CHAPTER 5: SETTINGS
CONTROL ELEMENTS
L30 LINE CURRENT DIFFERENTIAL SYSTEM – INSTRUCTION MANUAL
5-299
5
To ensure element accuracy for high overcurrent conditions, the maximum value of I/(k x I
B
) is limited to 8, even when
realistically it is exceeding this value.
The reset time of the thermal overload protection element is also time delayed using following formula:
Eq. 5-30
where
τ
rst
= thermal protection trip time constant
T
min
= a minimum reset time setting
Figure 5-160: IEC 255-8 sample operate and reset curves