Siemens SIPROTEC 4 7UT6 Series Manual page 392

Mounting and Commissioning
3.3 Commissioning
The trip circuit should be interrupted or the differential protection should be switched to DIFF. PROT. =
Block relay (address 1201) during these tests in order to avoid tripping.
Conclusions as to the effectiveness of the inrush restraint can be drawn from the recording of the differential
currents and the harmonic contents. If necessary the inrush current restraint effect can be increased (= smaller
value of the 2nd harmonic in address 1271 2. HARMONIC) when trip occurs or when the recorded data show
that the second harmonic content does not safely exceed the restraining threshold (address 1271). A further
method to increase inrush restraint is to set the crossblock function effective or to increase the duration of the
crossblock function (address 1272 CROSSB. 2. HARM) (For further details refer to the setting information
for differential protection under "Harmonic Restraint").
NOTE
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Do not forget to switch on the differential protection (address 1201) after completion of the test.
392 SIPROTEC 4, 7UT6x, Manual
C53000-G1176-C230-5, Edition 09.2016