ABB 615 series Technical Manual page 618

Section 4
Protection functions
612
For a detailed description of the voltage IDMT curves, see the
curves for overvoltage protection
When the operation timer has reached the value set by Trip delay time in the DT mode or
the maximum value defined by the IDMT, the TRIP output is activated.
When the user-programmable IDMT curve is selected, the trip 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 trip delay is
exceeded, the reset state is activated. The behavior in the drop-off situation depends on the
selected trip 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 PICKUP 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 510: Reset time functionality when IDMT operation time curve selected
Reset functionality
Instantaneous Operation timer is
reset "Reset
instantaneously"
when drop-off
occurs
Frozen timer Operation timer is
frozen during drop-
off
Linear decrease Operation timer
value linearly
decreases during
the drop-off
situation
section in this manual.
Setting Type of reset Setting Type of time
curve reset
"Immediate" Setting has no
effect
"Def time reset" "Freeze Op timer"
"Def time reset" "Decrease Op
timer"
1MAC059074-MB A
IDMT
Setting Reset delay
time
Setting has no
effect
Operate timer is
reset after the set
Reset delay time
has elapsed
Operate timer is
reset after the set
Reset delay time
has elapsed
615 series ANSI
Technical Manual