JP3352560B2 - Circuit breaker - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in short circuit breaking performance of a circuit breaker.

[0002]

2. Description of the Related Art In a circuit breaker, when a short-circuit current is interrupted, a high-temperature arc generated in an opening and closing contact portion causes a short circuit.
The surrounding metal is vaporized and a large amount of gas is generated in the vicinity of the switching contact. Japanese Patent Application Laid-Open No. Sho 60-112222 discloses a technique for improving short-circuit breaking performance by utilizing the gas pressure of a large amount of gas.

More specifically, this prior art relates to a circuit breaker in which an open / close contact portion is housed in a case made of a molded insulator, and this circuit breaker includes a pair of contacts. . The pair of contacts are arranged to face each other so as to cut off current by separating from each other.
The contact is provided with a gas pressure plate, and the opening speed of the contact is increased by the gas pressure, so that the breaking performance is improved.

[0004]

In the circuit breaker according to the prior art, since the gas pressure plate is flat, the generated arc gas is generated in the arc-extinguishing chamber formed inside the case of the insulating molded product. To spread. For this reason, the gas pressure cannot be used efficiently, and there is room for improvement in the breaking performance. In addition, a case having a strength sufficient to withstand the pressure of the arc gas is required, and it is necessary to use an expensive insulating material and a structure having a sufficient strength, and there is an economic problem.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an economical circuit breaker having a good breaking performance against short-circuit current.

[0006]

The circuit breaker according to the present invention includes a pair of contacts and a hollow insulating member. The pair of contacts can be contacted and separated. The hollow insulating member has an opening on one of the pair of contacts and the other side so that the side wall surrounds the contact portion when the pair of contacts is in contact. Are arranged on the side of the contact. Inside the side wall that defines the hollow space of the insulating member
The dimension is larger at the opening than at the other contactor side,
Or equal.

[0007]

[0008]

In the circuit breaker according to the first aspect, an initial arc is generated in the hollow insulating member when the contact is opened, and the internal pressure of the insulating member is instantaneously increased by the generated gas. Becomes Therefore, the gas is intensively injected from the opening toward one of the contacts. As a result, the gas pressure acts efficiently so that the pair of contacts are separated, and the contacts are separated at high speed. Moreover, since this action is more effective at the beginning of the separation, the blocking performance is extremely improved.

Moreover, the injection of the flow of arc gas is a gas hydrodynamically smooth. Therefore, the strength of the insulating member can be made appropriate, and the gas pressure can be used efficiently.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of a circuit breaker according to the present invention will be described below with reference to FIGS.

FIG. 1, FIG. 2 and FIG. 3 are side sectional views of a main part of a circuit breaker according to an embodiment of the present invention in a closed state, in a state where contacts are in an early stage of disconnection, and in a state in which a circuit breaker is in an end stage.

Referring to FIG. 1, the circuit breaker in this embodiment is a multi-pole type circuit breaker. This circuit breaker also has a conductive part housed in a case 1 consisting of a base and a cover made of molded insulation, an arc extinguishing device 3, an opening / closing mechanism, a handle 2, and a tripping mechanism. are doing. The conductive portion and the arc extinguishing device 3 are provided for each pole, and the conductive portion includes an opening / closing contact portion. Opening / closing mechanism, handle 2
The trip mechanism is provided in common for each pole, the opening / closing mechanism opens and closes the opening / closing contact section, the handle 2 operates the opening / closing mechanism manually, and the trip mechanism receives an overcurrent in one of the poles. Then, the opening / closing contact portion is opened via the opening / closing mechanism.

Since the opening / closing mechanism and the tripping mechanism are not the main parts of the present invention, their drawings and detailed description are omitted.

The conductive portion includes a fixed contact 4 also serving as a power supply terminal, a contact base 6 to which the fixed contact 5 provided on the fixed contact 4 is fixed, and a movable contact 7 which can be separated from and separated from the fixed contact 5. Movable contact 8, a flexible wire 9 fixed to the movable contact 8, and a load-side terminal (not shown).

The movable contact 8 is held rotatably about the shaft 11 of the movable contact holder 10 as a fulcrum.
Are biased in the counterclockwise direction in the figure by a contact pressure spring 12 stretched between a shaft provided on the movable contact holder 10 and the movable contact holder 10. The contact pressure spring 12 generates a contact pressure between the movable contact 7 and the fixed contact 5 in the closed state shown in FIG. The movable contact holder 10 is fixed to the fixed shaft 2.
2 and rotatably supported by the opening / closing mechanism. The movable contact holders 10 of the respective poles are integrally connected by a cross bar 13. Arc extinguishing device 3
Has a configuration in which a plurality of arc-extinguishing grids 14 made of a magnetic material are attached to an insulating support 15 facing the same.

Next, the structure of the opening / closing contact portion, which is a feature of the present invention, will be described. With reference to FIG.
, A fixed contact 5, a contact base 6, and an insulating cover 16 are attached. The fixed contact 5 is attached to the fixed contact 4 via a contact base 6. The insulating cover 16 covers the periphery of the fixed contact 4 and the contact base 6 in order to prevent damage due to a high-temperature arc generated between the fixed contact 5 and the movable contact 7, and an opening end of a hollow member 17 described later. The outer periphery is columnar so as to surround.

A recess 8b is formed at a position of the movable contact 8 facing the fixed contact 5. This recess 8b
The opening is formed so that the opening dimension becomes wider from the bottom (base end) toward the opening, that is, the opening becomes wider. At the bottom (base end) of the recess 8b, a contact base 8a for fixing the movable contact 7 is formed. A hollow member 17 made of a frustum-shaped insulating member is attached along the wall surface from the bottom (base end) of the concave portion 8b of the movable contact 8 to the opening. This hollow member 17 has a side surface 17a,
The contact extends between the fixed contact 5 and the movable contact 7 toward the fixed contact 4, and surrounds the movable contact 7, the fixed contact 5, and the contact base 6.

The circuit breaker thus constructed is shown in FIG.
By operating the handle 2 from the thrown state of
Alternatively, the operation of shifting to the open state between the fixed contact 5 and the movable contact 7 due to the flow of the short-circuit current will be described below.

First, the operation of operating the handle 2 to separate the contacts 5 and 7 will be briefly described because it is not a main part of the present invention. When the handle 2 is rotated clockwise in the figure, an opening / closing mechanism (not shown) operates, the movable contact holder 10 rotates clockwise together with the movable contact 8, and the movable contact 7 moves from the fixed contact 5 to the movable contact 7. Break apart.

When a large current such as a short-circuit current flows through the circuit breaker, a tripping mechanism (not shown) operates to operate the switching mechanism, and the fixed contact 5 and the movable contact 7 are opened. Initiate the release action. In such an operation, there is a mechanical delay from the beginning of the flow of the short-circuit current to the opening of both contacts. However, when a short-circuit current flows in parallel with the operation of such a mechanism, an electromagnetic repulsive force is generated between the fixed contact 5 and the movable contact 7, and both contacts are instantaneously separated. This state is shown in FIG.

Referring to FIG. 2, the movable contact 7 is separated from the fixed contact 5 by electromagnetic repulsion without rotating the movable contact holder 10, and an arc is generated therebetween.
The high-temperature arc vaporizes a part of the fixed contact 5 and the movable contact 7. Thereby, the hollow member 17
Arc gas is generated in a small space surrounded by. Therefore, the pressure increases in the hollow member 17 due to the arc gas.

For this reason, the arc gas is exhausted from the opening so as to be jetted directionally in the direction of the fixed contact 5 and the insulating cover 16 along the direction of arrow A. The movable contact 8 moves at a high speed in a direction in which the movable contact 7 and the fixed contact 5 are separated from each other by the reaction of the ejected exhaust gas. As a result, the arc resistance is rapidly increased and the interruption time is shortened. Also, the arc current is limited, the arc energy is reduced, and the interruption performance is improved. The final stage of this shutoff is shown in FIG.

Referring to FIG. 3, in this state, the arc is attracted to arc extinguishing device 3 to increase the arc length, and is further cooled by arc-extinguishing grid 14 so that the arc resistance further increases and the arc is extinguished. To complete the shutdown.

During this operation, the above-mentioned tripping mechanism operates and the movable contact holder 1 is moved via the opening / closing mechanism.
Numeral 0 rotates clockwise in the figure to hold the movable contact 8 at the open position, and to reach the final shut-off completion position (not shown).

As described above, in the circuit breaker of this embodiment, when breaking a large current, the arc energy becomes small, the amount of generated gas is small, and the pressure in the case 1 does not increase, so that the strength is increased. Eliminates the need.

In the above embodiment, the hollow member 17 has a truncated cone shape, but may have a truncated cone shape or a truncated pyramid shape, and may have one end located at the bottom (base end) of the recess 8b. The other end of the opening may have a columnar shape of the same size.

In the above-described embodiment, the example in which the hollow member is provided on the movable contact side has been described. However, the hollow member of the circuit breaker according to the present invention is not limited to this embodiment. For example, FIG. ) To (c).

FIGS. 4A to 4C are side views showing a modified example of the hollow member used in the circuit breaker in one embodiment of the present invention.

First, referring to FIG.
a may be provided on the fixed contact 18 to which the fixed contact 5 is fixed. Also, referring to FIG.
b is provided on the fixed contact 18 side, and the hollow member 20
A hollow member 21b having a wall surface surrounding the outer peripheral wall b may be provided on the movable contact 19 side to which the movable contact 7 is fixed. Referring to FIG. 4C, a hollow member 20c is provided on the movable contact 19 side, and a hollow member 21c having a wall surrounding the outer peripheral wall of the hollow member 20c is fixed to the fixed contact 18.
It may be provided on the side.

In the example shown in FIGS. 4B and 4C, the contact portion between the fixed contact 5 and the movable contact 7 is surrounded by a double hollow member. For this reason, the inner hollow members 20b, 2
0c is applied to the outer hollow members 21b, 21b.
The diffusion is limited by c, and the driving force for opening the movable contact 19 can be increased.

Although each hollow member shown in FIGS. 4A to 4C is shown as a column, it may be a truncated cone.

Furthermore, in each embodiment, one of the contacts is a fixed contact and the other is a movable contact circuit breaker.
A circuit breaker having both movable contacts by electromagnetic repulsion may be used.

[0033]

According to the present invention, the contact can be separated at a high speed, so that the breaking performance is good, and the internal pressure of the case can be kept low. A circuit breaker can be realized.

[Brief description of the drawings]

FIG. 1 is a side sectional view of a main part in a closed state of a circuit breaker according to an embodiment of the present invention.

FIG. 2 is a side sectional view of a main part of the circuit breaker according to the embodiment of the present invention in a state where contacts of the circuit breaker are in an initial stage of separation.

FIG. 3 is a side sectional view of a main part of the circuit breaker according to the embodiment of the present invention in a state where the circuit breaker is terminated.

FIG. 4 is a view showing modified examples (a) to (c) of a hollow member used for a circuit breaker according to one embodiment of the present invention.

[Explanation of symbols]

4, 18 Fixed contact 5 Fixed contact 6 Contact block 7 Movable contact 8, 19 Movable contact 16 Insulating cover 17, 20a, 20b, 20c, 21a, 21b, 21
c hollow member

Claims (1)

(57) [Claims] A pair of contacts that can be contacted and separated and an opening is formed on one of the pair of contacts.
And the side wall is in contact with the pair of contacts.
Placed on the other contact side so as to surround the contact part of
And a hollow insulating member, wherein the inner dimension of the side wall that defines the hollow space of the insulating member is larger or equal to the opening portion than the other contactor side , circuitry breaker.