
6
HIGH IMPEDANCE REF
The device provides a high impedance restricted earth fault protection function. An external resistor is required to
provide stability in the presence of saturated line current transformers. Current transformer supervision signals do
not block the high impedance REF protection. The appropriate logic must be configured in PSL to block the high
impedance REF when any of the above signals is asserted.
6.1
HIGH IMPEDANCE REF PRINCIPLE
This scheme is very sensitive and can protect against low levels of fault current, typical of winding faults.
High Impedance REF protection is based on the differential principle. It works on the circulating current principle as
shown in the following diagram.
V00671
R
Z
m1
R
CT1
R
L1
Z
m2
V
s
R
CT2
R
L3
I
F
I
S
R
L4
R
L2
Healthy CT
Saturated CT
A-G
Protected
circuit
I
R
ST
I = I
s
+ I
F
Figure 211: High Impedance REF principle
When subjected to heavy through faults the line current transformer may enter saturation unevenly, resulting in
imbalance. To ensure stability under these conditions a series connected external resistor is required, so that most
of the unbalanced current will flow through the saturated CT. As a result, the current flowing through the device
will be less than the setting, therefore maintaining stability during external faults.
Voltage across REF element V
s
= I
F
(R
CT2
+ R
L3
+ R
L4
)
Stabilising resistor R
ST
= V
s
/I
s
–R
R
where:
●
I
F
= maximum secondary through fault current
●
R
R
= device burden
●
R
CT
= CT secondary winding resistance
●
R
L2
and R
L3
= Resistances of leads from the device to the current transformer
●
R
ST
= Stabilising resistor
High Impedance REF can be used for either delta windings or star windings in both solidly grounded and
resistance grounded systems. The connection to a modern IED are as follows:
Chapter 13 - Current Protection Functions
P446SV
376
P446SV-TM-EN-1
Содержание MiCOM P40 Agile
Страница 2: ......
Страница 24: ...Contents P446SV xxii P446SV TM EN 1 ...
Страница 33: ...CHAPTER 1 INTRODUCTION ...
Страница 34: ...Chapter 1 Introduction P446SV 2 P446SV TM EN 1 ...
Страница 46: ...Chapter 1 Introduction P446SV 14 P446SV TM EN 1 ...
Страница 47: ...CHAPTER 2 SAFETY INFORMATION ...
Страница 48: ...Chapter 2 Safety Information P446SV 16 P446SV TM EN 1 ...
Страница 60: ...Chapter 2 Safety Information P446SV 28 P446SV TM EN 1 ...
Страница 61: ...CHAPTER 3 HARDWARE DESIGN ...
Страница 62: ...Chapter 3 Hardware Design P446SV 30 P446SV TM EN 1 ...
Страница 88: ...Chapter 3 Hardware Design P446SV 56 P446SV TM EN 1 ...
Страница 89: ...CHAPTER 4 SOFTWARE DESIGN ...
Страница 90: ...Chapter 4 Software Design P446SV 58 P446SV TM EN 1 ...
Страница 101: ...CHAPTER 5 CONFIGURATION ...
Страница 102: ...Chapter 5 Configuration P446SV 70 P446SV TM EN 1 ...
Страница 124: ...Chapter 5 Configuration P446SV 92 P446SV TM EN 1 ...
Страница 125: ...CHAPTER 6 SAMPLED VALUE OPERATION ...
Страница 126: ...Chapter 6 Sampled Value Operation P446SV 94 P446SV TM EN 1 ...
Страница 136: ...Chapter 6 Sampled Value Operation P446SV 104 P446SV TM EN 1 ...
Страница 137: ...CHAPTER 7 DISTANCE PROTECTION ...
Страница 138: ...Chapter 7 Distance Protection P446SV 106 P446SV TM EN 1 ...
Страница 196: ...Chapter 7 Distance Protection P446SV 164 P446SV TM EN 1 ...
Страница 197: ...CHAPTER 8 CARRIER AIDED SCHEMES ...
Страница 198: ...Chapter 8 Carrier Aided Schemes P446SV 166 P446SV TM EN 1 ...
Страница 240: ...Chapter 8 Carrier Aided Schemes P446SV 208 P446SV TM EN 1 ...
Страница 241: ...CHAPTER 9 NON AIDED SCHEMES ...
Страница 242: ...Chapter 9 Non Aided Schemes P446SV 210 P446SV TM EN 1 ...
Страница 256: ...Chapter 9 Non Aided Schemes P446SV 224 P446SV TM EN 1 ...
Страница 257: ...CHAPTER 10 POWER SWING FUNCTIONS ...
Страница 258: ...Chapter 10 Power Swing Functions P446SV 226 P446SV TM EN 1 ...
Страница 281: ...CHAPTER 11 AUTORECLOSE ...
Страница 282: ...Chapter 11 Autoreclose P446SV 250 P446SV TM EN 1 ...
Страница 376: ...Chapter 11 Autoreclose P446SV 344 P446SV TM EN 1 ...
Страница 377: ...CHAPTER 12 CB FAIL PROTECTION ...
Страница 378: ...Chapter 12 CB Fail Protection P446SV 346 P446SV TM EN 1 ...
Страница 389: ...CHAPTER 13 CURRENT PROTECTION FUNCTIONS ...
Страница 390: ...Chapter 13 Current Protection Functions P446SV 358 P446SV TM EN 1 ...
Страница 416: ...Chapter 13 Current Protection Functions P446SV 384 P446SV TM EN 1 ...
Страница 417: ...CHAPTER 14 VOLTAGE PROTECTION FUNCTIONS ...
Страница 418: ...Chapter 14 Voltage Protection Functions P446SV 386 P446SV TM EN 1 ...
Страница 431: ...CHAPTER 15 FREQUENCY PROTECTION FUNCTIONS ...
Страница 432: ...Chapter 15 Frequency Protection Functions P446SV 400 P446SV TM EN 1 ...
Страница 438: ...Chapter 15 Frequency Protection Functions P446SV 406 P446SV TM EN 1 ...
Страница 439: ...CHAPTER 16 MONITORING AND CONTROL ...
Страница 440: ...Chapter 16 Monitoring and Control P446SV 408 P446SV TM EN 1 ...
Страница 476: ...Chapter 16 Monitoring and Control P446SV 444 P446SV TM EN 1 ...
Страница 477: ...CHAPTER 17 SUPERVISION ...
Страница 478: ...Chapter 17 Supervision P446SV 446 P446SV TM EN 1 ...
Страница 490: ...Chapter 17 Supervision P446SV 458 P446SV TM EN 1 ...
Страница 491: ...CHAPTER 18 DIGITAL I O AND PSL CONFIGURATION ...
Страница 492: ...Chapter 18 Digital I O and PSL Configuration P446SV 460 P446SV TM EN 1 ...
Страница 504: ...Chapter 18 Digital I O and PSL Configuration P446SV 472 P446SV TM EN 1 ...
Страница 505: ...CHAPTER 19 FIBRE TELEPROTECTION ...
Страница 506: ...Chapter 19 Fibre Teleprotection P446SV 474 P446SV TM EN 1 ...
Страница 522: ...Chapter 19 Fibre Teleprotection P446SV 490 P446SV TM EN 1 ...
Страница 523: ...CHAPTER 20 ELECTRICAL TELEPROTECTION ...
Страница 524: ...Chapter 20 Electrical Teleprotection P446SV 492 P446SV TM EN 1 ...
Страница 534: ...Chapter 20 Electrical Teleprotection P446SV 502 P446SV TM EN 1 ...
Страница 535: ...CHAPTER 21 COMMUNICATIONS ...
Страница 536: ...Chapter 21 Communications P446SV 504 P446SV TM EN 1 ...
Страница 606: ...Chapter 21 Communications P446SV 574 P446SV TM EN 1 ...
Страница 607: ...CHAPTER 22 CYBER SECURITY ...
Страница 608: ...Chapter 22 Cyber Security P446SV 576 P446SV TM EN 1 ...
Страница 625: ...CHAPTER 23 INSTALLATION ...
Страница 626: ...Chapter 23 Installation P446SV 594 P446SV TM EN 1 ...
Страница 637: ...CHAPTER 24 COMMISSIONING INSTRUCTIONS ...
Страница 638: ...Chapter 24 Commissioning Instructions P446SV 606 P446SV TM EN 1 ...
Страница 695: ...CHAPTER 25 MAINTENANCE AND TROUBLESHOOTING ...
Страница 696: ...Chapter 25 Maintenance and Troubleshooting P446SV 664 P446SV TM EN 1 ...
Страница 712: ...Chapter 25 Maintenance and Troubleshooting P446SV 680 P446SV TM EN 1 ...
Страница 713: ...CHAPTER 26 TECHNICAL SPECIFICATIONS ...
Страница 714: ...Chapter 26 Technical Specifications P446SV 682 P446SV TM EN 1 ...
Страница 741: ...APPENDIX A ORDERING OPTIONS ...
Страница 742: ...Appendix A Ordering Options P446SV P446SV TM EN 1 ...
Страница 744: ...Appendix A Ordering Options P446SV A2 P446SV TM EN 1 ...
Страница 745: ...APPENDIX B SETTINGS AND SIGNALS ...
Страница 746: ...Appendix B Settings and Signals P446SV P446SV TM EN 1 ...
Страница 954: ...Appendix B Settings and Signals P446SV B208 P446SV TM EN 1 ...
Страница 955: ...APPENDIX C WIRING DIAGRAMS ...
Страница 956: ...Appendix C Wiring Diagrams P446SV P446SV TM EN 1 ...
Страница 960: ......
Страница 961: ......