Schweitzer Engineering Laboratories SEL-421-4 - Page 1106

10.10
SEL-400 Series Relays Instruction Manual Date Code 20171006
Testing, Troubleshooting, and Maintenance
Test Methods
Testing With SER
You can set the relay to generate a report from the SER to test relay elements;
include the element that you want to test in the SER Points and Aliases list. Set
aliases for the element name, set state, and clear state in the relay SER to simplify
reading the SER report. See Sequential Events Recorder (SER) on page 9.28 for
complete information on the SER.
Example: Testing the SEL-451 51S1 Element Using the SER
The SER gives exact time data for testing time-overcurrent element time-outs.
Subtract the 51S1T assertion time from the 51S1 assertion time to check the
operation time for this element. Use the factory defaults for the operating quan-
tity, pickup level, curve, time dial, electromechanical reset, and torque control
(Table 10.4).
The procedure in the following steps shows how to set the SER trigger lists to
capture the selectable operating quantity time-overcurrent element 51S1 operat-
ing times. The procedure also shows how to set the torque control supervision for
the 51S1 element.
The relay uses Equation 10.1 and Equation 10.2 to determine the operating time
for the 51S1 element. For a current input 50 percent greater than the default
pickup, the test value, I
TEST
, is:
Equation 10.1
where M is the pickup multiple and 51S1P is the element pickup value (see Table 10.4).
Table 10.4 Selectable Operating Quantity Time-Overcurrent Element (51S1)
Test Se t t i n g s
Setting Description 5A
51S1O 51S1 Operating Quantity (IAn, IBn, ICn, IMAXn, IAnR, IBnR, ICnR,
IMAXnR, I1L, 3I2L, 3I0n)
a
a
n = L, 1, and 2 for Line, Circuit Breaker 1, and Circuit Breaker 2, respectively. R suffix selects rms
quantities. For more information on rms, refer to RMS in the Glossary.
3I0L
51S1P 51S1 Overcurrent Pickup (0.25–16 A, secondary) 0.75
51S1C 51S1 Inverse-Time Overcurrent Curve (U1–U5, C1–C5) U3
51S1TD 51S1 Inverse-Time Overcurrent Time Dial (0.50–15.00) 1.00
51S1RS 51S1 Inverse-Time Overcurrent EM Reset (Y, N) N
51S1TC 51S1 Torque Control (SEL
OGIC control equation) 1
I
TEST
M • (51S1P)=
1.5 • (0.75 A) =
1.125 A=