ABB REG650 Technical Manual page 190

Section 8
Current protection
184
Voltage polarizing
When voltage polarizing is selected the protection will use either the residual voltage
3V or the negative sequence voltage V
0
The residual 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
open delta winding of a three phase main VT.
2. calculated from three phase voltage input within the IED (when the fourth analog
input into 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 case the pre-processing block will calculate 3V
three inputs into the pre-processing block by using the following formula:
VPol=3V0=(VA +VB +VC)
ANSIEQUATION2407 V1 EN
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.
The negative sequence voltage is calculated from the three-phase voltage input within
the IED by using the pre-processing block. The preprocessing block will calculate the
negative sequence voltage from the three inputs into the pre-processing block by using
the following formula:
= + × + ×
VPol ( VA alpha VB alpha VC
GUID-F09A69D7-A8A6-4354-B0B8-F4EC7BBE603F V2 EN
where:
VA, VB, VC
alpha
as polarizing quantity V3P.
2
are fundamental frequency phasors of three individual phase voltages.
)/3
are fundamental frequency phasors of three individual phase voltages.
unit phasor with an angle of 120 degrees.
1MRK 502 043-UUS B
from the first
0
(Equation 41)
(Equation 42)
Technical Manual