The T_ENARESTART output indicates in seconds the duration for which the
BLK_RESTART output still remains active. The value is available in the Monitored
data view.
Timer calculates the start duration value START_DUR, which indicates the
percentage ratio of the start situation and the set operating time. The value is
available in the Monitored data view.
Blocking logic
There are three operation modes in the blocking functionality. The operation
modes are controlled by the BLOCK input and the global setting Configuration >
System > Blocking mode which selects the blocking mode. The BLOCK input can be
controlled by a binary input, a horizontal communication input or an internal signal
of the protection relay's program. The influence of the BLOCK signal activation is
preselected with the global setting
Blocking mode
.
The
Blocking mode
setting has three blocking methods. In the "Freeze timers"
mode, the operation timer is frozen to the prevailing value. In the "Block all" mode,
the whole function is blocked and the timers are reset. In the "Block OPERATE
output" mode, the function operates normally but the OPERATE output is not
activated.
4.5.8.5 Timer characteristics
OEPVPH supports both DT and IDMT characteristics. The DT timer characteristics
can be selected as "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
Operate delay time
and
Reset
delay time
settings.
OEPVPH also supports four overexcitation IDMT characteristic curves: "OvExt IDMT
Crv1", "OvExt IDMT Crv2", "OvExt IDMT Crv3" and "OvExt IDMT Crv4".
Overexcitation inverse definite minimum time curve (IDMT)
In the inverse time modes, the operate time depends on the momentary value of the
excitation: the higher the excitation level, the shorter the operate time. The operate
time calculation or integration starts immediately when the excitation level exceeds
the set
Start value
and the START output is activated.
The OPERATE output is activated when the cumulative sum of the integrator
calculating the overexcitation 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 operate time
and
Maximum operate time
settings define the
minimum operate time and maximum operate time possible for the IDMT mode.
For setting these parameters, a careful study of the particular IDMT curves is
recommended.
The operation time of the function block can vary much between
different operating curve types even if other setting parameters for the
curves were not changed.
Once activated, the Timer activates the START output for the IDMT curves. If the
excitation level drops below the
Start value
setting before the function operates,
the reset timer is activated and the START output resets immediately. If START
Protection functions
1MRS757644 H
676 620 series
Technical Manual
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