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The minimum operate fault current is automatically reduced to 75% of its set value, if the
distance protection zone has been set for the operation in reverse direction.
7.4.3.10
Setting of directional mode
SEMOD154469-176 v3
Setting of the directional mode is by default set to forward by setting the parameter
DirMode
to
Forward.
The selection of
Offset mho can be used for sending block signal in blocking teleprotection
scheme, switch onto fault application and so on.
The
Reverse mode might be use in comparison schemes where it is necessary to absolute
discriminate between forward and reverse fault.
7.4.3.11
Setting of direction for offset mho
SEMOD154469-181 v3
If offset mho has been selected, one can select if the offset mho shall be
Non-Directional,
Forward or Reverse by setting the parameter OfffsetMhoDir.
When forward or reverse operation is selected, then the operation characteristic will be cut off
by the directional lines used for the mho characteristic. The setting is by default set to
Non-
Directional.
7.4.3.12
Setting of timers for distance protection zones
SEMOD154469-138 v7
The required time delays for different distance protection zones are independent of each
other. Distance protection zone 1 can also have a time delay if so required for selectivity
reasons. One can set the time delays for all zones in a range of 0 to 60 seconds. The tripping
function of each particular zone can be inhibited by setting the corresponding
Operation
parameter to
Off.
Different time delays are possible for the phase-to-earth
tPE and for the phase-to-phase tPP
measuring loops in each distance protection zone separately, to further increase the total
flexibility of a distance protection.
In the case of evolving faults or momentary current transformer saturation conditions, the pick
up of the zones may get delayed. Zone timer logic improves the operating time in such
conditions. The zone timer logic can be set using the parameter
ZnTimerSel. The triggering
signal of phase-to-earth and phase-to-phase timers can be selected using
ZnTimerSel.
1MRK 505 343-UEN B
Section 7
Impedance protection
241
Application manual
Содержание Relion 670 series
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