
A.11 Isolated Ground Fault Detection (Optional)	A-61
A.11.1 Fault Detection	A-61

July 27, 1995 A-1