Hitachi Relion 670 Series Applications Manual page 163

1MRK506375-UEN Rev. N
IEC16000027 V1 EN-US
Figure 62:
In a normal transmission network a normal value of RCA is about 65°.
Normally voltage polarizing from the internally calculated residual sum or an external open delta is
used.
UPolMin: Minimum polarization (reference) polarizing voltage for the directional function, given in %
of UBase/2.
I>Dir: Operate residual current release level in % of IB for directional stage. The setting is given in %
of IB. The output signals, STFW and STRV can be used in a teleprotection scheme. The appropriate
signal should be configured to the communication scheme block.
8.4.4.3
nd
2 harmonic restrain
If a power transformer is energized there is a risk that the current transformer core will saturate
during part of the period, resulting in a transformer inrush current. This will give a declining residual
current in the network, as the inrush current is deviating between the phases. There is a risk that the
residual over-current function will give an unwanted trip. The inrush current has a relatively large ratio
nd
of 2 harmonic component. This component can be used to create a restrain signal to prevent this
unwanted operation.
At current transformer saturation a false residual current can be measured by the protection. Here
nd
the 2 harmonic restrain can prevent unwanted operation as well.
2ndHarmStab: The rate of 2
signal. The setting is given in % of the fundamental frequency residual current.
8.5 Sensitive directional residual overcurrent and power
protection SDEPSDE
Railway application RER670
Application manual
RCA
Operation
I>Dir
Relay characteristic angle given in degree
nd
harmonic current content for activation of the 2
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Upol = -2U
0
IEC16000027-1-en.vsdx
Section 8
Current protection
M15282-90 v7
nd
harmonic restrain
SEMOD171436-1 v4
157