ABB RED615 Technical Manual page 482

Section 4
Protection functions
476
When the user-programmable IDMT curve is selected, the operate time
characteristics are defined by the parameters Curve parameter A, Curve parameter
B, Curve parameter C, Curve parameter D and Curve parameter E.
If a drop-off situation occurs, that is, a fault suddenly disappears before the operate
delay is exceeded, the reset state is activated. The behavior in the drop-off situation
depends on the selected operate time characteristics. If the DT characteristics are
selected, the reset timer runs until the set Reset delay time value is exceeded. If the
drop-off situation exceeds the set Reset delay time, the timer is reset and the
START output is deactivated.
When the IDMT operate time curve is selected, the functionality of the timer in the
drop-off state depends on the combination of the Type of reset curve and Reset
delay time settings.
Table 392: The reset time functionality when the IDMT operate time curve is selected
Type of reset curve
"Immediate"
"Def time reset"
"DT Lin decr rst"
Description of operation
The operate timer is reset instantaneously when
drop-off occurs
The operate timer is frozen during drop-off.
Operate timer is reset after the set
time is exceeded
The operate timer value linearly decreases
during the drop-off situation. The operate timer is
reset after the set Reset delay time is exceeded
1YHT530004D05 D
Reset delay
615 series
Technical Manual