Hitachi Relion 670 Series Applications Manual page 98

Section 7
Impedance protection
After the above event, another restrike occurs on L2, the voltage on L1 increases and the distance or
residual current protection operates again. To confirm that the fault exists on phase L2, phase-to-
earth voltage of L1 will be checked. Normally in a compensated earthing system, the change in
measured voltage is big if fault persists on L2 and is typically 70% UB.
The voltage function has a reset drop-off about 0.1 s to ensure the correct function without timing
problems.
Setting guidelines
The settings for 2-phase Distance protection zones, quadrilateral characteristic (ZRWPDIS) are done
in primary values. The instrument transformer ratio that has been set for the analog input card is
used to automatically convert the measured secondary input signals to primary values used in
ZRWPDIS.
The default values given should be validated for each application and adopt the appropriate setting
values.
The parameters for ZRWPDIS are set via the local HMI or PCM600.
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 GBASVAL.
General settings
GlobalBaseSel: Selects the global base value group used by the function to define (IBase), (UBase)
and (SBase).
Operation: Sets the protection to On or Off.
System Earthing: To select the type of system earthing (i.e. Compensated, Solidly and High
impedance).
LineAng:To set the distance protection characteristic angle. It should be set to line angle of the
protected transmission line. The default value is 75 deg.
IMinOpPE: To select the minimum operating current for the phase-to-earth loops. If the minimum
current is exceeded, the distance protection calculates the impedance. The default setting is 10% IB.
IMinOpPP: To select the minimum operating current for the phase-to-phase loops. If the minimum
current is exceeded, the distance protection calculates the impedance. The default setting is 10% IB.
OpLoadEnch: To select the load discrimination characteristic operation to On or Off. The default
value is Off.
RLd: To set the resistive reach within the load impedance of load discrimination characteristic. This
setting can be calculated according to equation:
RLd 
IECEQUATION15051 V1 EN-US
Where,
RLd is the resistive reach within the load impedance area measured in Ohm/Phase
P is the maximum exporting power
max
U is the minimum phase-to-phase voltage for which P
min
0.8 is security factor.
92
2
U
min
0 8 .
P
max
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GUID-F9BB43B1-7A1C-40A4-84DB-58ACE7B12C28 v2
GUID-30CF921D-34EE-4F24-B050-C92036619F59 v4
can occur
max
Railway application RER670
1MRK506375-UEN Rev. N
(Equation 15)
Application manual