ABB RELION 620 Series Technical Manual page 472

Section 4
Protection functions
4.2.7.8
4.2.7.9
Table 463: WPWDE Group settings (Basic)
Parameter
Directional mode
Current start value
Voltage start value
Power start value
Reference power
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466
has zero phase shift compared to the residual voltage. In such networks, the
characteristic angle is chosen as 0º. Often the magnitude of an active component is
small and must be increased by means of a parallel resistor in a compensation coil. In
networks where the neutral point is earthed through a low resistance, the characteristic
angle is always 0º.
As the amplitude of the residual current is independent of the fault location, the
selectivity of the earth-fault protection is achieved with time coordination.
The use of wattmetric protection gives a possibility to use the dedicated inverse
definite minimum time characteristics. This is applicable in large high-impedance
earthed networks with a large capacitive earth-fault current.
In a network employing a low-impedance earthed system, a medium-size neutral point
resistor is used. Such a resistor gives a resistive earth-fault current component of about
200...400 A for an excessive earth fault. In such a system, the directional residual
power protection gives better possibilities for selectivity enabled by the inverse time
power characteristics.
Signals
Table 461: WPWDE Input signals
Name
Io
Uo
BLOCK
RCA_CTL
Table 462: WPWDE Output signals
Name
OPERATE
START
Settings
Values (Range) Unit
2=Forward
3=Reverse
0.010...5.000 xIn
0.010...1.000 xUn
0.003...1.000 xPn
0.050...1.000 xPn
Type Default Description
SIGNAL 0 Residual current
SIGNAL 0 Residual voltage
BOOLEAN 0=False Block signal for activating the blocking mode
BOOLEAN 0=False Relay characteristic angle control
Type Description
BOOLEAN Operate
BOOLEAN Start
Step Default
2=Forward
0.001 0.010
0.001 0.010
0.001 0.003
0.001 0.150
1MRS757644 F
Description
Directional mode
Minimum operate residual current for
deciding fault direction
Start value for residual voltage
Start value for residual active power
Reference value of residual power for
Wattmetric IDMT curves
Technical Manual
620 series