A2
B2
C2
A1
B1
C1
a2
b2
c2
yn
a1
b1
c1
A2
B2
C2
A1
B1
C1
YN
b2
a2
c2
b2
a2
c2
a
b
c
A2
B2
C2
A1
B1
C1
a2
b2
c2
a1
b1
c1
YN
yn
A2
B2
C2
A1
B1
C1
a2
b2
c2
a1
b1
c1
b1
c1
a1
a1
b1
c1
b
a
c
Yy6
Dy11
A2
C2
B2
A
A2
B2
C2
B
C
B
A2
B2
C2
A
C
HV winding
LV winding
Winding Connection
Phase Shift
Type
180°
Dd6
180°
30°
Yd11
A2
C2
B2
30°
Dz6
Yz11
30°
C2
a4
b4
c4
A2
C2
B2
a3
b3
c3
A2
B2
C2
n
c2
c4
c1
b4
b2
b1
a1
a2
a4
a4
b4
c4
n
c3
c2
c1
b3
b2
b1
a1
a2
a3
A
A2
B2
B
C
c3
b3
a3
180°
A2
B2
C2
A1
B1
C1
YN
V03126
c2
b2
a2
a1
b1
c1
c
Figure 37: Transformer winding connections - part 2
2.4
PHASE AND AMPLITUDE COMPENSATION
A power transformer is designed to convert voltages. This means the line currents either side of the transformer
are different in magnitude. If identical CTs were used on both sides of the transformer, the differential protection
circuit would be unbalanced, causing a differential current. Obviously, this has to be compensated for. Amplitude
compensation is theoretically arranged by having a suitable turns ratio on the secondary CT. Ideally, selecting CT
ratios that exactly match the inverse of the transformer turns ratio would compensate for the difference in the
transformer current magnitudes. However, the CT ratios associated with available CTs typically do not provide
exact ratio matching. Also for Y-delta or delta-Y connected transformers, the voltage and current magnitudes used
are changed by a factor of
Ö
3. Further, a phase shift is introduced, meaning the secondary side is out of phase with
the primary side. So further amplitude compensation, as well as phase compensation is required.
Before the advent of numerical IEDs, this compensation was achieved by choosing CTs with appropriate turns
ratios and connection types, and introducing interposing CTs with appropriate connection types. Of course, having
CTs with different turns ratios and connection types on each side of the protected zone exacerbates the CT errors,
therefore increasing the need for good through-fault compensation.
With modern IEDs, it is possible to do a great deal of the compensation in software, so simple Y-connected CTs can
be used on both sides of the transformer irrespective of the connection types. The CTs are chosen such that their
respective turns ratios provide a nominal current usable by the IED (1A or 5A). This in itself provides a certain
amount of amplitude compensation, but there will invariably be a CT ratio mismatch. This mismatch is
compensated for by software in the IED. The device calculates suitable values based on the reference power
rating, transformer voltage ratings, CT ratios and connection type (star or delta) to scale the secondary currents to
a common base.
Chapter 6 - Transformer Differential Protection
P64x
104
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: ......
Страница 591: ......