ABB RET670 Product Manual page 14

Transformer protection RET670
Pre-configured
Product version: 1.1
xx05000058.vsd
IEC05000058 V1 EN
Figure 6. Autotransformer low impedance REF
Impedance protection
Distance measuring zone, quadrilateral
characteristic ZMQPDIS, ZMQAPDIS
The line distance protection is a four zone
full scheme protection with three fault loops
for phase-to-phase faults and three fault
loops for phase-to-earth fault for each of the
independent zones. Individual settings for
each zone in resistive and reactive reach
gives flexibility for use as back-up protection
for transformer connected to overhead lines
and cables of different types and lengths.
ZMQPDIS together with Phase selection with
load encroachment FDPSPDIS has
functionality for load encroachment, which
increases the possibility to detect high
resistive faults on heavily loaded lines.
The distance protection zones can operate
independently of each other in directional
(forward or reverse) or non-directional mode.
Full-scheme distance measuring, Mho
characteristic ZMHPDIS
The numerical mho line distance protection is
afour zone full scheme protection for back-up
detection of short circuit and earth faults. The
four zones have fully independent measuring
and settings, which gives high flexibility for
all types of lines.
The function can be used as under
impedance back-up protection for
transformers and generators.
Phase selection, quadrilateral
characteristic with fixed angle FDPSPDIS
The operation of transmission networks
today is in many cases close to the stability
14
1MRK 504 091-BEN B
limit. Due to environmental considerations,
the rate of expansion and reinforcement of
the power system is reduced, for example,
difficulties to get permission to build new
power lines. The ability to accurately and
reliably classify the different types of fault, so
that single pole tripping and autoreclosing
can be used plays an important role in this
matter. Phase selection, quadrilateral
characteristic with fixed angle FDPSPDIS is
designed to accurately select the proper fault
loop in the distance function dependent on
the fault type.
The heavy load transfer that is common in
many transmission networks may make fault
resistance coverage difficult to achieve.
Therefore, FDPSPDIS 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.
Full-scheme distance protection,
quadrilateral for earth faults ZMMPDIS,
ZMMAPDIS
The distance protection is a four zone
protection with three fault loops for phase-to-
earth fault for each of the independent zones.
Individual settings for each zone resistive and
reactive reach give flexibility for use on
overhead lines and cables of different types
and lengths.
The Full-scheme distance protection,
quadrilateral for earth faults functions
ZMMDPIS and ZMMAPDIS have functionality
for load encroachment, which increases the
possibility to detect high resistive faults on
heavily loaded lines .
The independent measurement of impedance
for each fault loop together with a sensitive
and reliable built in phase selection makes
the function suitable in applications with
single phase auto-reclosing.
Issued: June 2010
ABB