7-20 Maintenance and Testing Date Code 20011026
SEL-321/321-1 Instruction Manual
Step 3. Connect a single current source to a phase current input of the relay. Refer to the
current connections shown in Figure 7.6 as an example.
Step 4. Because the 50H overcurrent element operates based upon the magnitude of any
single-phase current, the 50H element asserts when any phase current exceeds 11.25
amps.
Step 5. Turn on the current test source and slowly increase the magnitude of current applied
until the 50H element asserts, causing OUT8 to close. This should occur when
current applied is approximately 11.25 amps.
Note: As you perform this test, other protection elements may assert, causing the relay to
close other output contacts and assert relay targets. This is normal and is not a cause
for concern.
Phase-to-Phase Overcurrent Element: 50PP2
• The SEL-321 Relay uses the 50PP overcurrent elements to supervise operation of the phase
mho distance elements. If a phase distance element zone is not enabled by the PMHOZ
setting, the 50PP element setting is not displayed and the element cannot pick up.
• The steps taken in the example test for the 50PP2 overcurrent element may be applied to test
the 50PP1, 50PP3, and 50PP4 phase-to-phase overcurrent elements.
Step 1. Execute the SHOWSET command and verify the relay setting for the 50PP2
overcurrent element. The example relay settings set the 50PP2 element to pick up at
2.22 amps, secondary.
Step 2. Select an output contact to indicate operation of the 50PP2 overcurrent element. In
this example we use the OUT8 output.
From Access Level 2, execute the SET L n command to configure Output 8 to close
for assertion of the 50PP2 overcurrent element.
=>>SET L 1 OUT8 <ENTER>
SET L 1 OUT8 <ENTER>SET L 1 OUT8 <ENTER>
SET L 1 OUT8 <ENTER>
SELogic group 1
OUT8 =NA
? 50PP2 <ENTER>
50PP2 <ENTER>50PP2 <ENTER>
50PP2 <ENTER>
OUT9 =NA
? 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 OUT8 to the sense input of your test set, an ohmmeter, or some other
contact sensing device.
Step 3. Connect a single current source to two relay phase current inputs. Refer to the
current connections shown in Figure 7.7 as an example.
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