Date Code 20011205
Testing and Troubleshooting
13-37
SEL-311B Instruction Manual
Pole Open Logic
If significant pole-scatter occurs when a circuit breaker closes, sensitive ground distance
elements may operate undesirably due to the unbalanced signals applied. The SEL-311B Relay
disables the ground distance elements during Three-Pole Open conditions and for a short,
settable time after the breaker closes. The time is set by the 3POD time delay settings. To
simplify distance element tests, apply control voltage to any inputs assigned to perform the 52
auxiliary functions.
Ground Mho Distance Element Test Using Three Voltage Sources and One Current
Source
Note:
This test refers directly to the Zone 2 ground mho distance element, but may be
applied to any other forward-reaching ground mho distance element zone. To test
reverse-reaching zones, simply add 180° to the calculated test current phase angle.
Verify correct operation of the 32GR element for the test voltage and current signals
using Equation 13.1 in the Negative-Sequence Directional Element Test Procedure.
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
W
; 50L2 = 0.50; 50GZ2 =
0.50; k0M = 0.726; k0A = -3.69; ORDER = Q; Z2F = 0.77
W
; 50QF = 0.5 amps
secondary.
Execute the
SET
command and change the following settings. Change E21XG to N
and ELOP from Y to N. Changing the E21XG setting prevents the relay ground
quadrilateral distance elements from interfering with the test. 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 2.
Select an output contact to indicate operation of the Z2G element. In this example
we use the OUT106 output.
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>
SET L 1 OUT106 <ENTER>
SET L 1 OUT106 <ENTER>
SET L 1 OUT106 <ENTER>
SELogic group 1
OUT106 =0
? Z2G <ENTER>
Z2G <ENTER>
Z2G <ENTER>
Z2G <ENTER>
OUT107 =0
? END <ENTER>
END <ENTER>
END <ENTER>
END <ENTER>
After you type
END <ENTER>
to end the set procedure, the relay displays the
current logic settings. Type
Y <ENTER>
to accept those settings.
Connect output OUT106 to the sense input of your test set, an ohmmeter, or some
other contact sensing device.
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