The inverse-time characteristic is shown in the following figure.
[dwovpinv, 2, en_US]
Figure 6-182
Operate Curve of Inverse-Time Characteristic
The inverse-time delay is calculated with the following formula:
Where
T
inv
Inverse-time delay
T
p
Time multiplier (parameter Time dial )
V Measured voltage
V
thresh
Threshold value (parameter Threshold )
k Curve constant k (parameter Charact. constant k )
α Curve constant α (parameter Charact. constant α )
c Curve constant c (parameter Charact. constant c )
When V/V
thresh
is equal to or greater than 20, the inverse-time delay does not decrease any further.
Dropout Behavior
When the voltage falls below the dropout threshold (0.95 × pickup factor × threshold value), the pickup signal
is going and the dropout is started. You can define the dropout behavior via parameter Reset time . Instan-
taneous reset takes place by setting Reset time to 0 s. A delayed reset takes place by setting the desired
delay time.
During the Reset time (> 0 s), the elapsed operate delay is frozen. If the pickup value is exceeded again
within this period, the stage operates when the rest of operate delay expires.
Protection and Automation Functions
6.23 Overvoltage Protection with 3-Phase Voltage
700 SIPROTEC 5, Overcurrent Protection, Manual
C53000-G5040-C017-8, Edition 07.2017
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