GE P742

A
pplication Notes P74x/EN AP/N
a7
MiCOM P74
1, P742, P743 (AP) 6-
1
AP
CONTENTS
1. INTRODUCTION 3
1.1 Protection of Substation Busbars 3
2. APPLICATION OF INDIVIDUAL PROTECTION FUNCTIONS 4
2.1 Busbar Protection 4
2.1.1 Busbar Protection Setting guidelines 4
2.2 Additional protections 14
2.2.1 Dead Zone protection (DZ) 14
2.2.2 Over Current protection (OC) 15
2.2.3 Earth Fault protection (EF) 15
2.2.4 Stub protection 15
2.2.5 Circuit Breaker Fail (CBF) 16
2.2.6 External Fault Detection by High-Set Overcurrent or Earth Fault Element 16
2.2.7 Setting guidelines 18
2.2.8 EIA(RS)232 InterMiCOM (“MODEM InterMiCOM”) 18
3. CURRENT TRANSFORMERS 20
3.1 Current Transformers Supervision 20
3.1.1 “Low voltage” Current Transformers Supervision 20
3.1.2 ““High Voltage” Current Transformers Supervision 20
4. CIRCUIT BREAKER FUNCTION 21
4.1 Circuit breaker state monitoring 21
4.2 Trip relays and Trip Circuit Supervision 21
4.2.1 TCS scheme 1 21
4.2.2 Scheme 1 PSL 22
4.2.3 TCS scheme 2 23
4.2.4 Scheme 2 PSL 23
4.2.5 TCS scheme 3 24
4.2.6 Scheme 3 PSL 24
5. ISOLATION AND REDUCED FUNCTION MODE 25
5.1 Normal mode 25
5.2 Peripheral Units (P742 and P743) 25
5.2.1 CB Failure Protection (50BF) disabled 25
5.2.2 Overhaul 26
5.3 Central processing unit (P741) 28
5.3.1 Busbar protection (87BB) Blocked 28
5.3.2 87BB Blocked & 50BF disabled 28
5.4 System operation under failed communications situation 28
5.5 Waiting Configuration 29
6. TOPOLOGY 30
6.1 Topology Configuration Tool 30
6.2 Nodal Assignment 31
6.3 Topology Communication 32
6.4 Topology data 32