disappears before the module operates, the reset timer is activated. If the reset timer
reaches the value set with the Reset delay time setting, the operation timer resets
and the START output is deactivated. 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.
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 IED 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 operate 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.
4.2.4.5 Neutral admittance characteristics
The applied characteristic should always be set to cover the total admittance of the
protected feeder with a suitable margin. However, more detailed setting value
selection principles depend on the characteristic in question.
The settings defining the admittance characteristics are given in
primary milliSiemens.
The forward and reverse boundary settings should be set so that the forward setting
is always larger than the reverse setting and that there is space between them.
Overadmittance characteristic
The overadmittance criterion is enabled with the setting Operation mode set to
"Yo". The characteristic is a circle with the radius defined with the Circle radius
setting. For the sake of application flexibility, the midpoint of the circle can be
moved away from the origin with the Circle conductance and Circle susceptance
settings. Default values for Circle conductance and Circle susceptance are 0.0 mS,
that is, the characteristic is an origin-centered circle.
Operation is achieved when the measured admittance moves outside the circle.
The overadmittance criterion is typically applied in unearthed networks, but it can
also be used in compensated networks, especially if the circle is set off from the origin.
Section 4 1YHT530004D05 D
Protection functions
324 615 series
Technical Manual
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