ABB Relion 670 series, Technical Reference Manual, Page: 449 / 1232

The function indicate forward/reverse direction to the fault. Reverse direction is
defined as φ is within the angle sector:
RCADir + 180° ± ROADir
This variant has definite time delay.
Directional functions
For all the directional functions there are directional pickup signals PUFW: fault in the
forward direction, and PUREV: Pickup in the reverse direction. Even if the directional
function is set to operate for faults in the forward direction a fault in the reverse
direction will give the pickup signal PUREV. Also if the directional function is set to
operate for faults in the reverse direction a fault in the forward direction will give the
pickup signal PUFW.
Non-directional ground fault current protection
This function will measure the residual current without checking the phase angle. The
function will be used to detect cross-country faults. This function can serve as
alternative or back-up to distance protection with phase preference logic. To assure
selectivity the distance protection can block the non-directional ground fault current
function via the input BLKNDN.
The non-directional function is using the calculated residual current, derived as sum of
the phase currents. This will give a better ability to detect cross-country faults with
high residual current, also when dedicated core balance CT for the sensitive ground
fault protection will saturate.
This variant has the possibility of choice between definite time delay and inverse time
delay. The inverse time delay shall be according to IEC 60255-3.
For trip, the residual current 3I
0
shall be larger than the set level ( INNonDirPU ).
Trip from this function can be blocked from the binary input BLKNDN.
When the function is activated binary output signal PUNDIN is activated. If the output
signal is active after the set delay
tINNonDir or after the inverse time delay the binary
output signals TRIP and TRNDIN are activated.
Residual overvoltage release and protection
The directional function shall be released when the residual voltage gets higher than a
set level.
There shall also be a separate trip, with its own definite time delay, from this level set
voltage level.
For trip, the residual voltage 3V
0
shall be larger than the set level ( UN_PU ).
Trip from this function can be blocked from the binary input BLKVN.
1MRK505222-UUS C
Section 7
Current protection
443
Technical reference manual