ABB RELION 670 Series Technical Manual page 521

1MRK 502 066-UUS B
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 backup 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
TimeChar parameter). The inverse time delay shall be according to IEC 60255-3.
(
For trip, the residual current 3I
Trip from this function can be blocked from the binary input BLKNDN.
When the function picks up, binary output signal PUNDIN is activated. If the output signal PUNDIN
remains active for the set delay
TRIP and TRNDIN get activated.
Residual overvoltage release and protection
All the directional functions shall be released when the residual voltage gets higher than a set level
VNRelPU .
In addition, there is also a separate non-directional residual over voltage protection, with its own
definite time delay
For trip, the residual voltage 3V
Trip from this function can be blocked from the binary input BLKVN.
When the function picks up, binary output signal PUVN is activated. If the output signal PUVN is
active for the set delay
simplified logical diagram of the total function is shown in Figure 271.
Technical manual
shall be larger than the set level (
0
tINNonDir or after the inverse time delay the binary output signals
tVN and set level VN_PU .
shall be larger than the set level (
0
tVNNonDir , the binary output signals TRIP and TRUN get activated. A
Current protection
INNonDirPU ).
VN_PU ).
Section 8
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SEMOD171963-72 v7
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