GB2564562A

GB2564562A - A high breaking capacity miniature circuit breaker

Info

Publication number: GB2564562A
Application number: GB1809424.3A
Authority: GB
Inventors: Li Wenjie
Original assignee: Dalian Ino Tech Co Ltd
Current assignee: Dalian Ino Tech Co Ltd
Priority date: 2017-06-08
Filing date: 2018-06-08
Publication date: 2019-01-16
Anticipated expiration: 2038-06-08
Also published as: CN107369593A; GB2564562B; CN207425751U; CN107359087A; AU2018100776A4; GB201809424D0; CN107369593B; CN207097761U

Abstract

A high-breaking capacity MCB comprises a housing 1, a cover 2, an operating mechanism, an instantaneous-actuating mechanism, an arc-ignition device (16,17, figure 2), and an arc extinguishing device (12, figure 2). The instantaneous-actuating mechanism comprises a handle 3 having a torsional spring 4 and an instantaneous actuating rod 5 capable of moving at both ends. One end of the rod proximal to a lower end of the handle comprises a limiting slot 51, where a lower end of the handle comprises a protruding portion that is positioned within the limiting slot. The other end of the rod furthest from the limiting slot comprises an elastic arm 52 having a hook-shaped end 53 that engages with the operating mechanism of the MCB. When the handle is moved by a user, the protruding end of the handle bears against a sidewall of the limiting slot, and the hook engaged with a shaft pile 6 of the MCB provides resistance until the operating force reaches a level where it disengages the hook. The handle thrust then instantly unloads into the operating mechanism, actuating the operating mechanism instantly to reduce the effect of arcing and increase operator safety.

Description

A High Breaking Capacity Miniature Circuit Breaker

This invention relates to the technical field of circuit breakers, in particular to a high breaking capacity miniature circuit breaker (MCB).

The MCB is mainly used in electrical circuits and devices of 50\60HZ, 230V\415V and below rated voltage to protect overload, short circuit and electric leakage in modern buildings, and is also used in infrequent operation and isolation of the lines. A pre-requisite to achieve these functions is to cut off the electrical current or close the circuit.

The process of cutting off the current or closing the circuit is realized through the coordination of each unit of the circuit breaker. When there are electrical failures generated in the circuit which are within the protection of the circuit breaker, the circuit breaker can trip automatically, and the moving and fixed contacts are separated, and the lines are cut off, thus protecting the electrical circuits and terminal electrical appliances and preventing fire and related facilities being damaged.

The circuit breakers on the market are all produced based on the purpose of above functions, but the difference is that the performances of various circuit breakers are not the same. Due to the shortcomings of the product design, especially in industrial applications, the miniature circuit breakers on the market are often powerless when cutting off large short-circuit current in the workspaces near the transformers, which means the products lack stabilities, lack sufficiently fast circuit-breaking speed, lack strong arc extinction capacity, but with serious arc flash short circuit problem, thus damaging the circuit breaker.

With the continuous development of society and people’s living standards getting higher and higher, the requirements for various living conditions including electrical environment are also increasing, therefore electricity consumption has to increase and stability have to improve more than ever before. This requires electrical companies continue to have product innovation and technology revolution to meet these requirements. In the past, household low-voltage electrical lines only required 40A, 50A rated current and 3K, 4.5K, 6K instantaneous short circuit fault current, therefore conventional circuit-breaker products were sufficient. However, these products will be powerless if being applied to the lines of 63A rated current and 10K instantaneous short circuit fault current. Comparing to the above 3K, 4.5K, 6K instantaneous short circuit fault current, the energy generated for a 10K instantaneous short circuit is simply not in the same order of magnitude. If the arc-ignition functional block is without an anti-arc penetration design, there is no boosting tripping device in the operating mechanism ofthe circuit breaker and the arc extinguishing area is not large enough, then the operation mechanism of the circuit breaker would not be able to open and close the circuit sufficiently rapidly. Even if it can break the circuit rapidly, because the arc cannot be quickly extinguished, the arc can re-ignite and the energy of the arc light (or arc flash) can increase suddenly to burn out the circuit breaker instantaneously.

Another scenario is, after the circuit breaker cutting off the faulty circuit, as the users were not aware or thought it was broken off manually, the users may then reclose the faulty circuit by mistake. By then, if the circuit breaker could not handle the impact of a large secondary current, the operating personnel, due to improper operation, incompetency or instability of the circuit breaker, would lose his life. This could be accompanied by serious fire incidents, resulting in loss of human life and serious property damage. Such serious incidents occur every year.

This invention aims to address the deficiencies in prior art technology by providing a safe and effective high breaking capacity MCB.

This invention is achieved by the following technical solutions.

According to one aspect ofthe present invention, there is provided a high breaking capacity MCB comprising a housing, a cover, an operating mechanism, an instantaneous-actuating mechanism, an arc-ignition device and an arc extinguishing device. The instantaneous-actuating mechanism comprises a handle, a handle torsional spring and an instantaneous-actuating rod, which is able to move at both ends. One end of the instantaneous-actuating rod proximal to a lower end of the handle is provided with a limiting slot, the lower end of the handle having a protruding end portion positioned into the limiting slot. Another end of the instantaneous-actuating rod furthest from the limiting slot incorporates an elastic arm with a hook shaped end capable of engaging with the operating mechanism of the MCB.

In one embodiment, a high breaking capacity MCB comprises a housing, a cover, an operating mechanism, an instantaneous mechanism, an arc-ignition device and an arc extinguishing device. The operating mechanism, the instantaneous mechanism, the arc-ignition device and the arc extinguishing device are disposed in the housing. The instantaneous mechanism comprises a handle, a handle torsional spring and an instantaneous rod, and one end of the handle torsional spring is embedded into a side seam beside a center aperture of the handle, and the other end is locked to a locating endpoint of the handle. Along with the movement of the handle, the handle torsional spring sleeves or envelopes a locating shaft of the handle, the locating shaft connected to the housing of the MCB. After the handle is installed into the housing, the end of the handle torsional spring located at the handle locating endpoint is embedded (along with the locating endpoint of the handle) into a socket of the housing. Therefore, when pushing up the handle, the handle torsional spring provides the handle with rebound resilience. The instantaneous-actuating rod may be placed on the bottom of the housing and can move at both ends, and the conditions for moving depend on pushing the handle up or down. The up and down positions are located between the shaft end of the operating mechanism and the housing profile. At one end of the instantaneous-actuating rod near the handle, there is provided a limiting slot, and the lower end of the handle has a protruding end portion for positioning into the limiting slot. The open and closed positions of the handle are disposed at two side walls of the limiting slot, respectively. Due to this arrangement, when pushing the handle up drives the movement of one side wall and when pushing the handle down drives the movement of other side wall. The end of the instantaneous-actuating rod furthest from the limit slot may be bent, and out of the bent end (or the re-folded part) protrudes an elastic arm, in particular an elastic curved arm. The end of the elastic curved arm is shaped as a hook and hung towards an end of a shaft pile disposed on or extending from the housing. One side of the instantaneous-actuating rod is disposed near an inner wall of the housing.

Pushing up and pushing down the handle drives the movement of the instantaneous-actuating mechanism, including the simultaneous movement of the two side walls of the limiting slot. Pushing up is closing the circuit breaker, and, through a connecting rod, movement of the handle also drives the operating mechanism to operate. Simultaneously, the handle also pushes the instantaneous-actuating rod to operate in synchronization or cooperation with the motion of the operating mechanism. As the end of the elastic curved arm of the instantaneous-actuating mechanism is shaped as a hook and hung towards an end of a shaft pile of the operating mechanism, with increasing force, the increased force is transferred onto the handle. When the handle thrust reaches a level which disengages the hook, the handle thrust instantly unloads and transfers onto the operating mechanism. This instantaneous force closes the operating mechanism instantly which results in a rapid closure and very light ablation damage of the arc flash to those metal contacts responsible for the closure of the circuit, thus improving the product life. Pushing the handle down opens the circuit breaker such that both moving and fixed metal contacts are separated from each other, and meanwhile the end of the elastic curved arm shaped as a hook engages with (i.e. hooks) the shaft pile of the operating mechanism, which means the circuit breaker is in a disconnected position.

The operating mechanism comprises a concave wheel, a rotating arm, a lock wheel and a support shaft. In one embodiment, the support shaft is installed into the shaft pile extending from the housing, and the instantaneous-actuating rod is disposed at a backside of the concave wheel of the operating mechanism and towards an outer edge of the shaft pile. A torsional spring is placed in a groove of the concave wheel. One end of the torsional spring is disposed in an aperture in an inner wall of the groove and the other end is secured to the rotating arm. A raised shoulder of the rotating arm is positioned into the concave wheel and is locked together with the concave wheel by the torsional spring and combines into a support arm, the components of which can rotate independently or cooperatively. The support shaft of the operating mechanism extends through the middle of the support arm, which moves in a cambered or curved manner along the support shaft. The concave wheel and the rotating arm ofthe operating mechanism are arranged such that they form an expandable/contractible track on an upper end of the support arm, the track being able to contain one end of a U-rod. The other end of the U-rod is secured to the handle.

In one embodiment, the arc-ignition device is in the form of an iron sheet, which is placed in the housing and embedded into it, and is completely covered by the cover, thereby forming an integrated arc-ignition device.

In one embodiment, the arc extinguishing device is in the form of an arc chute which has an arc extinguishing chamber inside. The arc extinguishing device is preferably composed of iron sheets equidistantly arranged in two opposing rows, with seventeen iron sheets in each row. The iron sheets are embedded into an outer casing equidistantly. Through holes are provided on one side ofthe outer casing and are distributed equidistantly in two opposing rows. An upper edge of the outer casing of the arc chute is disposed near a magnetic steel outer wall and a lower edge is disposed near the arc-ignition device. At an external side ofthe extinguishing chamber that is near the housing and positioned behind the arc chute, there is provided a plurality of gas channels in various shapes. The arc extinguishing chamber and the tripper chamber are connected.

In one embodiment, a moving contact is placed in the middle ofthe arc-ignition device. The arc-ignition device has an arc-ignition angle, which is spread along a riveting shaft disposed in the middle of the housing. A copper part of the arc-ignition angle is spread along the riveting shaft. There is also an arc-ignition bent iron disposed in the arc-ignition angle.

In one embodiment, a grip-shape arm rod extends from a lower end of the lock wheel. An upper end of the grip-shape arm rod incorporates a half arc-trench-shape gap, which contains an arc-shape wall protruded by the support arm, and the lock wheel moves along the arc-shape wall.

In one embodiment, a tripping rod is placed at one end of the grip-shape arm rod. One end of the tripping rod is restrictively located at a raised boundary of a base and moves back and forth along the raised boundary, and the other end of the tripping rod is restrictively located within a groove disposed in a boundary of the base. There is a thermal tripping device disposed between two ends of the tripping rod.

In one preferred embodiment, both inner sides of the housing of the high breaking capacity MCB are provided with arc-ignition devices, which are installed on the housing but are spaced from the housing (by partitions), which is convenient for gas to flow away instantaneously. In fact, when circuit breakers are used to regulate large electrical current, the gas may be a high heat, fast expanding plasma gas accompanied by arc and instantaneously attaches to the arc-ignition device. If the arc-ignition device is exposed at the moment, the arc will burn out the arc-ignition device unavoidably, and the arc flash will re-ignite and burn out the circuit breaker under serious situations. If the area (or span) of the arc-ignition device is very narrow, yet the arc-ignition device is disposed below an arc-ignition channel, then with small short-circuit current such as 6K\4.5K\3K, the hot gas and arc generally will not impact (or spread to) the opposite side of the arc-ignition device, accordingly it will not cause arc flash short circuit or re-ignition. However, the 10K short-circuit current is at a rather different level, the arc flash, arc heat, energy and gas are all generated more instantaneously and at a larger scale, therefore the measures for protecting the arc-ignition device and guiding the gas flow are especially important.

The high breaking capacity MCB is provided with an arc extinguishing device in the form of an arc chute, and the arc chute may be composed by seventeen iron sheets in one row, which are embedded in an outer casing equidistantly. The through holes are distributed on one side of the outer casing and arranged in two opposing rows. The upper edge of the outer casing of the arc chute is disposed near the magnetic steel outer wall and the lower edge is close to the arc extinguishing device. These arrangements aim to increase the arc spacing of the arc extinguishing area, which provides 18 arc spaces or intervals. When the arc flash becomes more divided into equal parts, the voltage of both ends of the arc chute will be increased, thus the arc flash will not rekindle or re-ignite. This enables the arc flash to subside or die out along the arc path formed of the spaced iron sheets. Also, using a greater number of iron sheets can increase the metal area that enables metal arc cooling, which in turn lowers the temperature rapidly, and the arc flash will disappear naturally because of the rapidly reduced temperature.

Gas channels of various shapes are disposed at the back of the arc chute, also being the external side of the arc extinguishing chamber near the housing. The arc extinguishing chamber and the tripper chamber are connected. When the circuit breaker opens and closes the circuit in instances of large faulty current, the energy generated instantaneously will heat up the gas, which scatters inside the housing together with the arc flash. However, the optimized channels can assist with the even thermal expansion of the housing so that the circuit breaker will not burst or explode.

The moving contact of the operating mechanism of the high breaking capacity MCB is attached on the operating mechanism by one or more screws. This connection is different from a glue connection, in that it is convenient for disassembly and assembly, i.e. it is easy and quick to assemble without the effect of the instability of the glue, so that the housing components can be firmly and efficiently assembled. The moving contact is preferably located in the middle of the arc-ignition device. There is a riveting shaft disposed in the middle of the housing, and a copper part of the arc-ignition angle is spread along the riveting shaft. There is an arc-ignition bent iron in the arc-ignition angle.

The instantaneous-actuating mechanism of this invention enables the moving and fixed contacts to instantaneously contact one another, which will reduce a large number of arc comparing to the traditional slow contact of a conventional MCB, thus making the product according to the present invention more safe and reliable.

Figure 1 is an internal structure schematic of this invention;

Figure 2 is a rear view of the internal structure of Figure 1;

Figure 3 is a structure schematic of the arc chute of Figure 1;

Figure 4 is a structure schematic of the concave wheel of Figure 1;

Figure 5 is a structure schematic of the rotating arm of Figure 1;

Figure 6 is a structure schematic of the lock wheel of Figure 1; and

Figure 7 is a structure schematic ofthe instantaneous rod of Figure 1.

This invention will be further described with reference to the implementation examples as follows.

Implementation examples. A high breaking capacity MCB as illustrated in Figures 1-7, which comprises a housing (1), a cover (2), an operating mechanism, an instantaneous-actuating mechanism, an arc-ignition device and an arc extinguishing device. The operating mechanism, the instantaneous mechanism, the arc-ignition device and the arc extinguishing device are disposed in the housing (1). The instantaneous-actuating mechanism comprises a handle (3), a handle torsional spring (4) and an instantaneous-actuating rod (5). One end ofthe handle torsional spring (4) is embedded into the side seam (32) beside the center aperture (31) of the handle, and the other end is locked to the locating endpoint (33) of the handle. Along with the movement of the handle (3), the torsional spring sleeves or envelopes the locating shaft (34) of the handle, the locating shaft connected to the housing. After the handle is installed into the housing, the end of the handle torsional spring (4) located at the handle locating endpoint (33) is embedded into a socket of the housing. Therefore, when pushing up the handle, the handle torsional spring provides the handle with rebound resilience, hence the handle may rebound immediately. The instantaneous-actuating rod (5) is placed on the bottom of the housing (1) and can move at both ends, and the conditions for moving depend on pushing the handle (3) up or down. The up and down positions are located between the shaft end of the operating mechanism and the housing profile. There is a limiting slot (51) at one end of the instantaneous-actuating rod (5) located near the handle (3). The lower end of the handle has a protruding end portion (34) for positioning into the limiting slot (51). The open and closed positions of the handle are disposed at two side walls of the limiting slot, respectively. Due to this arrangement, when pushing the handle up drives the movement of one side wall and pushing the handle down drives the movement of other side wall. The end of the instantaneous-actuating rod (5) furthest from the limiting slot is bent, and out of the bent end (or the re-folded part) protrudes an elastic curved arm (52). The end of the elastic curved arm is shaped as a hook (53) and hung towards an end of the shaft pile (6) which is disposed on or extends from the housing. The other end of the instantaneous-actuating rod is located near an inner wall of the housing.

Pushing up and pushing down the handle (3) drive the movement of the instantaneous-actuating mechanism, including the simultaneous movement of the two side walls of the limiting slot. Pushing up is closing the circuit breaker, and, through a connecting rod, movement of the handle also drives the operating mechanism to operate. Simultaneously, the handle also pushes the instantaneous-actuating rod to operate in synchronization or cooperation with the motion of the operating mechanism. As the end of the elastic curved arm of the instantaneous-actuating mechanism is shaped as a hook and hung towards an end of the shaft pile of the operating mechanism, with increasing force, the increased force is transferred onto the handle. When the handle thrust reaches a level which disengages the hook, the handle thrust instantly unloads and transfers onto the operating mechanism. This instantaneous force closes the operating mechanism instantly which results in a rapid closure and very light ablation damage of the arc flash to those metal contacts responsible for the closure ofthe circuit, thus improving the product life. Pushing the handle down opens the circuit breaker such that both the moving and fixed contacts are separated from each other, and meanwhile the end of the elastic curved arm shaped as a hook engages with (or hooks) the shaft pile of the operating mechanism, which means the circuit breaker is in a disconnected position.

The operating mechanism comprises a concave wheel (7), a rotating arm (8), a lock wheel (9) and a support shaft (10). The support shaft is installed into the shaft pile (6) of the housing, and the instantaneous-actuating rod (5) is located at the back of the concave wheel (7) of the operating mechanism towards an outer edge of the shaft pile (6). A torsional spring (not shown in the figures) is placed in a groove ofthe concave wheel. One end of the torsional spring is disposed in an aperture in an inner wall ofthe groove and the other end is secured to the rotating arm. A raised shoulder of the rotating arm is position into the concave wheel and is locked together with the concave wheel by the torsional spring and combines into a support arm, the components of which can rotate independently or cooperatively. The support shaft (10) extends through the middle of the support arm, which moves in a cambered or curved manner along the support shaft. The concave wheel and the rotating arm of the operating mechanism are arranged such that the form an expandable/contractible track on an upper end of the support arm, the track being able to contain one end of a U-rod (11). The other end of the U-rod (11) is secured to the handle (3).

The arc-ignition device is in the forme of an iron sheet (12), which is placed in the housing and embedded into it and completely covered by the cover to thereby forming an integrated arc-ignition device.

The moving contact (15) is placed in the middle of the arc-ignition device. There is a riveting shaft in the middle of the housing, and a copper part of the arc-ignition angle (16) is spread along the riveting shaft. There is also an arc-ignition bent iron (17) disposed in the arc-ignition angle.

The grip-shape arm rod (91) extends from a lower end of the lock wheel (9), the upper end of the grip-shape arm rod is hollowed out and incorporates a half arc-trench-shape gap (92), which contains an arc-shape wall (81) protruded by the support arm, and the lock wheel (9) moves along the arc-shape wall. A tripping rod (18) is placed at one end of the grip-shape arm rod (91), and one end of the tripping rod is restrictively located at the raised boundary (19) of the base and moves back and forth along the raised boundary, and the other end of the tripping rod is restrictively located within the groove (20) disposed at a boundary of the base. There is a thermal tripping device (21) between two ends of the tripping rod.

Both inner sides of the housing of the high breaking capacity MCB are provided with arc-ignition devices, which are installed on the housing but are spaced from the housing (by partitions), which is convenient for gas to flow away instantaneously. In fact, when the circuit breakers are used to regulate large electrical currents, the gas may be a high heat, fast expanding plasma gas accompanied by arc and instantaneously attaches to the arc-ignition device. If the arc-ignition device is exposed at the moment, the arc will burn out the arc-ignition device unavoidably, and the arc flash will rekindle and burn out the circuit breaker under serious situations. If the area (or span) of the arc-ignition device is very narrow, yet the arc-ignition device is disposed below the arc-ignition channel, then with small short-circuit current such as 6K\4.5K\3K, the hot gas and arc generally will not expand into the opposite side of the arc-ignition device therefore it will not cause arc flash short circuit and rekindling. However, the 10K short-circuit current is at a rather different level, the arc light, arc heat, energy and gas are all generated more instantaneously and at a larger scale, so the measures for protecting the arc-ignition device and guiding the gas flow are especially important.

The arc extinguishing device is in the form of an arc chute (13) which has an arc extinguishing chamber inside. Through holes are distributed on one side of the outer casing of the arc chute (13) and are arranged in two opposing rows. The upper edge of the outer casing of the arc chute is close to the magnetic steel outer wall (14) and the lower edge is close the arc-ignition device. At an external side of the arc extinguishing chamber near the housing, and positioned behind the arc chute, is provided a plurality of gas channels of various shapes. The arc extinguishing chamber and the tripper chamber are connected. The arc chute is composed by two rows of seventeen iron sheets, each row is embedded into the outer casing equidistantly. This arrangement aims to increase the arc spacing of the arc extinguishing area and increase the arc spaces to 18 intervals. When the arc flash is more divided into equal parts, the voltage at both ends of the arc chute will be increased, thus the arc flash will not rekindle or re-ignite. This enables the arc flash to subside or die out along the arc path formed of the spaced iron sheets. Also, using a greater number of iron sheets to form the arc chute increases the metal area and accordingly the area of metal arc cooling, which can lower the temperature rapidly, and the arc light will disappear naturally because of the rapidly reduced temperature. When the circuit breaker opens and closes the circuit in instances of large faulty current, the energy generated instantaneously will heat the gas, which scatters in the housing accompanied by arc flash. However, the optimized channels can assist with the even thermal expansion of the housing so that the circuit breaker will not burst or explode.

The moving contact of the operating mechanism of the high breaking capacity MCB is attached to the operating mechanism (not shown in the figures) by one or more screws. This connection is different from the glue connection, which is convenient for disassembly and assembly, i.e. it is easy and quick to assemble without the effect of the instability of the glue so that the housing components can be firmly and efficiently assembled. The moving contact is located in the middle of the arc-ignition device. A riveting shaft is dispose in the middle of the housing, and the copper part ofthe arc-ignition angle spreads along the riveting shaft. There is also an arc-ignition bent iron in the arc-ignition angle.

The basic principles, main features and advantages of this invention have been shown and described above. The technicians of this field should realize that this invention is not restricted by above implementation examples, which are only to explain or illustrate the principles or workings of the present invention. Under the premise of being without departing from the spirit and scope of this invention, simple changes and replacements by ordinary technicians of this field are both within the scope of protection of this invention.

Claims

1. A high breaking capacity MCB comprises a housing, a cover, an operating mechanism, an instantaneous-actuating mechanism, an arc-ignition device and an arc extinguishing device, wherein the instantaneous-actuating mechanism comprises a handle, a handle torsional spring and an instantaneous-actuating rod; the instantaneous-actuating rod is able to move at both ends; one end of the instantaneous-actuating rod proximal to a lower end of the handle is provided with a limiting slot, the lower end of the handle having a protruding end portion positioned into the limiting slot; another end ofthe instantaneous-actuating rod furthest from the limiting slot incorporates an elastic arm with a hook shaped end capable of engaging with the operating mechanism of the MCB.

2. A high breaking capacity MCB according to claim 1, wherein the operating mechanism comprises a concave wheel, a rotating arm, a lock wheel a support shaft, and a torsional spring connecting the concave wheel and the rotating arm.

3. A high breaking capacity MCB according to claim 1 or 2, wherein the arc-ignition device is in the form of an iron sheet, the iron sheet is embedded in the housing and disposed beneath the cover, thereby forming an integrated arc-ignition device, which has a moving contact and an arc-ignition angle comprising a copper part spread along a riveting shaft, an arc-ignition bent iron being disposed in the arc-ignition angle.

4. A high breaking capacity MCB according to claim 3, wherein the arc extinguishing device is an arc chute formed from iron sheets equidistantly arranged in two rows with seventeen iron sheets in each row, the arc chute having an extinguishing chamber therein, a plurality of gas channels being disposed adjacent the extinguishing chamber and positioned behind the arc chute, the arc extinguishing chamber being connected to a tripper chamber.

5. A high breaking capacity MCB according to any one of claims 1 to 3, wherein a grip-shape arm rod extends from a lower end of the lock wheel, an upper end of the grip-shape arm rod incorporates a half arc-trench-shape gap, which contains an arc-shape wall protruded by a support arm, and the lock wheel moves along the arc-shape wall; and wherein a tripping rod is placed at one end of the grip-shape arm rod, the tripping rod capable of moving along a base, and a thermal tripping device is disposed between two ends of the tripping rod.