4–162
889 GENERATOR PROTECTION SYSTEM – INSTRUCTION MANUAL
PROTECTION
CHAPTER 4: SETPOINTS
The curves for the I
2
t are derived from the formula:
Where:
T = operate time (in seconds)
TDM = Multiplier setting
I = input current
I
pickup
= Pickup Current setting
T
RESET
= reset time in seconds (assuming energy capacity is 100% and RESET is
“Timed”)
Table 4-30: I
2
T CURVE TRIP TIMES (IN SECONDS)
I
4
T CURVES
The curves for the I
4
t are derived from the formula:
Where:
T = operate time (in seconds)
TDM = Multiplier setting
I = input current
I
pickup
= Pickup Current setting
T
RESET
= reset time in seconds (assuming energy capacity is 100% and RESET is
“Timed”)
Table 4-31: I
4
T CURVE TRIP TIMES (IN SECONDS)
FLEXCURVES
MULTIPLIER
(TDM)
CURRENT (I/I
pickup
)
1.5
2.0
3.0
4.0
5.0
6.0
7.0
8.0
9.0
10.0
0.01
0.44
0.25
0.11
0.06
0.04
0.03
0.02
0.02
0.01
0.01
0.10
4.44
2.50
1.11
0.63
0.40
0.28
0.20
0.16
0.12
0.10
1.00
44.44
25.00
11.11
6.25
4.00
2.78
2.04
1.56
1.23
1.00
10.00
444.44
250.00
111.11
62.50
40.00
27.78
20.41
15.63
123.5
10.00
100.00
4444.44
2500.00
1111.1
625.00
400.00
277.78
204.08
156.25
123.46
100.00
600.00
26666.7
15000.0
6666.7
3750.0
2400.0
1666.7
1224.5
937.50
740.74
600.00
MULTIPLIER
(TDM)
CURRENT (I/I
pickup
)
1.5
2.0
3.0
4.0
5.0
6.0
7.0
8.0
9.0
10.0
0.01
0.1975
0.0625
0.0123
0.0039
0.0016
0.0008
0.0004
0.0002
0.00015
0.0001
0.10
1.9753
0.6250
0.1235
0.0391
0.0160
0.0077
0.0042
0.0024
0.0015
0.0010
1.00
19.753
6.250
1.235
0.391
0.160
0.077
0.042
0.024
0.015
0.010
10.00
197.531
62.500
12.346
3.906
1.600
0.772
0.416
0.244
0.152
0.100
100.00
1975.31
625.00
123.46
39.06
16.00
7.72
4.16
2.44
1.52
1.00
600.00
11851.9
3750.0
740.7
234.4
96.00
46.3
25.0
14.65
9.14
6.00
