Positive Sequence Impedance Angle (Pang); Zero Sequence Impedance Angle (Gang); Zero Sequence To Positive Sequence Impedance Ratio (Zr); Backup System Settings - Version With Distance Option Only - ABB REL 356 Instruction Booklet

Positive Sequence Impedance Angle (PANG)

This setting relates directly to the positive sequence angle of the line. It defines the Zone 2 and Zone 3 phase impedance
unit maximum torque angle in degrees. This setting is also used for defining the slope of the blinders for OST and OSB
an for the fault locator algorithm.

Zero Sequence Impedance Angle (GANG)

This setting defines the impedance angle of the zero sequence (ZI0) impedance of the line. Zone 2 and Zone 3 ground
impedance units use this angle for their operation.

Zero Sequence to Positive Sequence Impedance Ratio (ZR)

This setting is used for all ground fault measurements. It reflects the magnitude ratio of the zero sequence impedance
to the positive sequence impedance of the line and is determined as ZR = ZL0/ZL1.
For example: If ZL0 = 15 ohms @ 60
Backup System Settings – Versions with Distance Option only

Backup System Enable (BKUP)

This setting determines if and when the distance backup system will be activated. There are three possible BKUP
settings:
BKUP = NONE
BKUP = CT
BKUP = CTDD

Loss of Potential Block (LOPB)

This setting enables the loss of potential logic (V0 and notI0) to block all Zone 2 and Zone 3 impedance units if the logic
is satisfied.
The loss of potential logic does not affect the differential protection which uses currents only.

Directional Units Settings

Forward Directional Phase Unit (FDOP)

If the system has voltage inputs, then the high set phase overcurrent units (IPH) can be made directional if FDOP is set
to IN.

Forward Directional Ground Unit (FDOG)

If the system has voltage inputs, then the high set ground overcurrent unit (IPG) can be made directional if FDOG is set
to IN.
Settings and Application
°
and ZL1 = 3 ohms @ 75
The backup distance system, even though included, will be deactivated at all times and will not
trip.
The backup distance system will be activated 150 msec after a CT (channel trouble) condition
occurs. It will stay enabled until the channel comes back into service when it will automatically
be switched out.
The backup distance system will be activated 150 msec after a CT (channel trouble) condition
occurs or a differential protection disable condition occurs. Differential protection disable can
be activated by a energizing a local or remote input. The backup system will stay enabled until
the channel comes back into service or the disable condition resets and will then automatically
be switched out.
ABB REL 356 Current Differential Protection
°
set ZR = 15/3 = 5.0
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