Patent Description:
It is known that switching devices, such as for example circuit breakers, disconnectors, contactors, limiters, hereinafter referred to as switches, for reasons of brevity, generally comprise a casing and a plurality of electrical poles, associated to each of which there is at least one pair of contacts that can be coupled to and uncoupled from one another. Switches of the known art also comprise control means that cause relative movement of said pairs of contacts so that they can assume at least one first, coupling, position (circuit closed) and one second, separation, position (circuit open).

As known, during the useful life of a low voltage switch, phenomena which expose the switch and the network to particularly heavy stresses can occur. This happens in the first place when the switch is required to withstand, even for short periods, currents greater than the rated values.

Thus, in general, in low voltage circuit breakers, the critical function of interrupting the current (whether nominal, overload or short-circuit current) is provided in a specific portion of the circuit breaker which is constituted by the so-called deionizing arc chamber.

Generally associated to each pole of the switch there is therefore at least one arc chamber, i.e., a region of space which is particularly suited to fostering electric-arc interruption. Arc chambers can be simple regions provided in the casing of the switch, or else can comprise various modular elements shaped, for example, like casings made of insulating material equipped with arc-breaking plates. Modular arc chambers, which are more advanced, present the advantage of being easily replaceable; moreover they can also be manufactured using materials that are more suitable as compared, for example, to the ones used for the casing of the switch.

Under operating conditions, as a consequence of the opening movement, the voltage between the contacts causes the dielectric discharge of the air, leading to the formation of the electric arc in the chamber. The arc is propelled by electromagnetic and fluid-dynamics effects inside a series of arc-breaking metal plates arranged in the chamber, which are meant to extinguish said arc by cooling and splitting actions.

During arc formation, the energy released by Joule effect is very high and causes thermal and mechanical stresses inside the plate containment region. It is worth noting that, depending on the kind of switch and the arching phenomenon that takes place, the pressure in the contact zone, and in particular in the arc chamber, can reach very high values, e.g. as high as <NUM>-<NUM> bars, while the temperature of the ionized gases can reach values of <NUM>-<NUM> °K.

It is therefore necessary that the arc chamber is provided with an adequate system for venting off and cooling the hot gases that develop during arching. To this purpose, the existing arc chambers for low voltage switching devices are generally provided with openings for the discharge of the hot gases produced during arching and with a filtering system which, among others, has the functions of cooling the gas, reducing the velocity of the flow at the discharge, preventing the emission of flame and/or incandescent gases.

However, depending on the application and the type of interventions, the ionized gas vented off through the venting openings may create discharge problems between adjacent phases and between each phase and the front door of the panel into which the circuit breaker is normally positioned. Document <CIT> discloses a low voltage circuit breaker, having a plurality of phases each provided with a lug for electrical connection of said circuit breaker, a venting aperture for venting off gases, and a device for door and phase segregation comprising a conductive element fixed to a corresponding lug of said circuit breaker and provided with electrical connection means for electrical connection of said circuit breaker, whereby said device comprises an insulating element interposed between two adjacent phases of said circuit breaker.

The main aim of the present invention is to provide a low voltage circuit breaker, in particular a molded case circuit breaker, provided with a system that allows solving or at least reducing the above-mentioned problems.

It is therefore an object of the present invention to provide a device able to guarantee an effective segregation between the various phases of a low voltage circuit breaker when ionized gases are vented off the arching chamber of each pole.

It is a further object of the present invention to provide a device able to guarantee an effective segregation between each phases of a low voltage circuit breaker and the front door of the panel into which the circuit breaker is positioned when ionized gases are vented off the arching chamber of each pole.

Still another object of the present invention is to provide a device able to guarantee an effective door and phase segregation in low voltage circuit breakers, in particular in molded case circuit breakers, that can be easily manufactured at industrial level, at competitive costs with respect to the solutions of the state of the art.

A low voltage circuit breaker, in particular a molded case circuit breaker, provided with a reliable door and phase segregation device is also an object of the present invention.

In order to fulfill these objects, the present invention provides a device for door and phase segregation in low voltage circuit breakers, in particular in molded case circuit breakers, having a plurality of phases each provided with a lug for electrical connection of said circuit breaker and a venting aperture for venting off gases; the device of the invention comprises a conductive element adapted to be fixed to a corresponding lug of said circuit breaker and provided with electrical connection means for electrical connection of said circuit breaker. The device for door and phase segregation of the present invention is characterized in that it comprises a first insulating element covering said conductive element and a second insulating element adapted to be interposed between two adjacent phases of said circuit breaker.

In this way, it is possible to provide a low voltage circuit breaker, particularly a molded case circuit breaker, which is capable to withstand the negative effects brought about by the hot ionized gases coming from the arc chamber.

In practice, as better explained hereinafter, in the system of the present invention the first and the second insulating elements are able to create an effective segregation between the various phases and between each phase and the front door of the panel, thereby solving, or at least greatly reducing, the problems of the prior art systems.

For the purposes of the present invention, in the description the terms "vertical", "horizontal", "front", "rear", "lateral", "top" and "bottom" refers to the typical operating configuration of the circuit breaker.

In a largely preferred embodiment of the device for door and phase segregation of the present invention, the conductive element is substantially L-shaped. In turn, the first insulating element comprises a first insulating body which is also substantially L-shaped and which is fitted onto said conductive element. In particular, the first insulating element has a first and a second lateral surface which are substantially continuous and substantially L-shaped, and a top surface which is conveniently provided with an opening for accessing the connection means of said conductive element.

Preferably, said first insulating body has a rear and a bottom surface which are also provided with openings allowing the passage of said conductive element, so that the first insulating body can be slidingly inserted onto said conductive element and covers it completely on the front and lateral sides, thereby creating an effective insulation of said conductive element.

Typically, in an embodiment of the device for door and phase segregation presently disclosed, the conductive element is provided with first fixing means for the mechanical connection to a corresponding lug of said circuit breaker; the conductive element can be also provided with second fixing means for mechanical connection of said electrical connection means.

As better explained hereinafter, in this case, the first insulating body can be advantageously shaped with a front surface having a first portion and a second portion raised with respect to said first portion. One or more openings can be advantageously positioned on said first and/or second portion for accessing said first and/or second fixing means, thereby making very easy the installation of the device on the circuit breaker and the connection of this latter to the electrical circuit into which it is positioned.

For example, said first and second fixing means can be screw means adapted to effectively fix the conductive element to the terminals of the circuit breaker and to conductors (e.g., cables or bars) of the electrical circuit.

In an embodiment of the device for door and phase segregation of the present invention, said first insulating body is conveniently provided with an elongated protrusion substantially perpendicular to said first and second lateral surface and vertically extending along at least a portion of said first and second lateral surface.

In this way, the elongated protrusion form a sort of screen, thereby channeling them away from the more sensitive parts of the circuit breaker.

Moreover, in a particular embodiment of the device for door and phase segregation presently disclosed, the first insulating body can be advantageously provided with a tab which is adapted to rest on a surface of said circuit breaker proximate to a venting aperture of said circuit breaker, on a front side thereof. In this way the hot ionized gases can be prevented to flow toward the front door of the panel into which the circuit breaker is inserted.

For instance, said tab can be conveniently positioned in an intermediate position between said first and second portions of the front surface of the first insulating body.

In a further largely preferred embodiment of the device for door and phase segregation of the present invention, said second insulating element advantageously comprises an insulating fin vertically extending between two adjacent phases of said circuit breaker.

Moreover, said insulating fin is shaped so as to have a third and a fourth substantially continuous lateral surfaces and is conveniently provided with a third and a fourth lateral protrusions which are substantially perpendicular to said third and fourth lateral surfaces and which run vertically along at least a portion of said third and fourth lateral surfaces.

In practice, according to this embodiment, the main body of the insulating fin provides an effective segregation between the various phases, while the third and fourth lateral protrusions provide an effective contribution to the segregation between the each phase and the front door of the panel.

In this respect, in an embodiment of the device for door and phase segregation in low voltage circuit breakers of the present invention, said third and fourth lateral protrusions of the insulating fin are adapted to rest on a surface of said circuit breaker proximate to a venting aperture of said circuit breaker, thereby providing an effective screen for the hot ionized gases coming from the arc chamber.

A low voltage circuit breaker, in particular a molded case circuit breaker comprising a device for door and phase segregation as disclosed herein is also part of the present invention.

Further features and advantages of the invention will emerge from the description of preferred, but not exclusive embodiments of the device for door and phase segregation, according to the invention, non-limiting examples of which are provided in the attached drawings, wherein:.

With reference to the attached Figures, the device for door and phase segregation according to the invention, is adapted to be used in low voltage circuit breakers, in particular in a molded case circuit breaker <NUM> as represented in <FIG>.

The circuit breaker <NUM> has a plurality of phases <NUM>, in the present case three phases, and associated to each of which there is at least a pair of contacts that can be coupled to and uncoupled from one another, thereby achieving a closed or open configuration. The circuit breaker also comprises control means that cause relative movement of said pairs of contacts so that they can assume a first, coupling, position (circuit closed) and a second, separation, position (circuit open). In general, the operating principles and functioning, as well as the related components and mechanisms, of the circuit breaker used in the present invention can be of the conventional type and will not be described in further details.

Each phase <NUM> of the circuit breaker <NUM> is also provided with one terminal <NUM> for the electrical connection of the circuit breaker <NUM> to a corresponding electrical circuit. On the top surface of the circuit breaker <NUM>, in correspondence of each phase <NUM>, there is usually positioned one or more venting apertures <NUM>, <NUM> for venting off gases coming from the arc chamber.

In its more general definition, the device for door and phase segregation of the present invention comprises a conductive element <NUM> which is adapted to be fixed to a corresponding lug or terminal <NUM> of each phase <NUM> of the circuit breaker <NUM>.

The conductive element <NUM> is normally provided with electrical connection means <NUM>, <NUM> for electrical connection of said circuit breaker <NUM> to the corresponding electrical circuit. In the present case, the electrical connection means are represented by the seats (holes) <NUM>, <NUM>, into which the terminal portion of, e.g. a connection cable or - more in general - a connection element, can be inserted.

One of the distinguishing features of the device for door and phase segregation of the present invention, is given by the fact that that it comprises a first insulating element <NUM> which covers said conductive element <NUM> and/or a second insulating element <NUM> which is adapted to be interposed between two adjacent phases <NUM> of said circuit breaker <NUM>.

More in details, with reference to <FIG> and <FIG>, the conductive element <NUM> is substantially L-shaped. In turn, with reference also to <FIG>, the first insulating element <NUM> comprises a first insulating body <NUM> which is also substantially L-shaped so as to match the shape of the conductive element <NUM>.

As shown in <FIG>, the first insulating body <NUM> is fitted onto the conductive element <NUM> and has a first <NUM> and a second <NUM> lateral surfaces which are substantially continuous and substantially L-shaped; the first insulating body <NUM> has also a top surface <NUM> which is provided with an opening <NUM> for accessing the connection means <NUM>, <NUM>, e.g. the seats <NUM>, <NUM> of connection cables, of the conductive element <NUM>.

Moreover, as shown in particular in <FIG>, the first insulating body <NUM> has a rear surface <NUM> and a bottom surface <NUM>, which are provided with openings allowing the passage of said conductive element <NUM>. In the embodiments shown, the rear surface <NUM> of the first insulating body <NUM> is substantially completely open.

In this way, the first insulating body <NUM> can be inserted over the conductive element <NUM> with a sliding action, thereby achieving the configuration of <FIG>, and can be kept in place by small portions of the rear surface <NUM> and bottom surface <NUM>.

With reference to <FIG>, the conductive element <NUM> is conveniently provided with first fixing means <NUM> for mechanical connection to a corresponding lug/terminal <NUM> of the circuit breaker <NUM> and second fixing means <NUM> for the mechanical connection of said electrical connection means, e.g. the terminal portion of one or more connection cables.

As shown in particular in <FIG>, the first insulating body <NUM> has a front surface <NUM> which is shaped so as to match the shape of the conductive element <NUM>. In particular, the front surface <NUM> has a first portion <NUM> and a second portion <NUM> which is raised with respect to said first portion <NUM>, so as to follow the L-shape of the conductive element <NUM>. One or more openings <NUM>, <NUM> are conveniently positioned on the first portion <NUM> and/or on the second portion <NUM> of the front surface <NUM> for accessing the first <NUM> and/or second <NUM> fixing means positioned on the conductive element <NUM>.

In the embodiment shown, since there are foreseen two connection cables housed in the seats <NUM> and <NUM> (and therefore there are also two corresponding fixing means <NUM>), a third hole is positioned on the second portion <NUM> of the front surface <NUM> of the first insulating body <NUM>, said third hole being closed by a cover <NUM> in the embodiment shown in the attached figure.

For example, the first <NUM> and second <NUM> fixing means can be screw means, that are easily accessible through the openings <NUM> and <NUM> (as well as through the opening closed by the cover <NUM>) and can therefore be easily operated to fix the device to the circuit breaker <NUM> and to fix the cable terminals to the conductive element <NUM>.

With reference to <FIG> and <FIG>, in a particular embodiment of the device for door and phase segregation of the invention, the first insulating body <NUM> is provided on both sides thereof with an elongated protrusion <NUM> which is substantially perpendicular to the first <NUM> and second <NUM> lateral surface the first insulating body <NUM>. The elongated protrusions <NUM> extend vertically along at least a portion of the first <NUM> and second <NUM> lateral surface of the first insulating body <NUM>.

Thus, as shown in <FIG>, the first <NUM> and second <NUM> lateral surface of the first insulating body <NUM> create a screen for the passage of the hot gases coming out from the venting aperture <NUM>, <NUM> toward the rear portion of the circuit breaker <NUM>.

Moreover, with reference to <FIG> and <FIG>, the first insulating body <NUM> can be conveniently provided with a tab <NUM> which is adapted to rest on a surface of said circuit breaker <NUM> proximate to a venting aperture <NUM>, <NUM> of said circuit breaker <NUM>. In particular, said tab <NUM> can be conveniently positioned in an intermediate position between said first <NUM> and second <NUM> portions of the front surface <NUM> of the first insulating body <NUM>.

In this way, as shown in <FIG>, the tab <NUM> of the first insulating body <NUM> creates a screen for the passage of the hot gases coming out from the venting aperture <NUM>, <NUM> toward the front portion of the circuit breaker <NUM>, thereby effectively segregating each phase <NUM> from the front door of the panel.

With reference to <FIG>, in an embodiment of the device for door and phase segregation of the present invention, the second insulating element <NUM> typically comprises an insulating fin <NUM> which extends vertically between two adjacent phases <NUM> of said circuit breaker <NUM>.

As shown in <FIG> and <FIG>, the insulating fin <NUM> is therefore able to effectively segregate the various phases <NUM> form each other. In practice, the insulating fin <NUM> can be easily inserted between the phases <NUM> with a simple sliding action. To this purpose, the base of the insulating fin <NUM> can be conveniently shaped so as to match the shape of a guide positioned on the circuit breaker <NUM> between the various phases <NUM>. Other fixing or insertion means can however be used depending on the needs.

More in details, with reference to <FIG>, said insulating fin <NUM> is shaped so as to have a third <NUM> and a fourth <NUM> substantially continuous lateral surfaces. The insulating fin <NUM> is provided on both sides thereof with a third <NUM> and a fourth <NUM> lateral protrusions which are substantially perpendicular to the third <NUM> and fourth <NUM> lateral surfaces of the insulating fin <NUM>. The third <NUM> and a fourth <NUM> lateral protrusions run vertically along at least a portion of said third <NUM> and fourth <NUM> lateral surfaces of the insulating fin <NUM>.

As shown in <FIG> and <FIG>, said third <NUM> and fourth <NUM> lateral protrusions are adapted to rest on a surface of said circuit breaker <NUM> proximate to a venting aperture <NUM>, <NUM> of said circuit breaker <NUM>. Shape and dimensions of the third <NUM> and fourth <NUM> lateral protrusions can be any according to the needs.

In this way, as shown in <FIG> and <FIG>, the third <NUM> and fourth <NUM> lateral protrusions of the insulating fin <NUM> creates a screen for the passage of the hot gases coming out from the venting aperture <NUM>, <NUM> toward the front portion of the circuit breaker <NUM>, thereby effectively segregating each phase <NUM> from the front door of the panel.

It is clear from the above that the device for door and phase segregation in low voltage circuit breakers of the present invention allows solving the previously underlined technical problems. Indeed, it has been seen that a device for door and phase segregation according to the present invention, thanks to its structure, is able to effectively segregate the various phases among each other and also with respect to the front.

As shown in <FIG>, an effective segregation can be carried out by using the first insulating element <NUM> alone, while, as shown in <FIG> and <FIG>, an effective segregation can be also carried out by using the second insulating element <NUM> alone.

However, very effective results can be obtained by combining the two embodiments, i.e. by using both the first insulating element <NUM> and the second insulating element <NUM>, as shown in <FIG>.

Claim 1:
A low voltage circuit breaker (<NUM>), in particular a molded case circuit breaker, having a plurality of phases (<NUM>) each provided with a lug (<NUM>) for electrical connection of said circuit breaker, a venting aperture (<NUM>, <NUM>) for venting off gases, and a device for door and phase segregation comprising a conductive element (<NUM>) fixed to a corresponding lug (<NUM>) of said circuit breaker (<NUM>) and provided with electrical connection means (<NUM>, <NUM>) for electrical connection of said circuit breaker (<NUM>), whereby said device comprises a first insulating element (<NUM>) covering said conductive element (<NUM>) and a second insulating element (<NUM>) interposed between two adjacent phases (<NUM>) of said circuit breaker (<NUM>).