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3
PHASE OVERCURRENT PROTECTION
Phase current faults are faults where fault current flows between two or more phases of a power system. The fault
current may be between the phase conductors only or, between two or more phase conductors and earth.
Although not as common as earth faults (single phase to earth), phase faults are typically more severe.
3.1
PHASE OVERCURRENT PROTECTION FOR POWER TRANSFORMERS
A fault external to a power transformer can result in damage to the transformer. If the fault is not cleared
promptly, the resulting overload on the transformer can cause severe overheating and failure. Overcurrent
elements may be used to clear the transformer from a faulted bus or line before the transformer is damaged.
For faults internal to the transformer, the overcurrent protection is less effective because sensitive settings and
fast operation times are usually not possible.
Sensitive settings are not possible because the pickup should allow overloading of the transformer when required.
Fast operating times are not possible because of the grading required with respect to downstream overcurrent
relays.
3.2
PHASE OVERCURRENT PROTECTION IMPLEMENTATION
The product provides three overcurrent elements for backup phase overcurrent protection. Each element provides
four-stages of non-directional or directional three-phase overcurrent protection with independent time delay
characteristics. You can select the overcurrent element operating quantity for each of the elements with the
setting cells Overcurrent 1, Overcurrent 2 and Overcurrent 3 in the OVERCURRENT column of the relevant settings
group. You can set each element as
T1
,
T2
,
T3
,
T4
,
T5
,
HV winding
,
LV winding
or
TV winding
. The HV, LV
and TV windings comprise the vector sums of the CT inputs assigned to that particular winding.
All overcurrent and directional settings apply to all three phases but are independent for each of the four stages.
You may set the overcurrent element as directional only if the three phase VT input is available in the P643/5 and if
the two single phase VT inputs are available in the P642. You may assign the VT to either of the HV, LV or TV
windings. Therefore, overcurrent directional elements are available for the current inputs associated with the
winding that has the VT input assigned.
The first two stages of overcurrent protection have time-delayed characteristics which you can set as IDMT or DT.
The third and fourth stages have definite time characteristics only.
Stages 1, 2 provide a choice of operate and reset characteristics, where you can select between:
●
A range of standard IDMT (Inverse Definite Minimum Time) curves
●
DT (Definite Time)
This is achieved using the cells
●
I>(n) Function for the overcurrent operate characteristic
●
I>(n) Reset Char for the overcurrent reset characteristic (IEEE curves only)
where (n) is the number of the stage.
The IDMT-capable stages (1 and 2) also provide a Timer Hold facility. This is configured using the cells I>(n) tReset,
where (n) is the number of the stage. This is not applicable for curves based on the IEEE standard.
Note:
Stages 3 and 4 can have definite time characteristics only.
Chapter 9 - Current Protection Functions
P64x
202
P64x-TM-EN-1.3
Содержание P642
Страница 2: ......
Страница 18: ...Contents P64x xvi P64x TM EN 1 3 ...
Страница 24: ...Table of Figures P64x xxii P64x TM EN 1 3 ...
Страница 25: ...CHAPTER 1 INTRODUCTION ...
Страница 26: ...Chapter 1 Introduction P64x 2 P64x TM EN 1 3 ...
Страница 36: ...Chapter 1 Introduction P64x 12 P64x TM EN 1 3 ...
Страница 37: ...CHAPTER 2 SAFETY INFORMATION ...
Страница 38: ...Chapter 2 Safety Information P64x 14 P64x TM EN 1 3 ...
Страница 50: ...Chapter 2 Safety Information P64x 26 P64x TM EN 1 3 ...
Страница 51: ...CHAPTER 3 HARDWARE DESIGN ...
Страница 52: ...Chapter 3 Hardware Design P64x 28 P64x TM EN 1 3 ...
Страница 87: ...CHAPTER 4 SOFTWARE DESIGN ...
Страница 88: ...Chapter 4 Software Design P64x 64 P64x TM EN 1 3 ...
Страница 98: ...Chapter 4 Software Design P64x 74 P64x TM EN 1 3 ...
Страница 99: ...CHAPTER 5 CONFIGURATION ...
Страница 100: ...Chapter 5 Configuration P64x 76 P64x TM EN 1 3 ...
Страница 121: ...CHAPTER 6 TRANSFORMER DIFFERENTIAL PROTECTION ...
Страница 122: ...Chapter 6 Transformer Differential Protection P64x 98 P64x TM EN 1 3 ...
Страница 165: ...CHAPTER 7 TRANSFORMER CONDITION MONITORING ...
Страница 166: ...Chapter 7 Transformer Condition Monitoring P64x 142 P64x TM EN 1 3 ...
Страница 189: ...CHAPTER 8 RESTRICTED EARTH FAULT PROTECTION ...
Страница 190: ...Chapter 8 Restricted Earth Fault Protection P64x 166 P64x TM EN 1 3 ...
Страница 215: ...CHAPTER 9 CURRENT PROTECTION FUNCTIONS ...
Страница 216: ...Chapter 9 Current Protection Functions P64x 192 P64x TM EN 1 3 ...
Страница 249: ...CHAPTER 10 CB FAIL PROTECTION ...
Страница 250: ...Chapter 10 CB Fail Protection P64x 226 P64x TM EN 1 3 ...
Страница 259: ...CHAPTER 11 VOLTAGE PROTECTION FUNCTIONS ...
Страница 260: ...Chapter 11 Voltage Protection Functions P64x 236 P64x TM EN 1 3 ...
Страница 274: ...Chapter 11 Voltage Protection Functions P64x 250 P64x TM EN 1 3 ...
Страница 275: ...CHAPTER 12 FREQUENCY PROTECTION FUNCTIONS ...
Страница 276: ...Chapter 12 Frequency Protection Functions P64x 252 P64x TM EN 1 3 ...
Страница 286: ...Chapter 12 Frequency Protection Functions P64x 262 P64x TM EN 1 3 ...
Страница 287: ...CHAPTER 13 MONITORING AND CONTROL ...
Страница 288: ...Chapter 13 Monitoring and Control P64x 264 P64x TM EN 1 3 ...
Страница 306: ...Chapter 13 Monitoring and Control P64x 282 P64x TM EN 1 3 ...
Страница 307: ...CHAPTER 14 SUPERVISION ...
Страница 308: ...Chapter 14 Supervision P64x 284 P64x TM EN 1 3 ...
Страница 322: ...Chapter 14 Supervision P64x 298 P64x TM EN 1 3 ...
Страница 323: ...CHAPTER 15 DIGITAL I O AND PSL CONFIGURATION ...
Страница 324: ...Chapter 15 Digital I O and PSL Configuration P64x 300 P64x TM EN 1 3 ...
Страница 336: ...Chapter 15 Digital I O and PSL Configuration P64x 312 P64x TM EN 1 3 ...
Страница 337: ...CHAPTER 16 COMMUNICATIONS ...
Страница 338: ...Chapter 16 Communications P64x 314 P64x TM EN 1 3 ...
Страница 397: ...CHAPTER 17 CYBER SECURITY ...
Страница 398: ...Chapter 17 Cyber Security P64x 374 P64x TM EN 1 3 ...
Страница 415: ...CHAPTER 18 INSTALLATION ...
Страница 416: ...Chapter 18 Installation P64x 392 P64x TM EN 1 3 ...
Страница 429: ...5 2 CASE DIMENSIONS 60TE E01409 Figure 167 60TE case dimensions P64x Chapter 18 Installation P64x TM EN 1 3 405 ...
Страница 431: ...CHAPTER 19 COMMISSIONING INSTRUCTIONS ...
Страница 432: ...Chapter 19 Commissioning Instructions P64x 408 P64x TM EN 1 3 ...
Страница 454: ...V01505 Figure 173 Harmonic Restraint Test Plane Chapter 19 Commissioning Instructions P64x 430 P64x TM EN 1 3 ...
Страница 460: ...Chapter 19 Commissioning Instructions P64x 436 P64x TM EN 1 3 ...
Страница 461: ...CHAPTER 20 MAINTENANCE AND TROUBLESHOOTING ...
Страница 462: ...Chapter 20 Maintenance and Troubleshooting P64x 438 P64x TM EN 1 3 ...
Страница 477: ...CHAPTER 21 TECHNICAL SPECIFICATIONS ...
Страница 478: ...Chapter 21 Technical Specifications P64x 454 P64x TM EN 1 3 ...
Страница 507: ...APPENDIX A ORDERING OPTIONS ...
Страница 508: ...Appendix A Ordering Options P64x P64x TM EN 1 3 ...
Страница 512: ...Appendix A Ordering Options P64x A4 P64x TM EN 1 3 ...
Страница 513: ...APPENDIX B SETTINGS AND SIGNALS ...
Страница 515: ...APPENDIX C WIRING DIAGRAMS ...
Страница 516: ...Appendix C Wiring Diagrams P64x P64x TM EN 1 3 ...
Страница 590: ......
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