GE Multilin G650 Manual page 177

5.4 PROTECTION ELEMENTS
5.4.2.3 IAC CURVES
This family of curves follows the time response of the General Electric IAC electromechanical relays. The following
formulas define these curves:
Where:
t = Operation time in seconds
Dial = multiplier setting
I = Input current
Itap = Current pickup value
A, B, C, D, E = predefined constants
T = reset time in seconds
RESET
t = characteristic constant.
r
5
Table 5–33: CONSTANTS FOR IAC CURVES
IAC CURVE SHAPE
IAC Extremely Inverse
IAC Very Inverse
IAC Inverse
5-34
NAME A B
IAC Ext Inv 0.0040 0.6379
IAC Very Inv 0.0900 0.7955
IAC Mod Inv 0.2078 0.8630
G650 Generator Protection & Control System
C D E
0.6200 1.7872 0.2461
0.1000 -1.2885 7.9586
0.8000 -0.4180 0.1947
5 SETTINGS
TR
6.008
4.678
0.990
GEK-113285A