Timer Characteristics - ABB 615 series Technical Manual

1MAC059074-MB A
4.4.4.5
615 series ANSI
Technical Manual
The timer calculates the pickup duration value PICKUP_DUR, which indicates the
percentage ratio of the pickup situation and the set trip time. The value is available in the
monitored data view.

Timer characteristics

46M supports both DT and IDMT characteristics. The DT timer characteristics can be
selected with "ANSI Def. Time" or "IEC Def. Time" in the Operating curve type setting.
The functionality is identical in both cases. When the DT characteristics are selected, the
functionality is only affected by the Trip delay time and Reset delay time settings.
The protection relay provides two user-programmable IDMT characteristics curves, "Inv.
curve A" and "Inv. curve B".
Current-based inverse definite minimum time curve (IDMT)
In inverse-time modes, the trip time depends on the momentary value of the current: the
higher the current, the shorter the trip time. The trip time calculation or integration starts
immediately when the current exceeds the set Pickup value and the PICKUP output is
activated.
The TRIP output of the component is activated when the cumulative sum of the integrator
calculating the overcurrent situation exceeds the value set by the inverse time mode. The
set value depends on the selected curve type and the setting values used.
The Minimum trip time and Maximum trip time settings define the minimum trip time and
maximum trip time possible for the IDMT mode. For setting these parameters, a careful
study of the particular IDMT curves is recommended.
Inv. curve A
The inverse time equation for curve type A is:
k
t s
[ ]
=
2
I
 
2
 
I
 r 
GUID-D8A4A304-6C63-4BA4-BAEA-E7891504557A V1 EN
t[s] Trip time in seconds
Machine time Mult
k Set
I Negative-sequence current
2
Rated current
I Set
r
Section 4
Protection functions
(Equation 117)
605