
Note:
For circuits with infeed from more than one terminal, the fault resistance will appear greater. This is because the protection
cannot measure the current contribution from a remote terminal. The apparent fault resistance increase could be between 2
to 8 times the calculated resistance. For this reason, we recommended setting the zone Resistive reaches to 4 times the
calculated arc resistance.
In this example, the minimum phase fault level is 1000 MVA. This is equivalent to an effective short-circuit fault
feeding impedance of:
Z = kV
2
/MVA = 230
2
/1000 = 53
W
(primary)
The lowest phase fault current level is equivalent to:
Ifault = (MVA x 1000)/(
Ö
3 x kV)
= (1000 x 1000)/(
Ö
3 x 230)
= 2.5 kA
Giving, according to the (van) Warrington formula, an arc resistance of:
Ra = 4
W
Iterative calculations could be performed to refine the expected fault current (which decreases as refined values of
Ra are included in the calculation), but as Ra is relatively small compared to the initially calculated value of Z, this
value is acceptable.
To compensate for remote infeed a small additional factor can be added to account for the expected fault current
being lower than that used in the calculation. So rather than set the zone Resistive reaches to 4 times the
calculated arc resistance, a factor of 5 could be used.
Using a factor of 5 gives a minimum setting of:
Phase Resistive Reach = 5 x Ra = 20
W
(primary value)
The Phase Resistive Reach could be set higher than this (for example using the rule-of-thumb: [2.3 - 0.0045 x Line
length (km)] x Zone 1 reach), so typically it would be set higher than 20Ω but lower than the Load Avoidance
setting.
Earth-Fault Elements
Fault resistance would comprise arc-resistance and tower footing resistance. A typical resistive reach coverage
setting would be 40
W
(primary).
For high resistance earth faults, the situation could arise where no distance elements would operate. In such
cases, supplementary earth fault protection (for example Aided DEF protection) should be applied. If
supplementary earth fault protection is used, large resistive reaches for Earth-Fault Distance protection do not
need to be used so that the Earth-Fault Resistive reach can be set according to the utility practice. In the absence
of specific guidance, a recommendation for setting Zone 1 is:
●
Cables: Resistive Reach = 3 x Zone 1 reach
●
Overhead lines: Choose Resistive Reach in the range [2.3 - 0.0045] x Line length(km) x Zone 1 Reach
●
Lines longer than 400 km: Choose Resistive Reach = 0.5 x Zone 1 Reach
6.12
TEED FEEDER APPLICATIONS
Distance protection can be applied to protect three terminal lines (teed feeders). Interconnecting three terminals,
however, affects the apparent impedances seen by the distance elements and creates certain problems.
Consider, as an example, the following figure which represents a teed feeder with terminals A, B, and C, with a fault
applied near to terminal B:
Chapter 7 - Distance Protection
P446SV
162
P446SV-TM-EN-1
Summary of Contents for MiCOM P40 Agile
Page 2: ......
Page 24: ...Contents P446SV xxii P446SV TM EN 1 ...
Page 33: ...CHAPTER 1 INTRODUCTION ...
Page 34: ...Chapter 1 Introduction P446SV 2 P446SV TM EN 1 ...
Page 46: ...Chapter 1 Introduction P446SV 14 P446SV TM EN 1 ...
Page 47: ...CHAPTER 2 SAFETY INFORMATION ...
Page 48: ...Chapter 2 Safety Information P446SV 16 P446SV TM EN 1 ...
Page 60: ...Chapter 2 Safety Information P446SV 28 P446SV TM EN 1 ...
Page 61: ...CHAPTER 3 HARDWARE DESIGN ...
Page 62: ...Chapter 3 Hardware Design P446SV 30 P446SV TM EN 1 ...
Page 88: ...Chapter 3 Hardware Design P446SV 56 P446SV TM EN 1 ...
Page 89: ...CHAPTER 4 SOFTWARE DESIGN ...
Page 90: ...Chapter 4 Software Design P446SV 58 P446SV TM EN 1 ...
Page 101: ...CHAPTER 5 CONFIGURATION ...
Page 102: ...Chapter 5 Configuration P446SV 70 P446SV TM EN 1 ...
Page 124: ...Chapter 5 Configuration P446SV 92 P446SV TM EN 1 ...
Page 125: ...CHAPTER 6 SAMPLED VALUE OPERATION ...
Page 126: ...Chapter 6 Sampled Value Operation P446SV 94 P446SV TM EN 1 ...
Page 136: ...Chapter 6 Sampled Value Operation P446SV 104 P446SV TM EN 1 ...
Page 137: ...CHAPTER 7 DISTANCE PROTECTION ...
Page 138: ...Chapter 7 Distance Protection P446SV 106 P446SV TM EN 1 ...
Page 196: ...Chapter 7 Distance Protection P446SV 164 P446SV TM EN 1 ...
Page 197: ...CHAPTER 8 CARRIER AIDED SCHEMES ...
Page 198: ...Chapter 8 Carrier Aided Schemes P446SV 166 P446SV TM EN 1 ...
Page 240: ...Chapter 8 Carrier Aided Schemes P446SV 208 P446SV TM EN 1 ...
Page 241: ...CHAPTER 9 NON AIDED SCHEMES ...
Page 242: ...Chapter 9 Non Aided Schemes P446SV 210 P446SV TM EN 1 ...
Page 256: ...Chapter 9 Non Aided Schemes P446SV 224 P446SV TM EN 1 ...
Page 257: ...CHAPTER 10 POWER SWING FUNCTIONS ...
Page 258: ...Chapter 10 Power Swing Functions P446SV 226 P446SV TM EN 1 ...
Page 281: ...CHAPTER 11 AUTORECLOSE ...
Page 282: ...Chapter 11 Autoreclose P446SV 250 P446SV TM EN 1 ...
Page 376: ...Chapter 11 Autoreclose P446SV 344 P446SV TM EN 1 ...
Page 377: ...CHAPTER 12 CB FAIL PROTECTION ...
Page 378: ...Chapter 12 CB Fail Protection P446SV 346 P446SV TM EN 1 ...
Page 389: ...CHAPTER 13 CURRENT PROTECTION FUNCTIONS ...
Page 390: ...Chapter 13 Current Protection Functions P446SV 358 P446SV TM EN 1 ...
Page 416: ...Chapter 13 Current Protection Functions P446SV 384 P446SV TM EN 1 ...
Page 417: ...CHAPTER 14 VOLTAGE PROTECTION FUNCTIONS ...
Page 418: ...Chapter 14 Voltage Protection Functions P446SV 386 P446SV TM EN 1 ...
Page 431: ...CHAPTER 15 FREQUENCY PROTECTION FUNCTIONS ...
Page 432: ...Chapter 15 Frequency Protection Functions P446SV 400 P446SV TM EN 1 ...
Page 438: ...Chapter 15 Frequency Protection Functions P446SV 406 P446SV TM EN 1 ...
Page 439: ...CHAPTER 16 MONITORING AND CONTROL ...
Page 440: ...Chapter 16 Monitoring and Control P446SV 408 P446SV TM EN 1 ...
Page 476: ...Chapter 16 Monitoring and Control P446SV 444 P446SV TM EN 1 ...
Page 477: ...CHAPTER 17 SUPERVISION ...
Page 478: ...Chapter 17 Supervision P446SV 446 P446SV TM EN 1 ...
Page 490: ...Chapter 17 Supervision P446SV 458 P446SV TM EN 1 ...
Page 491: ...CHAPTER 18 DIGITAL I O AND PSL CONFIGURATION ...
Page 492: ...Chapter 18 Digital I O and PSL Configuration P446SV 460 P446SV TM EN 1 ...
Page 504: ...Chapter 18 Digital I O and PSL Configuration P446SV 472 P446SV TM EN 1 ...
Page 505: ...CHAPTER 19 FIBRE TELEPROTECTION ...
Page 506: ...Chapter 19 Fibre Teleprotection P446SV 474 P446SV TM EN 1 ...
Page 522: ...Chapter 19 Fibre Teleprotection P446SV 490 P446SV TM EN 1 ...
Page 523: ...CHAPTER 20 ELECTRICAL TELEPROTECTION ...
Page 524: ...Chapter 20 Electrical Teleprotection P446SV 492 P446SV TM EN 1 ...
Page 534: ...Chapter 20 Electrical Teleprotection P446SV 502 P446SV TM EN 1 ...
Page 535: ...CHAPTER 21 COMMUNICATIONS ...
Page 536: ...Chapter 21 Communications P446SV 504 P446SV TM EN 1 ...
Page 606: ...Chapter 21 Communications P446SV 574 P446SV TM EN 1 ...
Page 607: ...CHAPTER 22 CYBER SECURITY ...
Page 608: ...Chapter 22 Cyber Security P446SV 576 P446SV TM EN 1 ...
Page 625: ...CHAPTER 23 INSTALLATION ...
Page 626: ...Chapter 23 Installation P446SV 594 P446SV TM EN 1 ...
Page 637: ...CHAPTER 24 COMMISSIONING INSTRUCTIONS ...
Page 638: ...Chapter 24 Commissioning Instructions P446SV 606 P446SV TM EN 1 ...
Page 695: ...CHAPTER 25 MAINTENANCE AND TROUBLESHOOTING ...
Page 696: ...Chapter 25 Maintenance and Troubleshooting P446SV 664 P446SV TM EN 1 ...
Page 712: ...Chapter 25 Maintenance and Troubleshooting P446SV 680 P446SV TM EN 1 ...
Page 713: ...CHAPTER 26 TECHNICAL SPECIFICATIONS ...
Page 714: ...Chapter 26 Technical Specifications P446SV 682 P446SV TM EN 1 ...
Page 741: ...APPENDIX A ORDERING OPTIONS ...
Page 742: ...Appendix A Ordering Options P446SV P446SV TM EN 1 ...
Page 744: ...Appendix A Ordering Options P446SV A2 P446SV TM EN 1 ...
Page 745: ...APPENDIX B SETTINGS AND SIGNALS ...
Page 746: ...Appendix B Settings and Signals P446SV P446SV TM EN 1 ...
Page 954: ...Appendix B Settings and Signals P446SV B208 P446SV TM EN 1 ...
Page 955: ...APPENDIX C WIRING DIAGRAMS ...
Page 956: ...Appendix C Wiring Diagrams P446SV P446SV TM EN 1 ...
Page 960: ......
Page 961: ......