Internal Polarizing - ABB RES670 Technical Manual

Section 8
Current protection
8.2.7.2
200

Internal polarizing

A polarizing quantity is used within the protection in order to determine the direction
to the ground fault (forward/reverse).
The function can be set to use voltage polarizing, current polarizing or dual polarizing.
Voltage polarizing
When voltage polarizing is selected, the protection will use the residual voltage -3V
the polarizing quantity V3P.
This voltage can be:
1. directly measured (when a dedicated VT input of the IED is connected in PCM600
to the fourth analog input of the pre-processing block connected to EF4PTOC
(51N/67N) function input V3P). This dedicated IED VT input shall be then
connected to the open delta winding of a three-phase main VT.
2. calculated from three-phase voltage input within the IED (when the fourth analog
input of the pre-processing block, connected to EF4PTOC (51N/67N) analog
function input V3P, is NOT connected to a dedicated VT input of the IED in
PCM600). In such a case, the pre-processing block will calculate -3V
first three inputs into the pre-processing block by using the following formula:
VPol=3V0=(VA +VB +VC)
EQUATION2012 V1 EN-US
where:
VA, VB, VC
In order to use this, all three phase-to-ground voltages must be connected to three IED
VT inputs.
The residual voltage is pre-processed by a discrete fourier filter. Thus, the phasor of the
fundamental frequency component of the residual voltage is derived.
This phasor is used together with the phasor of the operating directional current, in
order to determine the direction to the ground fault (Forward/Reverse). In order to
enable voltage polarizing the magnitude of polarizing voltage shall be bigger than a
minimum level defined by setting parameter VPolMin.
are fundamental frequency phasors of three individual phase voltages.
1MRK 511 408-UUS A
from the
0
Phasor measurement unit RES670 2.2 ANSI
Technical manual
M13941-82 v11
as
0
(Equation 16)