Operation Principle - ABB RELION REX640 Technical Manual

Section 5
Protection related functions
5.15.5
1190

Operation principle

The function can be enabled and disabled with the Operation setting. The
corresponding parameter values are "on" and "off".
The operation of DNZSRDIR can be described with a module diagram. All the
modules in the diagram are explained in the next sections.
U
2
U3P
I
2
I3P
Uo
URES
Io
IRES
RCA_CTL
BLOCK
GUID-B59AE4A9-44E7-457A-96DD-114552800163 V1 EN
Figure 643: Functional module diagram
Directional detector
When "Neg. seq. volt." selection is made using the Pol quantity setting, the
Directional detector module compares the angle of the negative-sequence current (I
to the negative-sequence voltage (-U
the reference, the negative-sequence current angle is compared to the Characteristic
angle setting. If the angle difference is within the operating sector selected by
Direction mode setting, the Enable signal is sent to Timer.
The value of Characteristic angle should be chosen in such way 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 backward
zone.
The operating sector is defined by the settings Max forward angle, Max reverse angle,
Min forward angle and Min reverse angle. The options that can be selected for
Directional mode settings are "Forward" and "Reverse".
Characteristic angle is also known as Relay Characteristic Angle RCA, Relay Base
Angle or Maximum Torque Line.
Timer
t
Directional
detector
Low level
blocking
Blocking
logic
). Using the negative-sequence voltage angle as
2
1MRS759142 C
DIRECTION
RELEASE
Technical Manual
)
2
REX640