Siemens SIPROTEC 7UT613 series Manual Download

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1.2 Application Scope

7UT613/63x Manual
C53000-G1176-C160-2

1.2

Application Scope

The numerical differential protection SIPROTEC 4 7UT613/63x is a fast and selective
short-circuit protection for transformers of all voltage levels, for rotating machines, for
series and shunt reactors, or for short lines and mini-busbars with 2 to 5 feeders (de-
pending on the version). It can also be used as a single-phase protection for busbars
with up to 9 or 12 feeders (depending on the version). The individual application can
be configured, which ensures optimum matching to the protected object.

The device is also suited for two-phase connection for use in systems with 16.7 Hz
rated frequency.

A major advantage of the differential protection principle is the instantaneous tripping
in the event of a short-circuit at any point within the entire protected zone. The current
transformers limit the protected zone at the ends towards the network. This rigid limit
is the reason why the differential protection scheme shows such an ideal selectivity.

For use as transformer protection, the 7UT613/63x is normally connected to the
current transformer sets which limit the power transformer windings against the re-
mainder of the system. The phase displacement and the interlinkage of the currents
due to the winding connection of the transformer are matched in the device by calcu-
lation algorithms. The earthing conditions of the starpoint(s) can be adapted to the
user's requirements and are automatically considered in the matching algorithms.
Also, the currents from multiple measuring points on one side of the protected object
can be combined.

For use as generator or motor protection, the 7UT613/63x compares the currents in
the starpoint leads of the machine and at its terminals. Similar applies for series reac-
tors.

Short lines or mini-busbars with 3 to 5 end or feeders (depending on the version) can
be protected as well. "Short" means that the current transformers lead between the
CTs and the device do not form an impermissible burden for the CTs.

For transformers, generators, motors, or shunt reactors with earthed starpoint, the
current between the starpoint and earth can be measured and used for highly sensitive
earth fault protection.

The 9 or 12 measured current inputs (depending on the version) of the device allow
for a single-phase protection for busbars with up to 9 or 12 feeders. One 7UT613/63x
is used per phase in this case. Alternatively, (external) summation transformers can
be installed in order to allow a busbar protection for up to 9 or 12 feeders with one
single 7UT613/63x relay.

Where not all analog measuring inputs are needed for the measured values of the pro-
tected object, the remaining inputs can be used for other, independent measurement
or protection tasks. If a 7UT635 (with 3 three-phase measuring inputs) is used, for in-
stance, on a three-winding transformer, the two remaining measuring inputs can be
used for overcurrent protection of a different protected object, e.g. the auxiliaries
system circuit.

One or two additional current inputs designed for very high sensitivity are also avail-
able. They may be used e.g. for detection of small leakage currents between the tank
of transformers or reactors an earth, thus recognising even high-resistance faults.
High-resistance voltage measurement is also possible using an external series resis-
tor.

For transformers (including auto-transformers), generators, and shunt reactors, a
high-impedance unit protection system can be formed using high-impedance earth
fault protection. In this case, the currents of all current transformers (of equal design)

Siemens SIPROTEC 7UT613 series, Manual

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