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Maintenance and Testing
Date Code 20011026
SEL-321/321-1 Instruction Manual
Ground Distance Element Disable Inputs
The SEL-321 Relay is equipped with ground distance element disabling inputs, PARA, PARB,
and PARC. When a relay input assigned to one of these functions is asserted, the relay disables
the ground distance elements associated with that phase. For instance, if Input 4 is assigned to
PARA, each time Input 4 is asserted, all of the A-ground distance elements are disabled.
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 32QR element for the test voltage and current signals
using Equation 7.2 in the Negative-Sequence Directional Element Test Procedure.
Step 1.
Execute the
SHOWSET
command and verify the following relay settings: Z1MAG,
Z1ANG, GMHOZ, DIR2, Z2MG, 50L2, 50G2, k0M, k0A, Z2F, and 50QF. The
example relay settings use the following settings: Z1MAG = 7.8; Z1ANG = 83.97°;
GMHOZ = 3; DIR2 = F; Z2MG = 9.36
Ω
; 50L2 = 0.90; 50G2 = 0.60; k0M = 0.726;
k0A = -3.69; Z2F = 0.77
Ω
; 50QF = 0.5 amps secondary.
Execute the
SET
command and change the following settings. Change QUADZ to N
and ELOP from Y to N. Changing the QUADZ 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 OUT7 output.
From Access Level 2, execute the
SET L n
command to configure Output 7 to close
for assertion of the Z2G element.
=>>SET L 1 OUT7 <ENTER>
SET L 1 OUT7 <ENTER>
SET L 1 OUT7 <ENTER>
SET L 1 OUT7 <ENTER>
SELogic group 1
OUT7 =NA
? Z2G
Z2G
Z2G
Z2G <ENTER>
<ENTER>
<ENTER>
<ENTER>
OUT8 =32QR
? 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 OUT7 to the sense input of your test set, an ohmmeter, or some other
contact sensing device.
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