The automatic reclosing switch circuit breaker is automatically reclosed by mechanical means or relay automatic device after it has been tripped for some kind of fault. If the fault occurred in the power system is temporary, after the circuit breaker trips to cut off the power supply by the relay protection device, it will automatically reclose after a predetermined time.
4. 1 2
The automatic reclosing switch
circuit breaker is automatically
reclosed by mechanical means
or relay automatic device after
it has been tripped for some
kind of fault.
If the fault occurred in the power
system is temporary, after the circuit
breaker trips to cut off the power
supply by the relay protection device, it
will automatically reclose after a
predetermined time.
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5. 3 4
If the fault has been automatically
eliminated by itself, the will resume
power supply; if the fault is
continuous Then, the circuit breaker
is tripped again and no longer
reclose.
According to the number of reclosing, there
are one-time auto recloser and multiple-time
recloser; according to the number of phases,
there are three-phase and single-phase
automatic recloser; according to the
application circumstances, there are single-
side power supply recloser and double-side
power supply automatic recloser.
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6. 01
02
In the failure of power systems, most of them are faults of transmission lines (especially
overhead lines). Operational experience has shown that overhead line faults are mostly
“transient”, for example, flashover caused by lightning, flashing caused by strong winds,
short circuits caused by birds and branches falling on the wires, etc.
After being quickly disconnected by the relay protection, the arc is
extinguished, and external objects (such as branches, birds, etc.) are also
burned by the arc and disappear. At this time, if the disconnected circuit
breaker is closed again, normal power supply can be restored.
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7. 03
04
Therefore, such a fault is called a "transient fault." In addition to this, there are also
"permanent failures" such as failures due to line reversal, wire breakage, insulator
breakdown or damage, and they are still present after the line is disconnected. At
this time, even if the power is turned on, since the fault still exists, the line is again
disconnected by the relay protection, and thus the normal power supply cannot be
restored.
Since the fault on the transmission line has the above properties, it is possible to
greatly improve the reliability of the power supply by performing a closing after
the line is disconnected. For this reason, an automatic reclosing device capable of
automatically closing the circuit breaker after the circuit breaker trips is widely
used in the power system.
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9. The automatic reclosing device is an automatic device that automatically inputs the circuit
breaker as needed after the fault has been removed. The experience of power system
operation shows that the vast majority of faults in overhead lines are “instantaneous”, and
permanent faults are generally less than 10%. Therefore, after the short-circuit fault is removed
by the relay protection action, the arc will automatically extinguish, and in most cases the
insulation at the short-circuit can be automatically restored. Therefore, automatically
overlapping the circuit breakers not only improves the safety and reliability of the power
supply, but also reduces the power loss, and also increases the transient level of the power
system, increases the power transmission capacity of the high voltage line, and corrects the
miss-trip due to Mal-operation caused by the relay or relay protection device. Therefore,
automatic reclosing is required for overhead lines.
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10. The main role of automatic reclosing
greatly improve the reliability of
power supply, reduce the number
of power outages, especially the
single-circuit line of single-sided
power supply;
The use of reclosing on the high-
voltage transmission line can also
improve the stability of the parallel
operation of the power system;
In the process of designing and
constructing the power grid, in some
cases, due to the role of reclosing, it
is possible to suspend the double-
circuit line to save investment;
It can also correct the malfunction
of the circuit breaker itself due to
malfunction of the mechanism or
malfunction of the relay protection.
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