Siemens SIPROTEC 7UT613 series Manual page 403

7UT613/63x Manual
C53000-G1176-C160-2
– If there are differential currents in the size of the restraint currents (approximately
twice the through-flowing test current), you may assume a polarity reversal of the
current transformer(s) at one side. Check the polarity again and set it right after
short-circuiting all six current transformers. If you have modified these current
transformers, repeat the angle test.
– If there are differential currents which are nearly equal in all three phases, match-
ing of the measured values may be erroneous. Wrong vector group of a power
transformer can be excluded because it should already have been detected
during the phase angle test. Re-check the settings for current matching. These
are mainly the data of the protected object (Power System Data 1, Section 2.1.4):
For all kinds of power transformers, addresses 311 and 312 for side 1 under
„Object Data with Transformers" and accordingly the parameters for the other
side(s) under test. Furthermore, addresses 512 and 513 for measuring location
M1 under „Current Transformer Data for 3-phase Measuring Locations", and ac-
cordingly the parameters for the other measuring location(s) under test.
For generators, motors, reactors, addresses 361 and 362 under „Object Data
with Generators, Motors or Reactors", and addresses 512 and 513 for measur-
ing location 1 under „Current Transformer Data for 3-phase Measuring Loca-
tions" and accordingly the parameters for the other measuring location(s) under
test.
For mini-busbars (3-phase), address 372 under „Object Data with Mini-Busbars
or Short Lines" (3-phase)" for feeder 1 and accordingly the parameters for the
other feeder(s) under test, and addresses 512 and 513 for measuring location 1
under „Current Transformer Data for 3-phase Measuring Locations" and accord-
ingly the parameters for the other measuring location(s) under test.
For single-phase busbar protection, address 381 under „Object Data with
Busbars (1-phase Connection) with up to 6 or 9 or 12 feeders" and addresses
562 and 563 under „Current Transformer Data for single-phase Busbar Protec-
tion" for feeder 1 and accordingly the parameters for the other feeders under test.
If interposed summation transformers are used, matching errors can be caused
by wrong connections at the summation CTs.
• Finally, switch off the test source and the protected object (shut down the genera-
tor).
• If parameter settings have been changed for the tests, reset them to the values nec-
essary for operation.
Please keep in mind that the previous tests must be repeated for each current path.
3.3 Commissioning
403