5-10
Trip and Target Logic
Date Code 20011205
SEL-311A Instruction Manual
F
RONT
----P
ANEL
T
ARGET
LED
S
Table 5.1: SEL-311A Relay Front-Panel Target LED Definitions
LED
Number
LED
Label
Definition
1 EN
Relay Enabled—see subsection
Relay Self-Tests
in
Section 13:
Testing and Troubleshooting
2
TRIP
Indication that a trip occurred, by a protection or control element
3
TIME
Time delayed trip
4
DT
Direct transfer trip (DTT)
5 SOTF
Switch-onto-fault
trip
6 LOP
Loss-of-potential
7
51P
Phase time-overcurrent trip
8
51G
Ground time-overcurrent element trip
9
A
Phase A involved in the fault
10
B
Phase B involved in the fault
11
C
Phase C involved in the fault
12
G
Ground distance or residual ground element picked up at time of
trip
13
1
Zone/Level 1 element picked up at time of trip
14
2
Zone/Level 2 element picked up at time of trip
15
67P
Phase instantaneous torque-controlled element picked up at time
of trip
16
67G
Forward directional ground instantaneous torque-controlled
element picked up at time of trip
Target LEDs numbered 2 through 5 and 7 through 16 in Table 5.1 are updated and then latched
for every new assertion (rising edge) of the TRIP Relay Word bit. The TRIP Relay Word bit is
the output of the trip logic (see Figure 5.1).
Further target LED information follows. Refer also to Figure 2.2 and Figure 2.3 in
Section 2:
Installation
for the placement of the target LEDs on the front panel.
Additional Target LED Information
TRIP Target LED
The TRIP target LED illuminates at the rising edge of trip (the new assertion of the TRIP Relay
Word bit).
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