JP2002270080A - Current limiting mechanism and circuit breaker with the mechanism - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a current limiting mechanism capable of providing a higher current limiting performance without being limited by the strength of a casing and a circuit breaker with the mechanism. SOLUTION: This current limiting mechanism comprises a pair of contactors 1 and 5 having contact points 2 and 6 at one end parts thereof and supported so that the contact points can come into contact with and be separated from each other and an insulator 8 disposed at least on both sides of a plane including the locus of the contact points when the contactors performs opening and closing operations so that the opening and closing operations of the contactors are not interfered near the contact points in closed state and producing gas including hydrogen by a heat from an arc generated between the contact points during current limiting operation. At least one of the pair of contact points is formed with a material provided by mixing cadmium oxide into the main component of silver or copper.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a current limiting mechanism for generating an arc during a current limiting operation and performing a current limiting using an arc voltage, and a circuit breaker having the same.

[0002]

2. Description of the Related Art FIG. 13 shows, for example, Japanese Patent Application Laid-Open No. 7-302535.
FIG. 1 is a side view for explaining a conventional current limiting mechanism disclosed in Japanese Patent Application Laid-Open Publication No. HEI 10-115,036. In the figure, reference numeral 1 denotes a movable contact comprising a movable contact 2 and a movable arm 3, which is rotatably held by a rotating shaft 4 at an end opposite to the movable contact 2. Reference numeral 5 denotes a fixed contact, which has a fixed contact 6 and a fixed conductor 7, and is provided substantially parallel to and opposed to the movable contact 1 in a closed state.
Reference numeral 8 denotes an insulator (a pair of insulating plates) that generates a gas containing hydrogen by the heat of an arc generated between the contacts 2 and 6, and the movable contact 1 does not hinder the opening and closing operation of the movable contact 1. They are arranged on both sides of a plane including the trajectory of the movable contact 2 during the opening and closing operations. Reference numerals 9 and 10 are insulators that cover the conductors around the contacts 2 and 6, respectively. These insulators 8, 9,
Numeral 10 is made of a synthetic resin containing hydrogen as a constituent element or the above synthetic resin reinforced with ceramics, and contains a substance containing hydroxide or water of crystallization in order to promote generation of hydrogen. It may be done.

Next, the operation when this current limiting mechanism is applied to a circuit breaker will be described. Opening and closing normal contacts
The opening and closing operation is performed by a separately provided mechanism (not shown). When an accident current such as a short-circuit current occurs, a current in a substantially parallel and reverse direction flows before the operation of the mechanism. The contacts 2 and 6 are opened by the electromagnetic repulsion generated between the arranged contacts 1 and 5, and an arc is generated between the contacts 2 and 6. Due to the heat of the arc, a large amount of gas containing hydrogen is generated from the insulators 8, 9, and 10, and the pressure in the arc-generating space (arc-generating space) rises sharply. At this time, the arc diameter is narrowed by the effects of the high-pressure atmosphere and the hydrogen gas, and the arc voltage rises sharply, thereby limiting the fault current.

[0004] However, unless the initial stage of the opening before the fault current increases, the fault current cannot be limited to a small value by the sharp rise of the arc voltage. Therefore, in order to obtain high current limiting performance, it is necessary to dispose insulators 8, 9, and 10, which are means for generating a high-pressure atmosphere with a gas containing hydrogen, in the vicinity of the closed contacts 2, 6. Yes, for example, Patent No. 29
No. 18752, Japanese Patent Publication No. 8-8048, WO0
Japanese Patent Application Publication No. 0/41202 discloses a technique for obtaining such high current limiting performance.

[0005]

The conventional current limiting mechanism and the circuit breaker provided with the same are configured as described above, and the heat of the arc generated between the contacts immediately after the contact opening at the beginning of the current limiting operation. Since a large amount of hydrogen-containing gas is generated from the insulator placed in the vicinity and the rise of the arc voltage is accelerated, the distance between the insulator and the arc should be reduced as much as possible to obtain higher current limiting performance Although it is necessary, there is a problem that there is a limit to shorten the distance between the arc and the insulator due to the contact space dimension determined by the moving space of the movable contact and the energizing current value, taking into account the shaking during the switching operation. Was.

It is effective to raise the arc voltage quickly to improve the current limiting performance. However, if an arc voltage higher than necessary occurs after the current peak during the current limiting operation, the pressure inside the housing increases. Then, a housing crack occurs.

As described above, in the conventional current limiting mechanism and the circuit breaker including the same, it is necessary to reduce the distance between the insulator and the arc between the contacts in order to accelerate the rise of the arc voltage. There is a conflicting requirement that it is necessary to keep the arc away from the insulator so that an unnecessarily high arc voltage does not occur after the current peak during current operation.To improve current limiting performance, a housing with high mechanical strength is required. Is necessary,
There was a problem that the current limiting performance was limited by the strength of the housing.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems of the prior art, and a current limiting mechanism having higher current limiting performance without limiting the strength of the housing and a current limiting mechanism having the same. It is an object of the present invention to provide a circuit breaker having the same.

[0009]

A first current limiting mechanism according to the present invention has a contact at one end thereof, and a contact pair in which the contact is supported so as to be able to contact and separate from the contact. Hydrogen is generated by the heat of an arc generated between the contacts during a current-limiting operation, and is disposed on at least both sides of a plane including the locus of the contacts during the contact opening / closing operation so as not to hinder the opening / closing operation of the contacts near the contact pair. And at least one of the contact pairs is made of a material containing silver or copper as a main component and cadmium oxide mixed therein.

The second current limiting mechanism according to the present invention has an instantaneous current value of 3.6 kA or more during the current limiting operation and a pressure of 5.9 × 10 ⁵ N / m ² or more at the outer periphery of the arc. Things.

In a third current limiting mechanism according to the present invention, the contact pair is provided with an electric path through which currents in substantially parallel and opposite directions flow in the closed state.

In a fourth current limiting mechanism according to the present invention, at least one of the pair of contacts has a substantially L-shape, and a contact is fixed to a tip portion of the shorter side of the substantially L-shape, and an insulating member is provided. The object is arranged so as to surround the contact pair in a closed state in a cylindrical shape from all sides.

In a fifth current limiting mechanism according to the present invention, one of the pair of contacts is substantially L-shaped to form a movable contact, and a contact is fixed to a tip of the shorter side of the substantially L-shape. The other is a fixed contact, an arc runner extending in a direction away from the movable contact in a closed state from an end having a contact of the fixed contact, and the movable in an open state in a space on the contact arrangement side of the fixed contact. An arc extinguishing plate arranged at a position facing the contact of the contact, and a space sandwiched by insulators arranged on both sides of a plane including the trajectory of the contact when the contact is opened and closed is opened. When viewed from the contact of the movable contact, the space width near the arc runner is smaller than the space width near the contact of the fixed contact.

A first circuit breaker according to the present invention includes any one of the above-described first to fifth current limiting mechanisms.

A second circuit breaker according to the present invention includes a current limiting mechanism, and an opening / closing mechanism for opening and closing at least one contact of the current limiting mechanism, wherein the current limiting mechanism and the switching mechanism are combined. It is housed in another housing.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1 1 to 3 are views for explaining a current limiting mechanism and a circuit breaker provided with the current limiting mechanism according to Embodiment 1 of the present invention. More specifically, FIG. 1 is a circuit breaker in a closed state. Sectional view showing the main part of the container,
2 is a plan view of the fixed contact 5 and the insulator 8 of FIG. 1 as viewed from above in FIG. 1. FIG. 3 is an exploded perspective view of the fixed contact 5 and the insulator 8. The cross section of the insulator 8 in FIG. 3 is taken along the line CC in FIG. 2 so that the internal shape can be understood.

1 to 3, reference numeral 1 denotes a movable contact comprising a movable contact 2 and a substantially L-shaped movable arm 3, and the movable contact 2 is a tip of a shorter side of the substantially L-shaped movable arm 3. And is rotatably held by a rotating shaft 4 at the end of a movable arm opposite to the movable contact 2, and is opened and closed by a mechanism (not shown). . Reference numeral 5 denotes a fixed contact, which comprises a substantially J-shaped fixed conductor 7 and a fixed contact 6 arranged on the space side surrounded by the J-shaped fixed conductor 7. The J-shaped fixed conductor 7 is provided with an electric path 7a in which current flows in a substantially parallel and opposite direction in opposition to the movable contact 1 in the closed state, and a horizontal conductor 7b extending horizontally from the terminal 13 and a horizontal conductor 7b. And a vertical conductor portion 7c extending in the vertical direction on the side opposite to the terminal portion of the conductor portion 7b. Reference numeral 11 denotes a slit provided in the fixed contact 5 for passing the movable contact 1, and reference numeral 13 denotes a terminal portion of the fixed contact 5.

Reference numeral 8 denotes an insulator that is disposed near the pair of contacts 2 and 6 in a closed state and generates a gas containing hydrogen by the heat of an arc generated between the contacts 2 and 6. For example, one insulator includes hydrogen. It is made of an insulating material containing a synthetic resin or a hydroxide as an element. The insulator 8 is configured to cover the fixed contact 5 from the movable contact 1 side, and covers the inner surface of the slit 11 of the fixed contact 5 provided so as not to hinder the opening and closing operation of the movable contact 1. Parts (parts arranged on both sides of a plane including the trajectory of the movable contact 2 during the opening and closing operation of the movable contact 1 so as not to hinder the opening and closing operation of the movable contact 1) 8a
A portion 8 covering the upper surface of the horizontal conductor portion 7b extending in the horizontal direction from the terminal portion 13 and the surface of the vertical conductor portion 7c extending in the vertical direction on the rotating shaft 4 side on the side opposite to the terminal portion 13 of the horizontal conductor portion 7b.
b and a portion 8c surrounding the pair of contacts 2 and 6 in a closed state in a cylindrical shape from four sides.
Gas containing hydrogen is generated by the heat of the arc generated between the six. The tip of the movable contact 1 on the movable contact 2 side in the closed state is located in a space surrounded by the fixed conductor 7 and the insulator 8, but in the open state, it faces a plurality of arc extinguishing plates 12 outside the space. It is arranged to become. Arc extinguishing plate 12
The movable contact 1 is disposed at a position facing the contact 2 of the movable contact 1 in the open state in the space on the contact 6 arrangement side of the fixed contact 5.

Examples of the insulator containing a synthetic resin containing hydrogen as a constituent element include polyamide-based resins such as nylon 6, nylon 46 and nylon 66. Fibers and ceramics may be mixed. Further, as an insulator containing a hydroxide, for example, magnesium hydroxide or aluminum hydroxide impregnated in paper or cloth, or a mixture of magnesium hydroxide or aluminum hydroxide and a synthetic resin containing hydrogen as a constituent element. And the like.

In this embodiment, one end of each of the contacts 2 and
6, a pair of contacts 1 and 5 in which the contacts 2 and 6 are supported so as to be able to contact and separate from each other, an insulator 8 disposed near the pair of contacts 2 and 6 in a closed state, and an arc-extinguishing plate 12. , Contacts 2 and 6 during current limiting operation
An arc is generated in between, and a current limiting mechanism that limits the current using an arc voltage is configured.

Reference numeral 26 denotes a base to which the fixed contact 5 is fixed. Reference numeral 27 denotes a cover that covers the current limiting mechanism, and constitutes a housing that houses the current limiting mechanism together with the base 26.
Reference numeral 17 denotes an exhaust port provided in the cover 27.

The structure of the current limiting mechanism and the circuit breaker provided with the same are described in, for example, WO 00/41202. In the present embodiment, at least one of the contacts 2 and 6 is made of a material containing silver or copper as a main component and containing cadmium oxide.

According to the present invention, the inventors of the present invention have conducted intensive studies on combinations of the insulator 8 and various contact materials. As a result, the insulator 8 that generates a gas containing hydrogen by the heat of the arc generated between the contacts 2 and 6 is obtained. By combining with the contacts 2 and 6 made of a material containing silver or copper and cadmium oxide as a main component, the rise of the arc voltage can be accelerated without increasing the arc voltage after the current peak. Was found to be possible,
With this combination, it is possible to improve the current limiting performance without causing an unnecessary increase in the internal pressure of the housing.

Next, the operation will be described. In the circuit breaker thus configured, normal opening and closing are performed by operating a mechanical unit (not shown) manually or by an external signal. Using a gas containing a large amount of hydrogen generated from the insulator 8 by the heat of the arc generated between the contacts 2 and 6, the electrodes are opened by the electromagnetic repulsion caused by the current components in approximately 1,5 pairs of substantially parallel and opposite directions. The sharp increase in the arc voltage is the same as in the conventional case.

The operation and effect unique to this embodiment will be described below with reference to specific experimental examples. First, the silver-based contact materials 1 and 2 containing cadmium oxide according to the present embodiment.
An experimental example will be described in which the basic arc characteristics in the case of using silver alloy are compared with those in the case of using other typical silver-based contact materials 3, 4, and 5. Table 1 shows the compositions of the contact materials 1 to 5 and the magnitude (rank) of the rise of the arc voltage measured by the experimental configuration shown in FIG. The magnitude of the rise of the arc voltage is determined by the experimental configuration shown in FIG.
An AC arc having substantially the same current waveform was generated by starting a fuse between the electrodes, and an arc voltage waveform generated between the electrodes 101 and 102 was measured by a voltmeter 103 and determined by comparison.
FIG. 5 shows a configuration around an electrode when a cylindrical insulator 107 (nylon 6) is arranged so as to surround the round bar electrodes 101 and 102. The pressure inside the cylinder is measured by a pressure gauge 108. Was measured.

[0026]

[Table 1]

As shown in Table 1, when the cylindrical insulator 107 is used in the atmosphere, the rise of the arc voltage when the contact materials 1 and 2 containing cadmium oxide are used is different from that of the other contact materials 3. Greater than 4,5. On the other hand, when a free arc is generated in the atmosphere, the contact material 5 containing graphite has a slightly large rise in arc voltage, but no remarkable difference is observed in the contact materials 1 to 4. Also, a gauge pressure of 9.8 × 10 ⁵ N
/ M ² , the arc voltage is slightly higher in the contact material 4 having a small silver content, but no remarkable difference is observed in the other contact materials. From the above, when using a current limiting method in which a hydrogen-containing gas is generated from an insulator disposed in the vicinity of the arc to quickly raise the arc voltage, current limiting performance is improved by using a contact material containing cadmium oxide. You can see that

FIG. 6 shows typical arc current and voltage waveforms when the cylindrical insulator 107 shown in FIG. 5 is used. In FIG. 6, the current starts to flow at time t0, and after a sharp voltage peak due to the blowing of the fuse, an arc A is generated between the contacts 101 and 102. This arc voltage increases with an increase in the instantaneous current value, but a difference occurs in the arc voltage in the region from time t1 to t2 due to the contact material. While the contact materials 1 and 2 containing cadmium oxide show an arc voltage waveform with a rapid rise as shown by a solid line, the other contact materials 3, 4, and 5 rise as shown by a broken line in the region from time t1 to t2. The arc voltage waveform becomes slow. On the other hand, in the large current region and the current decrease region after time t2, no remarkable difference due to the contact material is observed. The region between times t1 and t2 where the difference in arc voltage occurs is approximately 3.6 k in instantaneous current value.
A to 8 kA. At time t1 (the instantaneous current value of 3.6 kA), the pressure inside the cylinder 107 (corresponding to the pressure at the outer peripheral portion of the arc A) has increased to about 5.9 × 10 ⁵ N / m ² , and thereafter, The rise of the pressure waveform tends to be larger for the contact materials 1 and 2 where the rise of the arc voltage is faster.

As described above, the insulator 8 which generates a gas containing hydrogen by the heat of an arc, such as an insulator containing a synthetic resin or a hydroxide containing hydrogen as a constituent element, and cadmium oxide are used. In the combination of the contact materials 1 and 2 included, the arc voltage increases only in the region where the current rises, and is equal in the larger current region as compared with the combination with the other contact materials 3 to 5. Therefore, by applying such a combination to an actual current limiting mechanism (circuit breaker),
It is possible to accelerate only the arc voltage rise at the rise of the fault current without causing unnecessary increase of the arc voltage after the current peak, and it is possible to improve the current limiting performance without being limited by the housing strength. Becomes

Table 2 shows that a short-circuit breaking test was conducted on a prototype circuit breaker for a wiring provided with a current limiting mechanism having the same configuration as that of FIG. 1 in a circuit with a single-phase AC of 265 V and an estimated short-circuit current of 50 kA. It shows the current limiting performance at the time of the above. In Table 2, Test No. 1 is the case where the movable contact and the fixed contact are made of the above-mentioned contact material 2 containing cadmium oxide, and Test No. 2 is that the movable contact and the fixed contact are the above-mentioned contact material 4 which does not contain cadmium oxide. 5 and 5 respectively. Other conditions are the same for both tests, and test number 1
Is lower than test number 2 in current peak (higher current limiting performance)
, And it can be seen that the internal pressure rise is suppressed.

[0031]

[Table 2]

As described above, in the present embodiment,
Since the arc immediately after the opening is confined in a narrow space surrounded by the cylindrical portion 8c of the insulator 8, the movable contact 2 and the fixed contact 6, a rapid rise of the arc voltage can be realized, Is in the narrow space, the interaction between the arc and the insulator 8 is large, and the arc voltage rises due to the combination of the contact material containing cadmium oxide and the insulator generating a gas containing hydrogen by the heat of the arc. The effect appears more prominently.

In the above description, the case where a contact (silver-based contact) composed of a material in which cadmium oxide is mixed as a main component of silver is used is described, but cadmium oxide is used as a main component of copper. The same effect is obtained in a contact (copper-based contact) made of a material into which is mixed.

Embodiment 2 7 and 8 are views for explaining a current limiting mechanism and a circuit breaker provided with the current limiting mechanism according to Embodiment 2 of the present invention. More specifically, FIG. FIG. 8 is a plan view of the object 8 as viewed from above, and FIG.
The cross section of the insulator 8 in FIG. 8 is taken along the line CC in FIG. 7 so that the internal shape can be understood. Other configurations are the same as those described in the first embodiment. In FIGS. 7 and 8, components denoted by the same reference numerals as those in FIGS. 1 to 3 are the same or corresponding components.

The fixed contact 8 has a 3 / 4-turn blowout coil 7d having one end connected to the terminal portion 13 and one end connected to the other end of the blowout coil 7d. Are connected to the electric circuit 7a, a 3 / 4-turn blowout coil 7e, an electric circuit 7a in which current flows in a substantially parallel and opposite direction in a closed state, and an end having the contact 6 of the fixed contactor 5. An arc runner 15 extends in a direction away from the movable contact in the closed state, and the fixed contact 6 is sandwiched between blowout coils 7d and 7e.

Further, the insulators 8 are provided on both sides of a plane including the locus of the movable contact at the time of the movable contact opening / closing operation.
a, a part 8d that insulates a part that can be seen from the movable contacts of the blowout coils 7d and 7e, and a part 8e that surrounds the contact pair in a closed state from all sides, and is integrally formed.
As in the case of the first embodiment, a material that generates a gas containing hydrogen by the heat of an arc generated between the contacts, for example,
It is composed of a synthetic resin containing hydrogen as a constituent element or an insulator containing hydroxide. Further, the movable contact-side tip of the movable contact in the closed state is in a space surrounded by the fixed contact 5 and the insulator 8, but in the open state, a plurality of arc-extinguishing plates (not shown) outside the space are provided. Embodiment 1), in which at least one of the contact pairs is made of a material in which cadmium oxide is mixed with silver or copper as a main component.
Is the same as

Next, the operation will be described. In the circuit breaker configured as described above, normal opening and closing are performed by operating a mechanism (not shown) manually or by an external signal. Open at a higher speed due to the electromagnetic repulsion by the substantially parallel and opposite current components and the electromagnetic opening force generated by the blowout coils 7d and 7e, and are generated from the insulator 8 by the heat of the arc generated between the contacts. The arc voltage is rapidly increased using a gas containing a large amount of hydrogen. Also, the combination of the insulator 8 that generates a gas containing hydrogen by the heat of the arc and the contact material in which cadmium oxide is mixed with silver or copper as a main component has been described in the first embodiment. Similarly to the above, the current limiting performance can be improved without generating an unnecessary increase in the pressure in the housing.

In general, a circuit breaker must perform not only short-circuit current interruption required for current limiting performance, but also open / close of ordinary current and overload interruption of relatively small current. For cost reduction by reduction,
In some cases, the same circuit breaker may ensure both AC and DC circuit breaking performance. In the case where the current to be interrupted is relatively small or in an interrupt in a DC circuit, it is difficult to secure the interrupting performance unless the arc-extinguishing plate is used effectively. In particular, in the case of a DC circuit having a high circuit voltage, the use of an arc extinguishing plate is indispensable. However, when the periphery of the fixed contact 6 is surrounded by an insulator in a cylindrical shape from all sides as in the first embodiment, the arc spot on the fixed contact 5 side cannot move from the fixed contact 6, and the fixed contact 5 An arc-extinguishing plate (not shown) arranged in a position facing the contact of the movable contact in the open state in the upper space (the space on the contact 6 side of the fixed contact 5) cannot be used effectively.

Therefore, in the present embodiment, the first embodiment
Unlike this, the arc runner 15 is provided, and as shown in FIG. 7, a notch 33 having a width W2 is provided at a portion of the insulator 8 above the arc runner 15 to include the trajectory of the movable contact during the opening and closing operation of the movable contact. Insulators 8a are arranged on both sides of the plane, and the arc spot on the fixed contact 5 side immediately before the interruption is transferred to the arc runner 15 to effectively utilize the high arc-extinguishing effect of the arc-extinguishing plate.

In the present embodiment, the width W2 is smaller than the width W1 of the notch above the fixed contact 6 of the insulator 8, that is, both sides of the plane including the locus of the movable contact at the time of the opening and closing operation of the movable contact. When the space sandwiched by the insulators 8 (8a) arranged at the position is viewed from the contact point of the movable contact in the open state,
Since the space width W2 in the vicinity of the arc runner 15 is smaller than the space width W1 in the vicinity of the contact 6 of the fixed contact 5, in the initial stage of opening at the time of interrupting a large current for which current limiting performance is required. The arc is confined in a narrow space surrounded by the portion of the insulator 8 having the width W1 and the movable contact 2 and the fixed contact 6, and does not migrate to the notch 33 having the width W2. Therefore, the arc voltage rises sharply by the cooling action of the hydrogen-containing gas generated from the insulator 8 and the high-pressure atmosphere, and very high current limiting performance can be realized. Also, when the current is attenuated and the arc diameter becomes smaller in the latter half of the current limiting interruption operation,
The arc can be transferred to the notch 33 having the width W2, and the current interruption is completed by effectively using the arc-extinguishing plate.

In the present embodiment, in order to make the arc transfer more reliably, the ventilation path 34 is provided in the insulator 8 in the direction in which the arc moves.

Embodiment 3 9 to 11 are diagrams illustrating a current limiting mechanism according to Embodiment 3 of the present invention and a circuit breaker including the same. More specifically, FIG.
Is a perspective view for explaining the configuration of the main part of the circuit breaker, in which the housing on the near side is omitted and a partial cross section is taken so that the internal configuration can be seen. FIG. 10 is an exploded perspective view for explaining the entire configuration of the circuit breaker, and FIG. 11 is an exploded perspective view of the fixed contact 5 and the insulator 8. 9 to 11, the same reference numerals as those in FIGS. 1 to 3 denote the same or corresponding components.

9 to 11, reference numeral 21a denotes a part of the unit case for accommodating the current limiting mechanism, and the unit case 2 together with the omitted front side part 21b (not shown).
1. Inside the unit case 21, a movable contact 1 having a movable contact 2, a fixed contact 5 having a fixed contact 6, and a closed contact 2, arranged near the pair of contacts 6, and an arc generated between the contacts An insulator 8 that generates a gas containing hydrogen by the heat of the above, a plurality of arc-extinguishing plates 12 held by an arc-extinguishing side plate 16, and a sliding contact for electrically connecting the movable contact 1 to a terminal portion 13b. 19, a spring 29 for generating a contact pressure between the contacts 1 and 5, and a rotor 20 for transmitting the movement of the mechanism 23 outside the unit case 21 to the movable contact 1.
Are stored, and constitute the arc extinguishing unit 22. Further, as shown in FIG. 10, a plurality of arc extinguishing units 22 are connected by a cross bar 25, and a mechanism 23 for opening and closing a contact via the cross bar 25, and a relay for detecting an abnormal current and operating the mechanism 23. A multi-pole circuit breaker is formed by adding a handle 28 for manually operating the unit 18 and the mechanism unit 23 and storing them in a housing including the base 26 and the cover 27. The terminal portion 13b is provided on the arc extinguishing unit 22, and the arc extinguishing unit 22 and the relay portion 18 are provided.
The terminal 13c is provided in the relay unit 18 and connects the multi-pole circuit breaker to an external circuit.

The basic structure of the current limiting mechanism in the arc extinguishing unit 22 is that at least one of the contacts 2 and 6 is made of a material containing silver or copper as a main component and cadmium oxide mixed therein. Except, for example, Japanese Patent No. 2918
This is basically the same as that disclosed in Japanese Patent No. 752.
The fixed contact 5 is constituted by a substantially J-shaped fixed conductor 7 and a fixed contact 6 arranged on the space side surrounded by the J-shaped fixed conductor 7. It is located in the space surrounded by the J-shaped fixed conductor 7. The movable contact 1 in a closed state from the end of the fixed contact 5 having the contact 6.
An arc runner 15 is provided extending in a direction away from the arc runner. The fixed contact 5 is provided with a slit 11 so as not to hinder the opening and closing operation of the movable contact 1.
In the opened state, the movable contact 2 moves from the space surrounded by the J-shaped fixed conductor 7 to the space where the plurality of arc extinguishing plates 12 are arranged.

The insulator 8 containing a synthetic resin or hydroxide containing hydrogen as a constituent element is used to form the movable contact 2 during the opening / closing operation of the movable contact 1 so as not to hinder the opening / closing operation of the movable contact 1. Parts arranged on both sides of the plane including the trajectory (parts that sandwich the arc at the beginning of the short-circuit current interruption operation from the left and right) 8
a and a horizontal conductor portion 7 extending horizontally from the terminal portion 13a
b, and a portion 8b covering the surface of the vertical conductor portion 7c extending in the vertical direction on the side opposite to the terminal portion 13a of the horizontal conductor portion 7b on the rotation axis 4 side, and the arc generated between the contacts 2 and 6 extends. 8f covering the front surface of the slit end 11a on the side to be cut
And a portion 8g that covers the conductor near the fixed contact 6 and is integrally formed, and generates a gas containing hydrogen by the heat of the arc generated between the contacts 2 and 6. Also, the arc extinguishing plate 12
Is arranged at a position facing the contact 2 of the movable contact 1 in the open state in the space on the contact 6 arrangement side of the fixed contact 5.

Next, the operation will be described. When the short circuit is interrupted, the contact is opened mainly by the electromagnetic repulsion between the electric path 7a of the fixed contact 5 and the movable contact 1 and an arc is generated between the contacts 2 and 6. Due to the heat of the arc, a gas containing hydrogen is generated from the insulator 8 to increase the arc voltage. The insulator 8 has not only a portion 8a that sandwiches the arc at the beginning of the short-circuit current interrupting operation from the left and right, but also a portion 8f that is disposed on the driving side of the magnetically driven arc (a portion that covers the front surface of the slit end 11a). Therefore, it is possible to more efficiently generate the insulating evaporant gas containing hydrogen than the conventional arc extinguishing device shown in FIG. Further, in the latter half of the current limiting interruption operation in which the instantaneous value of the fault current exceeds the peak value, the movable contact 2 moves to a position facing the arc-extinguishing plate 12 outside the space surrounded by the insulator 8, so that an unnecessary casing is not required. Prevent the rise of internal pressure, and
There is an advantage that the high arc-extinguishing function of the arc-extinguishing plate can be used. In particular,
In this embodiment, at least one of the pairs of contacts 2 and 6 is made of a material in which cadmium oxide is mixed with silver or copper as a main component. Similarly to the above, the current limiting performance can be improved without generating an unnecessary rise in the internal pressure of the housing.

Further, in the present embodiment, the current limiting mechanism and the opening / closing mechanism are housed in separate housings, so that the gas containing hydrogen generated by the current limiting mechanism during the current limiting operation is out of the unit case 21. It is hard to escape and acts effectively on the arc. Moreover, since the gas hardly escapes and the gas pressure is high, the effect of the combination of the contact containing cadmium oxide and the insulator 8 which is the source of the hydrogen-containing gas appears more remarkably.

Embodiment 4 FIG. 12 is a side view showing the inside of a circuit breaker for wiring according to a fourth embodiment of the present invention by cutting a part thereof. In the figure, 1a is a movable contact, 2a
Is a movable contact, 5a is a fixed contact, 6a is a fixed contact, 30
Is a partition, 31 is a standard circuit breaker, and 32 is a current limiting unit having a current limiting mechanism.

By connecting the current limiting unit 32 to the standard circuit breaker 31 at one terminal portion 13b, a circuit breaker for wiring having excellent current limiting performance is realized. Inside each pole of the current limiting unit 32, two pairs of contacts 1a, 5a, 1b, 5b (1b, 5b are not shown) connected in series are provided substantially in plane symmetry with a partition wall 30 interposed therebetween. ing. Of these contacts 1a, 5a, 1b, and 5b, at least one contact of each contact pair is made of a material in which cadmium oxide is mixed with silver or copper as a main component. These contact pairs are arranged vertically with respect to the longitudinal direction of the circuit breaker. Arcs generated between the contacts are extinguished by a plurality of arc extinguishing plates 12 provided above and facing the contact pairs. Arced. The arc-extinguishing plate 12 is held by an arc-extinguishing side plate 16 made of an insulator that generates a gas containing hydrogen by the heat of the arc generated between the contacts. They are arranged on both sides of the plane including the trajectory of the movable contact at the time of opening and closing the contact so as not to hinder the operation (so as to sandwich the contact pair from the left and right).

The basic structure of the current limiting unit 32 is, for example, that the current limiting unit 32 is made of, for example, Japanese Patent Publication No. 8-80 except that at least one of the contact pairs is made of a material containing silver or copper as a main component and cadmium oxide mixed therein. It is basically the same as that disclosed in Japanese Patent No. 8048.

Next, the operation will be described. When the short-circuit is interrupted, the contact is opened by the electromagnetic repulsion between the electric path 7a and the movable contact 1a in which a current in a substantially parallel and opposite direction flows in opposition to the closed movable contact 1a, and an arc is generated between the contacts 2a and 6a. appear. Due to the heat of the arc, a gas containing a large amount of hydrogen is generated from the arc extinguishing side plate 16, thereby increasing the arc voltage and performing current limiting. In this embodiment, at least one of the contact pairs is made of a material in which cadmium oxide is mixed with silver or copper as a main component, and an insulating material that generates a gas containing hydrogen by the heat of the arc. By combining the arc-extinguishing side plate 16 made of a material and a contact material in which cadmium oxide is mixed with silver or copper as a main component, unnecessary current limiting is performed in the same manner as described in the first to third embodiments. The current limiting performance can be improved without increasing the pressure in the unit 32.

In each of the above embodiments, the case where one contact is fixed and only the other contact performs the opening / closing operation has been described. However, the present invention relates to the case where both contacts perform the opening / closing operation. Can also be applied.

[0053]

As described above, according to the first current limiting mechanism of the present invention, a contact pair having a contact at one end thereof, the contact being supported so as to be able to contact and separate, and a closed state Is arranged on at least both sides of a plane including the trajectory of the contact at the time of the contact opening / closing operation so as not to hinder the opening / closing operation of the contact in the vicinity of the contact pair. And an insulator that generates a gas containing hydrogen by the current limiting mechanism, at least one of the contact pairs is made of a material in which cadmium oxide is mixed with silver or copper as a main component. Without increasing the subsequent arc voltage, the rise of the arc voltage at the time of the current limiting operation can be hastened, and without being limited by the housing strength.
A current limiting mechanism having higher current limiting performance can be provided.

According to the second current limiting mechanism of the present invention, when the instantaneous current value during the current limiting operation is 3.6 kA or more and the pressure at the arc outer peripheral portion is 5.9 × 10 ⁵ N / m ² or more. Therefore, without increasing the arc voltage after the current peak, it is possible to hasten the rise of the arc voltage during current limiting operation, and without limiting the strength of the housing, a current limiting mechanism with higher current limiting performance Can be provided.

According to the third current limiting mechanism of the present invention, the contactor pair is provided with an electric path through which currents in substantially parallel and opposite directions are opposed to each other in the closed state. The current limiting operation can be started by the repulsive force.

According to the fourth current limiting mechanism of the present invention, at least one of the pair of contacts is substantially L-shaped, and the contact is fixed to the tip of the shorter side of the substantially L-shape; Since the insulator is arranged so as to surround the closed contact pair in a cylindrical shape from all sides, the arc immediately after opening the contact, the insulator surrounding the contact pair in a cylindrical shape from all sides, the movable contact, and the fixed contact The interaction between the arc and the insulator is large because it is in a narrow space surrounded by the above, and the combination of the contact mixed with cadmium oxide and the insulator that generates a gas containing hydrogen by the heat of the arc, The effect of hastening the rise of the arc voltage becomes more remarkable.

According to the fifth current limiting mechanism of the present invention, one of the contact pairs is made substantially L-shaped to form a movable contact, and the contact is fixed to the tip of the shorter side of the above-mentioned substantially L-shape. The other being a fixed contact, the arc runner extending in a direction away from the movable contact in the closed state from the end having the contact of the fixed contact, and the open state in the space on the contact arrangement side of the fixed contact. An arc extinguishing plate arranged at a position facing the contact of the movable contact, and opening a space sandwiched between insulators arranged on both sides of a plane including the locus of the contact when the contact is opened and closed; When viewed from the contact point of the movable contact in the state, the space width in the vicinity of the arc runner is configured to be smaller than the space width in the vicinity of the contact of the fixed contact. And high arc extinguishing performance can be obtained at the same time.

Since the first circuit breaker according to the present invention includes any one of the above-described first to fifth current limiting mechanisms, it is possible to increase the arc voltage during the current limiting operation without increasing the arc voltage after the current peak. It is possible to provide a circuit breaker having a higher current limiting performance without increasing the strength of the housing because the rise of the voltage can be hastened.

A second circuit breaker according to the present invention includes a current limiting mechanism, and an opening / closing mechanism for opening and closing at least one contact of the current limiting mechanism, wherein the current limiting mechanism and the switching mechanism are combined. Since it is housed in a separate housing, the hydrogen-containing gas generated from the insulator during the current limiting operation is unlikely to escape to the outside of the current limiting mechanism and effectively acts on the arc. In addition, since the gas hardly escapes and the gas pressure is high, the effect of accelerating the rise of the arc voltage is more remarkable due to the combination of the contact mixed with cadmium oxide and the insulator generating the gas containing hydrogen by the heat of the arc. Becomes

[Brief description of the drawings]

FIG. 1 is a cross-sectional view for explaining a configuration of a main part of a current limiting mechanism and a circuit breaker provided with the current limiting mechanism according to Embodiment 1 of the present invention.

FIG. 2 is a plan view of the fixed contact and the insulator of FIG. 1 as viewed from above.

FIG. 3 is a partial sectional perspective view in which a fixed contact and an insulator of FIG. 1 are disassembled.

FIG. 4 is an experimental configuration diagram for explaining basic arc characteristics according to the first embodiment of the present invention.

FIG. 5 is a partial cross-sectional view near an electrode used for an experiment for explaining basic arc characteristics according to the first embodiment of the present invention.

FIG. 6 is a schematic diagram of current and voltage waveforms for describing basic arc characteristics according to the first embodiment of the present invention.

FIG. 7 is a plan view of a current limiting mechanism according to a second embodiment of the present invention and a fixed contactor and an insulator of a circuit breaker including the same, as viewed from above.

FIG. 8 is a partial sectional perspective view in which a fixed contact and an insulator of a current limiting mechanism and a circuit breaker including the same according to a second embodiment of the present invention are disassembled.

FIG. 9 is a partial cross-sectional perspective view illustrating a configuration of a main part of a current limiting mechanism and a circuit breaker including the same according to a third embodiment of the present invention.

FIG. 10 is an exploded perspective view for describing an entire configuration of a current limiting mechanism and a circuit breaker including the same according to a third embodiment of the present invention.

FIG. 11 is a partial sectional perspective view in which a fixed contact and an insulator of a current limiting mechanism and a circuit breaker including the same according to a third embodiment of the present invention are disassembled.

FIG. 12 is a side view showing an inside of a circuit breaker according to a fourth embodiment of the present invention by cutting a part of the circuit breaker;

FIG. 13 is a side view illustrating a conventional current limiting mechanism.

[Explanation of symbols]

1,1a movable contact, 2,2a movable contact, 3
Movable arm, 4 rotating shafts, 5, 5a fixed contact,
6, 6a fixed contact, 7 fixed conductor, 7a electric circuit, 8 insulator, 11 slit, 12 arc extinguishing plate, 15 arcrunner, 16 arc extinguishing side plate, 22
Arc extinguishing unit, 23 mechanism, 26 base, 2
7 cover, 29 spring, 31 standard circuit breaker,
32 current limiting unit, 33 notch, 34 air passage, 101, 102 round bar electrode, 103 voltmeter, 104 ammeter, 105 closing switch, 1
06 AC power supply, 107 cylindrical insulator, 108 pressure gauge.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Masahiro Fushimi 2-3-2 Marunouchi, Chiyoda-ku, Tokyo Inside Mitsubishi Electric Corporation (72) Inventor Shigeki Yukimoto 2-3-2 Marunouchi, Chiyoda-ku, Tokyo No. Mitsubishi Electric Corporation (72) Inventor Kazunori Fukuya 2-3-2 Marunouchi, Chiyoda-ku, Tokyo F-term in Mitsubishi Electric Corporation (reference) 5G030 AA06 AA09 DE02 FA02 FB15 YY07

Claims (7)

[Claims] 1. A contact pair having a contact at one end thereof, the contact being supported so as to be able to contact and separate from the contact, and the contact so as not to hinder the opening / closing operation of the contact near the contact in a closed state. A current limiting mechanism disposed on at least both sides of a plane including the trajectory of the contact at the time of opening and closing the contact, and an insulator generating a gas containing hydrogen by the heat of the arc generated between the contacts during the current limiting operation. , At least one of the contact pairs is
A current limiting mechanism comprising a material in which cadmium oxide is mixed with silver or copper as a main component. 2. The current instantaneous value during current limiting operation is 3.6 kA or more, and the pressure at the outer periphery of the arc is 5.9 × 10 ⁵ N / m.
^{2. The} current limiting mechanism according to claim 1, wherein the number is ^two or more. 3. The current limiting mechanism according to claim 1, wherein the contact pair is provided with an electric path through which currents in substantially parallel and opposite directions are opposed to each other in the closed state. 4. At least one of a pair of contacts is substantially L-shaped, a contact is fixed to a tip of a shorter side of the substantially L-shape, and an insulator is connected to the contact pair in a closed state. The current limiting mechanism according to any one of claims 1 to 3, wherein the current limiting mechanism is arranged so as to surround the cylinder from all sides. 5. A movable contact in which one of the contact pairs is substantially L-shaped, a contact is fixed to a tip of the shorter side of the substantially L-shape, and the other is a fixed contact, and the fixed contact is formed. An arc runner extending in a direction away from the movable contact in the closed state from the end having the contact of the contact; and an arc runner disposed at a position facing the contact of the movable contact in the open state in a space on the contact arrangement side of the fixed contact. And a space interposed between insulators disposed on both sides of a plane including the trajectory of the contact at the time of opening and closing the contact as viewed from the contact of the movable contact in an open state. 4. The current limiting mechanism according to claim 1, wherein the space width near the arc runner is smaller than the space width near the contact point of the fixed contact. 6. A circuit breaker comprising the current limiting mechanism according to any one of claims 1 to 5. 7. A current limiting mechanism, and an opening / closing mechanism for opening and closing at least one contact of the current limiting mechanism, wherein the current limiting mechanism and the opening / closing mechanism are housed in separate housings. 7. The circuit breaker according to claim 6, wherein: