7
EARTH FAULT PROTECTION
Earth faults are overcurrent faults where the fault current flows to earth. Earth faults are the most common type of
fault.
Earth faults can be measured directly from the system by means of:
●
A separate current Transformer (CT) located in a power system earth connection
●
A separate Core Balance Current Transformer (CBCT), usually connected to the SEF transformer input
●
A residual connection of the three line CTs, where the Earth faults can be derived mathematically by
summing the three measured phase currents.
Depending on the device model, it will provide one or more of the above means for Earth fault protection.
7.1
EARTH FAULT PROTECTION ELEMENTS
Earth fault protection is implemented in the columns EARTH FAULT 1 and EARTH FAULT 2 of the relevant settings
group.
Each column contains an identical set of elements. EARTH FAULT 1 (EF1) is used for earth fault current that is
measured directly from the system (measured). EARTH FAULT 2 (EF2) uses quantities derived internally from
summing the three-phase currents.
The product provides four stages of Earth Fault protection with independent time delay characteristics, for each
EARTH FAULT column.
Stages 1 and 2 provide a choice of operate and reset characteristics, where you can select between:
●
A range of IDMT (Inverse Definite Minimum Time) curves
●
A range of User-defined curves
●
DT (Definite Time)
For the EF1 column, this is achieved using the cells:
●
IN1>(n) Function for the overcurrent operate characteristics
●
IN1>(n) Reset Char for the overcurrent reset characteristic
●
IN1>(n) Usr RstChar for the reset characteristic for user-defined curves
For the EF2 column, this is achieved using the cells:
●
IN2>(n) Function for the overcurrent operate characteristics
●
IN2>(n) Reset Char for the overcurrent reset characteristic
●
IN2>(n) Usr RstChar for the reset characteristic for user-defined curves
where (n) is the number of the stage.
Stages 1 and 2 provide a Timer Hold facility. This is configured using the cells IN1>(n) tReset for EF1 and
IN2>(n) tReset for EF2.
Stages 3 and 4 can have definite time characteristics only.
The fact that both EF1 and EF2 elements may be enabled at the same time leads to a number of applications
advantages. For example, some applications may require directional earth fault protection for upstream
equipment and backup earth fault protection for downstream equipment. This can be achieved with a single IED,
rather than two.
P24xM
Chapter 6 - Current Protection Functions
P24xM-TM-EN-2.1
109
Summary of Contents for P24DM
Page 2: ......
Page 17: ...Appendix C Wiring Diagrams 467 P24xM Contents P24xM TM EN 2 1 xv...
Page 18: ...Contents P24xM xvi P24xM TM EN 2 1...
Page 24: ...Table of Figures P24xM xxii P24xM TM EN 2 1...
Page 25: ...CHAPTER 1 INTRODUCTION...
Page 26: ...Chapter 1 Introduction P24xM 2 P24xM TM EN 2 1...
Page 37: ...CHAPTER 2 SAFETY INFORMATION...
Page 38: ...Chapter 2 Safety Information P24xM 14 P24xM TM EN 2 1...
Page 51: ...CHAPTER 3 HARDWARE DESIGN...
Page 52: ...Chapter 3 Hardware Design P24xM 28 P24xM TM EN 2 1...
Page 66: ...Chapter 3 Hardware Design P24xM 42 P24xM TM EN 2 1...
Page 67: ...CHAPTER 4 SOFTWARE DESIGN...
Page 68: ...Chapter 4 Software Design P24xM 44 P24xM TM EN 2 1...
Page 77: ...CHAPTER 5 CONFIGURATION...
Page 78: ...Chapter 5 Configuration P24xM 54 P24xM TM EN 2 1...
Page 94: ...Chapter 5 Configuration P24xM 70 P24xM TM EN 2 1...
Page 95: ...CHAPTER 6 CURRENT PROTECTION FUNCTIONS...
Page 96: ...Chapter 6 Current Protection Functions P24xM 72 P24xM TM EN 2 1...
Page 188: ...Chapter 6 Current Protection Functions P24xM 164 P24xM TM EN 2 1...
Page 189: ...CHAPTER 7 RESTRICTED EARTH FAULT PROTECTION...
Page 190: ...Chapter 7 Restricted Earth Fault Protection P24xM 166 P24xM TM EN 2 1...
Page 201: ...CHAPTER 8 CB FAIL PROTECTION...
Page 202: ...Chapter 8 CB Fail Protection P24xM 178 P24xM TM EN 2 1...
Page 215: ...CHAPTER 9 CURRENT TRANSFORMER REQUIREMENTS...
Page 216: ...Chapter 9 Current Transformer Requirements P24xM 192 P24xM TM EN 2 1...
Page 224: ...Chapter 9 Current Transformer Requirements P24xM 200 P24xM TM EN 2 1...
Page 225: ...CHAPTER 10 VOLTAGE PROTECTION FUNCTIONS...
Page 226: ...Chapter 10 Voltage Protection Functions P24xM 202 P24xM TM EN 2 1...
Page 245: ...CHAPTER 11 FREQUENCY PROTECTION FUNCTIONS...
Page 246: ...Chapter 11 Frequency Protection Functions P24xM 222 P24xM TM EN 2 1...
Page 261: ...CHAPTER 12 POWER PROTECTION FUNCTIONS...
Page 262: ...Chapter 12 Power Protection Functions P24xM 238 P24xM TM EN 2 1...
Page 265: ...CHAPTER 13 MONITORING AND CONTROL...
Page 266: ...Chapter 13 Monitoring and Control P24xM 242 P24xM TM EN 2 1...
Page 294: ...Chapter 13 Monitoring and Control P24xM 270 P24xM TM EN 2 1...
Page 295: ...CHAPTER 14 SUPERVISION...
Page 296: ...Chapter 14 Supervision P24xM 272 P24xM TM EN 2 1...
Page 312: ...Chapter 14 Supervision P24xM 288 P24xM TM EN 2 1...
Page 313: ...CHAPTER 15 DIGITAL I O AND PSL CONFIGURATION...
Page 314: ...Chapter 15 Digital I O and PSL Configuration P24xM 290 P24xM TM EN 2 1...
Page 327: ...CHAPTER 16 COMMUNICATIONS...
Page 328: ...Chapter 16 Communications P24xM 304 P24xM TM EN 2 1...
Page 386: ...Chapter 16 Communications P24xM 362 P24xM TM EN 2 1...
Page 387: ...CHAPTER 17 CYBER SECURITY...
Page 388: ...Chapter 17 Cyber Security P24xM 364 P24xM TM EN 2 1...
Page 405: ...CHAPTER 18 INSTALLATION...
Page 406: ...Chapter 18 Installation P24xM 382 P24xM TM EN 2 1...
Page 419: ...CHAPTER 19 COMMISSIONING INSTRUCTIONS...
Page 420: ...Chapter 19 Commissioning Instructions P24xM 396 P24xM TM EN 2 1...
Page 443: ...CHAPTER 20 MAINTENANCE AND TROUBLESHOOTING...
Page 444: ...Chapter 20 Maintenance and Troubleshooting P24xM 420 P24xM TM EN 2 1...
Page 453: ...CHAPTER 21 TECHNICAL SPECIFICATIONS...
Page 454: ...Chapter 21 Technical Specifications P24xM 430 P24xM TM EN 2 1...
Page 486: ...Chapter 21 Technical Specifications P24xM 462 P24xM TM EN 2 1...
Page 487: ...APPENDIX A ORDERING OPTIONS...
Page 488: ...Appendix A Ordering Options P24xM 464 P24xM TM EN 2 1...
Page 491: ...APPENDIX B SETTINGS AND SIGNALS...
Page 493: ...APPENDIX C WIRING DIAGRAMS...
Page 494: ...Appendix C Wiring Diagrams P24xM 468 P24xM TM EN 2 1...
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