JPH0223966B2 - - Google Patents

Description

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

An example of a conventional circuit breaker has a structure as shown in FIG. FIG. 1A is a partially sectional plan view taken along line 1E-1A in FIG. That is, in the figure, 1 is an enclosure made of an insulator and forms the outer frame of the circuit or disconnector, 2 is a fixed conductor, and the electrical contact surface of the fixed conductor 2 is provided with a wire as shown in FIG. A fixed contact 3 is attached to. 2 and 3 constitute one of a pair of electrical contacts. In addition, Figure 2 A, B,
C is a front view, a top view, and a right side view of an electric contact, respectively. In addition, 4 is a movable conductor, and its electrical contact surface is similar to that shown in Fig. 2.
A movable contact 5 is attached. 4 and 5 constitute the other of the pair of electrical contacts. Reference numeral 6 indicates an operating mechanism section for opening and closing the movable conductor 4; 7 indicates an arc extinguishing plate for cooling the arc 8 generated between the fixed contact 3 and the movable contact 5; and 9 indicates an arc or hot gas formed in the enclosure 1. It is an outlet for

The conventional circuit breaker 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 supplied from the power supply side to the load side via the fixed conductor 2, fixed contact 3, movable contact 5, and movable conductor 4 in this order. Ru. In this state, when a large current such as a short-circuit current flows through this circuit, the operating mechanism section 6 is activated and the movable contact 5 is connected to the fixed contact 3.
Separate from. 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 of the movable contact 5 from the fixed contact 3 increases, and at the same time, the arc 8 is attracted and expanded in the direction of the arc extinguishing plate 7 by magnetic force. , further increases. In this way, the arc current reaches a current zero point, extinguishing the arc 8, and completing the breakage. During such closing and disconnecting operations, a large amount of energy is generated between the movable contact 5 and the fixed contact 3 by the arc 8 within a short period of time, that is, several milliseconds, and therefore, a large amount of energy is generated within the enclosure 1. The temperature and pressure of the gas rise rapidly, and this high-temperature, high-pressure gas is released into the atmosphere from the outlet 9.

The circuit breakers and breakers and their internal components operate as described above when breaking, but the performance that circuit breakers and breakers that operate in this way must have is due to 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 have high protection performance for various electrical equipment, including distribution lines, that are placed in series with the circuit breakers and breakers, and protect circuits that are connected in series with each other. Selective coordination between disconnectors and disconnection areas,
Alternatively, the cutting area will be expanded at the same time.

Conventionally, in this type of circuit breakers, in order to generate a high arc voltage, the movable conductor 5 is opened at high speed, or the arc 8 is extended using magnetic force. 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 switchgear of this invention,
The behavior of arc voltage, etc. between the fixed and movable 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. It is electrically conductive, 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. , has been determined.

The behavior of such contact particles or electrode particles will be explained based on conventional circuits and disconnectors. FIG. 3 is a schematic explanatory diagram between the contacts, where 3 indicates a fixed contact and 5 indicates a movable contact, and the X plane is the opposing surface that is the contact surface when the respective contacts 3 and 5 make contact. In addition, the Y plane shows a part of the contact surface and the conductor surface other than the opposing surface Furthermore, a, b, and c are schematic representations of contact particles emitted from the contact, where a represents the contact particles emitted from near the center of the opposing surface X, and b
are the contact and conductor particles emitted from the Y plane of the contact surface and part of the conductor surface, and c is the contact particles a and b.
The contact particles are emitted from the vicinity of the periphery of the opposing surface

Contact particles emitted from such contacts 3 and 5 are heated from the boiling point temperature of the contact metal, which is about 3000°C, to a conductive temperature of 8000°C or higher, or an even higher temperature of about 20000°C. To,
It removes energy from the arc space and lowers the temperature of the arc space, resulting in arc resistance. Note that the amount of energy taken away by the contact particles from the arc space is greatly influenced by the degree of temperature rise, and the degree of temperature rise is determined by the position in the arc space of the contact particles emitted from the contact and the release path. However, in the conventional circuit breaker shown in Fig. 3, contact particles a emitted from near the center of the opposing surface X take away a large amount of energy from the arc space, but The contact particles b partially 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 surface X This means that only an intermediate amount of energy will be taken away. That is, in the range where contact particles a flow, a large amount of energy is taken away to lower the temperature of the arc space, thereby increasing the arc resistivity ρ, but in the range where contact particles b and c flow, a large amount of energy is taken away. Since the temperature is not stolen, the temperature of the arc space decreases little, and therefore the arc resistivity ρ
Moreover, since the arc is generated from the opposing surface X plane and the contact surface Y plane, the arc cross-sectional area also increases, and the arc resistance also decreases.

Since the outflow of energy from the arc space due to such contact particles is balanced with the electrically injected energy, if the amount of contact particles generated between the contacts, especially contact particles a and c, injected into the arc space is It can be seen that by enlarging the arc, 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.

Therefore, in the prior art of the present invention, the surface of the electric contact has been developed with the aim of overcoming the limit on the rise in arc voltage in conventional circuit breakers and breakers, and to obtain a circuit breaker that can greatly increase the arc voltage. In order to limit the size of the arc foot generated between the contacts and to increase the amount of contact particles generated between the contacts, especially contact particles a and c, injected into the arc space, on each conductor of a pair of electric contacts. A pressure reflector is formed around the contact point. Furthermore, in this invention, the pressure reflector is made of thermosetting polyester resin, and based on the temperature rise of the insulator caused by the arc, the arc voltage is further increased by the decomposition gas generated from the insulator. It is intended to rise.

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

FIG. 4 shows a fixed electric contact incorporated in the circuit breaker of the present invention, in which A is a front view and B is a plan view. Note that the movable electric contact has the same configuration and will therefore be omitted. The fixed conductor 2 is provided with a fixed contact 3, and a pressure reflection plate 20 made of thermosetting polyester resin is provided to leave the contact surface of the fixed contact 3, cover its periphery, and face the arc space. is installed and fixed. 2
Reference numeral 2 denotes a groove formed in the pressure reflecting plate 20, which is formed so that the conductor 2 is exposed from the side surface of the contact point 3 in the direction in which the arc travels.

FIG. 5 shows a circuit breaker showing an embodiment of the present invention;
B is a partially sectional side view taken along line 5-5 in A.
FIG. 5 shows the pressure reflecting plate 20 explained in FIG.
A fixed electrical contact is provided, and a movable electrical contact is also provided with a pressure reflecting plate 21. A groove 23 is formed so that the conductor 4 is exposed from the side surface of the contact 5 in the direction in which the arc travels. By forming the grooves 22 and 23, when the arc is extended, the arc concentrates on the grooves 22 and 23 and moves along the grooves. It goes without saying that it is sufficient to have only one of the grooves 22 and 23. Since the opening/closing operation in FIG. 5 is the same as that of the conventional device, a description thereof will be omitted, but since the behavior of contact particles between both contacts is different from that of the conventional device, it will be described next.

FIG. 6 is a schematic explanatory diagram between the contacts, and numerals 3 and 5 are a pair of contacts that face each other, and the fixed conductor 2 covers the entire circumference of each contact and faces the arc space. , pressure reflecting plate 2 on movable conductor 4
0 and 21 are provided. Also, in the figure X, a,
c and m are the same as those shown in FIG. are contact particles C flowing through different paths
In addition, Q reflects the pressure generated by the arc 8 by the pressure reflection plates 20 and 21, increasing the pressure that would have decreased in the conventional type without pressure reflection plates. The space is indicated by crossed or diagonal lines.

Contact particles between the contacts in such circuit breakers and breakers behave as follows. That is, the pressure value in the space Q cannot be higher than 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 reflecting plate is provided. Therefore, the value is overwhelmingly higher than that in the case where no pressure reflecting plate is provided, and therefore, the pressure reflecting plate 2
The considerably high pressure in the space Q caused by 0 and 21 becomes a force that suppresses the expansion of the space of the arc 8 and "squeezes" the arc 8 into a narrow space. This means that the streamlines of the contact particles a, c, etc. emitted from the opposing surface X are squeezed into the arc space and confined. Therefore, the contact particles emitted from the opposing surface For this purpose, the arc space is significantly cooled, thus significantly increasing the arc resistivity or arc resistance and the arc voltage.

The pressure reflector is generally made of a high-resistance material that has a higher resistivity than the material that forms the conductor of the electrical contact, and can be fixed to the electrical contact in the form of a plate or formed into a tape. If possible, cover the electrical contacts with a tape-like material.

In this invention, the pressure reflector is particularly made of thermosetting polyester resin. Since the pressure reflector made of thermosetting polyester resin is an insulator, the legs of the arc that occurs between the contacts when the current is cut off cannot spread around the contacts, and in the case of a large current arc, the arc The legs are reduced and a large arc voltage is generated. Furthermore, since this pressure reflector is an organic material, the temperature rises due to the arc and decomposition gas is generated. At this time, arc energy is taken away to generate decomposed gas, and the arc is cooled by the decomposed gas. In addition, due to the generation of decomposition gas, the pressure on the surface of the pressure reflector increases, promoting the arc constriction effect, and increasing the pressure applied to the pressure reflector, which is applied to the movable electrical contact and opens. Can increase extreme speed.
Therefore, the effect unique to the thermosetting polyester resin is added to the effect of the pressure reflector alone, making it possible to further increase the arc voltage.

Thermosetting polyester resin has a high heat deformation temperature, so there is little risk of deformation of the pressure reflector due to temperature rise at the contact points when energized, and its low coefficient of thermal expansion reduces the risk of deformation due to temperature rise and arcing when energized. There is less fear that a gap will form between the conductor and the pressure reflector due to the heat generated when the pressure reflector is attached to the conductor, which becomes hot. Further, it has little wear due to arcing and has excellent moldability.

As a polyester resin, it has good arc resistance, good impact resistance, very good heat resistance, and little wear due to arcing. In addition, it has good moisture resistance, so there is little concern that the pressure reflector will deform or the insulation will deteriorate due to moisture absorption.

As explained above, in the present invention, since the pressure reflector is made of thermosetting polyester resin, the decomposition gas generated from the insulating material increases due to the temperature rise of the insulating material due to the arc.
The arc voltage can be increased even more,
Therefore, it is possible to obtain a circuit or disconnector having high current-limiting performance. Furthermore, polyester resin has good arc resistance, impact resistance, and heat resistance, is less consumed by arcing, and has excellent moisture resistance, so it is suitable as a material for pressure reflectors.

[Brief explanation of drawings]

Fig. 1 shows a conventional circuit disconnector, in which A is a partially sectional plan view taken along line 1E-1A in B; Fig. 2 shows a conventional fixed electric contact; A, B, and C are respectively a front view, a top view, and a right side view; Fig. 3 is a schematic explanatory diagram between the contacts of a conventional circuit breaker; FIG. 4 shows a fixed electric contact according to the present invention, A and B show a front view and a plan view, respectively, and FIG. E-
Partial cross-sectional plan view of line 5A, whose line B is 5R-5 of A.
FIG. 6 is a partially cross-sectional side view of the line B, and is a schematic explanatory diagram between the contacts of the circuit and disconnector according to the present invention. In the figure, 2 is a fixed conductor, 3 is a fixed contact, 4 is a movable conductor, 5 is a movable contact, 7 is an arc-extinguishing plate, 20 and 21 are pressure reflectors, and 22 and 23 are grooves. In addition, in the figures, the same reference numerals indicate the same or corresponding parts.

Claims (1)

[Claims] 1. A pair of electrical contacts consisting of a conductor that carries a circuit current and a contact provided on this conductor, and a pair of electrical contacts provided on each of the pair of electrical contacts,
The pressure reflector is formed on the conductor and surrounds the contact, and the pressure reflector is made of thermosetting polyester resin, and at least one of the pressure reflectors is arced from the side of the contact. 1. A circuit breaker or circuit breaker, characterized in that a groove is provided in the running direction of the contact, which is narrower than the width of the contact and exposes the surface of the conductive part.