The present invention relates to a circuit breaker used for direct current applications, and more specifically, the invention relates to a circuit breaker with an electromagnetic arc blow that is bi-directional, in that it operates regardless of the polarity of the current flowing through the circuit breaker.
Circuit breakers are extremely well known and are used in connection with a myriad of applications. A well-known problem with circuit breakers, however, arises when energized contacts are opened while under load. As the contacts separate, transitioning from a closed to an open position, or when the opposite occurs, an electrical 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 breaker, even potentially creating a safety hazard. These negative effects can also have adverse consequences on the functioning of the circuit breaker.
One possible consequence is that the arc may short to objects inside the circuit breaker 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 breaker, 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, thereby creating ozone, carbon monoxide, and other dangerous compounds. The arc can also ionize surrounding gasses, potentially creating alternate conduction paths.
Because of these detrimental effects, it is very important to quickly suppress or quench the arc to prevent the above-described situations, and various techniques for improved arc quenching are known. For example, it has been conceived to incorporate a permanent magnet into the circuit breaker, which produces a magnetic field to guide an arc toward an arc splitter. However, permanent magnets produce a magnetic field having a fixed direction with respect to the magnet. Thus, traditional solutions for guiding an arc into an arc path using a permanent magnet are circuit polarity dependent. This is due to the fact that a magnetic field produced by a fixed permanent magnet has a fixed direction. As such, the mechanism for magnetically guiding the arc into the path depends upon the direction the current is flowing through the circuit interrupter.
More recently, various designs have been proposed employing multiple permanent magnets and multiple arc splitters in order to achieve polarity independence. However, these designs generally tend to be relatively bulky, heavy and/or costly due to the redundancy of components, particularly the use of multiple permanent magnets, which themselves generally tend to be relatively heavy and costly.
Other known designs for improved arc quenching propose the use of an electromagnetic field to guide an arc toward an arc splitter. While these designs generally do allow for polarity independence, since the orientation of the magnetic field varies with the polarity of the current flowing therethrough, known solutions also suffer from some disadvantages. For example, generating an electromagnetic field to move an arc requires the use of power, which consequently generates heat in the device.
It is therefore desired to provide a circuit breaker with enhanced arc quenching capabilities that overcomes the above-described disadvantages. Specifically, it is desirable to provide for enhanced arc quenching that is polarity independent, while also minimizing the amount of power consumed (and thus heat generated).
Toward this end, and in accordance with one exemplary embodiment of the invention, a circuit interrupter providing for arc suppression is provided, having a first contact electrically connectable to a power source and a second contact electrically connectable to a load. The first and second contacts are actuatable relative to each other between a closed position wherein the power source and the load are in electrical communication and an open position wherein the power source and the load are not in electrical communication. An arc extinguisher is also provided for extinguishing an arc that develops in the vicinity of the first and second contacts. An electromagnetic coil, when energized, generates a magnetic field that permeates an area where the arc develops, the magnetic field urging the arc toward the arc extinguisher regardless of a polarity of the contacts. An auxiliary switch is operably connected to at least one of the first and second contacts, such that upon movement of the first and second contacts relative to each other from the closed position toward the open position, the auxiliary switch is activated so as to energize a circuit feeding power to the electromagnetic coil, thereby generating the magnetic field.
In some embodiments, the arc extinguisher comprises a first arc path and a second arc path. In certain of these embodiments, the electromagnetic coil is disposed to urge the arc toward the first arc path when a polarity of the first contact is positive, and is disposed to urge the arc toward the second arc path when the polarity of the first contact is negative.
In certain embodiments, the arc extinguisher comprises a plurality of arc splitting plates, each plate comprising a first leg partially defining the first arc path and a second leg partially defining the second arc path. In certain embodiments, the arc extinguisher comprises a first plurality of arc splitting plates defining the first arc path and a second plurality of arc splitting plates defining the second arc path.
In some embodiments, control circuitry is provided in communication with the auxiliary switch and the circuit feeding power to the electromagnetic coil, the control circuitry comprising a timer and a relay, the timer automatically causing the relay to deenergize the circuit feeding power to the electromagnetic coil after a period of time has elapsed following activation of the auxiliary switch and energizing of the circuit feeding power to the electromagnetic coil, whereby the electromagnetic coil is energized only for the period of time.
In certain of these embodiments, the period of time is less than 1 second. In certain of these embodiments, the period of time is less than 100 milliseconds. In certain of these embodiments, the period of time is about 50 milliseconds.
In some embodiments, the control circuitry, the auxiliary switch and the circuit feeding power to the electromagnetic coil receive power from a line side of the circuit interrupter.
In some embodiments, the control circuitry, the auxiliary switch and the circuit feeding power to the electromagnetic coil receive power from an auxiliary power source. In certain of these embodiments, the auxiliary power source comprises an auxiliary power supply disposed in a panel in which the circuit interrupter is disposed, along with other circuit interrupters. In certain embodiments, the auxiliary power supply comprises a transformer disposed in the panel.
In some embodiments, the circuit interrupter comprises a circuit breaker.
In accordance with another exemplary embodiment of the invention, a circuit breaker providing for arc suppression includes a first contact electrically connectable to a power source and a second contact electrically connectable to a load, the first and second contacts being actuatable relative to each other between a closed position wherein the power source and the load are in electrical communication and an open position wherein the power source and the load are not in electrical communication. An arc extinguisher is provided for extinguishing an arc that develops in the vicinity of the first and second contacts, the arc extinguisher comprising a first arc path and a second arc path. An electromagnetic coil, when energized, generates a magnetic field that permeates an area where the arc develops, the magnetic field urging the arc toward the first arc path when a polarity of the first contact is positive, and urging the arc toward the second arc path when the polarity of the first contact is negative. A relay is in electrical communication with a circuit feeding power to the electromagnetic coil, such that when the relay is open, no power is fed to the electromagnetic coil and when the relay is closed, the circuit feeding power to the electromagnetic coil is energized, thereby generating the magnetic field. An auxiliary switch is operably connected to at least one of the first and second contacts, such that upon movement of the first and second contacts relative to each other from the closed position toward the open position, the auxiliary switch is activated so cause the relay to close. A timer circuit automatically causes the relay to open after a period of time has elapsed following closing of the relay, whereby the electromagnetic coil is energized only for the period of time.
In some embodiments, the arc extinguisher comprises a plurality of arc splitting plates, each plate comprising a first leg partially defining the first arc path and a second leg partially defining the second arc path.
In some embodiments, the arc extinguisher comprises a first plurality of arc splitting plates defining the first arc path and a second plurality of arc splitting plates defining the second arc path.
In some embodiments, the period of time is less than 1 second. In certain of these embodiments, the period of time is less than 100 milliseconds. In certain of these embodiments, the period of time is about 50 milliseconds.
In some embodiments, the relay, the timer circuit, the auxiliary switch and the circuit feeding power to the electromagnetic coil receive power from a line side of the circuit breaker.
In some embodiments, the relay, the timer circuit, the auxiliary switch and the circuit feeding power to the electromagnetic coil receive power from an auxiliary power source. In certain of these embodiments, the auxiliary power source comprises an auxiliary power supply disposed in a circuit breaker panel in which the circuit breaker is disposed, along with other circuit breakers. In certain embodiments, the auxiliary power supply comprises a transformer disposed in the circuit breaker panel.
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.
Referring now to the drawings, wherein like reference numerals designate corresponding structure throughout the views,
The circuit interrupter (10) includes a pair of contacts (12) as is known in the art, and as is more fully described below in connection with exemplary embodiments of the invention. The contacts (12) are actuatable relative to each other between a closed position wherein a power source (14) and a load (16) are in electrical communication via, respectively, a line terminal (18) and a load terminal (20) and an open position wherein the power source (14) and the load (16) are not in electrical communication,
An arc extinguisher (22) for extinguishing an arc that develops in the vicinity of contacts (12) is provided, as is discussed more fully below in connection with exemplary embodiments thereof. An electromagnetic coil (24) is provided that, when energized, generates a magnetic field that permeates an area where the arc develops, the magnetic field urging the arc toward the arc extinguisher (22) regardless of a polarity of the contacts (12), as described more fully below. The electromagnetic coil may act through one or more pole pieces (26), to aid in the positioning and configuration of the magnetic field generated by the electromagnetic coil (24).
An auxiliary switch (28) is operably connected to at least one of the contacts (12), such that upon movement of the contacts (12) relative to each other from the closed position toward the open position, the auxiliary switch (28) is activated so as to energize a circuit (30) feeding power to the electromagnetic coil (24), thereby generating the magnetic field.
More specifically, control circuitry (32) is provided in communication with the auxiliary switch (28) and the circuit (30) feeding power to the electromagnetic coil (24), which control circuitry (32) includes a timer (34) and a relay (36). Activation of the auxiliary switch (28) causes the energizing of the circuit (30) feeding power to the electromagnetic coil (24), thereby generating the magnetic field, by causing the relay (36) to close. The timer (34) automatically causes the relay (36) to open, thereby deenergizing the circuit (30) feeding power to the electromagnetic coil (24) after a period of time has elapsed following closing of the relay (36), such that the electromagnetic coil (24) is energized only for said period of time.
For purposes of illustration, but not limitation, it may be assumed that in certain situations it takes approximately 20 milliseconds following an overcurrent or fault situation for the contacts (12) to fully open and for an arc therebetween to be extinguished. In such case, for example, the control circuitry (32) may be configured to provide power to the electromagnetic coil (24) for approximately 50 milliseconds to ensure adequate time for the arc to be extinguished.
As will be recognized, providing power to the electromagnetic coil (24) for such a short period of time will generate very little heat, particularly as compared to prior art designs where power is provided continuously to the coils of an electromagnet. Thus, it is desired for the electromagnetic coil (24) to be energized for as short of a time as possible, while still ensuring adequate time for the arc to be fully extinguished. While 50 milliseconds has been found to be optimal in many situations, a shorter or longer duration may be used. For example, 100 milliseconds has also been found to provide excellent results. Preferably, however, the duration of the time period for energization of the electromagnetic coil is kept below 1 second, an any longer duration has been found to provide very little, if any, benefit, but to generate unnecessary heat.
In certain preferred embodiments, the circuit interrupter (10) takes the form of a circuit breaker, including an overcurrent trip coil or the like (38), exemplary embodiments of which are discussed in more detail below. However, such is not strictly necessary, and the present invention may find use in other types of circuit interrupters, such as switches or the like.
In the embodiment shown in
This alternative design (shown in
On the other hand, the provision of a separate panel mounted power supply (42) does have disadvantages, including increased cost and the fact that if the power supply (42) fails, one would have to pull apart the entire panel (40) in order to replace the power supply (42). This is obviously much more cumbersome that replacing a single circuit interrupter should a failure occur therein.
Turning now to
Referring specifically to
The moveable contact arm (106) is coupled to a vertical plate (114) that includes a pin (116) connected to a linkage (118). The linkage (118) is coupled to both an overcurrent measurement device (120) and a handle (122) that extends out a top side (124) of a housing (126).
In operation, the moveable contact arm (106) will displace the moveable contact (102) along axis (CA). The moveable contact (102) is illustrated in a “closed” position where moveable contact (102) is physically contacting stationary contact (108). Also shown is moveable contact (102) in an “open” position (dashed line) where moveable contact (102) has been moved a distance away from stationary contact (108) along axis (CA).
The displacement of moveable contact arm (106) is controlled by the automatic actuation of the overcurrent measurement device (120) based on a measured current flow, or by the manual actuation of the handle (122) to open, reset and close the contacts.
Electrical power is provided to the circuit breaker (100) via line terminal (128), which is connected to first end (130) of stationary contact arm (112). Electrical power is then transferred to stationary contact arm (112), which is formed of a conductive material, and then to stationary contact (108). If moveable contact (102) is in physical contact with stationary contact (108), electrical power is transmitted to moveable contact arm (104) and through vertical plate (114). Vertical plate (114) is connected to an input of overcurrent measurement device (120) via conductor (132). Electrical power is then passed from an output of overcurrent measurement device (120) via conductor (134) and to load terminal (136), which will supply power to the load (not shown).
When the moveable contact (102) is displaced along axis (CA) away from stationary contact (108), it is contemplated that an arc (138) may form in the space between the contacts. As discussed previously, the formation of an arc can have deleterious effects on the circuit breaker (100) itself and surrounding equipment. Accordingly, it is advantageous to extinguish the arc (138) as quickly as possible. To accomplish this, a lower leg (140) of pole piece (26) (as shown in
In the embodiment of
A lower arc runner (170) is illustrated that extends from the first arc path (152) to the second arc path (156). The lower arc runner (170) is positioned such that it forms the lower most arc plate for both of the arc paths (152, 156). In addition, a flexible conductor (172) is provided that electrically connects the moveable contact arm (106) to the lower arc runner (170). In one configuration, the flexible conductor (172) is coupled to the lower surface (142) of moveable contact arm (106). In another configuration, the flexible conductor (170) is connected at opposite ends of the moveable contact arm (106). It is contemplated that the flexible conductor (172) may be affixed to the moveable contact arm (106) and the lower arc runner (170) by a weld or any other suitable means of permanently bonding the flexible conductor (172) in place.
When the moveable contact arm (106) is moved to the open position, it can be seen that the ends of the moveable contact arm (106) come within close proximity to two raised portions (174, 176) of lower arc runner (170). This close proximity, along with the force of the magnetic field, urges any arc (138) that forms during opening of the contacts, to be transferred off of the contacts (102, 108), onto the stationary and moveable contact arms (106, 112) and onto the lower arc runner (170) and into the arc path (152, 156) depending on the polarity of the DC voltage.
The urging of the arc (138) into either the first or second arc path (152, 156) is further discussed above in connection with
It is contemplated that the various conductive portions of the circuit interrupter (100) can be supplied as a metal conductive material as is commonly used in the art, and the housing can be provided as an insulating material, such as a thermoset polyester resin material or the like, as is commonly used in the art.
Referring now specifically to
The circuit interrupter (200) is provided with a stationary contact (202), which is electrically connected to a line terminal (204) via a conductor (206). The line terminal (204) receives electrical power from a power source (not shown), which in some applications is supplied by a power company. It will, however, be understood by those of skill in the art that the power may be provided and conditioned by any commercial means including, but not limited to, a commercial electrical power grid, a generator(s), solar panels, fuel cells, and so on. In the present example, stationary contact (202) is connected to a lower arc runner (208), as discussed in more detail below. Those of skill in the art will understand that lower arc runner (208) may be connected in a number of different configurations as desired without departing from aspects of the invention.
A movable contact (210) is disposed on a movable contact arm (212), which is pivotable between a closed and an open position relative to the stationary contact (202). In
Movable contact (210) is connected to load terminal (214) through a conductor (216). When contact arm (212) is in the closed position as shown, movable contact (210) is electrically connected to stationary contact (202) such that electrical current is allowed to flow between line terminal (204) and load terminal (214).
When the moveable contact (210) is pivoted with contact arm (212) away from stationary contact (202), it is contemplated that an arc (not shown) may form in the space between the contacts. As discussed previously, the formation of an arc can have deleterious effects on the circuit breaker (200) itself and surrounding equipment. Accordingly, it is advantageous to extinguish the arc as quickly as possible. To accomplish this, a lower leg (218) of pole piece (26) (as shown in
In the embodiment of
As is shown in
The urging of the arc into either the first or second arc path (224, 226) is further discussed above in connection with
The present invention thus provides for enhanced arc quenching that is polarity independent, while also minimizing the amount of power consumed (and thus heat generated).
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.
This application claims the benefit of priority to U.S. Provisional Patent Application No. 63/254,685, filed Oct. 12, 2021, entitled “Bi-Directional DC Circuit Breaker with Smart Electromagnetic Arc Blow,” which application is incorporated herein by reference in its entirety.
Number | Date | Country | |
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63254685 | Oct 2021 | US |