blocks in this document. The configuration can be written to the protection relay
once the mismatch is corrected.
4.4.2.5 Operation principle
The function can be enabled and disabled with the
Operation setting
. The
corresponding parameter values are "on" and "off".
The operation of DNSPDOC can be described with a module diagram. All the
modules in the diagram are explained in the next sections.
BLOCK
OPERATE
Blocking
logic
START
Level
detector
t
Timer
Directional
calculation
U3P
U
2
I3P
I
2
IRES
Io
Figure 468: Functional module diagram
Level detector
The operating signal is compared to the set
Start value
. If the operating signal
exceeds the set
Start value
, Level detector sends an enabling signal to the Timer
module. Timer starts when it is enabled and the directional criterion is fulfilled. A
suitable operating quantity can be selected with the
Operating quantity
setting.
The options are "Negative seq" or "Residual". The value of operating quantity I_OPER
is also available in the Monitored data view.
Irrespective of the operating quantity selected, directional calculation is
always determined using the negative-sequence current.
Directional calculation
Directional calculation compares the negative-sequence current phasor with the
negative-sequence voltage phasor, that is, the polarizing quantity. The directional
operation can be selected with the
Directional mode
setting. The options are
"Nondirectional", "Forward" or "Reverse" operation. By setting the value of
Allow
Non Dir
to "True", the non-directional operation is allowed when the directional
information is invalid.
The
Characteristic angle
setting is used to turn the directional characteristics. The
value of
Characteristic angle
should be chosen so that all the faults in the operating
direction are seen in the operating zone and all the faults in the opposite direction
are seen in the non-operating zone. The value of
Characteristic angle
depends on
the network configuration.
1MRS759142 F
Protection functions
REX640
Technical Manual
827
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