Positive Sequence Impedance Line Angle ("Ang Pos."); Zero Sequence Impedance Angle (Ang Zero); Zero Sequence/Positive Sequence Ratio (Zol/Z1L); Low Voltage Settings (Low V) - ABB REL 301 Instruction Leaflet

3.3.19

Positive Sequence Impedance Line Angle ("Ang Pos.")

Set the Positive Sequence Line Impedance Angle setting "Ang Pos.", to the value of the posi-
tive sequence line impedance angle. From the example data (Section 3.2), the setting would
be "Ang Pos." = "77
3.3.20 Zero Sequence Impedance Angle ("Ang Zero")
Set the Zero Sequence Impedance Angle setting ("Ang Zero") to the value of the zero se-
quence line impedance angle. From the example data (Section 3.2), the setting would be "Ang
Zero" = "73
3.3.21 Zero Sequence/Positive Sequence Ratio ("Z
Set the "Z OL /Z 1L " value based on the absolute value of the ratio of the line impedances. From
the example data (Section 3.2), the setting would be "Z OL /Z 1L " = "3.3".
3.3.22 Low Voltage Settings ("Low V")
The low voltage units are used to supervise close into fault logic and weakfeed trip logic (REL
302 only). "Low V" should normally be set to "40 Volts" unless a higher setting is required for
more sensitive applications.
3.3.23

Polarizing Settings

Settings for the directional ground overcurrent polarization is controlled by the setting of "Dir
Type". It has 3 selections:
"Zero Sequence"
"Negative Sequ."
"Dual Polariz."
3.3.24

Overcurrent Ground Backup

The overcurrent ground backup function provides seven sets of curves, which are similar to the
CO curves, for backing up the ground distance protection. Four settings "GB Type", "GB Pick-
up", "GBT Curve" and "GB Dir." must be determined for applying this function.
a. "GB Type" is the ground backup curve selection. Seven sets of familiar CO curves are
provided (C02,5,6,7,8,9 and 11), and are shown in Figures 2-32 through 2 -38. The selec-
tion is based on the application and coordination time. A selection of "Disabled" prevents
the ground backup function from operating.
b. "GB Pickup" is the current level setting. The setting range is 0.5 to 4.0 amperes in 0.5
steps. In general, the current level setting criteria is:
(I
Fmin
where I
3. See application note under Section 3.2.1
4. See application note under Section 3.2.1
o
".
o
".
— Zero sequence voltage polarization.
— Negative sequence voltage polarization.
— Both zero sequence voltage and current polarization.
/2) > "GB Pickup" > 2 x Max. Residual 3I
= Minimum ground fault current for a fault two buses away
Fmin
3
3
4
/Z )
"
OL 1L
0
I.L. 40-386.4
3-13