ABB RELION REX640 - Page 845

Figure 478: MNSPTOC Inverse Curve A
If the negative sequence current drops below the Start value setting, the reset time
is defined as:
t s a
b
[ ]
= ×






100
(Equation 238)
t[s]
Reset time in seconds
a set Cooling time
b
percentage of start time elapse ( START_DUR)
When the reset period is initiated, the time for which START has been active is
saved. If the fault reoccurs, that is, the negative-sequence current rises above the
1MRS759142 F
Protection functions
REX640
Technical Manual
845