ABB RELION REX640 Technical Manual page 1297

1MRS759142 F
Max impedance angle
Min impedance angle
Figure 736: Operating sectors for load blinder
The blinder directional operation can be selected with the
The alternatives are "Non-directional", "Forward" and "Reverse" operation.
Forward operation is allowed if
part value of positive sequence impedance is higher than
the angle of positive sequence impedance stays in the range limited with the
impedance angle and Min impedance angle on forward area, the function output
LB_FORWARD is activated.
Reverse operation is allowed if
part value of positive sequence impedance exceeds the limitation of
Rv and the angle of positive sequence impedance stays in the range limited with the
Max impedance angle and Min impedance angle on reverse area, the function output
LB_REVERSE is activated.
In case
directions according to conditions described above.
Activation of the BLOCK input deactivates the function outputs.
5.16.6 Application
Load blinder or load encroachment, function LBRDOB is used to block the
directional overcurrent protection aiming at avoiding incorrect trip in case of heavy
loading condition in network. In general, the active power increases to the level
leading to a high power factor, the network turns into heavy load status, and there
exists risk of incorrect trip for the directional overcurrent protection because of
high level of load current.
The suitability of
the activation of load blinder function. If
are set beyond the network minimal resistive load, the function will not be activated
in the case that the load impedance approaches the network minimal impedance
load. Hence, the absolute values of
be set less than that of the minimal resistive load.
REX640
Technical Manual
Load blinder reverse area
(Load-in region or Load importing)
Load blinder reverse area
(Load-in region or Load importing)
Directional mode is set to "Non-directional", operation is allowed both
Resistive reach Fw and Resistive reach Rv settings will influence
X
Resistive
Resistive
reach Fw
reach Rv
Directional mode is set to "Forward". If the resistive
Directional mode is set to "Reverse". If the resistive
Resistive reach Fw and Resistive reach Rv
Resistive reach Fw and Resistive reach Rv should
Protection related functions
Nominal impedance
circle
Max impedance angle
Load blinder forward area
(Load-out region or Load exporting)
Load blinder forward area
(Load-out region or Load exporting)
Min impedance angle
Directional mode setting.
Resistive reach Fw and
Resistive reach
R
Max
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