GE UR Series L90, Instruction Manual, Page: 331 / 846

GE Multilin L90 Line Current Differential System 5-193
5 SETTINGS 5.6 GROUPED ELEMENTS
5
I2t CURVES:
The curves for the I
2
t are derived from the formulae:
, (EQ 5.14)
where: T = Operate Time (sec.); TDM = Multiplier Setting; I = Input Current; I
pickup
= Pickup Current Setting;
T
RESET
= Reset Time in sec. (assuming energy capacity is 100% and RESET: Timed)
FLEXCURVES:
The custom FlexCurves are described in detail in the FlexCurves section of this chapter. The curve shapes for the Flex-
Curves are derived from the formulae:
(EQ 5.15)
(EQ 5.16)
where: T = Operate Time (sec.), TDM = Multiplier setting
I = Input Current, I
pickup
= Pickup Current setting
T
RESET
= Reset Time in seconds (assuming energy capacity is 100% and RESET: Timed)
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 instanta-
neous to 600.00 seconds in steps of 10 ms.
(EQ 5.17)
(EQ 5.18)
where: T = Operate Time (sec.), TDM = Multiplier setting
I = Input Current, I
pickup
= Pickup Current setting
T
RESET
= Reset Time in seconds (assuming energy capacity is 100% and RESET: Timed)
RECLOSER CURVES:
The L90 uses the FlexCurve feature to facilitate programming of 41 recloser curves. Please refer to the FlexCurve section
in this chapter for additional details.
Table 5–23: I
2
T CURVE TRIP TIMES
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 12.35 10.00
100.00 4444.4 2500.0 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
T TDM
100
I
I
pickup
----------------
 
 
2
--------------------------

=
T
RESET
TDM
100
I
I
pickup
----------------
 
 
2
–
----------------------------

=
T TDM FlexCurve Time at
I
I
pickup
----------------
 
 

=
when
I
I
pickup
----------------
 
 
1.00

T
RESET
TDM FlexCurve Time at
I
I
pickup
----------------
 
 

when
I
I
pickup
----------------
 
 
0.98

=
T TDM in seconds, when I I
pickup

=
T
RESET
TDM in seconds
=