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5
SENSITIVE EARTH FAULT PROTECTION
With some earth faults, the fault current flowing to earth is limited by either intentional resistance (as is the case
with some HV systems) or unintentional resistance (e.g. in very dry conditions and where the substrate is high
resistance, such as sand or rock).
To provide protection in such cases, it is necessary to provide an earth fault protection system with a setting that is
considerably lower than for normal line protection. Such sensitivity cannot be provided with conventional CTs,
therefore the SEF input would normally be fed from a core balance current transformer (CBCT) mounted around
the three phases of the feeder cable. The SEF transformer should be a special measurement class transformer.
5.1
SEF PROTECTION IMPLEMENTATION
The product provides four stages of SEF protection with independent time delay characteristics.
Stages 1, 2 provide a choice of operate and reset characteristics, where you can select between:
●
A range of IDMT (Inverse Definite Minimum Time) curves
●
DT (Definite Time)
This is achieved using the cells
●
ISEF>(n) Function for the overcurrent operate characteristic
●
ISEF>(n) Reset Chr for the overcurrent reset characteristic
where (n) is the number of the stage.
Stages 1 and 2 also provide a Timer Hold facility. This is configured using the cells ISEF>(n) tReset.
Stages 3 and 4 have definite time characteristics only.
Each stage can be individually inhibited with a DDB signal Inhibit ISEF>(n), where n is the stage number.
5.2
EPATR B CURVE
The EPATR B curve is commonly used for time-delayed Sensitive Earth Fault protection in certain markets. This
curve is only available in the Sensitive Earth Fault protection stages 1 and 2. It is based on primary current settings,
employing a SEF CT ratio of 100:1 A.
The EPATR_B curve has 3 separate segments defined in terms of the primary current. It is defined as follows:
Segment
Primary Current Range Based on 100A:1A CT Ratio
Current/Time Characteristic
1
ISEF = 0.5A to 6.0A
t = 432 x TMS/ISEF 0.655 secs
2
ISEF = 6.0A to 200A
t = 800 x TMS/ISEF secs
3
ISEF above 200A
t = 4 x TMS secs
where TMS (time multiplier setting) is 0.025 - 1.2 in steps of 0.025.
P54A/B/C/E
Chapter 9 - Current Protection Functions
P54xMED-TM-EN-1
207
Содержание P4A
Страница 2: ......
Страница 20: ...Contents P54A B C E xviii P54xMED TM EN 1 ...
Страница 27: ...CHAPTER 1 INTRODUCTION ...
Страница 28: ...Chapter 1 Introduction P54A B C E 2 P54xMED TM EN 1 ...
Страница 38: ...Chapter 1 Introduction P54A B C E 12 P54xMED TM EN 1 ...
Страница 39: ...CHAPTER 2 SAFETY INFORMATION ...
Страница 40: ...Chapter 2 Safety Information P54A B C E 14 P54xMED TM EN 1 ...
Страница 52: ...Chapter 2 Safety Information P54A B C E 26 P54xMED TM EN 1 ...
Страница 53: ...CHAPTER 3 HARDWARE DESIGN ...
Страница 54: ...Chapter 3 Hardware Design P54A B C E 28 P54xMED TM EN 1 ...
Страница 86: ...Chapter 3 Hardware Design P54A B C E 60 P54xMED TM EN 1 ...
Страница 87: ...CHAPTER 4 SOFTWARE DESIGN ...
Страница 88: ...Chapter 4 Software Design P54A B C E 62 P54xMED TM EN 1 ...
Страница 99: ...CHAPTER 5 CONFIGURATION ...
Страница 100: ...Chapter 5 Configuration P54A B C E 74 P54xMED TM EN 1 ...
Страница 120: ...Chapter 5 Configuration P54A B C E 94 P54xMED TM EN 1 ...
Страница 121: ...CHAPTER 6 CURRENT DIFFERENTIAL PROTECTION ...
Страница 122: ...Chapter 6 Current Differential Protection P54A B C E 96 P54xMED TM EN 1 ...
Страница 149: ...CHAPTER 7 AUTORECLOSE ...
Страница 150: ...Chapter 7 Autoreclose P54A B C E 124 P54xMED TM EN 1 ...
Страница 207: ...CHAPTER 8 CB FAIL PROTECTION ...
Страница 208: ...Chapter 8 CB Fail Protection P54A B C E 182 P54xMED TM EN 1 ...
Страница 219: ...CHAPTER 9 CURRENT PROTECTION FUNCTIONS ...
Страница 220: ...Chapter 9 Current Protection Functions P54A B C E 194 P54xMED TM EN 1 ...
Страница 244: ...Chapter 9 Current Protection Functions P54A B C E 218 P54xMED TM EN 1 ...
Страница 247: ...CHAPTER 10 VOLTAGE PROTECTION FUNCTIONS ...
Страница 248: ...Chapter 10 Voltage Protection Functions P54A B C E 222 P54xMED TM EN 1 ...
Страница 261: ...CHAPTER 11 FREQUENCY PROTECTION FUNCTIONS ...
Страница 262: ...Chapter 11 Frequency Protection Functions P54A B C E 236 P54xMED TM EN 1 ...
Страница 268: ...Chapter 11 Frequency Protection Functions P54A B C E 242 P54xMED TM EN 1 ...
Страница 269: ...CHAPTER 12 MONITORING AND CONTROL ...
Страница 270: ...Chapter 12 Monitoring and Control P54A B C E 244 P54xMED TM EN 1 ...
Страница 300: ...Chapter 12 Monitoring and Control P54A B C E 274 P54xMED TM EN 1 ...
Страница 301: ...CHAPTER 13 SUPERVISION ...
Страница 302: ...Chapter 13 Supervision P54A B C E 276 P54xMED TM EN 1 ...
Страница 312: ...Chapter 13 Supervision P54A B C E 286 P54xMED TM EN 1 ...
Страница 323: ...CHAPTER 14 DIGITAL I O AND PSL CONFIGURATION ...
Страница 324: ...Chapter 14 Digital I O and PSL Configuration P54A B C E 298 P54xMED TM EN 1 ...
Страница 336: ...Chapter 14 Digital I O and PSL Configuration P54A B C E 310 P54xMED TM EN 1 ...
Страница 337: ...CHAPTER 15 FIBRE TELEPROTECTION ...
Страница 338: ...Chapter 15 Fibre Teleprotection P54A B C E 312 P54xMED TM EN 1 ...
Страница 354: ...Chapter 15 Fibre Teleprotection P54A B C E 328 P54xMED TM EN 1 ...
Страница 355: ...CHAPTER 16 ELECTRICAL TELEPROTECTION ...
Страница 356: ...Chapter 16 Electrical Teleprotection P54A B C E 330 P54xMED TM EN 1 ...
Страница 366: ...Chapter 16 Electrical Teleprotection P54A B C E 340 P54xMED TM EN 1 ...
Страница 367: ...CHAPTER 17 COMMUNICATIONS ...
Страница 368: ...Chapter 17 Communications P54A B C E 342 P54xMED TM EN 1 ...
Страница 439: ...CHAPTER 18 CYBER SECURITY ...
Страница 440: ...Chapter 18 Cyber Security P54A B C E 414 P54xMED TM EN 1 ...
Страница 457: ...CHAPTER 19 INSTALLATION ...
Страница 458: ...Chapter 19 Installation P54A B C E 432 P54xMED TM EN 1 ...
Страница 469: ...5 2 CASE DIMENSIONS 60TE E01409 Figure 197 60TE case dimensions P54A B C E Chapter 19 Installation P54xMED TM EN 1 443 ...
Страница 471: ...CHAPTER 20 COMMISSIONING INSTRUCTIONS ...
Страница 472: ...Chapter 20 Commissioning Instructions P54A B C E 446 P54xMED TM EN 1 ...
Страница 513: ...CHAPTER 21 MAINTENANCE AND TROUBLESHOOTING ...
Страница 514: ...Chapter 21 Maintenance and Troubleshooting P54A B C E 488 P54xMED TM EN 1 ...
Страница 530: ...Chapter 21 Maintenance and Troubleshooting P54A B C E 504 P54xMED TM EN 1 ...
Страница 531: ...CHAPTER 22 TECHNICAL SPECIFICATIONS ...
Страница 532: ...Chapter 22 Technical Specifications P54A B C E 506 P54xMED TM EN 1 ...
Страница 558: ...Chapter 22 Technical Specifications P54A B C E 532 P54xMED TM EN 1 ...
Страница 559: ...APPENDIX A ORDERING OPTIONS ...
Страница 560: ...Appendix A Ordering Options P54A B C E P54xMED TM EN 1 ...
Страница 565: ...APPENDIX B SETTINGS AND SIGNALS ...
Страница 566: ...Appendix B Settings and Signals P54A B C E P54xMED TM EN 1 ...
Страница 790: ...Appendix B Settings and Signals P54A B C E B224 P54xMED TM EN 1 ...
Страница 835: ...APPENDIX C WIRING DIAGRAMS ...
Страница 836: ...Appendix C Wiring Diagrams P54A B C E P54xMED TM EN 1 ...
Страница 849: ......