GE L90 Instruction Manual page 225

5 SETTINGS
a) SETTINGS
PATH: SETTINGS SYSTEM SETUP
FLEXCURVE A
FlexCurves™ A through D have settings for entering times to reset and operate at the following pickup levels: 0.00 to 0.98
and 1.03 to 20.00. This data is converted into two continuous curves by linear interpolation between data points. To enter a
custom FlexCurve™, enter the reset and operate times (using the VALUE keys) for each selected pickup point (using the
MESSAGE UP/DOWN keys) for the desired protection curve (A, B, C, or D).
Table 5–5: FLEXCURVE™ TABLE
RESET TIME RESET
MS
0.00 0.68
0.05 0.70
0.10 0.72
0.15 0.74
0.20 0.76
0.25 0.78
0.30 0.80
0.35 0.82
0.40 0.84
0.45 0.86
0.48 0.88
0.50 0.90
0.52 0.91
0.54 0.92
0.56 0.93
0.58 0.94
0.60 0.95
0.62 0.96
0.64 0.97
0.66 0.98
The relay using a given FlexCurve™ applies linear approximation for times between the user-entered points. Spe-
cial care must be applied when setting the two points that are close to the multiple of pickup of 1; that is, 0.98 pu
and 1.03 pu. It is recommended to set the two times to a similar value; otherwise, the linear approximation may
NOTE
result in undesired behavior for the operating quantity that is close to 1.00 pu.
GE Multilin
FLEXCURVES FLEXCURVE A(D)
FLEXCURVE A TIME AT
0.00 xPKP:
TIME OPERATE TIME
MS MS
1.03
1.05
1.1
1.2
1.3
1.4
1.5
1.6
1.7
1.8
1.9
2.0
2.1
2.2
2.3
2.4
2.5
2.6
2.7
2.8
L90 Line Current Differential System
Range: 0 to 65535 ms in steps of 1
0 ms
OPERATE TIME OPERATE
MS
2.9 4.9
3.0 5.0
3.1 5.1
3.2 5.2
3.3 5.3
3.4 5.4
3.5 5.5
3.6 5.6
3.7 5.7
3.8 5.8
3.9 5.9
4.0 6.0
4.1 6.5
4.2 7.0
4.3 7.5
4.4 8.0
4.5 8.5
4.6 9.0
4.7 9.5
4.8 10.0
5.4 SYSTEM SETUP
5.4.7 FLEXCURVES™
TIME OPERATE TIME
MS MS
10.5
11.0
11.5
12.0
12.5
13.0
13.5
14.0
14.5
15.0
15.5
16.0
16.5
17.0
17.5
18.0
18.5
19.0
19.5
20.0
5-79
5