4.3.2.4 Operation principle
The function can be enabled and disabled with the
Operation
setting. The
corresponding parameter values are "On" and "Off".
The operation of PDNSPTOC can be described by using a module diagram. All the
modules in the diagram are explained in the next sections.
Figure 207: Functional module diagram
I
2
/I
1
The I
2
/I
1
module calculates the ratio of the negative and positive sequence current.
It reports the calculated value to the level detector.
Level detector
The level detector compares the calculated ratio of the negative and positive-
sequence currents to the set
Start value
. If the calculated value exceeds the set
Start value
and the min current check module has exceeded the value of
Min phase
current
, the level detector reports the exceeding of the value to the timer.
Min current check
The min current check module checks whether the measured phase currents are
above the set
Min phase current
. At least one of the phase currents needs to be
above the set limit to enable the level detector module.
Timer
Once activated, the timer activates the START output. The time characteristic is
according to DT. When the operation timer has reached the value set by
Operate
delay time
, the OPERATE output is activated. If the fault disappears before the
module operates, the reset timer is activated. If the reset timer reaches the
value set by
Reset delay time
, the operate 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.
Protection functions
1MRS758755 C
416 REC615 & RER615
Technical Manual
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