ABB RELION REX640 Technical Manual page 843

1MRS759142 F
In a drop-off situation, that is, when the value of the negative-sequence current
drops below the
output resets after the time delay of
IDMT, the reset time depends on the curve type selected.
For the IDMT curves, it is possible to define minimum and maximum operate times
with the
time Mult setting parameter corresponds to the machine constant, equal to the I
constant of the machine, as stated by the machine manufacturer. In case there is a
mismatch between the used CT and the protected motor's nominal current values,
it is possible to fit the IDMT curves for the protected motor using the
reference setting.
The activation of the OPERATE output activates the BLK_RESTART output. The
deactivation of the OPERATE output activates the cooling timer. The timer is set
to the value entered in the
kept active until the cooling timer is exceeded. If the negative-sequence current
increases above the set value during this period, the OPERATE output is activated
immediately.
T_ENARESTART indicates the duration for which the BLK_RESTART output remains
active, that is, it indicates the remaining time of the cooling timer. The value is
available in the monitored data view.
When the ST_EMERG_ENA emergency start is set high, the value of the
T_ENARESTART is immediately set to "False". This disables BLK_RESTART and in turn
makes the restart of the motor possible.
The timer calculates the start duration value START_DUR, which indicates the
percentage ratio of the start situation and the set operation time. The value is
available in the monitored data view.
The T_ENARESTART output indicates the duration for which the BLK_RESTART
output remains active, that is, it indicates the remaining time of the cooling timer.
The value is available in the monitored data view.
When the ST_EMERG_ENA emergency start is set high, the value of the
T_ENARESTART is immediately set to "False". This disables BLK_RESTART and in turn
makes the restart of the motor possible.
The timer calculates the start duration value START_DUR, which indicates the
percentage ratio of the start situation and the set operation time. The value is
available in the monitored data view.
4.4.5.6 Timer characteristics
MNSPTOC supports both DT and IDMT characteristics. The DT timer characteristics
can be selected with "ANSI Def. Time" or "IEC Def. Time" in the
setting. The functionality is identical in both cases. When the DT characteristics
are selected, the functionality is only affected by the
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 operate time depends on the momentary value of the
current: the higher the current, the shorter the operate time. The operate time
REX640
Technical Manual
Start value setting, the reset timer is activated and the START
Minimum operate time and Maximum operate time settings. The Machine
Cooling time setting. The BLK_RESTART output is
Reset delay time for the DT characteristics. For
Operate delay time and Reset
Protection functions
2
t
2
Current
Operating curve type
843