GE B90 Instruction Manual page 313

CHAPTER 5: SETTINGS
2
I t curves
2
The I t curves are derived as follows:
where
T = Operate time (in seconds)
TDM = Multiplier setting
I = Input current
I = Pickup Current setting
pickup
T = reset time in seconds (assuming energy capacity is 100% and RESET is "Timed")
RESET
2
Table 5-28: I t curve trip times
Multiplier Current ( I / I
(TDM)
1.5
0.01 0.44
0.10 4.44
1.00 44.44
10.00 444.44
100.00 4444.4
600.00 26666.7
Definite time curve
The Definite Time curve shape operates as soon as the pickup level is exceeded for a specified period of time. The base
definite time curve delay is in seconds. The curve multiplier of 0.00 to 600.00 makes this delay adjustable from
instantaneous to 600.00 seconds in steps of 10 ms. The definite time curve shapes are defined as follows:
where
T = Operate Time (in seconds)
TDM = Multiplier setting
I = Input Current
I = Pickup Current setting
pickup
T = Reset Time in seconds (assuming energy capacity is 100% and RESET: Timed)
RESET
5.6.6.3 Instantaneous overcurrent (ANSI 50)
SETTINGS  GROUPED ELEMENTS  SETTING GROUP 1(6)  CURRENT ELEMENTS  INSTANTANEOUS
OVERCURRENT 1(24)
 INSTANTANEOUS
 OVERCURRENT 1
B90 LOW IMPEDANCE BUS DIFFERENTIAL SYSTEM – INSTRUCTION MANUAL
)
pickup
2.0 3.0 4.0
0.25 0.11 0.06
2.50 1.11 0.63
25.00 11.11 6.25
250.00 111.11 62.50
2500.0 1111.1 625.00
15000.0 6666.7 3750.0
IOC1 FUNCTION:

Disabled
IOC1 CT:

F1
IOC1 PICKUP:

1.200 pu
5.0 6.0 7.0
0.04 0.03 0.02
0.40 0.28 0.20
4.00 2.78 2.04
40.00 27.78 20.41
400.00 277.78 204.08
2400.0 1666.7 1224.5
Range: Disabled, Enabled
Range: Available current channels
Range: 0.020 to 30.000 pu in steps of 0.001
GROUPED ELEMENTS
Eq. 5-8
8.0 9.0 10.0
0.02 0.01 0.01
0.16 0.12 0.10
1.56 1.23 1.00
15.63 12.35 10.00
156.25 123.46 100.00
937.50 740.74 600.00
Eq. 5-9
Eq. 5-10
5-157
5