JPH0215977B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a circuit or breaker, and particularly to a circuit or breaker with improved current-limiting performance when the breaker is disconnected.

An example of a conventional circuit breaker has a structure as shown in FIGS. 1A and 1B of the accompanying drawings. That is, in the same figure, 1 is an enclosure made of an insulator and forms the outer frame of the circuit or disconnector, and 2 is 1
It is a fixed conductor that constitutes one of the pair of electrical contacts 20 and 40, that is, one of the two main body parts, and the electrical contact surface of the fixed conductor 2 is
As shown in C, a fixed contact 3 is attached. Further, 4 is a movable conductor which is the main body of the other electric contact 40, and its electric contact surface also includes:
As shown in FIG. 3, a movable contact 5 is attached. Reference numeral 6 denotes an operating mechanism section for opening and closing the movable conductor 4; 7 an arc extinguishing plate for cooling the arc 8 generated between the fixed contact 3 and the movable contact 5; and 9 an arc extinguishing plate formed in the enclosure 1. Alternatively, the hot gas outlet 10 is a side plate that together with the arc extinguishing plate 7 constitutes an arc extinguishing chamber 11.

The conventional circuit and disconnector is constructed as described above, and its operation will be explained next.

Now, when the movable contact 5 and the fixed contact 3 are in contact, the power is transferred from the power source to the fixed conductor 2, the fixed contact 3, the movable contact 5, and the movable conductor 4.
It is supplied to the load side via sequentially. In this state, when a large current such as a short circuit current flows through this circuit, the operating mechanism section 6 operates to separate the movable contact 5 from the fixed contact 3. At this time, an arc 8 is generated between the fixed and movable contacts 3 and 5, and an arc voltage is generated between the fixed and movable contacts 3 and 5.
This arc voltage increases as the separation distance between the fixed contact 3 and the movable contact 5 increases, and
At the same time, the arc 8 is drawn toward the arc-extinguishing plate 7 by the magnetic force and extends, so that it further rises.
In this way, the arc current reaches a current zero point and the arc 8 is extinguished, completing the shearing.

During such disconnection or disconnection operation, the movable contact 5
A large amount of energy is generated between the arc 8 and the fixed contact 3 within a short period of time, ie, a few milliseconds, which causes the temperature of the gas inside the enclosure 1 to rise and the pressure to increase. Although the temperature rises rapidly, this high-temperature, high-pressure gas is discharged into the atmosphere from the arc outlet 9.

The circuit breakers and breakers and their internal components operate as described above when the circuit breaks, but the performance that circuit breakers and breakers that operate in this manner is limited by the high arc voltage. Depending on the height of this arc voltage, the arc current flowing during the breaker operation is suppressed, and the magnitude of the current flowing through the circuit breaker is reduced. Therefore, circuit breakers and breakers that generate high arc voltages are
It has high protection performance for various electrical equipment including distribution lines arranged in series with circuits and disconnectors, and is designed to prevent selective coordination and disconnection between circuits and disconnectors connected in series, or simultaneous disconnection. The area will be expanded.

In response to such demands, conventional circuit breakers and breakers of this type have either opened the movable conductor 5 at high speed or used magnetic force to generate the arc 8 in order to generate a high arc voltage. However, in these cases, there was a certain limit to the increase in arc voltage, and a drawback was that a satisfactory result could not be obtained.

Before explaining the circuit and disconnector of the present invention, the behavior of the arc voltage and the like between the fixed contacts 3 and 5 will be explained.

Generally, arc resistance has the following relationship.

That is, R=ρl/S where R: arc resistance (Ω) ρ: arc resistivity (Ω・cm) l: arc length (cm) S: arc cross-sectional area (cm ² ) However, generally speaking, In a short arc with a large current and an arc length of 50 mm or less, the arc space is occupied by contact particles, but the emission of these contact particles occurs in a direction perpendicular to the contact surface. In addition, the ejected particles have a temperature close to the boiling point of the contact metal material at the time of ejection, and as soon as they are injected between the arcs, they are injected with electrical energy and become high temperature and high pressure, and become conductive. It expands in a direction that follows the pressure distribution in the arc space and flows away from the contact point at high speed.
In this way, the arc resistivity ρ and the arc cross-sectional area S in the arc space are determined by the amount of contact particles generated and their emission direction, and therefore the arc voltage also depends on the behavior of the contact particles. ,
It has been decided.

The behavior of such electrode particles will be explained based on conventional circuits and disconnectors. As shown in Figure 3, 3
indicates a fixed contact, 5 indicates a movable contact, the X plane is the opposing surface which is the contact surface when the respective contacts 3 and 5 make contact, and the Y plane is the electrical contact other than the opposing surface X side. A contact surface and a part of a conductor surface are shown. In the figure, a circle Z indicated by a dashed line indicates the outer circle of the arc 8 generated between the contacts 3 and 5. Furthermore, a, b, and c schematically show contact particles emitted from contacts 3 and 5, where a represents contact particles emitted from near the center of the opposing surface X, and b represents contact particles emitted from the contact surface and conductor. Contact particles and conductor particles are emitted from a part of the Y plane of the surface, and c is a contact particle emitted from around the circumference of the opposing surface X plane, which is an intermediate position between contact particles a and b. The post-release path of each particle a, b and c follows the respective streamlines indicated by arrows m, n and o, respectively.

The contact particles a, b, and c emitted from such contacts 3 and 5 rise from the boiling point temperature of the contact metal, which is about 3000°C, to the temperature at which it becomes conductive, that is, about 3000°C.
Since the temperature is increased to over 8,000°C or even higher to about 20,000°C, energy is removed from the arc space, lowering the temperature of the arc space, and as a result, arc resistance occurs. Note that the amount of energy taken away by contact particles a, b, and c from the arc space is due to a large degree of temperature rise;
It is determined by the position in the arc space of the electrode particles emitted from the contact and the emission path. However, in the conventional circuit breaker shown in Fig. 3, the contact particles a emitted from near the center of the opposing surface X take away a large amount of energy from the arc space; The contact particles b emitted from the Y plane take away less energy from the arc space than the contact particles a, and the contact particles c emitted from the peripheral part of the opposing face X take away more energy than the contact particles a and b. This means that only an intermediate amount of energy is taken away.

That is, in the range where the contact particles a flow, a large amount of energy is taken away, lowering the temperature of the arc space, and thus increasing the arc resistivity ρ.
In the range where contact particles b and c flow,
Since a large amount of energy is not taken away, the temperature of the arc space does not decrease, and therefore the arc resistivity ρ cannot be increased.Moreover, since the arc is generated from the opposing surface X surface and the contact surface Y surface, the arc The cross-sectional area also increases and therefore the arc resistance decreases.

Since the outflow of energy from the arc space due to such contact particles is balanced with the electrical injection energy, if the amount of contact particles a generated between contacts 3 and 5 injected into the arc space is increased. It can be seen that by doing so, the temperature of the arc space can naturally be greatly reduced, and as a result, the arc resistivity can be increased and the arc voltage can be greatly increased.

This invention thus overcomes the limitations of conventional circuits and circuit breakers with respect to the rise in arc voltage.
The main purpose is to greatly increase the arc voltage by increasing the amount of contact particles generated between the contacts injected into the arc space using the pressure reflector installed on the electric contact. By specifying the path and the slit of the arc-extinguishing plate, the present invention provides a circuit and a breaker that has a large current limiting effect and can improve the cutting performance.

Hereinafter, one embodiment of the present invention will be described based on the drawings.

4A and 4B and FIGS. 5A and 5B show an embodiment according to the present invention, and FIG. 4 shows a fixed contact portion. 12a and 12b are pressure reflectors, and each conductor 2, except the contact surface of contacts 3 and 5,
The conductor 4 is fixed to the movable conductor 4 and the fixed conductor 2 so as to surround the outer periphery of the conductor 4 . Pressure reflector 12a, 1
As the material 2b, a material having higher resistivity than the materials constituting each conductor 2 and 4 is used. The formation method includes coating each of the conductors 2 and 4 with a high resistance material such as ceramic using, for example, plasma jet spraying, or coating each conductor 2 and 4 with a plate-like material made of a high resistance material. It sticks to 4. Examples of high-resistance materials include organic or inorganic insulators, nickel, iron, steel, nickel,
High resistance metals such as copper manganese, manganin, iron-carbon, iron nickel, or iron chromium. If the pressure reflectors 12a and 12b are coated by thermal spraying or the like, it is not only inexpensive and easy to do, but also reduces the weight, especially on the side of the movable contact 40, so that the moment of inertia is reduced and the movable The opening speed of the contactor 40 increases, and the arc voltage increases. One reflector, for example pressure reflector 1
2a, an arc travel path 13 is formed by exposing the conductor 2, for example, through a slit in a direction away from the end face of the contact toward the arc extinguishing chamber 11, and which is narrower than the fixed contact 3. Furthermore, a slit 7a is formed in the arc extinguishing plate 7 in correspondence with the arc running path 13. Pressure reflector 1
The width dimension t ₂ of the arc running path 13 of 2a and the slit width dimension t ₁ of the arc extinguishing plate 7 are set in a relationship of t ₁ t ₂ .
The arc running path 13 is not limited to the means for exposing the conductor 2, and may be fixed with a molded article made of a material having higher conductivity than the pressure reflector 12a. The arc-extinguishing plate 7 is made of a magnetic or non-magnetic material, but if it is made of a non-magnetic material, it is possible to solve the problem of temperature rise of the arc-extinguishing plate due to eddy currents when it is made of a magnetic material. Next, the operation of the above configuration will be explained.

Since its operation is similar to that of conventional circuits and disconnectors, its explanation will be omitted, but the behavior of contact particles between both contacts is different from that of conventional circuits, so it will be explained below.

In FIG. 6, reference numerals 3 and 5 denote a pair of contacts facing each other, and the fixed conductor 2, the movable conductor 4, and the pressure reflector 12a, covering the entire circumference of each contact and facing the arc space. 12b is provided. In addition, X, a, c, and m in the figure are the same as those shown in _FIG . Z ₂ (Fig. 7) shows the outer shape of the arc 8 when the arc spot moves to the arc travel path 13, and O ₁ also shows a path different from the conventional one by using the circuit and breaker of this invention. Q reflects the pressure generated by the arc 8 by the pressure reflectors 12a and 12b, increasing the pressure that was lower in the conventional type without pressure reflectors. The space indicated by the crossed diagonal lines is shown.

The electrode particles between the contacts in the circuit and disconnector of this invention behave as follows. In other words, the pressure value in the space Q cannot exceed the pressure value in the space of the arc 8 itself, but at least it shows an overwhelmingly higher value than in the case where no pressure reflector is provided. Therefore, the considerably high pressure in the space Q generated by the pressure reflectors 12a and 12b becomes a force that suppresses the expansion of the space of the arc 8, and "squeezes" the arc 8 into a narrow space. Become. In other words, contact particles a, emitted from the opposing surface
The streamlines such as c are squeezed into the arc space and confined. Therefore, contact particles a, c emitted from the opposing surface X are effectively injected into the arc space, and as a result, a large amount of effectively injected contact particles a, c
In order to remove a large amount of energy from the arc space that is incomparable to the conventional one, the arc space is significantly cooled, and therefore the arc resistivity or arc resistance is significantly increased and the arc voltage is extremely increased. let

Furthermore, since the pressure between the contacts 3 and 5 becomes high as described above, a strong air current is generated toward the discharge port 9, and the arc spot on the contact 3 moves on the arc travel path 13 of the pressure reflector 12a as shown in FIG. Move like this. By the way, the width of the large current arc positive column portion 8 has grown to approximately the same size as the width _t2 of the arc running path 13 due to the action of the pressure reflectors 12a and 12b, so the arc 8 running along the running path 13 The arc extinguishing plate 7 is always in contact with the arc extinguishing plate 7 having the slit 7a having a width t ₁ smaller than the width t ₂ to melt and vaporize the arc extinguishing plate 7, thereby cooling the arc 8. In other words, in the configuration of this invention,
The contact area of the arc 8 with the arc-extinguishing plate 7 is expanded most effectively, the arc 8 is efficiently cooled, and the arc voltage can be increased.

As described above, according to the present invention, at least one of the contacts having a pressure reflector disposed on the conductor so as to surround the contact has an arc running in a direction that extends away from the contact and is narrower than the contact. By providing a path, the arc generated between the contacts is prevented from penetrating into the narrow arc travel path due to the large diameter of the arc foot when the current is large, and the arc squeezing effect by the pressure reflector is fully exerted. Become,
This has the effect of improving current limiting performance. Moreover, since the arc moves along the arc travel path toward the arc extinguishing plate while being narrowed down by the pressure reflector, there is an advantage that the current limiting effect is maintained as is during this movement. Furthermore, since the arc-extinguishing plate has a slit narrower than the arc running path, the contact area of the arc with the arc-extinguishing plate after moving along the arc running path is increased, and the arc-extinguishing performance is improved.

[Brief explanation of drawings]

Figure 1 shows an example of a conventional circuit and disconnector.
Figure A is a partially sectional plan view of the same, Figure B is a cross-sectional view taken along line B-B in Figure 1 A, Figure 2 A, B and C.
3 are a front view, a top view, and a right side view of the electrical contacts of each conventional circuit and disconnector, and FIG. 3 is a schematic explanatory diagram of the behavior of electrode particles between the contacts of the conventional circuit and disconnector. , FIGS. 4A and 4B are a front view and a plan view, respectively, of a pressure reflection plate in an example of the circuit breaker according to the present invention, and FIG. 5 is an embodiment of the circuit breaker according to the present invention. Figure A is a partially sectional plan view, Figure B is a cross-sectional view taken along the line B-B of Figure 5A, and Figures 6 and 7 are contacts of the circuit breaker of the present invention. FIG. 3 is a schematic explanatory diagram of the behavior of contact particles between the two. 2... Fixed conductor, 3... Fixed contact, 4... Movable conductor, 5... Movable contact, 7... Arc-extinguishing plate, 7a...
Slit, 8...Arc pillar, 12a, 12b...
Pressure reflector, 13... Arc travel path, 20, 40
...Electric contact, t ₁ ... Slit width, t ₂ ... Arc running path width. Note that the same numbers in the figures indicate the same or equivalent parts.

Claims (1)

[Claims] 1 A pair of contacts, each consisting of a conductor and a contact fixed to this conductor, and a contact that is provided on both contacts, is made of a material with higher resistivity than the conductor, and a pressure reflector disposed on the conductor so as to surround the outer periphery of the child contact; and a pressure reflector provided on at least one contact and formed to have higher conductivity than the pressure reflector; an arc travel path extending in a direction away from the contact point of the contact so as to move the compressed arc column away from the contact point, and having a width narrower than the contact point, and an arc travel path formed corresponding to the arc travel path; and an arc-extinguishing plate having a slit narrower than the running path.