ABB Relion 620 Series, Technical Manual

Page: 1120 / 1224

Figure 590: Drop-off period is longer than the set Reset delay time
When the drop-off period is longer than the set Reset delay time, as described
in Figure 590 , the input signal for the definite timer (here: timer input) is active,
provided that the current is above the set Start value. The input signal is inactive
when the current is below the set Start value and the set hysteresis region. The
timer input rises when a fault current is detected. The definite timer activates the
START
output and the operate timer starts elapsing. The reset (drop-off) timer
starts when the timer input falls, that is, the fault disappears. When the reset (drop-
off) timer elapses, the operate timer is reset. Since this happens before another
start occurs, the
OPERATE
output is not activated.
General function block features 1MRS757644 H
1120 620 series
Technical Manual