Tests Related To Protected Objects With Three Terminals - Siemens 7UT51 Instruction Manual

7UT51 v3
Figure 18.5 WinDIGSI Example of Differential and
Restraint Current Side 1Test
If considerable differential currents occur, recheck the
concerned parameters:
• For transformer protection,addresses 1102 to
1104 (matching of transformer Winding 1),
addresses 1121 to 1124 (matching of transformer
winding 2).
• For generator or motor protection, addresses
1202 and 1203 (matching of the rated machine
values).
• For branch point protection, addresses 1301 and
1302 (matching of Side 1) and 1304 (matching of
Side 2).
Address Test Messages
Test Dif/ST Test?
Display of the results of calculation of the
4161
differential and stabilizing currents? Confirm
with the Yes key or abort with the No key
Test Dif/ST
IL1,IL2, and IL3 diff = 0.4% (e.g.)
the differential current of measuring system
L1,L2, and L3 referred to the rated current of
the protected object, e.g. 0.4%. The value
should be negligible against the magnitude
of the line currents.
Test Dif/ST
IL1, IL2, and IL3 rest = 24.4 (e.g.)
of the stabilizing (restraint) current of
measuring system L1, L2, and L3 referred to
the rated current of the protected object, e.g.
24.4%. The value should be approximately
twice the test current.
If the 7UT51 is configured for a protected object with
two sides, the symmetrical current tests are thus
completed. Disconnect the protected object (shut
down the generator) and ground, disconnect test
arrangement and skip the next test.
PRIM-2330C
18.3.2
Modify the test arrangement such that the test current
will flow from Side 1 to Side 3 of the protected object.
Side 2 must be isolated: the short-circuit bridges at
Side 2 must be removed and inserted at Side 3.
After the test current has been switched on,
measurement request is initiated. Leave
Address 4161 by paging back to Address 4101 and
perform the measurement request as instructed in
Sections 18.3.1.
As soon as the first measured value appears in the
display, the test current can be switched off.
Since the test current is now flowing from Side 1 to
Side 3, all results that concerned Side 2 have the
message "****".
If the current magnitudes are consistent, page on to
Address 4121 to test the phase angle relations. It is
not necessary to request for a new measurement. The
results should follow Sections 18.3.1.
The polarity of the current connections and the
parameterized polarity are taken into consideration
when the angles are displayed. Thus, if all three
angles differ by 180
polarity of one complete current transformer set is
wrong. This can be corrected by checking and
changing the corresponding plant parameters:
-
displays
• Address 1105 for the primary winding of a
transformer; this should have already been
verified during the tests according to
Section 18.3.1 on page 199. If this parameter is
changed, the complete tests concerning Winding
1 against winding 2 would have to be repeated.
-
Display
• Address 1145 for the tertiary winding of a
transformer
• Address 1303 for Side 1 of a branch point: this
should have already been verified during the tests
according to Section 18.3.1 on page 199. If this
parameter is changed, the complete tests
concerning Side 1 against Side 2 would have to
be repeated.
• Address 1307 for Side 3 or a branch point.
Field Testing and Commissioning
Tests Related to Protected
Objects with Three
Terminals
o
from the theoretical value, the
18
201