Schweitzer Engineering Laboratories SEL-311L, Instruction Manual, Page: 551 / 734

Date Code 20010625 Standard Event Reports and SER 12-47
SEL-311L Instruction Manual
SER
Row No.
Explanation
22, 21, 20 B-phase, C-phase, and negative-sequence differential restraints deassert during
inception of the fault.
19, 18, 17 Differential element 87LC asserts which calls for a differential trip, TRIP87. 87L
which is 87LA + 87LB + 87LC + 87L2 + 87LG also asserts.
16 B-phase differential element 87LB asserts.
15 The Zone 2 distance element M2P asserts.
14 TRIP asserts.
13 The POTT scheme asserts Relay Word bit KEY which closes OUT104.
12 Negative-sequence differential element 87L2 asserts.
11 The Zone 1 distance element M1P asserts.
10–3 Protection elements deassert as the breaker opens, and fault is interrupted.
2, 1 TRIP and TRIP87 deassert. At first glance, SER records 1 and 2 do not appear to
correspond to the event report (Figure 12.5) with OUT101 = TRIP and OUT201 =
TRIP + TRIP87. In Figure 12.5, OUT201 deasserts 1/2 cycle after OUT101. This
is because the dedicated line current differential hardware controls outputs
OUT201–OUT206.
The 1/2 cycle delay reflects the time necessary for the result of the OUT201
equation to be passed to the line current differential hardware and for the contact
status to be passed back to the backup protection processor where the event report
is created.
Refer to High-Speed Output Contacts OUT201 Through OUT206 in Section 7:
Input, Output, Timers, and Other Control Logic for an in-depth explanation of
the TRIP and TRIP87 logic.