Internal Polarizing - ABB REG650 Technical Manual

Section 7
Current protection
7.2.7.2
158
PCM600). In such case the pre-processing block will calculate 3I
first three inputs into the pre-processing block by using the following formula:
= = + +
Iop 3I IL1 IL2 IL3
0
EQUATION1874 V2 EN
where:
IL1, IL2 and IL3 are fundamental frequency phasors of three individual phase currents.
The residual current is pre-processed by a discrete Fourier filter. Thus the phasor of
the fundamental frequency component of the residual current is derived. The
phasor magnitude is used within the EF4PTOC protection to compare it with the
set operation current value of the four steps (IN1>, IN2>, IN3> or IN4>). If the
residual current is larger than the set operation current and the step is used in non-
directional mode a signal from the comparator for this step is set to true. This
signal will, without delay, activate the output signal STINx (x=step 1-4) for this
step and a common START signal.

Internal polarizing

A polarizing quantity is used within the protection in order to determine the
direction to the earth 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
-3U as polarizing quantity U3P. This voltage can be:
0
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 function input U3P). 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 analog
function input U3P is NOT connected to a dedicated VT input of the IED in
PCM600). In such case the pre-processing block will calculate -3U
first three inputs into the pre-processing block by using the following formula:
UPol = -3U = -(UL1 + UL2 + UL3)
0
EQUATION1875 V2 EN
where:
UL1, UL2 and UL3
Note! In order to use this all three phase-to-earth voltages must be connected to three IED VT inputs.
are fundamental frequency phasors of three individual phase voltages.
1MRK 502 034-UEN -
from the
0
(Equation 39)
from the
0
(Equation 40)
Technical Manual