ABB Relion 620 Series - Page 1120

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