ABB RET670 Product Manual page 11

ABB
Transformer protection RET670
Customized
Product version: 1.2
and a voltage dependent resistor which are
mounted externally connected to the IED.
HZPDIF can be used to protect tee-feeders or
busbars. Six single phase function blocks are
available to allow application for two three-phase
zones busbar protection.
Restricted earth-fault protection, low impedance
REFPDIF
Restricted earth-fault protection, low-impedance
function (REFPDIF) can be used on all directly or
low-impedance earthed windings. The REFPDIF
function provides high sensitivity and high speed
tripping as it protects each winding separately
and thus does not need inrush stabilization.
The low-impedance function is a percentage
biased function with an additional zero sequence
current directional comparison criterion. This
gives excellent sensitivity and stability during
through faults.
REFPDIF can also protect autotransformers. In
this case, the negative sequence current
directional comparison must be used. The most
typical and the most complicated configuration of
an autotransformer is shown in figure 2. Five
currents are measured in the case illustrated in
figure 2.
YNdx
CT
d
Y
CB CB
CT
IED
The most typical
application
IEC05000058-2 V1 EN
Figure 2. Examples of applications of the REFPDIF
IEC05000058 V1 EN
Figure 3.
4. Impedance protection
Distance measuring zone, quadrilateral
characteristic ZMQPDIS, ZMQAPDIS (21)
The line distance protection is a five zone full
scheme protection with three fault loops for
phase-to-phase faults and three fault loops for
phase-to-earth faults 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.
CT CT
CB CB
The distance protection zones can operate
independently of each other in directional (forward
Autotransformer
or reverse) or non-directional mode.
Distance measuring zone, quadrilateral
CB CT characteristic for series compensated lines
CB
CT
The most complicated
ZMCPDIS, ZMCAPDIS
application - autotransformer
The line distance protection is a five zone full
IEC05000058-2-en.vsd
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 resistive
and reactive reach give flexibility for use on
overhead lines and cables of different types and
lengths.
Quadrilateral characteristic is available.
ZMCPDIS function has functionality for load
encroachment which increases the possibility to
detect high resistive faults on heavily loaded lines.
1MRK 504 117-BEN D
xx05000058.vsd
Autotransformer low impedance REFPDIF
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