GE T35 Instruction Manual page 412

GROUPED ELEMENTS
IEC curves
For European applications, the relay offers three standard curves defined in IEC 255-4 and British standard BS142. These
are defined as IEC Curve A, IEC Curve B, and IEC Curve C. The IEC curves are derived by the operate and reset time
equations.
where
T = operate time (in seconds)
TDM = Multiplier setting
I = input current
I = Pickup Current setting
pickup
K, E = constants defined in the table
t = characteristic constant defined in the table
r
T = reset time in seconds (assuming energy capacity is 100% and
RESET
Table 5-29: 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
5
Table 5-30: IEC curve trip times (in seconds)
Multiplier Current ( I / I
(TDM)
1.5
IEC Curve A
0.05 0.860
0.10 1.719
0.20 3.439
0.40 6.878
0.60 10.317
0.80 13.755
1.00 17.194
IEC Curve B
0.05 1.350
0.10 2.700
0.20 5.400
0.40 10.800
0.60 16.200
0.80 21.600
1.00 27.000
IEC Curve C
0.05 3.200
0.10 6.400
0.20 12.800
0.40 25.600
0.60 38.400
5-210
K E
0.140 0.020
13.500 1.000
80.000 2.000
0.050 0.040
)
pickup
2.0 3.0 4.0
0.501 0.315 0.249
1.003 0.630 0.498
2.006 1.260 0.996
4.012 2.521 1.992
6.017 3.781 2.988
8.023 5.042 3.984
10.029 6.302 4.980
0.675 0.338 0.225
1.350 0.675 0.450
2.700 1.350 0.900
5.400 2.700 1.800
8.100 4.050 2.700
10.800 5.400 3.600
13.500 6.750 4.500
1.333 0.500 0.267
2.667 1.000 0.533
5.333 2.000 1.067
10.667 4.000 2.133
16.000 6.000 3.200
is "Timed")
RESET
t
r
9.7
43.2
58.2
0.500
5.0 6.0 7.0
0.214 0.192 0.176
0.428 0.384 0.353
0.856 0.767 0.706
1.712 1.535 1.411
2.568 2.302 2.117
3.424 3.070 2.822
4.280 3.837 3.528
0.169 0.135 0.113
0.338 0.270 0.225
0.675 0.540 0.450
1.350 1.080 0.900
2.025 1.620 1.350
2.700 2.160 1.800
3.375 2.700 2.250
0.167 0.114 0.083
0.333 0.229 0.167
0.667 0.457 0.333
1.333 0.914 0.667
2.000 1.371 1.000
T35 TRANSFORMER PROTECTION SYSTEM – INSTRUCTION MANUAL
CHAPTER 5: SETTINGS
Eq. 5-33
8.0 9.0 10.0
0.165 0.156 0.149
0.330 0.312 0.297
0.659 0.623 0.594
1.319 1.247 1.188
1.978 1.870 1.782
2.637 2.493 2.376
3.297 3.116 2.971
0.096 0.084 0.075
0.193 0.169 0.150
0.386 0.338 0.300
0.771 0.675 0.600
1.157 1.013 0.900
1.543 1.350 1.200
1.929 1.688 1.500
0.063 0.050 0.040
0.127 0.100 0.081
0.254 0.200 0.162
0.508 0.400 0.323
0.762 0.600 0.485