GE GEK-106273L Instruction Manual page 170

The curves for the General Electric type IAC relay family are derived from the formulae:
where:
IAC Curve Shape
IAC Extremely Inverse
IAC Very Inverse
IAC Inverse
IAC Inverse Long
IAC Inverse Short
GEK-106273L
ANNEX 2 TIME CURRENT CURVES FOR 51P AND 51N UNITS
⎛
⎜
⎜
⎜
= +
T TDM * A
⎜
⎛
⎜
⎜
⎜
⎜
I
⎝
⎝
Table 2.1: GE TYPE IAC INVERSE TIME CURVE CONSTANTS
HMI
Extr Inverse
Very Inverse
Mod Inverse
Inverse Long
Inverse Short
MIF Digital Feeder Protection
B D
+
⎞
⎛
⎛ ⎞
I
⎟
− I
⎜
⎜ ⎟
−
C
⎟
C
⎜ ⎟
⎜
⎠
I
⎝ ⎠
⎝
pkp
pkp
A B
0.0040 0.6379
0.0900 0.7955
0.2078 0.8630
0.3754 17.8307
0.0442 0.0482
⎞
⎟
⎟
⎟
E
+
⎟
2 3
⎞ ⎛ ⎞
⎛ ⎞
⎟
I
⎟ ⎜ ⎟
⎜ ⎟
−
C
⎜ ⎟
⎟ ⎜ ⎟ ⎟
I
⎝ ⎠
⎠ ⎝ ⎠
⎠
pkp
C D
0.6200 1.7872
0.1000 -1.2885
0.8000 -0.4180
0.32 -23.7187
0.34 0.0223
E
0.2461
7.9586
0.1947
23.8978
0.0697
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