Iac Curves; Constants For Iac Curves - GE Multilin F650 Instruction Manual

5.4 PROTECTION ELEMENTS
5.4.2.3

IAC CURVES

This family of curves follows the time response of General Electric IAC electromechanical relays. The following formulas
define these curves:
Where:
t = Operation time in seconds
Dial = multiplier setpoint
I = Input current
Itap = Current pickup value
A, B, C, D, E = predefined constants
T = reset time in seconds
RESET
5
t = characteristic constant.
r
Table 5–32: CONSTANTS FOR IAC CURVES
IAC CURVE SHAPE
IAC Extremely Inverse
IAC Very Inverse
IAC Inverse
5-32
NAME A B
IAC Ext Inv 0.0040 0.6379
IAC Very Inv 0.0900 0.7955
IAC Mod Inv 0.2078 0.8630
F650 Digital Bay Controller
C D E
0.6200 1.7872 0.2461
0.1000 -1.2885 7.9586
0.8000 -0.4180 0.1947
5 SETPOINTS
TR
6.008
4.678
0.990
GE Multilin