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Mounting and Commissioning
3.3 Commissioning
3.3.6 Secondary Tests
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Checking the individual protection functions of the characteristic curves or pick-up values is not required since
these are part of the firmware programs which are monitored continuously. Analogue inputs are checked at the
primary commissioning at the protective object (Section 3.3 under „Symmetrical Current Tests on the Protective
Object“). Verification of connections, i.e. coupling with the plant, also takes place there. Measured quantities
deviation between the protective functions and phases can be excluded.
Secondary checks can never replace the primary checks described below, as connection errors cannot be
included. They can however be used as theoretical test of the setting values. Should you want to perform a
secondary test, please observe the following hints.
When performing tests with secondary test equipment, attention must be paid that no other measuring values
are applied and that the trip command to the circuit breakers are interrupted.
The tests should be done with the current setting values of the device. If these are not (yet) available, the test
should be done with the preset values.
Note
The measurement accuracy to be achieved depends on the electrical data of the test sources used. The
accuracies specified in the technical specifications can be expected only if the reference conditions in
accordance with VDE 0435/Part 303 or IEC 60255 are adhered to, and precision measurement instruments
are used. The stated tolerances refer to the preset data of the protective object. If the ( reference current transformer
rated current) rated current deviates greatly from the protective object, appropriately high pickup
tolerance has to be used.
Differential Protection
Every side of the differential protection can be checked. This is consistent with the simulation of a single source
error. If a side has several measuring locations, the not in a test involved measured inputs remain at zero
current. Checking the pickup value is performed by slowly increasing the test current.
Caution!
Tests with currents that exceed more than 4 times the rated device current cause an overload of the input
circuits and may only be performed for a short time.
See Technical Data
Afterwards the device has to cool off!
SIPROTEC, 7UT6x, Manual
C53000-G1176-C230-2, Release date 06.2012