JPH0228213B2 - - Google Patents

Description

Detailed Description of the Invention [Technical Field] The present invention has a main contact made of a low-resistance material and an auxiliary contact made of a high-melting point material. This invention relates to circuits and disconnectors that magnetically drive arc extinguishing devices using magnetic flux generated by current.

[Background technology]

In the case of circuit breakers and breakers, it is important to quickly extinguish the arc generated between the fixed and movable contacts by magnetically driving the arc extinguishing device.

As such a magnetic drive system, there is a structure in which a fixed contact plate and a movable contact plate are arranged in parallel so that the current directions are opposite to each other, and the magnetic flux generated between the two contact plates is utilized ( For example, Japanese Patent Application Publication No. 55
−53839). This is a so-called self-induction system that relies on the current flowing through both contact plates to generate magnetic driving force, so the magnetic driving force is not very strong.

There are also devices that insert a coil in series in the circuit from the power supply side terminal to the load side terminal and utilize the magnetic flux generated in the coil (for example, U.S. Patent No.
No. 3815059). This device has the disadvantage that since the coils are connected in series in the electrical circuit, current flows constantly and generates heat.

In addition, these have the problem of damage to both the fixed and movable contacts themselves.

Therefore, the fixed and movable contacts are separated into a main contact made of a low-resistance material and an auxiliary contact made of a high-melting point material, so that the arc mainly occurs at the auxiliary contact.
Furthermore, products that incorporate the above-mentioned advantages have been proposed.

However, even in this case, as the shear current increases, arcs will also occur between the main contacts made of low-resistance materials, and in this case, the main contacts will be damaged.

[Purpose of the invention]

The present invention was made in view of the above reasons, and
The purpose of this is to generate an arc at the auxiliary contacts made of high-melting point material and quickly transfer it to the arc extinguishing device, and at the same time, as the shearing current increases, an arc is generated between the main contacts made of low-resistance material. It is an object of the present invention to provide a circuit or breaker which can reduce damage to main contacts by quickly cooling and extinguishing the arc even in such a case.

[Disclosure of the invention]

Embodiment An embodiment of the present invention will be described below with reference to FIGS. 1 to 4.

1 is the circuit board and disconnector body, and the synthetic resin stand 2
and a cover 3. The device stand 2 has an exhaust hole 4 formed at one end thereof, and a power source side terminal fitting 5 is installed near the exhaust hole 4.

6 is a fixed contact plate, which has a long piece 6a and a short piece 6 facing each other.
b forms a U-shape. The long piece 6a is connected at its end to the power supply side terminal fitting 5, and is disposed so that most of the long piece 6a runs along the bottom of the device stand 2. The short piece 6b is continuously bent from the long piece 6a, and has a main fixed contact 7 made of a low resistance material such as a silver alloy near its tip. 8 is an insulator, both pieces 6
It is inserted between a and 6b to prevent the short piece 6b from shifting.

10 is a movable contact plate, which has a long plate shape and has a short piece 6b.
The proximal end is rotatably supported by a support member (not shown), linked to a general link mechanism (not shown), and electrically connected to a load-side terminal fitting (not shown). A main movable contact 9 made of a low resistance material such as a silver alloy is provided near the tip of the movable contact plate 10 and is made of a low-resistance material such as a silver alloy and moves into and out of contact with the main fixed contact 7.

Reference numeral 19 denotes an arc extinguishing device, which is composed of a large number of grids 20 stacked and supported by an insulating frame 21, and has an exhaust hole 4.
It is arranged at a predetermined interval in front of both main contacts 7 and 9, which are the sides.

Reference numeral 14 denotes an auxiliary fixed contact plate, one end of which faces the lowest grid 20, the other end extending to near the middle of the predetermined interval, and an auxiliary fixed contact plate made of a high melting point material such as tungsten alloy at the other end. 11 are provided.

Reference numeral 15 denotes an auxiliary movable contact plate, and an auxiliary movable contact 12 made of a high melting point material such as a tungsten alloy is provided at its tip to contact and separate from the auxiliary fixed contact 11. The auxiliary movable contact plate 15 has its base end electrically connected to the movable contact plate 10 via the braided wire 16, and
It is rotatably supported at the tip of the movable contact plate 10. Furthermore, a spring 18 tensioned between the movable contact plate 10 and the auxiliary movable contact plate 15 is biased in a direction in which contact pressure is applied between the auxiliary contacts 11 and 12. Therefore, when the movable contact plate 15 rotates in the direction of opening, the auxiliary contacts 11 and 12 are in contact immediately after the main contacts 7 and 9 are opened; Opens later than 9. Further, when all the contacts are in contact, the main contacts 7 and 9 and the auxiliary contacts 11 and 12 are in a parallel relationship.

A coil 13 is formed by winding a plate material about twice, and one end 13a is connected to the tip of the short piece 6b of the fixed contact plate 6, and the other end is connected between the other end of the auxiliary fixed contact plate 14. 22 is a winding frame of the coil 13. Therefore, in the above parallel relationship, the coil 13 is connected in series to the auxiliary contacts 11 and 12.

An insulating plate 23 is made of an inorganic material such as ceramic or mica, and is disposed between the main fixed contact 7 and the auxiliary fixed contact 11. This insulating plate 23 is used to cool the arc generated between the two main contacts 7 and 9 by contacting it, and is placed close to at least the main fixed contact 7. In this embodiment, it is joined to the auxiliary fixed contact plate 14, but it may be joined to the tip of the short piece 6b of the fixed contact plate 6.

5 to 7 show modified examples of the insulating plate 23. FIG. The insulating plate 23 in FIG. 5 has two parallel cooling fins 24, 24 protruding, and a sixth
The insulating plate 23 in the figure is similar to the cooling fin 24 of the previous modification,
The insulating plate 23 shown in FIG. 7 has a large number of cooling holes 26, 26, . . . formed thereinto to enhance the cooling effect.

(motion) Next, the operation will be explained.

In the state shown in FIG. 1, the electric circuit is in a closed state, and the main contacts 7 and 9 and the auxiliary contacts 11 and 12 are both in contact.
And these are in parallel. In this case, the electrical path including the auxiliary contacts 11 and 12 has a higher resistance than the electrical path including the main contacts 7 and 9 because the coil 13 is connected in series, and therefore the current in this electrical path is small and the heat generation is minimal. It is.

In this state, when a large current such as a short circuit current or an overload current flows, an electromagnetic repulsive force acts between both contact plates 6 and 10, causing the movable contact plate 10 to rotate, and as shown in FIG. 7 and 9 open. Immediately after the main contacts 7, 9 are opened, the auxiliary contacts 11, 12 remain in contact.

Therefore, the large current flows through the fixed contact plate 6 → coil 13 → auxiliary fixed contact plate 14 → auxiliary fixed contact 11 → auxiliary movable contact 12 → auxiliary movable contact 15 as shown by the arrow.
→ braided wire 16 → flow to movable contact plate 10, coil 1
3, a strong magnetic flux is generated.

In this case, if the shear current is not so large, no arc will occur between the main contacts 7 and 9, but if the shear current is large, an arc will occur between the main contacts 7 and 9. In the latter case, the arc comes into contact with the insulating plate 23, is cooled, and quickly disappears.

When the movable contact plate 10 further rotates from the state shown in FIG. 3, the auxiliary contacts 11 and 12 also open and an arc is generated between them, as shown in FIG. Arc device 1
It is quickly magnetically driven to 9. Then, the electric circuit becomes an open state.

〔Effect of the invention〕

Since the circuit breaker of the present invention is configured as described above, the arc is generated at the auxiliary contact made of a high-melting point material and quickly transferred to the arc extinguishing device, and the breaker current is increased. Even if an arc occurs between the main contacts made of low-resistance materials, the arc will come into contact with an insulating plate placed near the main contacts and be cooled, and can be quickly extinguished. Damage to the main contacts can be reduced.

[Brief explanation of drawings]

FIG. 1 is a vertical sectional view of the main part showing one embodiment of the present invention, FIG. 2 is a cross-sectional view of the main part, FIG. 3 is an explanatory diagram of the operation immediately after the main contact is opened, 5 is a perspective view showing a first modification of the insulating plate, and FIG. 6 is a perspective view showing a second modification of the insulating plate. , FIG. 7 is a perspective view showing a third modification of the insulating plate. 6... Fixed contact plate, 6a... Long piece, 6b... Short piece, 7... Main fixed contact, 10... Movable contact plate, 9
...Main movable contact, 14...Auxiliary fixed contact plate, 11
... Auxiliary fixed contact, 15 ... Auxiliary movable contact plate, 1
2... Auxiliary movable contact, 13... Coil, 19...
Arc extinguisher, 20... Grid, 23... Insulating plate.

Claims (1)

[Claims] 1. A fixed contact plate having a U-shape and having a main fixed contact made of a low-resistance material near the tips of the opposing short pieces; An arc extinguisher consisting of a movable contact plate linked to a link mechanism with a main movable contact made of a low-resistance material near its tip, and a number of grids arranged at predetermined intervals in front of both main contacts. an auxiliary fixed contact plate having one end facing the lowest grid and the other end extending to near the middle of the predetermined interval and provided with an auxiliary fixed contact made of a high melting point material, and an auxiliary fixed contact plate made of a high melting point material at the tip A movable contact is provided, the base end of which is electrically connected to the movable contact plate, rotatably supported by the tip of the movable contact plate, and biased by a spring in a direction to apply contact pressure between both auxiliary contacts. A circuit consisting of an auxiliary movable contact plate, which is connected to the auxiliary movable contact plate, and a coil connected between the tip of the fixed contact plate and the other end of the auxiliary fixed contact plate, in which the auxiliary contact opens later than the main contact during opening operation. A circuit breaker, characterized in that an insulating plate made of an inorganic material is disposed between the main fixed contact and the auxiliary fixed contact, at least in close proximity to the main fixed contact.