GE 745 Instruction Manual page 157

CHAPTER 5: SETPOINTS
745 TRANSFORMER PROTECTION SYSTEM – INSTRUCTION MANUAL
Table 5–5: ANSI curve trip times (in seconds)
TDM
1.5 2.0
10.0 13.509 7.574
IEC curves:
For European applications, the relay offers the four standard curves defined in IEC 255-4
and British standard BS142. These are defined as IEC Curve A, IEC Curve B, IEC Curve C, and
Short Inverse. The formulae for these curves are:
where: T = trip time (in seconds), M = multiplier setpoint, I = input current,
I = pickup current setpoint, and K, E = constants.
pickup
Table 5–6: IEC (BS) inverse time curve constants
IEC (BS) curve shape
IEC curve A (BS142)
IEC curve B (BS142)
IEC curve C (BS142)
IEC short inverse
Table 5–7: IEC curve trip times (in seconds)
TDM
1.5 2.0
IEC curve A
0.05 0.860 0.501
0.10 1.719 1.003
0.20 3.439 2.006
0.40 6.878 4.012
0.60 10.317 6.017
0.80 13.755 8.023
1.00 17.194 10.029
0.05 1.350 0.675
0.10 2.700 1.350
0.20 5.400 2.700
0.40 10.800 5.400
0.60 16.200 8.100
0.80 21.600 10.800
1.00 27.000 13.500
0.05 3.200 1.333
0.10 6.400 2.667
0.20 12.800 5.333
0.40 25.600 10.667
0.60 38.400 16.000
0.80 51.200 21.333
1.00 64.000 26.667 10.000
0.05 0.153 0.089
0.10 0.306 0.178
Current ( I / I
pickup
3.0 4.0 5.0 6.0
4.776 3.818 3.324 3.020
 
K
T M ×  ---------------------------- 
=
E
 
( I I ⁄ ) 1
–
pu
K
0.140
13.500
80.000
0.050
Current ( I / I
pickup
3.0 4.0 5.0 6.0
0.315 0.249 0.214 0.192
0.630 0.498 0.428 0.384
1.260 0.996 0.856 0.767
2.521 1.992 1.712 1.535
3.781 2.988 2.568 2.302
5.042 3.984 3.424 3.070
6.302 4.980 4.280 3.837
IEC curve B
0.338 0.225 0.169 0.135
0.675 0.450 0.338 0.270
1.350 0.900 0.675 0.540
2.700 1.800 1.350 1.080
4.050 2.700 2.025 1.620
5.400 3.600 2.700 2.160
6.750 4.500 3.375 2.700
IEC curve C
0.500 0.267 0.167 0.114
1.000 0.533 0.333 0.229
2.000 1.067 0.667 0.457
4.000 2.133 1.333 0.914
6.000 3.200 2.000 1.371
8.000 4.267 2.667 1.829
5.333 3.333 2.286
IEC short time
0.056 0.044 0.038 0.034
0.111 0.088 0.075 0.067
S4 ELEMENTS
)
7.0 8.0 9.0
2.815 2.666 2.554
E
0.020
1.000
2.000
0.040
)
7.0 8.0 9.0
0.176 0.165 0.156
0.353 0.330 0.312
0.706 0.659 0.623
1.411 1.319 1.247
2.117 1.978 1.870
2.822 2.637 2.493
3.528 3.297 3.116
0.113 0.096 0.084
0.225 0.193 0.169
0.450 0.386 0.338
0.900 0.771 0.675
1.350 1.157 1.013
1.800 1.543 1.350
2.250 1.929 1.688
0.083 0.063 0.050
0.167 0.127 0.100
0.333 0.254 0.200
0.667 0.508 0.400
1.000 0.762 0.600
1.333 1.016 0.800
1.667 1.270 1.000
0.031 0.029 0.027
0.062 0.058 0.054
10.0
2.465
(EQ 5.8)
10.0
0.149
0.297
0.594
1.188
1.782
2.376
2.971
0.075
0.150
0.300
0.600
0.900
1.200
1.500
0.040
0.081
0.162
0.323
0.485
0.646
0.808
0.026
0.052
5–61