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6 F 2 T 0 1 7 2
Table 2.1.1 Specification of IDMT Curves
Curve Description
IEC ref.
k
α
c
k
r
β
IEC Normal Inverse
A
0.14
0.02
0
-
-
IEC Very Inverse
B
13.5
1
0
-
-
IEC Extremely Inverse
C
80
2
0
-
-
UK Long Time Inverse
-
120
1
0
-
-
IEEE Moderately Inverse
D
0.0515
0.02
0.114
4.85
2
IEEE Very Inverse
E
19.61
2
0.491
21.6
2
IEEE Extremely Inverse
F
28.2
2
0.1217
29.1
2
US CO8 Inverse
-
5.95
2
0.18
5.95
2
US CO2 Short Time Inverse
-
0.02394
0.02
0.01694
2.261
2
User configurable curve
-
0.00 –
300.00
0.00 –
5.00
0.000 –
5.000
0.00 –
300.00
0.00 –
5.00
Note: kr and
β
are used to define the reset characteristic. Refer to equation (2).
IEEE Reset Curves
(Time Multiplier = 1)
1.00
10.00
100.00
1000.00
0.1
1
Current (Multiple of Setting)
T
im
e (
s)
MI
VI
EI
CO2
CO8
Figure 2.1.3 Dependent Time Reset Characteristics
2.1.2 Definite Time Overcurrent Protection
In a system in which the fault current does not vary a great deal in relation to the position of the
fault, that is, the impedance between the relay and the power source is large, the advantages of the
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Summary of Contents for GRE110
Page 183: ...6 F 2 T 0 1 7 2 Appendix B Signal List 184 ...
Page 191: ...6 F 2 T 0 1 7 2 Appendix C Event Record Items 192 ...
Page 196: ...6 F 2 T 0 1 7 2 Appendix D Binary Output Default Setting List 197 ...
Page 199: ...6 F 2 T 0 1 7 2 Appendix E Relay Menu Tree 200 ...
Page 210: ...6 F 2 T 0 1 7 2 Appendix F Case Outline 211 ...
Page 211: ...6 F 2 T 0 1 7 2 Case Outline for model 400 401 420 421 820 and 821 212 ...
Page 212: ...6 F 2 T 0 1 7 2 Case Outline for model 402 and 422 213 ...
Page 213: ...6 F 2 T 0 1 7 2 Appendix G Typical External Connection 214 ...
Page 245: ...6 F 2 T 0 1 7 2 Appendix J Return Repair Form 246 ...
Page 249: ...6 F 2 T 0 1 7 2 Customer Name Company Name Address Telephone No Facsimile No Signature 250 ...
Page 250: ...6 F 2 T 0 1 7 2 Appendix K Technical Data 251 ...
Page 256: ...6 F 2 T 0 1 7 2 Appendix L Symbols Used in Scheme Logic 257 ...
Page 259: ...6 F 2 T 0 1 7 2 Appendix M Modbus Interoperability 260 ...
Page 289: ...6 F 2 T 0 1 7 2 Appendix N IEC60870 5 103 Interoperability 290 ...
Page 296: ...6 F 2 T 0 1 7 2 Appendix O PLC Default setting 297 ...
Page 298: ...6 F 2 T 0 1 7 2 Appendix P Inverse Time Characteristics 299 ...
Page 304: ...6 F 2 T 0 1 7 2 Appendix Q IEC61850 Interoperability 305 ...