Siemens 7UT51 Instruction Manual page 168

16
Bench Testing
Figure 16.9 Standard Application of Restricted Ground
Fault Protection
Metering Test
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.
Since the restricted ground-fault function is sensitive
to unbalanced zero sequence currents between the
phase and ground inputs, temporarily turn Off the
RGF function in Address 1901 (OFF is the default
setting).
Connect the test set to the 7UT51 as shown in
Figure 16.10
168
.
Figure 16.10 Testing Restricted Ground
Secondary
Apply 1.0A to the ground input being used for the RGF
function using test source I
Read the Metered current for that ground input using
the relay's MMI (front display) or WinDIGSI
-
To read the value from the front panel of the relay:
1. Go to Address 4101.
"4101 Test Diff - Measuring?".
2. Press the Yes key.
3. "I1 PhA= xxx" will be displayed.
4. Press the No key to page through to the "IA"
current (or "IB" if you are using the second ground
current input.)
5. The display should approximately read: "IA=
20.0%" for the 1.0A current injected.
6. Go to Address "4801 STOP TEST - FINISH?"
7. Press the Yes key to end the Commissioning
Tests.
8. Reset all targets and annunciations.
To read these values on a PC using WinDIGSI, begin
communication with the relay, then:
1. Select "Test" from the menu bar.
2. Display "Commissioning Tests".
7UT51 v3
-
Fault on
( since 1/5 = .20 ).
2
PRIM-2330C