The residual power, measured by the sensitive earth fault protections in A and B
will be:
IECEQUATION16099 V1 EN-US (Equation 50)
IECEQUATION16100 V1 EN-US (Equation 51)
The residual power is a complex quantity. The protection will have a maximum
sensitivity in the characteristic angle RCA. The apparent residual power
component in the characteristic angle, measured by the protection, can be written:
IECEQUATION16101 V1 EN-US (Equation 52)
IECEQUATION16102 V1 EN-US (Equation 53)
The angles φ
A
and φ
B
are the phase angles between the residual current and the
residual voltage in the station compensated with the characteristic angle RCA.
The protection will use the power components in the characteristic angle direction
for measurement, and as base for the inverse time delay.
The inverse time delay is defined as:
IECEQUATION16103 V1 EN-US (Equation 54)
The function can be set On/Off with the setting of Operation.
Common base IED values for primary current (IBase), primary voltage (UBase)
and primary power (SBase) are set in a Global base values for settings function
GBASV
AL.
GlobalBaseSel: It is used to select a GBASVAL function for reference of base
values.
RotResU: It is a setting for rotating the polarizing quantity ( 2U
0
) by 0 or 180
degrees. This parameter is set to 180 degrees by default in order to inverse the
residual voltage ( 2U
0
) to calculate the reference voltage (-2U
0
e
-jRCADir
). Since the
reference voltage is used as the polarizing quantity for directionality, it is important
to set this parameter correctly.
With the setting OpMode the principle of directional function is chosen.
1MRK 506 375-UEN A Section 8
Current protection
Railway application RER670 2.2 IEC 179
Application manual
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