achieve. Therefore, the function has a built in algorithm for load
encroachment, which gives the possibility to enlarge the
resistive setting of both the phase selection and the measuring
zones without interfering with the load.
The extensive output signals from the phase selection gives
also important information about faulty phase(s) which can be
used for fault analysis.
A current-based phase selection is also included. The
measuring elements continuously measure three phase
currents and the residual current and, compare them with the
set values.
High speed distance protection, quadrilateral and mho
ZMFPDIS
The high speed distance protection (ZMFPDIS) provides a sub-
cycle, down towards a half-cycle operate time. Its six zone, full
scheme protection concept is entirely suitable in applications
with single-phase autoreclosing.
Each measurement zone is designed with the flexibility to
operate in either quadrilateral or mho characteristic mode. This
can even be decided separate for the phase-to-ground or
phase-to-phase loops. The six zones can operate either
independent of each other, or their start can be linked (per
zone) through the phase selector or the first starting zone. This
can provide fast operate times for evolving faults.
The operation of the phase-selection is primarily based on a
current change criteria (i.e. delta quantities), however there is
also a phase selection criterion operating in parallel which
bases its operation on voltage and current phasors exclusively.
Additionally the directional element provides a fast and correct
directional decision under difficult operating conditions,
including close-in three-phase faults, simultaneous faults and
faults with only zero-sequence in-feed.During phase-to-earth
faults on heavily loaded power lines there is an adaptive load
compensation algorithm that prevents overreaching of the
distance zones in the load exporting end, improving the
selectivity of the function. This also reduces underreach in the
importing end.
Distance zones quad with high speed distance for series
compensated networks ZMFCPDIS
The high speed distance protection (ZMCPDIS) provides a sub-
cycle, down towards a half-cycle operate time. Its six zone, full
scheme protection concept is entirely suitable in applications
with single-phase autoreclosing.
High speed distance protection ZMFCPDIS is fundamentally
the same function as ZMFPDIS but provides more flexibility in
zone settings to suit more complex applications, such as series
compensated lines. In operation for series compensated
networks, the parameters of the directional function are altered
to handle voltage reversal.
Each measurement zone is designed with the flexibility to
operate in either quadrilateral or mho characteristic mode. This
can even be decided separate for the phase-to-ground or
phase-to-phase loops. The six zones can operate either
independent of each other, or their start can be linked (per
zone) through the phase selector or the first starting zone. This
can provide fast operate times for evolving faults.
The operation of the phase-selection is primarily based on a
current change criteria (i.e. delta quantities), however there is
also a phase selection criterion operating in parallel which
bases its operation on voltage and current phasors exclusively.
Additionally the directional element provides a fast and correct
directional decision under difficult operating conditions,
including close-in three-phase faults, simultaneous faults and
faults with only zero-sequence in-feed.
During phase-to-earth faults on heavily loaded power lines
there is an adaptive load compensation algorithm that prevents
overreaching of the distance zones in the load exporting end,
improving the selectivity of the function. This also reduces
underreach in the importing end.
Power swing detection ZMRPSB
Power swings may occur after disconnection of heavy loads or
trip of big generation plants.
Power swing detection function ZMRPSB is used to detect
power swings and initiate block of all distance protection zones.
Occurrence of earth-fault currents during a power swing
inhibits the ZMRPSB function, to allow fault clearance.
Power swing logic PSLPSCH
Power Swing Logic (PSLPSCH) is a complementary function to
Power Swing Detection (ZMRPSB) function. It provides
possibility for selective tripping of faults on power lines during
system oscillations (power swings or pole slips), when the
distance protection function should normally be blocked. The
complete logic consists of two different parts:
• Communication and tripping part: provides selective
tripping on the basis of special distance protection zones
and a scheme communication logic, which are not
blocked during the system oscillations.
• Blocking part: blocks unwanted operation of
instantaneous distance protection zone 1 for oscillations,
which are initiated by faults and their clearing on the
adjacent power lines and other primary elements.
Pole slip protection PSPPPAM
The situation with pole slip of a generator can be caused by
different reasons.
A short circuit may occur in the external power grid, close to the
generator. If the fault clearing time is too long, the generator will
accelerate so much, that the synchronism cannot be
maintained.
Undamped oscillations occur in the power system, where
generator groups at different locations, oscillate against each
1MRK 505 346-BEN -
Line differential protection RED670 2.1 IEC
Product version: 2.1
28
ABB
