38
6
F
2
S
0
7
8
9
2.11 Characteristics of Measuring Elements
2.11.1 Percentage Current Differential Element DIF
The segregated-phase current differential element DIF has dual percentage restraining
characteristics. Figure 2.11.1 shows the characteristics of DF1 and DF2 on the differential
current (I
d
) and restraining current (I
r
) plane. I
d
is a vector summation of phase current of all
windings and I
r
is a scalar summation of phase current of all windings.
I
d
DF2
DF1
ik
kp
I
r
I
d
= 2I
r
(one-end infeed)
Figure 2.11.1 Current Differential Element
Characteristic DF1 is expressed by the following equation:
I
d
p1
I
r
(1
p1
/2)ik
where,
p1
: slope of DF1
ik : minimum operating current
Id and Ir are defined as follows for a three-winding transformer.
I
d
= |kct1
I
1
+ kct2
I
2
+ kct3
I
3
|
I
r
=(kct1
|I
1
|+ kct2
|I
2
|+ kct3
|I
3
|)/2
where,
kct1 ,kct2 ,kct3
: CT ratio matching settings of primary, secondary and tertiary winding
I
1
,I
2
,I
3
: currents of primary, secondary and tertiary winding
This characteristic has weaker restraint in the small current region and ensures sensitivity to low
level faults.
Characteristic DF2 is expressed by the following equation:
I
d
p2
I
r
(p1
p2
)kp
(1
p1
/2)ik
where,
p2 : slope of DF2
kp : break point of DF1 characteristic
This characteristic has stronger restraint in the large current region and ensures stability against
Summary of Contents for GRT100 Series
Page 142: ... 141 6 F 2 S 0 7 8 9 Appendix A Block Diagram ...
Page 144: ... 143 6 F 2 S 0 7 8 9 Appendix B Signal List ...
Page 159: ... 158 6 F 2 S 0 7 8 9 ...
Page 160: ... 159 6 F 2 S 0 7 8 9 Appendix C Variable Timer List ...
Page 162: ... 161 6 F 2 S 0 7 8 9 Appendix D Binary Output Default Setting List ...
Page 165: ... 164 6 F 2 S 0 7 8 9 ...
Page 166: ... 165 6 F 2 S 0 7 8 9 Appendix E Details of Relay Menu and LCD and Button Operation ...
Page 174: ... 173 6 F 2 S 0 7 8 9 Appendix F Case Outline Flush Mount Type Rack Mount Type ...
Page 179: ... 178 6 F 2 S 0 7 8 9 ...
Page 180: ... 179 6 F 2 S 0 7 8 9 Appendix G External Connections ...
Page 185: ... 184 6 F 2 S 0 7 8 9 ...
Page 200: ... 199 6 F 2 S 0 7 8 9 ...
Page 201: ... 200 6 F 2 S 0 7 8 9 Appendix J Return Repair Form ...
Page 205: ... 204 6 F 2 S 0 7 8 9 Customer Name Company Name Address Telephone No Facsimile No Signature ...
Page 206: ... 205 6 F 2 S 0 7 8 9 ...
Page 207: ... 206 6 F 2 S 0 7 8 9 Appendix K Technical Data ...
Page 220: ... 219 6 F 2 S 0 7 8 9 ...
Page 221: ... 220 6 F 2 S 0 7 8 9 Appendix M Symbols Used in Scheme Logic ...
Page 224: ... 223 6 F 2 S 0 7 8 9 ...
Page 225: ... 224 6 F 2 S 0 7 8 9 Appendix N Implementation of Thermal Model to IEC60255 8 ...
Page 228: ... 227 6 F 2 S 0 7 8 9 ...
Page 229: ... 228 6 F 2 S 0 7 8 9 Appendix O IEC60870 5 103 Interoperability and Troubleshooting ...
Page 241: ... 240 6 F 2 S 0 7 8 9 Appendix P Modbus Interoperability ...
Page 255: ... 254 6 F 2 S 0 7 8 9 ...
Page 256: ... 255 6 F 2 S 0 7 8 9 Appendix Q Inverse Time Characteristics ...
Page 259: ... 258 6 F 2 S 0 7 8 9 ...
Page 260: ... 259 6 F 2 S 0 7 8 9 Appendix R Failed Module Tracing and Replacement ...
Page 266: ... 265 6 F 2 S 0 7 8 9 Appendix S Ordering ...
Page 269: ... 268 6 F 2 S 0 7 8 9 3 1 Oct 2 2017 Republished under spin off company ...
Page 270: ......