Validate Metering - Siemens 7UT51 Instruction Manual

7UT51 v3
16.3.2

Validate Metering

Testing the metering of numerical relays is the
quickest method of determining if a relay is no longer
functioning or that it is incorrectly connected. If the
relay cannot correctly determine what is being applied
to its inputs, it can no longer protect by default.
Next, check the differential current metering of the
relay (taking into account phase relationships and CT
settings). These values can be read directly from the
front display of the relay or remotely (on a PC) using
WinDIGSI software.
To read these values directly from the front panel
display:
1. Press Dir Addr and enter 4101. The display
should now read "4101 Test Diff - Measuring?".
2. Press the Yes key. The display will report "I1 PhA=
xxx", where xxx is the PhA current on primary as a
percentage of 5 A. The value should be the
current you are injecting into I
A.
3. Press the No key to page through the metering of
the rest of the inputs. For the test shown in Figure
16.3 "I1 PhA" and "I1 PhC" should read
approximately 36.2% and I2 PhA should read
approximately 88.4%
4. Next display the differential current, which the
relay calculates. Press Dir Addr and enter 4161.
The display should now read "4161 TEST DIF/ST
- INDICATE RESULT?".
5. Press the Yes key. The display will report "IaDiff =
xxx", where xxx is the PhA differential current
calculated by the relay. It should measure from 1.0
to 2.0% of the differential current, if the test
sources being used are accurate.
6. Press the No key to page to "IbDiff" and "IcDiff".
These should also read under 2.0% differential
current. If this accuracy cannot be achieved, verify
the phase angles and magnitudes of the applied
signals.
7. Press Dir Addr and enter 4801. The display
should now read "4801 STOP TEST - FINISH?"
8. Press the Yes key to end the differential current
tests.
PRIM-2330C
PhA divided by 5
1
To read these values using WinDIGSI, begin
communication with the relay, then:
1. Click Test in the menu bar.
2. Select "Commissioning Tests."
3. Select the function "4101 Measuring and
indication of current values", then click Yes.
The following dialog box will appear in WinDIGSI:
The displayed current values are percentages
of 5A. "Ix Ly" is an abbreviation for the
Winding 'x' Phase 'y' current. The currents
should correspond to your test configuration.
4. Click Close. The Commissioning Tests dialog box
will become active again.
5. Select "4161 Indication of diff. and restr.
current values", the click Yes. The following
dialog box will be appear in WinDIGSI or each
value can be read out on the LCD:
If the test sources being used are accurate,
IL1diff", IL2diff" and IL3diff" should all
measure less than 2.0%
16
Bench Testing
163