ABB RELION 620 Series Technical Manual page 833

1MAC504801-IB E
620 series ANSI
Technical Manual
A070420-ANSI V1 EN
Figure 422: Drop-off period is shorter than the set Reset delay time
When the drop-off period is shorter than the set Reset delay time, as described in
422, the input signal for the definite timer (here: timer input) is active, provided that the
current is above the set Pickup value. The input signal is inactive when the current is below
the set Pickup value and the set hysteresis region. The timer input rises when a fault current
is detected. The definite timer activates the PICKUP output and the trip timer starts
elapsing. The reset (drop-off) timer starts when the timer input falls, that is, the fault
disappears. Another fault situation occurs before the reset (drop-off) timer has elapsed.
This causes the activation of the TRIP output, since the trip timer already has elapsed.
General function block features
Section 12
Figure
827