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.
4.2.7.9 Signals
WPWDE Input signals
Table 595: WPWDE Input signals
Name Type Default Description
IRES SIGNAL - Residual current
URES SIGNAL - Residual voltage
BLOCK BOOLEAN 0=False Block signal for acti-
vating the blocking
mode
RCA_CTL BOOLEAN 0=False Relay characteristic
angle control
WPWDE Output signals
Table 596: WPWDE Output signals
Name Type Description
OPERATE BOOLEAN Operate
START BOOLEAN Start
4.2.7.10 WPWDE Settings
Table 597: WPWDE Group settings (Basic)
Parameter
Values (Range) Unit Step Default Description
Directional mode
2=Forward
3=Reverse
2=Forward Directional mode
Current start value 0.010...5.000 xIn 0.001 0.010 Minimum operate
residual current for
deciding fault di-
rection
Voltage start value 0.010...1.000 xUn 0.001 0.010 Start value for re-
sidual voltage
Power start value 0.003...1.000 xSn 0.001 0.003 Start value for re-
sidual active power
Reference power 0.050...1.000 xSn 0.001 0.150 Reference value of
residual power for
Wattmetric IDMT
curves
Table continues on the next page
1MRS759142 F Protection functions
REX640
Technical Manual
539
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