Circuit breakers, sometimes referred to as circuit interrupters, include electrical contacts that connect to each other to pass current from a source to a load. The contacts may be separated in order to interrupt the delivery of current, either in response to a command or to protect electrical systems from electrical fault conditions such as current overloads, short circuits, and low level voltage conditions.
Opening the contacts in a circuit breaker can create an arc. To avoid this result, circuit breakers may use an insulated gas, oil, or a vacuum chamber in order to extinguish the current and the arc. Vacuum circuit interrupters include a separable pair of contacts positioned within an insulated and hermetically sealed vacuum chamber. The chamber is contained within a housing. Typically, one of the contacts is moveable and the other is fixed with respect to the housing, although in some vacuum interrupters both contacts may be moveable.
In certain circuits, such as medium voltage direct current (DC) circuits, it is desirable to have a vacuum circuit interrupter in which the contacts move with a fast opening speed. Some ultra-fast switching mechanisms can have opening speeds of as much as 5 meters per second (m/s), as compared to traditional vacuum circuit interrupters in which the opening speed is 0.5 to 1 m/s. However, fast opening speeds can create issues. Because the contacts' velocity of travel must remain high all the way through the contacts' end-of-travel position, contacts can slam against other parts, creating wear, bounce and other undesirable effects.
To mitigate this, in the prior art vacuum circuit interrupters have used dampers in the form of springs, rubber, and other elastic structures that serve as an energy absorber at the end of travel. However, when such materials are repeatedly compressed, their durability can deteriorate. In addition, when the movable contact hits the fixed contact it can bounce back, creating vibration and reducing the ability to precisely control movement of the moveable contact and thus the current interruption performance
This document describes methods and systems that are intended to address some or all of the problems described above.
In various embodiments, a circuit interrupter system includes a vacuum circuit interrupter that has a fixed contact and a moveable contact, both of which are contained within a vacuum chamber. A non-conductive rod is connected to the moveable contact and extends from the vacuum chamber. An actuator is connected to the non-conductive rod. The actuator can selectively move the non-conductive rod in a first direction that will drive the moveable contact away from the fixed contact, and in a second direction that will drive the moveable contact away from the fixed contact. A damper that provides an active damping force to the non-conductive rod when the non-conductive rod is moved in the first direction, the second direction, or both the first direction and the second direction. The damper includes a solenoid and a plunger.
Optionally, the actuator may include a Thomson coil that is wound around the non-conductive rod, an armature that is connected to the non-conductive rod, and a driver that is configured to energize the Thomson coil so that when the Thomson coil is energized the armature will be repelled from the Thomson coil and move the non-conductive rod in the second direction and open the vacuum circuit interrupter.
Optionally, the actuator may include a first Thomson coil that is wound around the non-conductive rod, a second Thomson coil that is wound around the non-conductive rod, an armature that is connected to the non-conductive rod and positioned between the first Thomson coil and the second Thomson coil, and a driver. The driver may be configured to selectively energize the first Thomson coil and the second Thomson coil. When the first Thomson coil is energized, the armature may be repelled from the first Thomson coil, and the armature will move the non-conductive rod in the first direction. When the second Thomson coil is energized, the armature may be repelled from the second Thomson coil, and the armature will move the non-conductive rod in the second direction.
Optionally, the actuator may include a first Thomson coil that is wound around the non-conductive rod, a second Thomson coil that is wound around the non-conductive rod, a first armature that is connected to the non-conductive rod and positioned between the first Thomson coil and the vacuum circuit interrupter, a second armature that is connected to the non-conductive rod and positioned so that the second Thomson coil is between the vacuum circuit interrupter and the second armature, and a driver. The driver may be configured to selectively energize the first Thomson coil and the second Thomson coil. When the first Thomson coil is energized, the first armature may be repelled from the first Thomson coil, and the first armature may thus move the non-conductive rod to close the vacuum circuit interrupter. When the second Thomson coil is energized, the second armature may be repelled from the second Thomson coil, and the second armature may move the non-conductive rod in the second direction to open the vacuum circuit interrupter.
Optionally, the plunger may include a permanent magnet. Also optionally, the system may include a solenoid actuator that is electrically connected to the solenoid and that is configured to vary damping force of the damper by varying a level of voltage or current provided to the solenoid.
In various additional embodiments, a circuit interrupter system includes a vacuum circuit interrupter having a fixed contact and a moveable contact contained within a vacuum chamber. A non-conductive rod is connected to the moveable contact and extends from the vacuum chamber. An actuator is connected to the non-conductive rod. The actuator may include a first Thomson coil that is wound around the non-conductive rod, a first armature that is connected to the non-conductive rod, and a driver that is configured to energize the first Thomson coil so that when the first Thomson coil is energized the armature will be repelled from the first Thomson coil and move the non-conductive rod to open the vacuum circuit interrupter. The system also may include a damper that includes a solenoid and a permanent magnet that is configured to provide an active damping force to the non-conductive rod when the non-conductive rod is moved to open the vacuum circuit interrupter.
Optionally, the actuator may include a second Thomson coil that is wound around the non-conductive rod, and the armature may be positioned between the first Thomson coil and the second Thomson coil. If so, the driver may be configured to selectively energize the first Thomson coil and the second Thomson coil so that when the second Thomson coil is energized, the armature will be repelled from the second Thomson coil, and the armature will move the non-conductive rod to close the vacuum circuit interrupter. Optionally, the damper also may be configured to provide an active damping force to the non-conductive rod when the non-conductive rod is moved to close the vacuum circuit interrupter.
Optionally, the first armature may be positioned between the first Thomson coil and the vacuum circuit interrupter, and the actuator also may include a second armature that is connected to the non-conductive rod, and a second Thomson coil that is positioned between the second armature and the first Thomson coil. The driver also may be configured to selectively energize the first Thomson coil and the second Thomson coil so that when the second Thomson coil is energized, the second armature will be repelled from the second Thomson coil, and the second armature will move the non-conductive rod to close the vacuum circuit interrupter.
Optionally, the circuit interrupter system may include a solenoid actuator that is electrically connected to the solenoid and that is configured to vary damping force of the damper by varying a level of voltage or current provided to the solenoid.
In any of the embodiments described above, the damper may be connected to the non-conductive rod. The actuator may be positioned between the damper and the vacuum circuit interrupter. Alternatively, the damper may be positioned between the actuator and the vacuum circuit interrupter. Alternatively, the damper may be connected to an additional non-conductive rod that is connected to the fixed contact, and that extends from the vacuum chamber.
In various additional embodiments, a method of operating a vacuum circuit interrupter may include actuating an actuator to operate a vacuum circuit interrupter that comprises a fixed contact and a moveable contact contained within a vacuum chamber. The actuator may include a first Thomson coil that is wound around the non-conductive rod, a first armature that is connected to the non-conductive rod, and a driver that is configured to energize the first Thomson coil. The actuator may be connected to a non-conductive rod that is connected to the moveable contact and that extends from the vacuum chamber. The actuating may include, by the driver, energizing the first Thomson coil so that when the first Thomson coil is energized the first armature will be repelled from the first Thomson coil and move the non-conductive rod to open the vacuum circuit interrupter. The method also may include causing a damper that is attached to the non-conductive rod to apply an active damping force to the non-conductive rod when the non-conductive rod is moved.
Optionally, the actuator also may include a second Thomson coil that is wound around the non-conductive rod, and the first armature may be positioned between the first and second Thomson coils. If so, then the actuating also may include, by the driver, energizing the second Thomson coil so that when the second Thomson coil is energized the first armature will be repelled from the second Thomson coil and move the non-conductive rod to close the vacuum circuit interrupter. Alternatively, the actuator may include both a second Thomson coil that is wound around the non-conductive rod and a second armature that is connected to the non-conductive rod, and the two Thomson coils may be positioned between the two armatures. If so, then the actuating may include, by the driver, energizing the second Thomson coil so that when the second Thomson coil is energized the second armature will be repelled from the second Thomson coil and move the non-conductive rod to open the vacuum circuit interrupter.
As used in this document, the singular forms “a,” “an,” and “the” include plural references unless the context clearly dictates otherwise. Unless defined otherwise, all technical and scientific terms used in this document have the same meanings as commonly understood by one of ordinary skill in the art. As used in this document, the term “comprising” (or “comprises”) means “including (or includes), but not limited to.” When used in this document, the term “exemplary” is intended to mean “by way of example” and is not intended to indicate that a particular exemplary item is preferred or required.
In this document, when terms such “first” and “second” are used to modify a noun, such use is simply intended to distinguish one item from another, and is not intended to require a sequential order unless specifically stated. The term “approximately,” when used in connection with a numeric value, is intended to include values that are close to, but not exactly, the number. For example, in some embodiments, the term “approximately” may include values that are within +/−10 percent of the value.
When used in this document, terms such as “top” and “bottom,” “upper” and “lower”, or “front” and “rear,” are not intended to have absolute orientations but are instead intended to describe relative positions of various components with respect to each other. For example, a first component may be an “upper” component and a second component may be a “lower” component when a device of which the components are a part is oriented in a direction in which those components are so oriented with respect to each other. The relative orientations of the components may be reversed, or the components may be on the same plane, if the orientation of the structure that contains the components is changed. The claims are intended to include all orientations of a device containing such components.
In this document, values that are described as being approximate, or that are characterized as being “approximately” a value, are intended to include a range of plus or minus 10 percent around the value.
In
In some embodiments, the driver 120 may selectively energize either the first Thomson coil 111 or the second Thomson coil 112. When the driver 120 energizes the first Thomson coil 111, the first Thomson coil 111 will generate a magnetic force that will repel the conductive plate 113 away from the first Thomson coil 111 and toward the second Thomson coil 112. This causes the rod 105 to move in a downward direction in the orientation shown, which moves the moveable contact 104 away from the fixed contact 103 and opens the circuit. In some embodiments, such as those in which a fast closing operation is desired, when the driver 120 energizes the second Thomson coil 112, the second Thomson coil 112 will generate a magnetic force that will repel the conductive plate 113 away from the second Thomson coil 112 and toward the first Thomson coil 111. This causes the rod 105 to move in an upward direction in the orientation shown, which moves the moveable contact 104 toward the fixed contact 103 and closes the circuit.
Alternatively as shown in
In
In some embodiments, the dampening force may vary as a function of the force applied to by the actuator, as well as the force applied by friction. This may be illustrated by the equation:
in which
is the damping force, t=time, FTC=the force applied by the actuator (such as the example Thomson coil), FEM=the active control force applied by the electromagnetic damper to provide damping to the rod, and FFRIC=the force of friction in the system.
In
In
Alternatively, the damper 330C or 330B may be positioned between actuator 310 and the vacuum circuit interrupter 301. In this embodiment, a contact spring 341 may be connected to the rod 305 between the actuator 310 and the vacuum circuit interrupter 301. The contact spring 341 provides additional damping force, but is optional and not required in all embodiments. If so, the damper 330B may be positioned in location B between the contact spring 341 and the vacuum circuit interrupter 301, or the damper 330C may be positioned in location C between the contact spring 341 and the actuator 310.
As an additional alternative, the damper 330A may be connected to the fixed contact 303, between the fixed electrodes of the vacuum interrupter 301 and ground. In this position the damper 330A would provide damping forces but the overall system, but it would not hold the rod 305 in any particular position.
In the various options shown in
The features and functions described above, as well as alternatives, may be combined into many other different systems or applications. Various alternatives, modifications, variations or improvements may be made by those skilled in the art, each of which is also intended to be encompassed by the disclosed embodiments.
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Vilchis-Rodriguez D.S. et al., Double-sided Thomson coil based actuator: Finite element design and performance analysis, ResearchGate, Conference Paper, Jan. 2016. |