5-32 F650 Digital Bay Controller GE Multilin
5.4 PROTECTION ELEMENTS 5 SETPOINTS
5
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
= reset time in seconds
t
r
= characteristic constant.
Table 5â32: CONSTANTS FOR IAC CURVES
IAC CURVE SHAPE NAME A B C D E TR
IAC Extremely Inverse IAC Ext Inv 0.0040 0.6379 0.6200 1.7872 0.2461 6.008
IAC Very Inverse IAC Very Inv 0.0900 0.7955 0.1000 -1.2885 7.9586 4.678
IAC Inverse IAC Mod Inv 0.2078 0.8630 0.8000 -0.4180 0.1947 0.990