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Contents
Section 1: Introduction .....................................................................................................................6
Current Transformer Circuits........................................................................................................6
External Resistors .......................................................................................................................6
Fibre Optic Communication .........................................................................................................6
Front Cover .................................................................................................................................6
Section 2: Hardware Description......................................................................................................9
2.1 General................................................................................................................................9
2.2 Case ....................................................................................................................................9
2.3 Front Cover..........................................................................................................................9
2.4 Power Supply Unit (PSU) ...................................................................................................10
2.5 Operator Interface/ Fascia..................................................................................................10
2.6 Current Inputs ....................................................................................................................12
2.7 Binary inputs ......................................................................................................................13
2.8 Binary Outputs (Output Relays) ..........................................................................................14
2.9 Virtual Input/Outputs...........................................................................................................15
2.10 Self Monitoring ...................................................................................................................15
2.10.1 Protection Healthy/Defective ..................................................................................15
Section 3: Protection Functions.....................................................................................................16
3.1 Overall High Impedance Differential Protection (87/50-n)....................................................17
3.2 Protection: Measured Earth Fault (50G) .............................................................................18
3.3 Protection: Restricted Earth Fault (87REF).........................................................................19
3.4 Protection: Mode Selection.................................................................................................20
3.4.1
'3 Pole Diff' + REF' Operation ................................................................................20
3.4.2
'3 Pole Diff + EF' Operation....................................................................................21
3.4.3
'REF1 + REF2' Operation ......................................................................................22
Section 4: Control & Logic Functions............................................................................................23
4.1 Zone Switching ..................................................................................................................23
4.2 Quick Logic ........................................................................................................................24
Section 5: Supervision Functions..................................................................................................26
5.1 CT Supervision (CT50).......................................................................................................26
5.2 Sustained Fault, CB Fail & CB Position Monitoring .............................................................27
5.2.1
CB/Circuit Position Monitoring................................................................................28
5.2.2
External CB Fail Input (Ext 87CBF) ........................................................................28
5.3 Trip Circuit Supervision (74TCS) ........................................................................................29
Section 6: Other Features...............................................................................................................30
6.1 Data Communications ........................................................................................................30
6.2 IEC 61850 Communications...............................................................................................30
6.3 Maintenance ......................................................................................................................30
6.3.1
Output Matrix Test .................................................................................................30
6.4 Data Storage......................................................................................................................31
6.4.1
General..................................................................................................................31
6.4.2
Event Records .......................................................................................................31
6.4.3
Waveform Records. ...............................................................................................31
6.4.4
Fault Records ........................................................................................................31
6.5 Metering.............................................................................................................................32
6.6 Operating Mode .................................................................................................................33
6.7 Control Mode .....................................................................................................................33
©2013 Siemens Protection Devices Limited
Chapter 1) 7SR23 DAD Description Of Operation
Chapter 1 Page 3 of 36
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