5.22
SEL-387-0, -5, -6 Relay
Instruction Manual
Date Code 20050919
Metering and Monitoring
Through-Fault Event Monitor
Through-Fault Event Monitor
shows a distribution feeder fault beyond the protection zone of the
SEL-387-5 and SEL-387-6 Relays. Nevertheless, the fault current passes
through the transformer bank, subjecting the windings to mechanical stress
and the winding insulation to thermal stress. The more feeders on a
distribution bus, the more the transformer bank is exposed to these through
faults.
Figure 5.6
Distribution Feeder Faults
Expose Transformer Bank to Through Faults
Monitor and document this through-fault activity with the through-fault event
monitor in the SEL-387-5 and SEL-387-6 relays. The through-fault event
monitor captures maximum current levels, duration, and date/time for each
transformer through fault. The monitor also performs a simple I
2
t calculation
(analogous to the energy expended during the through fault) and cumulatively
stores calculation results for each monitored phase.
Through-Fault Event
Monitor Settings
Activate and adjust the through-fault event monitor with the settings in
.
Setting ETHRU =N turns off the through-fault event monitor. Any other
setting selection for ETHRU designates the winding to monitor for through-
fault events. For example, ETHRU = 2 designates Winding 2 as the winding
to monitor for through-fault events. Specifically, Winding 2 current inputs
IAW2
,
IBW2
, and
ICW2
(A-phase, B-phase, and C-phase, respectively) are
monitored for maximum currents for through-fault events. Changing setting
ETHRU resets/clears through-fault event information (see
TFE C
and
TFE R
command discussions that follow).
SEL-387
Through-Fault Current
Table 5.3
Through-Fault Event Monitor Settings
Setting
Definition
Range
ETHRU
Enable Through-Fault Event Winding
N, 1, 2, 3, 4
THRU
Through-Fault Event Trigger
(SEL
OGIC
control equation)
Relay Word bits (
)
ISQT
Through-Fault I
2
t Alarm Threshold
OFF,
0-4294967 (kA)
2
seconds
Содержание SEL-387-0
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