Date Code 20011026 Maintenance and Testing 7-19
SEL-321/321-1 Instruction Manual
Element Type Operates based upon the magnitude of: Relay Elements
Residual Residual current: I
R
= I
A
+ I
B
+ I
C
.
Test using single-phase current.
50G1, 50G2, 50G3,
50G4, 50N1, 50N2,
50N3, 50N4
Negative-
Sequence
3 ⋅ I
2
= (I
A
+ a
2
⋅I
B
+ a⋅I
C
) Test using
single-phase current.
50Q1, 50Q2, 50Q3,
50Q4, 50QF, 50QR
Positive-
Sequence
I
1
= 1/3 (I
A
+ a⋅I
B
+ a
2
⋅I
C
) Test using
three-phase or single-phase current.
50ABC
Overcurrent Element Test Examples
Examples below illustrate the test methods used for several elements.
Single-Phase Overcurrent Element: 50H
Note: The steps taken in the example test for the 50H nondirectional phase overcurrent
element may be applied to test the 50M, 50L1, 50L2, 50L3, and 50L4 nondirectional
phase overcurrent element as well as the residual and negative-sequence overcurrent
elements 50G1, 50G2, 50G3, 50G4, 50N1, 50N2, 50N3, 50N4, 50Q1, 50Q2, 50Q3,
50Q4, 50QF, and 50QR.
Step 1. Execute the SHOWSET command and verify the relay setting for the 50H
overcurrent element. The example relay settings set the 50H element to pick up at
11.25 amps, secondary.
Step 2. Select an output contact to indicate operation of the 50H overcurrent element. In this
example we use the OUT8 output.
From Access Level 2, execute the SET L n command to configure output OUT8 to
close for assertion of the 50H 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
? 50H <ENTER>
50H <ENTER>50H <ENTER>
50H <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. You must type <ENTER> a second time to review the full
group of logic settings. At the prompt, 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.
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