Schweitzer Engineering Laboratories SEL-700G Series, Инструкция по эксплуатации

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5.19
Date Code 20170814 Instruction Manual SEL-700G Relay
Metering and Monitoring
Breaker Monitor
In Figure 5.19, note that the breaker maintenance curve levels off horizontally
above set point KASP1n, COSP1n. This is the close/open operation limit of
the circuit breaker (COSP1n = 10000), regardless of interrupted current value.
Also, note that the breaker maintenance curve falls vertically below set point
KASP3n, COSP3n. This is the maximum interrupted current limit of the
circuit breaker (KASP3n = 20.0 kA). If the interrupted current is greater than
setting KASP3n, the interrupted current is accumulated as a current value
equal to setting KASP3n.
Operation of SEL
OGIC
Control Equation Breaker Monitor Initiation Setting
BKMON
The SEL
OGIC
control equation breaker monitor initiation setting BKMONn in
Table 5.11 determines when the breaker monitor reads in current values
(Phases A, B, and C) for the breaker maintenance curve (see Figure 5.19) and
the breaker monitor accumulated currents/trips (see BRE n Command
(Breaker Monitor Data) on page 7.22).
The BKMONn setting looks for a rising edge (logical 0 to logical 1 transition)
as the indication to read in current values. The acquired current values are then
applied to the breaker maintenance curve and the breaker monitor
accumulated currents/trips (see references in previous paragraph).
In the factory-default settings, the SEL
OGIC
control equation breaker monitor
initiation setting is set:
BKMONn =
TRIP
n (
TRIP
n is the logic output of Figure 4.36)
Refer to Figure 5.19. When BKMONn asserts (Relay Word bit TRIPn goes
from logical 0 to logical 1), the breaker monitor reads in the current values
and applies these values to the breaker monitor maintenance curve and the
breaker monitor accumulated currents/trips.
As detailed in Figure 5.19, the breaker monitor actually reads in the current
values 1.5 cycles after the assertion of BKMONn. This helps especially if an
instantaneous trip occurs. The instantaneous element trips when the fault
current reaches its pickup setting level. The fault current may still be
“climbing” to its full value, at which it levels off. The 1.5-cycle delay on
reading in the current values allows time for the fault current to level off.
Figure 5.19 Operation of SEL
OGIC
Control Equation Breaker Monitor
Initiation Setting
See Figure 5.24 and accompanying text for more information on setting
BKMONn. The operation of the breaker monitor maintenance curve, when
new current values are read in, is explained in the following example.
Breaker Monitor
Operation Examples
As stated earlier, each phase (A, B, and C) has its own breaker maintenance
curve. For this example, presume that the interrupted current values occur on a
single phase in Figure 5.20 through Figure 5.23. Also, presume that the circuit
breaker interrupting contacts have no wear at first (brand new or recent
maintenance performed).
Read in
Current Values
BKMON
1.5 Cycle
Rising
Edge