GE C70 Instruction Manual page 283

CHAPTER 5: SETTINGS
Multiplier Current ( I / I
pickup
(TDM)
1.5 2.0
10.0 64.390 38.032
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.
T
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 5-24: 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 5-25: IEC curve trip times (in seconds)
Multiplier Current ( I / I
pickup
(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
IEC Curve B
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
IEC Curve C
0.05 3.200 1.333
0.10 6.400 2.667
C70 CAPACITOR BANK PROTECTION AND CONTROL SYSTEM – INSTRUCTION MANUAL
)
3.0 4.0 5.0
24.322 19.458 16.883
K
---------------------------------- -
E
,
= TDM × T
( I I ⁄ ) 1
–
RESET
pickup
K E t
r
0.140 0.020 9.7
13.500 1.000 43.2
80.000 2.000 58.2
0.050 0.040 0.500
)
3.0 4.0 5.0
0.315 0.249 0.214
0.630 0.498 0.428
1.260 0.996 0.856
2.521 1.992 1.712
3.781 2.988 2.568
5.042 3.984 3.424
6.302 4.980 4.280
0.338 0.225 0.169
0.675 0.450 0.338
1.350 0.900 0.675
2.700 1.800 1.350
4.050 2.700 2.025
5.400 3.600 2.700
6.750 4.500 3.375
0.500 0.267 0.167
1.000 0.533 0.333
6.0 7.0 8.0
15.255 14.117 13.267
t
r
---------------------------------- -
= TDM ×
2
1 ( I I ⁄ )
–
pickup
is "Timed")
RESET
6.0 7.0 8.0
0.192 0.176 0.165
0.384 0.353 0.330
0.767 0.706 0.659
1.535 1.411 1.319
2.302 2.117 1.978
3.070 2.822 2.637
3.837 3.528 3.297
0.135 0.113 0.096
0.270 0.225 0.193
0.540 0.450 0.386
1.080 0.900 0.771
1.620 1.350 1.157
2.160 1.800 1.543
2.700 2.250 1.929
0.114 0.083 0.063
0.229 0.167 0.127
GROUPED ELEMENTS
9.0 10.0
12.604 12.068
Eq. 5-8
9.0 10.0
0.156 0.149
0.312 0.297
0.623 0.594
1.247 1.188
1.870 1.782
2.493 2.376
3.116 2.971
0.084 0.075
0.169 0.150
0.338 0.300
0.675 0.600
1.013 0.900
1.350 1.200
1.688 1.500
0.050 0.040
0.100 0.081
5-159
5