ABB RET670 Product Manual page 13

ABB
Transformer protection RET670
Customized
Product version: 1.2
The distance protection zones can operate,
independent of each other, in directional (forward
or reverse) or non-directional mode. This makes
them suitable, together with different
communication schemes, for the protection of
power lines and cables in complex network
configurations, such as parallel lines, multi-
terminal lines.
Directional impedance element for Mho
characteristic ZDMRDIR
The phase-to-earth impedance elements can be
optionally supervised by a phase unselective
directional function (phase unselective, because it
is based on symmetrical components).
Mho impedance supervision logic ZSMGAPC
The Mho impedance supervision logic
(ZSMGAPC) includes features for fault inception
detection and high SIR detection. It also includes
the functionality for loss of potential logic as well
as for the pilot channel blocking scheme.
ZSMGAPC can mainly be decomposed in two
different parts:
1. A fault inception detection logic
2. High SIR detection logic
Faulty phase identification with load
encroachment FMPSPDIS
The operation of transmission networks today is
in many cases close to the stability 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
accurate and reliable classifying the different
types of fault so that single phase tripping and
autoreclosing can be used plays an important roll
in this matter.
The phase selection function is design to
accurately select the proper fault loop(s) in the
distance function dependent on the fault type.
The heavy load transfer that is common in many
transmission networks may in some cases
interfere with the distance protection zone reach
and cause unwanted operation. Therefore the
function has a built in algorithm for load
encroachment, which gives the possibility to
1MRK 504 117-BEN D
enlarge the resistive setting of the measuring
zones without interfering with the load.
The output signals from the phase selection
function produce important information about
faulty phase(s), which can be used for fault
analysis as well.
Distance protection zone, quadrilateral
characteristic, separate settings ZMRPDIS,
ZMRAPDIS
The line distance protection is up to five 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.
Mho alternative quadrilateral characteristic is
available.
ZMRPDIS together with Phase selection,
quadrilateral characteristic with settable angle
FRPSPDIS has functionality for load
encroachment, which increases the possibility to
detect high resistive faults on heavily loaded lines.
The distance protection zones can operate,
independent of each other, in directional (forward
or reverse) or non-directional mode.
Phase selection, quadrilateral characteristic with
settable angle FRPSPDIS
The operation of transmission networks today is
in many cases close to the stability 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. The phase selection function 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, the
function has a built in algorithm for load
13