Directional Functions; Non-Directional Earth Fault Current Protection; Residual Overvoltage Release And Protection - ABB REG650 Technical Manual

1MRK 502 034-UEN -
7.3.7.5
7.3.7.6
7.3.7.7
Technical Manual

Directional functions

For all the directional functions there are directional start signals STFW: fault in
the forward direction, and STRV: start 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 start signal STRV. Also if the directional function is
set to operate for faults in the reverse direction a fault in the forward direction will
give the start signal STFW.

Non-directional earth 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.
If available 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 earth fault protection will saturate.
This variant shall have 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
When the function is activated binary output signal STNDIN is activated. If the
activation 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 set
voltage level.
For trip, the residual voltage 3U
Trip from this function can be blocked from the binary input BLKUN.
When the function is activated binary output signal STUN is activated. If the
activation is active after the set delay tUNNonDir TRIP and TRUN are activated. A
simplified logical diagram of the total function is shown in figure 92.
shall be larger than the set levels (INNonDir>).
0
shall be larger than the set levels (UN>).
0
Section 7
Current protection
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