13.41
Date Code 20060320 Instruction Manual SEL-311C Relay
Testing and Troubleshooting
Test Procedures
Ground Mho Distance Element Test Using Three Voltage Sources and One
Current Source
Step 1. Execute the SHOWSET command and verify the following
relay settings: Z1MAG, Z1ANG, E21MG, E32, Z2MG, 50L2,
50GZ2, k0M1, k0A1, ORDER, Z2F, and 50QF.
The example relay settings use the following settings:
Z1MAG = 7.8
Z1ANG = 83.97°
E21G = 3
E32 = Y
Z2MG = 9.36 Ω
50L2 = 0.50
50GZ2 = 0.50
k0M = 0.726
k0A = –3.69
ORDER = Q
Z2F = 0.77 Ω
50QF = 0.5 amps secondary
Step 2. Execute the SET command and change the following settings.
a. Change E21XG to N.
Changing the E21XG setting prevents the relay ground
quadrilateral distance elements from interfering with
the test.
b. Change ELOP from Y to N.
Changing the ELOP setting prevents the Loss-of-
Potential logic from blocking operation of the relay
distance elements if the test signals fulfill Loss-of-
Potential conditions.
Step 3. Select an output contact to indicate operation of the Z2G
element. In this example, we use the OUT106 output.
Step 4. From Access Level 2, execute the SET L n command to
configure Output 6 to close for assertion of the Z2G element.
=>>SET L 1 OUT106 <Enter>
SELogic group 1
OUT106 =0
? Z2G <Enter>
OUT107 =0
? END <Enter>
Step 5. After you type END <Enter> to end the set procedure, the
relay displays the current logic settings.
Step 6. Type Y <Enter> to accept those settings.
Step 7. Connect output OUT106 to the sense input of your test set, an
ohmmeter, or some other contact sensing device.
Step 8. Connect the voltage sources to the A-phase, B-phase, and
C-phase to neutral relay voltage inputs.
NOTE: This test refers directly to the
Zone 2 ground mho distance element,
but it may be applied to any other
forward-reaching ground mho
distance element zone. To test
reverse-reaching zones, add 180° to
the calculated test current phase
angle. Verify correct operation of the
32GR element for the test voltage and
current signals through use of
Equation 13.1 in Negative-Sequence
Directional Element Based Upon
Negative-Sequence Impedance on
page 13.22.
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