ABB Relion 670 series, Technical Manual

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The residual current is pre-processed by a discrete fourier filter. Thus the phasor of the
fundamental frequency component of the polarizing current is derived. This phasor is then
multiplied with pre-set equivalent zero-sequence source Impedance in order to calculate
equivalent polarizing voltage VIPol in accordance with the following formula:
( )
IPol
S Pol Pol
V Zo I RNPol j XNPOL
I = × = + ×
×
EQUATION2013-ANSI V1 EN-US
(Equation 130)
which will be then used, together with the phasor of the operating current, in order to determine
the direction to the ground fault (Forward/Reverse).
In order to enable current polarizing the magnitude of polarizing current shall be bigger than a
minimum level defined by setting parameter
IPolMin.
Dual polarizing
When dual polarizing is selected the function will use the vectorial sum of the voltage based and
current based polarizing in accordance with the following formula:
( )
0 0 0
3 3
s
VTotPol VVPol VIPol V Z IPol V RNPol jXNPol IPol
= + = - + × = - + + ×
ANSIEQUATION1878 V1 EN-US
(Equation 131)
Vpol and Ipol can be either zero sequence component or negative sequence component depending
upon the user selection.
Then the phasor of the total polarizing voltage VTotPol will be used, together with the phasor of
the operating current, to determine the direction of the ground fault (Forward/Reverse).
8.4.7.3 External polarizing for ground-fault function
M13941-144 v4
The individual steps within the protection can be set as non-directional. When this setting is
selected it is then possible via function binary input BLKx to provide external directional control
(that is, torque control) by for example using one of the following functions if available in the IED:
1. Distance protection directional function.
2. Negative sequence polarized General current and voltage multi purpose protection function.
8.4.7.4 Directional detection for ground fault function
GUID-FC382DD3-E2C8-455E-8CD5-1DE1793DD178 v4
Zero sequence components will be used for detecting directionality for ground fault function. In
some cases zero sequence quantities might detect directionality wrong. Negative sequence
quantities will be used in such scenario. The user can select either zero sequence components or
negative sequence components for detecting directionality with the parameter
SeqTypeIPol.
I3PDIR input always connected to the same source as I3P input.
8.4.7.5 Base quantities within the protection
M13941-152 v5
The base quantities are entered as global settings for all functions in the IED. Base current (
IBase)
shall be entered as rated phase current of the protected object in primary amperes. Base voltage
(
VBase) shall be entered as rated phase-to-phase voltage of the protected object in primary kV.
Section 8 1MRK 502 066-UUS B
Current protection
482
Technical manual