High-voltage switches with arc preventing or extinguishing devic – Arc preventing or extinguishing devices – Air-current blowout
Reexamination Certificate
2001-09-24
2004-02-10
Donovan, Lincoln (Department: 2832)
High-voltage switches with arc preventing or extinguishing devic
Arc preventing or extinguishing devices
Air-current blowout
C218S087000
Reexamination Certificate
active
06689980
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a circuit breaker having a hybrid arc extinguishing function, and more particularly, to a circuit breaker having a hybrid arc extinguishing function that is capable of improving an arc extinguishing characteristic by promptly extinguishing an arc, increasing a conduction capacity, with a simple structure and compact size.
2. Description of the Background Art
In general, a circuit breaker is an electric protection instrument installed between an electrical power source and an electrical load for a function of protecting the load instrument and a cable from a possible incident current (a large current due to an incident such as a short or a ground fault) generated in an electric circuit, for a circuit switching and for a distribution function for switching a power supply to a different cable.
As for a currently used high voltage circuit breaker, SF
6
is mostly used as an insulation medium, and a vacuum interrupter is mostly used as an arc extinguisher.
The vacuum interrupter is an arc extinguisher which is mostly used for a high voltage circuit breaker. In spite of its excellent functional aspect, it is expensive, and since vacuum is used as an arc extinguishing medium, high switching surge occurs.
Since the insulation medium employs the SF
6
gas and the arc-extinguishing medium is a vacuum, it is disadvantageous in the aspect of an expense.
Accordingly, a high pressure arc-extinguishing function which would use the same SF
6
gas for the insulation medium and the arc-extinguishing medium but has the same function as the vacuum interrupter is required to be developed.
And in order to meet the requirement, a rotary arc type arc-extinguishing function has been developed. It is easily fabricated, its price is relatively low, and a switching surge does not occur.
The rotary arc type arc-extinguishing function has an advantage that, when an arc is generated between a fixed contactor and a movable contactor, an arc current flows in a magnetic coil and the arc is rotated by a magnetic flux generated from the magnetic coil, so that there is not much damage to an arc contactor and its structure can be simplified.
However, the rotary arc type arc-extinguishing function has the following problems. That is, in case of breaking a small current, the small current flows to the magnetic coil, failing to generate a sufficient driving magnetic flux, so that it is hard to break the small current. In addition, since only a cooling method according to an arc rotation is adopted, in case that a breaking capacity is increased, the size of a breaking portion and its stroke are increased, resulting in that there is a restriction to heightening of a breaking capacity.
In an effort to remove the shortcomings of the rotary arc type (method), a research on a hybrid arc-extinguishing function using more than two arc-extinguishing principles is being actively conducted.
That is, a hybrid arc-extinguishing function is being developed by uniting the rotary arc type (method) for cooling by rotating an arc and a heat expansion arc-extinguishing method in which, when an arc is generated, an internal pressure raised by heat expansion of an insulation medium is used to extinguish the arc.
FIG. 1
is a vertical sectional view of a hybrid arc-distinguishing function of a circuit breaker in accordance with a conventional art.
The conventional art of
FIG. 1
can refer to U.S. Pat. No. 5,166,483.
A circuit breaker having the hybrid arc-extinguishing function of the conventional art has an upper shell and a lower shell
111
and
112
which forms an extinguishing chamber (S) filled with an insulation medium such as SF
6
gas, a fixed electrode
131
having a fixed contactor
132
at an upper end fixed at the lower shell
112
, a movable electrode
141
disposed to be linearly movable at the upper shell
111
and having a movable contactor
136
which is conducted by being contacted with the fixed contactor
132
, and a magnetic coil
147
disposed around the fixed electrode
131
and forming a magnetic field to rotate an arc generated when the fixed contractor
132
and the movable contractor
136
are separated.
The above-described hybrid arc-extinguishing function for a circuit breaker is adopted to a three-phase circuit breaker, and since the three phases have the same form, one of which, thus, will now be described.
The upper shell
111
and the lower shell
112
are inserted in a sealed case (not shown), and mutually coupled to be square. A guide sleeve
113
for guiding the movable electrode
141
so as to be linearly movable is coupled at an upper face of the upper shell
111
, and a fixing hole
124
is formed at a lower face of the lower shell
112
, into which the fixed electrode
131
fixedly penetrates. A rectangular shielding member
145
is coupled along the inner wall face forming the extinguishing chamber (S).
The guide sleeve
113
penetrates in a manner that the movable electrode
141
is movable centering around a shaft, and a seal
115
is mounted at the inner face for sealing with the movable electrode
141
which is linearly moved. A retainer
117
is engaged at an upper side of the seal
115
to prevent the seal
115
from releasing.
In the fixed electrode
131
, in order to discharge SF
6
, gas filled in the extinguishjing chamber (S), an exhaust channel
126
communicating with inside of the case (not shown) is axially formed, and an arc aligning cylinder
137
made of a magnetic material is installed isolated from the upper end.
A magnetic coil
147
forming a magnetic field to rotate an arc to surround the outer circumferential face of the cylinder
137
and the outer circumferential face of the fixed electrode
131
.
The movable electrode
141
includes a cylinder
134
disposed to be slid to the guide sleeve
113
and having an exhaust channel
142
axially formed for discharging SF6 gas, a movable contactor
136
slidably inserted at a lower end of the cylinder
134
and contacting with the fixed contactor
132
, and a pressure spring
138
disposed between the movable contactor
136
and the cylinder
134
, for maintaining a contact pressure when the movable contactor
136
contacts with the fixed contactor
132
.
The movable electrode is driven by an external mechanical actuator(not shown).
In the circuit breaker having the hybrid arc-extinguishing function of the conventional art constructed as described above, the movable electrode
141
is separated from the fixed electrode
131
as it is slid upwardly according to an operation of the external mechanical actuator.
At this time, an arc formed between the fixed contractor
132
and the movable contractor
136
is rotated within the extinguishing chamber (S) by the magnetic filed formed by the magnetic coil
147
, and according to the rotation of the arc, the neighboring SF
6
gas is rotated up to the shield plate
145
. As the arc is formed, a temperature inside the extinguishing chamber (S) goes up, and accordingly, the internal pressure is increased.
As the pressure in the extinguishing chamber (S) is increased and the SF
6
gas is rotated, the gas inside the extinguishing chamber (S) is discharged outwardly through the exhaust channels
142
and
125
respectively formed at the movable electrode
141
and the fixed electrode
131
.
In this manner, the arc is rotated by the magnetic field, and at the same time, cooling is accelerated by the flow of the SF
6
gas according to the change of the pressure, so that the arc is quickly extinguished relatively.
When the external mechanical actuator is operated to move the movable electrode
141
downwardly for conduction, the movable contactor
136
is closed up the fixed contactor
132
to form a closed circuit.
At this time, an electron repulsive force is formed between the fixed contactor
132
and the movable contactor
136
. By allowing the pressure spring
138
to give an elastic force to the movable contactor
136
, the tightening force with the fixed contactor
132
can be maintained.
However, the
Donovan Lincoln
LG Industrial Systems Co. Ltd.
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