5
APPLICATION NOTES
5.1
SETTING GUIDELINES
The differential setting, Configuration/Diff Protection, should be set to
Enable
.
The basic pick up level of the low set differential element, Is1, is variable between
0.1 pu
and
2.5 pu
in
0.01
pu
steps. The setting will be dependant on the item of plant being protected and by the amount of differential
current that might be seen during normal operating conditions. When the device is used to protect a transformer,
we recommend a setting of
0.2 pu
.
When protecting generators and other items of plant, where shunt magnetizing current is not present, a lower
differential setting would be more typical. We recommend
0.1 pu
.
The P64x percentage bias calculation is performed 8 times per cycle. A triple slope percentage bias characteristic
is implemented. Both the flat and the lower slope provide sensitivity for internal faults. Under normal operation
steady state magnetizing current and the use of tap changers result in unbalanced conditions and hence
differential current. To accommodate these conditions the initial slope, K1, may be set to 30%. This ensures
sensitivity to faults while allowing for mismatch when the power transformer is at the limit of its tap range and CT
ratio errors. At currents above rated, extra errors may be gradually introduced as a result of CT saturation, Hence,
the higher slope may be set to 80% to provide stability under through fault conditions, during which there may be
transient differential currents due to saturation effect of the CTs. The through fault current, in all but ring bus or
mesh fed transformers, is given by the inverse of the per unit reactance of the transformer. For most transformers,
the reactance varies between 0.05 to 0.2 pu, therefore typical through fault current is given by 5 to 20 In.
The wide matching factor range is provided to allow the designer to trade off between the CT selection and the
scheme sensitivity. This is useful for applications such as busbar protection where a wide range of CT ratios may
be encountered. You should also note that the matching factor check should be carried out for all ends. One end
alone is not sufficient. The maximum sensitivity achieved in this product depends on the type of analog input and
is given in the CT requirements.
Note:
Differential protection alone may not achieve the full sensitivity required, and other protection functions such as REF may
have to be incorporated in conjunction with the differential protection.
The number of biased differential inputs required for an application depends on the transformer and its primary
connections. We recommend, where possible, that a set of biased CT inputs is used for each set of current
transformers. According to IEEE C37.110-2007, separate current inputs should be used for each power source to
the transformer. If the secondary windings of the current transformers from two or more supply breakers are
connected in parallel, under heavy through fault conditions, differential current resulting from the different
magnetizing characteristics of the current transformers flows in the IED. This current only flows through one
current input in the device and can cause maloperation. If each CT is connected to a separate current input, the
total fault current in each breaker provides restraint. You should only connect CT secondary windings in parallel
when both circuits are outgoing loads. In this condition, the maximum through fault level is restricted solely by the
power transformer impedance.
The P64x IED achieves stability for through faults in two ways, both of which are essential for correct relay
operation. The first consideration is the correct sizing of the current transformers. The second is by providing a bias
characteristic as shown below:
P64x
Chapter 6 - Transformer Differential Protection
P64x-TM-EN-1.3
121
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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