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DT3000
Instruction Leaflet
I.B. 17555D
Effective: Date 07/02
Page 61
For more information visit:
www.cutler-hammer.eaton.com
Supersedes I.B. 17555C dated November 1999
7-2 DIGITRIP 3000 CURVE EQUATIONS
Thermal Curve Equation
SLOPE
M
IT
1
I
2
T
2
I
4
T
4
T = Trip Time
D = Time Multiplier (0.2 to 40) IT 1
I = Input Current I2T 2
M = Slope (0 = FLAT, 1 = IT, 2 = I2T, 4 = 14T) I4T 4
K = 3 for phase, 1 for ground FLAT 0
FLAT
0
ANSI/IEC Curve Equation
Where:
I = Input Current
I
pu
= Pickup Current Setting
D = Time Multiplier Setting
P
A
B
ANSI MOD
Moderately Inverse
0.02
0.0515
0.114
ANSI VERY
Very Inverse
2
19.61
0.491
ANSI XTRM
Extremely Inverse
2
28.0
0.1217
D = 0.1 - 5.0
step of 0.1
IEC-A
Normal Inverse
0.02
0.14
0
IEC-B
Very Inverse
1
13.5
0
IEC-C
Extremely Inverse
2
80
0
IEC-D
Definite Time
0
4
D = 0.05 to 1.0
step of 0.05
I
M
I
n
T =
D * K
M
I
P
I
pu
T = D *
-1
+B
A