High voltage DC circuit breaker with double break contacts

The invention relates to a circuit interrupter used for high voltage applications, and more specifically, the invention relates to a circuit interrupter with a double break contact where each contact is provided with an arc chamber.

Circuit interrupters are electrical components that are used to open an electrical circuit, interrupting the flow of current. A basic example of a circuit interrupter is a switch, which generally consists of two electrical contacts in one of two states; either closed, meaning that the contacts are in electrical contact with each other allowing electricity to flow between them, or open, meaning that the contacts are not in electrical contact with each other preventing the flow of electricity. A switch may be directly manipulated to provide a control signal to a system, such as a computer keyboard button, or to control power flow in a circuit, such as a light switch.

Another example of a circuit interrupter is a circuit breaker. A circuit breaker is designed to protect an electrical circuit from damage caused by, for example, an overload, a ground fault or a short circuit. If a fault condition, such as a power surge occurs in the electrical wiring, the breaker will trip. This will cause a breaker that was in an “on” position to flip to an “off” position and interrupt the flow of electrical power through the breaker. Circuit breakers are generally provided to protect the electrical wiring by limiting the amount of current transmitted through the wires to a level that will not damage them. Circuit breakers can also prevent destruction of the devices that may draw too much current.

A standard circuit breaker has a first terminal connected to a source of electrical power, and a second terminal electrically connected to the wires that the breaker is intended to protect. Conventionally, these terminals are referred to as the “line” and “load”, respectively. The line is sometimes referred to as the input of the circuit breaker. The load is sometimes referred to as the output of the circuit breaker, which connects to the electrical circuit and components receiving the electrical power.

A circuit breaker can be used as a replacement for a fuse. Unlike a fuse, however, which typically operates to open in an over current situation and then must be replaced; a circuit breaker can be “reset” (either manually or automatically) to resume operation. Fuses perform a similar role to circuit breakers, however, circuit breakers are easier to use and typically safer to service and operate.

Unlike the situation when a fuse blows, when a circuit breaker trips, it is relatively easy to determine which circuit breaker feeds the interrupted circuit by looking at the electrical panel and noting which breaker has a handle in the “tripped” position. This breaker can then be simply moved to the “off” position (which resets the circuit breaker), and then moved to the “on” position and power will resume.

In general, a single pole circuit interrupter has at least two contacts positioned inside of a housing. The first contact is stationary and may be connected to either the line or the load. The second contact is movable with respect to the first contact, such that when the circuit breaker is in the “off” or “tripped” position, a gap exists between the first and second contact.

In high voltage applications, the opening and closing of contacts, can result in an arc developing between the contacts. High voltage applications typically are associated with high power transfer and therefore, the switching devices used in these applications must be able to effectively and safely switch even under load.

A problem with the above-described circuit interrupters arises when energized contacts are opened while under load. As the contacts separate, an electric arc may be formed in the gap between the contacts. An electrical arc is a plasma discharge between two points that is caused by electrical current that ionizes gasses in the air between the two points.

The creation of an arc during transition of the contacts can result in undesirable effects that negatively affect the operation of the circuit interrupter, even potentially creating a safety hazard. These negative effects can also have adverse consequences on the functioning of the circuit interrupter.

One possible consequence is that the arc may short to objects inside the circuit interrupter and/or to surrounding objects, causing damage and presenting a potential fire or safety hazard.

Another consequence of arcing is that the arc energy damages the contacts themselves, causing some material to escape into the air as fine particulate matter. The debris that has been melted off of the contacts can migrate or be flung into the mechanism of the circuit interrupter, destroying the mechanism or reducing its operational lifespan.

Still another effect of arcing is due to the extremely high temperature of the arc (tens of thousands of degrees Celsius), which can impact the surrounding gas molecules creating ozone, carbon monoxide, and other dangerous compounds. The arc can also ionize surrounding gasses, potentially creating alternate conduction paths.

The challenges faced in high voltage applications is further complicated with Direct Current (DC) applications as there is no zero voltage crossing. In Alternating Current (AC) applications, opening of the contacts can be timed to correspond with the zero voltage crossing to minimize potential arcing. However, in DC applications there is no zero voltage crossing; therefore switching must quite often happen at peak voltage under load.

It is therefore desired to provide a circuit interrupter usable in DC applications that overcomes the above-described limitations.

Accordingly, it is an object of the present invention to provide a circuit interrupter for use in high voltage applications having an arc extinguisher that functions to arrest an arc between the circuit interrupter contacts.

It is a further object of the present invention to provide a circuit interrupter for use in high voltage applications that is designed to minimize the formation of arcs when the contacts are opening or closing.

It is a further object of the present invention to provide a circuit interrupter for use in high voltage applications that is adapted to minimize arc formation and if and arc does form, will quickly function to extinguish the arc.

These and other objectives are achieved by providing a circuit interrupter that includes a first moveable contact and a second stationary contact (a first set of contacts). The first stationary contact is positioned on a first stationary contact arm that is elongated and generally flat and connected to a first terminal. A first moveable contact arm is also provided that has a first moveable contact mounted thereon. The first moveable contact arm is adapted to be moved such that the first movable contact moves into and out of contact with the first stationary contact.

In one configuration, the first movable contact is coupled to a first flexible conductor that is coupled to an input to an overcurrent measurement device. The output of the overcurrent measurement device is in turn, coupled to a second flexible conductor that is coupled to a second moveable contact. The second moveable contact is positioned on a second moveable contact arm. Also provided is a second stationary contact mounted on a second stationary contact arm. The second moveable contact and the second stationary contact (a second set of contacts) are adapted to be moved into and out of physical contact with each other. The second stationary contact is further connected to a second terminal.

Also provided in one configuration is a first arc extinguisher that is positioned in the vicinity of the first moveable and first stationary contacts. The first arc extinguisher is provided such that when an arc develops between the first movable and first stationary contacts, the arc is then drawn into the first arc extinguisher. Likewise, a second arc extinguisher is provided in the vicinity of the second moveable and second stationary contacts such that, if an arc develops between the second movable and second stationary contacts, the arc is drawn into the second arc extinguisher.

The circuit interrupter may further be provided with a housing within, which the working parts of the circuit interrupter are maintained. In one configuration, the first moveable contact arm is connected to a first linkage that is coupled to a handle that extends out a top side of the housing. The first linkage is provided such that, if the handle is moved to the Off position, this will function to move the first linkage to open the first and the second contacts. Alternatively, if the overcurrent measurement device detects an overcurrent condition, the overcurrent measurement device can function to move the first linkage to open the first and the second contacts.

The circuit interrupter is further provided with a second linkage that is coupled to the handle and to the second moveable contact arm. The second linkage is provided such that, if the handle is moved to the Off position, this will function to move the second linkage to open the second set of contacts.

In a further configuration, the circuit interrupter is provided with a single handle that is used to actuate both the first and second linkages such that the first set of contacts and the second set of contacts are opened and closed simultaneously.

As can be seen from the above description, the circuit interrupter is provided with a first set of contacts in series with a second set of contacts that are actuated simultaneously. This is advantageous for high voltage applications as the voltage developed across each of the individual sets of contacts will be equal to one half of the total voltage of the applied voltage. By splitting the voltage across two sets of contacts in series with each other, this functions to lower the arcing that will occur across each of the sets of contacts.

For this application the following terms and definitions shall apply:

The terms “first” and “second” are used to distinguish one element, set, data, object or thing from another, and are not used to designate relative position or arrangement in time.

The terms “coupled”, “coupled to”, “coupled with”, “connected”, “connected to”, and “connected with” as used herein each mean a relationship between or among two or more devices, apparatus, files, programs, applications, media, components, networks, systems, subsystems, and/or means, constituting any one or more of (a) a connection, whether direct or through one or more other devices, apparatus, files, programs, applications, media, components, networks, systems, subsystems, or means, (b) a communications relationship, whether direct or through one or more other devices, apparatus, files, programs, applications, media, components, networks, systems, subsystems, or means, and/or (c) a functional relationship in which the operation of any one or more devices, apparatus, files, programs, applications, media, components, networks, systems, subsystems, or means depends, in whole or in part, on the operation of any one or more others thereof.

The term “high” voltage is applied to applications in which a voltage higher than that used for power distribution. The lower limit is typically taken as 8,700V according to the National Electrical Safety Code (NFPA 70).

In one configuration of the system, a high voltage DC circuit interrupter is provided comprising a first stationary contact and a first moveable contact forming a first set of contacts, a first moveable contact arm having the first moveable contact positioned thereon, the first moveable contact adapted to be moved into and out of contact with the first stationary contact, and a first linkage coupled to the first moveable contact arm. The circuit interrupter further comprises a second stationary contact and a second moveable contact forming a second set of contacts, a second moveable contact arm having the second moveable contact positioned thereon, the second moveable contact adapted to be moved into and out of contact with the second stationary contact, and a second linkage coupled to the second moveable contact arm. The circuit interrupter also comprises an overcurrent measurement device coupled in series with the first and second sets of contacts and a handle coupled to the overcurrent measurement device and positioned in an upper side of a housing. The circuit interrupter is provided such that the overcurrent measurement device is adapted to actuate the first and second linkages in an overcurrent condition so that both the first and second sets of contacts are simultaneously opened during an overcurrent condition.

In another configuration of the system, a high voltage DC circuit interrupter is provided comprising a first stationary contact and a first moveable contact forming a first set of contacts, the first moveable contact positioned on a first moveable contact arm and adapted to be moved into and out of contact with the first stationary contact. The circuit interrupter further comprises a second stationary contact and a second moveable contact forming a second set of contacts, the second moveable contact positioned on a second moveable contact arm and adapted to be moved into and out of contact with the second stationary contact. The circuit interrupter also comprises a first linkage coupled to the first moveable contact arm and a second linkage coupled to the second moveable contact arm, a housing in which the first and second set of contacts and the first and second linkages are positioned, and an overcurrent measurement device coupled between with the first and second sets of contacts. The circuit interrupter is provided such that the overcurrent measurement device is adapted to actuate said first and second linkages in an overcurrent condition such that both said first and second sets of contacts are simultaneously opened during an overcurrent condition.

Other objects of the invention and its particular features and advantages will become more apparent from consideration of the following drawings and accompanying detailed description.

FIG. 1 is a diagram of a circuit interrupter according to one configuration.

FIG. 2 is a perspective view of the first stationary contact arm and first stationary contact according to FIG. 1 .

FIG. 3 is a block diagram of the functioning of the circuit interrupter according to FIG. 1 showing the handle in the Tripped position and the first and second sets of contacts open.

FIG. 4 is a block diagram of the functioning of the circuit interrupter according to FIG. 3 showing the handle in the Off position and the first and second sets of contacts open.

FIG. 5 is a block diagram of the functioning of the circuit interrupter according to FIG. 3 showing the handle in the On position and the first and second sets of contacts closed.

Referring now to the drawings, wherein like reference numerals designate corresponding structure throughout the views.

FIG. 1 is a view of a circuit interrupter 100 , which in one configuration, may comprise a circuit breaker. The circuit interrupter 100 is provided by a housing 102 , which may comprise an insulating material, such as a thermoset polyester resin material or the like, as is commonly used in the art.

An upper surface 104 of housing 102 is includes and opening in which a handle 106 is positioned. The handle 106 is moveable to one of three positions, On, Off and Tripped. Coupled to a lower portion of handle 106 is a first linkage 108 and a second linkage 110 . First linkage 108 is coupled to an overcurrent measurement device 112 and to first moveable contact arm 114 . Likewise, second linkage 110 is coupled to overcurrent measurement device 112 and to second moveable contact arm 116 .

A first moveable contact 118 is mounted on an underside of first moveable contact arm 114 and a second moveable contact 120 is mounted on an underside of second moveable contact arm 116 .

The first moveable contact arm 114 is coupled to an input 122 of the overcurrent measurement device 112 via a first flexible conductor 124 . The second moveable contact arm 116 is connected to an intermediate plate 126 by a second portion 128 of a second flexible conductor, and the intermediate plate 126 is connected to an output 130 of overcurrent measurement device 112 by a first portion 132 of the second flexible conductor.

The first moveable contact 118 is generally adapted to move in a radial path defined by rotation about first pivot 134 to come into contact with first stationary contact 136 . First stationary contact 136 is positioned on a first stationary contact arm 138 , which is formed as a flat conductor and better illustrated in FIG. 2 . First stationary contact arm 138 is provided having a U-shape configuration as seen in FIG. 1 with a lower portion providing a first terminal 140 . The first terminal is illustrated as being a screw-type of connection, however, it is contemplated that virtually any type of connector can effectively be used as is known in the art, including, for example, a stab connector, tines, or the like. The first moveable contact 118 and the first stationary contact 136 form a first set of contacts 158 .

The second moveable contact 120 is adapted to function in a similar manner as the first moveable contact 118 . A second stationary contact 142 is positioned on a second stationary contact arm 144 , which is formed as a flat conductor in a similar manner as first stationary contact arm 138 . Second stationary contact arm 144 is provided having a U-shape configuration as seen in FIG. 1 with a lower portion providing a second terminal 146 . The second terminal 146 may comprise any configuration as discussed in connection with first terminal 140 . The second moveable contact 120 and the second stationary contact 142 form a second set of contacts 160 .

Also shown in FIG. 1 is first arc extinguisher 148 and second arc extinguisher 150 . First and second arc extinguishers 148 , 150 each comprise a plurality of generally vertically stacked arc plates 152 , 154 that are spaced apart from each other. The first arc extinguisher 148 is positioned in proximity of the first set of contacts, whereas the second arc extinguisher 150 is positioned in proximity of the second set of contacts. Each of the arc extinguishers 148 , 150 are positioned such that an inner part of the arc plates 152 , 154 at least partially follow the radial path of the moveable contact arm 114 , 116 respectively. In this manner, in the event that an arc develops between either the first or second sets of contacts, the arc will be drawn away from the set of contacts and into the respective arc extinguisher 148 , 150 .

Also depicted in FIG. 1 is barrier 156 , which may be integrally formed as a part of housing 102 . Barrier 156 may comprise an insulating material and provide an insulating barrier between the first set of contacts and the second set of contacts, which is advantageous for high voltage environments.

Turning now to FIGS. 3-5 , functional block diagrams of circuit interrupter 100 are illustrated. FIG. 3 illustrates that in an overcurrent condition, overcurrent measurement device 112 will function to simultaneously open the first and second sets of contacts 158 , 160 thereby interrupting the flow of electricity between the first and second terminals 140 , 146 . As can be seen, when the circuit interrupter 100 encounters and overcurrent condition, the handle 106 is toggled to the Tripped position.

In order to clear the Tripped position of the handle 106 , it is illustrated in FIG. 4 that handle 106 should be moved to the Off position. This functions to “reset” the overcurrent measurement device and associated linkages. It will be noted that the first and second sets of contacts 158 , 160 remain in an open state.

The handle 106 may then be moved to the On position as shown in FIG. 5 , which functions to close the first and second sets of contacts 158 , 160 so that the circuit interrupter 100 is then allowing electricity to pass between the first and second terminals 140 , 146 .

As will be seen with reference to FIGS. 1 and 3-5 , the first set of contacts 158 are provided in series with the second set of contacts 160 between the first and second terminals 140 , 146 . In a high voltage application, this is advantageous as it means that when the sets of contacts are simultaneously opened, half of the voltage is developed across each of the sets of contacts as resistance increases during opening. This means that the arcing that occurs across the gap between each of the sets of contacts will be lessened due to the lower voltage drop.

Additionally, it should be noted that the circuit interrupter 100 is described as usable for DC high voltage applications. While DC voltage is polarity dependent as opposed to AC voltage, it will be understood by those of skill in the art that the circuit interrupter 100 can be used with the positive DC conductor connected to either the first terminal 140 or the second terminal 146 . In other words, the circuit interrupter 100 can be used for polarity sensitive applications. This is due to the fact that at least one arc extinguisher will always be oriented correctly and will function to quickly extinguish any arc that develops. Since the first and second pairs of contacts 158 , 160 are connected in series with each other, interruption of the flow of electricity in one set of contacts will function to interrupt the flow of electricity in the other pair of contacts effectively quenching the arc in both locations.

Although the invention has been described with reference to a particular arrangement of parts, features and the like, these are not intended to exhaust all possible arrangements or features, and indeed many other modifications and variations will be ascertainable to those of skill in the art.