Electrical contactor with passive fault response, and method of operation

Abstract

A contactor with passive fault response is disclosed that includes a moveable contact and an actuator assembly coupled to the moveable contact. The contactor also includes an actuator circuit configured, when energized, to generate a magnetic hold force that maintains the moveable contact in a closed position and a ferromagnetic base plate having a region shaped to conduct magnetic flux generated by current in a high-voltage circuit. The contactor also includes a ferromagnetic trip yoke positioned to intercept magnetic flux from the high-voltage circuit and redirect the intercepted flux into the actuator assembly in a direction opposing a magnetic flux produced by the actuator circuit. The redirected flux reduces the magnetic hold force during a fault condition and when the magnetic hold force falls below a spring force of the spring mechanism, the spring mechanism opens the moveable contact to interrupt the fault current without external sensing or control.

Description

ELECTRICAL CONTACTOR WITH PASSIVE FAULT RESPONSEFIELD OF THE TECHNOLOGY

[0001] The subject disclosure relates to an electrical contactor with passive fault response. BACKGROUND

[0002] Electromechanical switching devices, such as contactors and relays, are generally designed to carry a specified range of electrical currents for a corresponding range of operating times. However, many conventional designs struggle to perform reliably during very high current, short-duration events, commonly referred to as short-circuits, which can generate electromagnetic forces that separate the internal electrical contacts in an uncontrolled manner (often referred to as contact levitation), leading to severe arcing and potential damage.

[0003] In many commercialized contactor designs, low- and mid-level fault currents are not passively detected or interrupted by the contactor itself. These devices typically exhibit a grayzone of operation in which the fault current produces a contact blow-off force that is approximately equal to the counteracting spring force (F = 0), a condition under which arcing and contact welding are likely to occur. Faults below this F = 0 point are often ridden through until a controller or protection device initiates fault-mitigating action, while faults significantly above the F = 0 point may generate sufficient blow-off force to kinetically open the contactor by mechanical action alone, which can be unpredictable and may result in contact damage.SUMMARY

[0004] The following summary is meant to help one skilled in the art understand the various presently disclosed combinations of features. It is not meant to unduly limit the scope of any pending or future claims relating to the disclosure.

[0005] This disclosure presents contactors with passive fault response and methods of passively interrupting a fault current in a high-voltage circuit using a contactor. In a particular embodiment, an electrical contactor is disclosed that uses a unique "trip yoke" to scavenge flux from a high-voltage current and inject the flux into a magnetic actuator circuit. This forces high reluctance in the actuator circuit causing a reduction in hold force on the actuator assembly. When the hold force is reduced below a force of an actuator assembly spring, the contactor opens and interrupts the fault without external control.

[0006] In this embodiment, the contactor routes all the actuator flux through a channel or "High-Way" in a predetermined direction. The trip yoke is placed over the high-way in a wayto change the flux fields. The design is tuned by changing the thickness of the trip yoke and the width of the flux highway. This contactor design decouples the relationship of contact force to blow-off force, since the contacts are opened before the fault blow-off force equals the contact force (F=0). In the design it is desirable to maximize spring forces to rapid opening, minimum contact resistance and prevent current induced contact ringing.

[0007] In a particular embodiment, a contactor with passive fault response is disclosed that includes a moveable contact configured to selectively connect and disconnect a high-voltage circuit. The contactor also includes an actuator assembly coupled to the moveable contact and biased toward an open position by a spring mechanism. In addition, the contactor also includes an actuator circuit configured, when energized, to generate a magnetic hold force that maintains the moveable contact in a closed position. The contactor also includes a ferromagnetic base plate having a region shaped to conduct magnetic flux generated by current in the high-voltage circuit. In addition, the contactor also includes a ferromagnetic trip yoke positioned to intercept magnetic flux from the high-voltage circuit and redirect the intercepted flux into the actuator assembly in a direction opposing a magnetic flux produced by the actuator circuit. In this embodiment, the redirected flux reduces the magnetic hold force during a fault condition and when the magnetic hold force falls below a spring force of the spring mechanism, the spring mechanism opens the moveable contact to interrupt the fault current without external sensing or control.

[0008] In another embodiment, a method for passively interrupting a fault current in a high- voltage circuit using a contactor is disclosed that includes energizing an actuator circuit of the contactor to generate a magnetic hold force that maintains a moveable contact in a closed position against a spring mechanism during normal operation. In addition, the method also includes conducting current through the high-voltage circuit, the current generating magnetic flux in a region of a base plate shaped to conduct magnetic flux toward a trip yoke. The method also includes intercepting, with the trip yoke, magnetic flux produced by the current in the high-voltage circuit and redirecting the intercepted flux into an actuator assembly in a direction opposing magnetic flux generated by the actuator circuit. In addition, the method also includes reducing, during a fault condition, the magnetic hold force on the actuator assembly as a result of the redirected flux. The method also includes allowing the spring mechanism to drive the moveable contact to an open position when the magnetic hold force falls below a spring force of the spring mechanism, thereby interrupting the fault current without external sensing or control.

[0009] The foregoing and other objects, features and advantages of the invention will be apparent from the following more particular descriptions of exemplary embodiments of the invention as illustrated in the accompanying drawings wherein like reference numbers generally represent like parts of exemplary embodiments of the invention.BRIEF DESCRIPTION OF THE DRAWINGS

[0010] One or more aspects of the present disclosure are discussed below with reference to the accompanying Figures. It will be appreciated that for simplicity and clarity of illustration, elements shown in the drawings have not necessarily been drawn accurately or to scale. For example, the dimensions of some of the elements may be exaggerated relative to other elements for clarity or several physical components may be included in one functional block or element.

[0011] Further, where considered appropriate, reference numerals may be repeated among the drawings to indicate corresponding or analogous elements. For purposes of clarity, however, not every component may be labeled in every drawing. The Figures are provided for the purposes of illustration and explanation and are not intended to be limiting. In the Figures:

[0012] FIG. 1 A is a diagram illustrating an isometric view of an example contactor with passive fault response according to at least one embodiment of the present disclosure.

[0013] FIG. IB is a diagram illustrating another view of the example contactor of FIG. 1A according to at least one embodiment of the present disclosure.

[0014] FIG. 1C is a diagram illustrating another view of the example contactor of FIG. 1A according to at least one embodiment of the present disclosure.

[0015] FIG. ID is a diagram illustrating another view of the example contactor of FIG. 1A according to at least one embodiment of the present disclosure.

[0016] FIG. IE is a diagram illustrating an isometric view of the single sided coil yoke and actuator circuit of FIGs. 1A-D according to at least one embodiment of the present disclosure.

[0017] FIG. 2 is a diagram illustrating an isometric view of an example contactor with passive fault response according to at least one embodiment of the present disclosure.

[0018] FIG. 3A is a graph of test data that indicates device under test (DUT) voltage and coil current vs. time for an example contactor with passive fault response according to at least one embodiment of the present disclosure.

[0019] FIG. 3B is a graph of test data that indicates coil voltage and coil current vs. time for an example contactor with passive fault response according to at least one embodiment of the present disclosure.

[0020] FIG. 3C is a graph of test data that indicates break energy vs. time for an example contactor with passive fault response according to at least one embodiment of the present disclosure.

[0021] FIG. 4 is a diagram illustrating magnetic circuit interactions in an example contactor with passive fault response according to at least one embodiment of the present disclosure.

[0022] FIG. 5 is a flow chart illustrating a method of passively interrupting a fault current in a high-voltage circuit using a contactor.

[0023] FIG. 6 is a flow" chart illustrating another method of passively interrupting a fault current in a high-voltage circuit using a contactor.DETAILED DESCRIPTION

[0024] The terminology used herein for the purpose of describing particular examples is not intended to be limiting for further examples. Whenever a singular form such as “a”, "an" and “the” is used and using only a single element is neither explicitly or implicitly defined as being mandatory, further examples may also use plural elements to implement the same functionality. Likewise, when a functionality is subsequently described as being implemented using multiple elements, further examples may implement the same functionality using a single element or processing entity. It will be further understood that the terms “comprises”, “comprising”, “includes” and / or “including”, when used, specify7the presence of the stated features, integers, steps, operations, processes, acts, elements and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, processes, acts, elements, components and / or any group thereof.

[0025] It will be understood that when an element is referred to as being “connected” or “coupled” to another element, the elements may be directly connected or coupled or via one or more intervening elements. If two elements A and B are combined using an “or”, this is to be understood to disclose all possible combinations, i.e., only A, only B, as well as A and B. An alternative w ording for the same combinations is “at least one of A and B”. The same applies for combinations of more than tw o elements.

[0026] Accordingly, while further examples are capable of various modifications and alternative forms, some particular examples thereof are shown in the figures and will subsequently be described in detail. However, this detailed description does not limit further examples to the particular forms described. Further examples may cover all modifications, equivalents, and alternatives falling within the scope of the disclosure. Like numbers refer to like or similar elements throughout the description of the figures, which may be implementedidentically or in modified form when compared to one another while providing for the same or a similar functionality.

[0027] In general terms, the embodiments described herein relate to contactors that integrate a magnetic trip structure with a modified base plate to provide a passive response to fault currents. In these examples, a moveable contact is actuated by an actuator assembly that is held in a closed position by a magnetic hold force generated by an actuator circuit and biased toward an open position by a spring mechanism. A ferromagnetic base plate includes a region shaped to conduct magnetic flux generated by current in a high-voltage circuit toward an upper ferromagnetic trip yoke positioned adjacent the moveable contact. During a fault condition, the trip yoke scavenges flux from the high-voltage circuit and redirects the flux into the actuator assembly in a direction opposing the flux generated by the actuator circuit, thereby reducing the magnetic hold force. When the reduced magnetic hold force falls below the spring force, the spring mechanism drives the moveable contact to the open position, interrupting the fault current without the need for external sensing or control.

[0028] For further explanation, FIG. 1 A is a diagram illustrating an isometric view of an example contactor with passive fault response according to at least one embodiment of the present disclosure. FIG. IB is a diagram illustrating another view of the example contactor of FIG. 1A according to at least one embodiment of the present disclosure. FIG. 1C is a diagram illustrating another view of the example contactor of FIG. 1A according to at least one embodiment of the present disclosure. FIG. ID is a diagram illustrating another view of the example contactor of FIG. 1 A according to at least one embodiment of the present disclosure. FIG. IE is a diagram illustrating an isometric view of the single sided coil yoke and actuator circuit of FIGs. 1A-D according to at least one embodiment of the present disclosure.

[0029] The contactor 100 of FIGs. 1A includes a moveable contact 106, an upper ferromagnetic trip yoke 105, a high voltage negative (HV -negative) terminal 102, a HV- positive terminal 104, a modified base plate 110 with a flux ferrous material ‘‘High-Way”119, a single sided coil yoke and actuator circuit 115, and an actuator assembly enclosure120. The trip yoke 105 includes an upper ferromagnetic member 199.

[0030] The actuator assembly enclosure 120 houses and protects the components of the actuator assembly. Although not illustrated in FIG. 1A, the actuator assembly may include a plunger tube surrounding a plunger coupled to a plunger shaft, which is coupled to the moveable contact. In this example, a plunger spring may be coupled between the plunger and an upper coil yoke. The moveable contact 106 is configured to create or break the connectionbetween the HV -negative terminal 102 and the HV-positive terminal 104 in response to movement of the actuator assembly. The HV contacts 102, 104 may be coupled to external connections for coupling with external components, such as a power supply and an electrical application.

[0031] In the open state, the moveable contact 106 is not in contact with the HV contacts 102, 104, such that no current flows between the HV contacts 102. 104. In this open state, the plunger spring is configured to apply a pre-load force on the plunger to prevent the actuator assembly from moving to a closed state. In the closed state, the moveable contact 106 is in contact with the HV contacts 102, 104 such that current flows between the HV contacts 102, 104 through the moveable contact 106.

[0032] A controller (not shown in FIG. 1 A) may be coupled to the single sided actuator circuit 115 and configured to control a current flowing to the circuit. When the circuit 115 is connected to a power source and current flows through the circuit, a strong magnetic field is generated that flows through the coil actuator magnetic circuit pathw ay of the contactor. This electromagnetic field is guided by ferromagnetic materials of the contactor and flows in a first direction through the actuator assembly. In a particular embodiment, this magnetic field is guided to the plunger, which resides within the enclosed plunger tube, and magnetizes it. The magnetized plunger is then attracted by a magnetic force to an upper flux tube. The magnetic field forces the plunger with upper direction. When enough magnetic force is generated, the plunger will overcome any retaining spring forces (pre-load force from the plunger spring) and begin to move. The plunger and the plunger shaft drive the moveable contact 106 toward the HA’ contacts 102, 104 until the moveable contact 106 is in a closed position in which contact is established between the moveable contact 106 and the HV contacts 102. 104, thus transitioning the contactor 100 from the open state to the closed state. When the moveable contact 106 touches the HV contacts 102, 104, the high-voltage circuit is closed. When the plunger contacts the upper flux tube, the magnetic circuit is closed.

[0033] When the actuator circuit 115 is disconnected from the low-voltage power source, the ferromagnetic components lose their magnetization and the magnetic force on the plunger decreases. This decrease in magnetic field separates the plunger from the upper flux tube, opening the magnetic circuit. The plunger spring returns the plunger to its original position. That is, when the circuit 115 is de-energized, the plunger is driven downward from the force of the energy stored in the compressed plunger spring, and the actuator assembly pulls the moveable contact 106 downward until the moveable contact 106 is in an open position, thusbreaking the high voltage circuit between the moveable contact 106 and the HV contacts 102, 104.

[0034] In addition, the contactor 100 of FIG. 1A also represents an advancement over prior designs, by passively reacting to fault currents without requiring external control. In traditional systems, fault interruption ty pically depends on a controller to detect the fault and actively command the contactor to open. These designs involve electronics and sensors to monitor current levels, evaluate fault conditions, and trigger the actuator. Such systems introduce several drawbacks, including increased cost, complexity, and potential reliability issues due to the dependency on active components. Furthermore, many prior designs rely on irreversible mechanisms such as pyrotechnic (PYRO) fuses, which sever the circuit explosively and require replacement after each activation.

[0035] In contrast, the contactor 100 of FIG. 1 A passively detects and reacts to fault currents, eliminating the need for active monitoring systems. The trip yoke 105 scavenges magnetic flux from the fault current and redirects it into the actuator assembly, creating a trip yoke magnetic circuit that flows through the actuator assembly in a second direction that is opposite the first direction of the coil actuator magnetic circuit. The interactions of the trip yoke magnetic circuit and the coil actuator magnetic circuit flowing in opposite directions through the actuator assembly, reduces the magnetic hold force on the actuator assembly keeping the moveable contact 106 closed. Once this hold force drops below the opposing force of the high-strength plunger spring, the plunger spring rapidly drives the moveable contact open, interrupting the fault current. This passive process occurs inherently within the system’s magnetic and mechanical structure, requiring no external control or intervention. In the example of FIG. IB, the contactor 100 also includes a non-ferrous sealing plate 121 coupled to the bottom of the base plate 110 to help direct the magnetic circuit through the high way 119. In addition, FIGs. 1B-D include ferromagnetic plates 116 on either side of the trip yoke 105.

[0036] For further explanation, FIG. 2 sets forth a diagram illustrating an isometric view of an example contactor 200 with passive fault response according to at least one embodiment of the present disclosure. The contactor 200 includes a moveable contact 206 configured to make or break a connection between a high voltage negative (HV -negative) terminal (not pictured) and aHV-positive terminal (not pictured). An upper ferromagnetic trip yoke 205 surrounds the moveable contact 206 and is coupled to a modified base plate with flux “High- Way” 210. In the example of FIG. 2, a single sided actuator circuit 215 is configured to control an electric circuit an actuator assembly enclosure 220. As with the design of FIG.1 A, the contactor 200 of FIG. 2 is configured to passively detect and react to fault currents, eliminating the need for active monitoring systems. The trip yoke 205 scavenges magnetic flux from the fault current and redirects it into the single-sided actuator circuit 215. The contactor 200 includes ferromagnetic plates 299 on either side of the trip yoke 205. By increasing the reluctance of the actuator circuit, the trip yoke passively reduces the magnetic hold force on the actuator assembly keeping the moveable contact 206 closed. Once this hold force drops below the opposing force of a high-strength plunger spring, the plunger spring rapidly drives the moveable contact 206 open, interrupting the fault current. This passive process occurs inherently within the system’s magnetic and mechanical structure, requiring no external control or intervention.

[0037] For further explanation, FIGs. 3A-C illustrate the behavior of the contactor during a fault-clearing event, showcasing its passive fault-response mechanism as described earlier. FIG. 3A shows the voltage and current profiles for the device under test (DUT). The DUT voltage 432 remains steady during normal operation, indicating a closed circuit. At approximately 0.025 seconds, the current 430 begins to drop rapidly as the moveable contact 106 opens, interrupting the fault current. As the fault is cleared, the DUT voltage stabilizes at a higher level, and the current approaches zero, demonstrating successful fault isolation. FIG. 3B displays the behavior of the coil of the single-sided actuator circuit 115 during the faultclearing process. The coil voltage reflects the electromagnetic interactions as the trip yoke 105 scavenges flux and increases the circuit's reluctance, reducing the hold force on the actuator assembly. Simultaneously, the coil current 440 changes as the actuator assembly transitions from holding the contact closed to allowing it to open under the spring force. FIG. 3C illustrates the rise in break energy' over time, which remains negligible during normal operation but increases sharply after 0.025 seconds when the fault-clearing process begins. This energy rise reflects the work done by the system to open the contacts and dissipate the fault current, eventually leveling off as the fault is fully cleared. Together, the figures demonstrate the passive fault-clearing capability' of the contactor, with the system autonomously interrupting the fault current without external control, highlighting its efficiency, reliability, and cost-effectiveness.

[0038] For further explanation, FIG. 4 is a diagram illustrating magnetic circuit interactions in an example contactor 400 with passive fault response according to at least one embodiment of the present disclosure. The contactor 400 of FIG. 4 includes a moveable contact 406, an upper ferromagnetic trip yoke 405, a high voltage negative (HV -negative) terminal 402, a HV-positive terminal 404, a modified base plate 410 with a flux ferrous material “High-Way”419, a two-sided coil yoke and actuator circuit 415, and an actuator assembly enclosure 420. The trip yoke 405 includes an upper ferromagnetic member 499.

[0039] The actuator assembly enclosure 420 houses and protects the components of the actuator assembly. Although not illustrated in FIG. 4, the actuator assembly may include a plunger tube surrounding a plunger coupled to a plunger shaft, which is coupled to the moveable contact. In this example, a plunger spring may be coupled between the plunger and an upper coil yoke. The moveable contact 406 is configured to create or break the connection between the HV -negative terminal 402 and the HV-positive terminal 404 in response to movement of the actuator assembly. The HV contacts 402, 404 may be coupled to external connections for coupling with external components, such as a power supply and an electrical application.

[0040] In the open state, the moveable contact 406 is not in contact with the HV contacts 402, 404, such that no current flows between the HV contacts 402, 404. In this open state, the plunger spring is configured to apply a pre-load force on the plunger to prevent the actuator assembly from moving to a closed state. In the closed state, the moveable contact 406 is in contact with the HV contacts 402, 404 such that current flows between the HV contacts 402, 404 through the moveable contact 406.

[0041] A controller (not show n in FIG. 4) may be coupled to the two-sided coil yoke and actuator circuit 415 and configured to control a current flowing to the circuit. When the circuit 415 is connected to a power source and current flows through the circuit, a strong magnetic field is generated that flows through the coil actuator magnetic circuit pathway of the contactor. This electromagnetic field is guided by ferromagnetic materials of the contactor and flows in a first direction through the actuator assembly indicated by arrows 432. In a particular embodiment, this magnetic field is guided to the plunger, which resides within the enclosed plunger tube, and magnetizes it. The magnetized plunger is then attracted by a magnetic force to an upper flux tube. The magnetic field forces the plunger with upper direction. When enough magnetic force is generated, the plunger will overcome any retaining spring forces (pre-load force from the plunger spring) and begin to move. The plunger and the plunger shaft drive the moveable contact 406 toward the HV contacts 402, 404 until the moveable contact 406 is in a closed position in which contact is established betw een the moveable contact 406 and the HV contacts 402, 404, thus transitioning the contactor 400 from the open state to the closed state. When the moveable contact 406 touches the HV contacts 402. 404, the high-voltage circuit is closed. When the plunger contacts the upper flux tube, the magnetic circuit is closed.

[0042] When the actuator circuit 415 is disconnected from the low-voltage power source, the ferromagnetic components lose their magnetization and the magnetic force on the plunger decreases. This decrease in magnetic field separates the plunger from the upper flux tube, opening the magnetic circuit. The plunger spring returns the plunger to its original position. That is, when the circuit 415 is de-energized, the plunger is driven downward from the force of the energy stored in the compressed plunger spring, and the actuator assembly pulls the moveable contact 406 downward until the moveable contact 406 is in an open position, thus breaking the high voltage circuit between the moveable contact 406 and the HV contacts 402, 404.

[0043] In addition, the contactor 400 of FIG. 4 also represents an advancement over prior designs, by passively reacting to fault currents without requiring external control. In traditional systems, fault interruption typically depends on a controller to detect the fault and actively command the contactor to open. These designs involve electronics and sensors to monitor current levels, evaluate fault conditions, and trigger the actuator. Such systems introduce several drawbacks, including increased cost, complexity, and potential reliabilityissues due to the dependency on active components. Furthermore, many prior designs rely on irreversible mechanisms such as pyrotechnic (PYRO) fuses, which sever the circuit explosively and require replacement after each activation.

[0044] In contrast, the contactor 400 of FIG. 4 passively detects and reacts to fault currents, eliminating the need for active monitoring systems. The trip yoke 405 scavenges magnetic flux from the fault current and redirects it into the actuator assembly, creating a trip yoke magnetic circuit that flows through the actuator assembly in a second direction indicated by arrow s 431 that is opposite the first direction of the coil actuator magnetic circuit 432. In the example of FIG. 4. there is a reluctance gap 440 in the base plate 410 to direct the trip yoke magnetic circuit from one end of the trip yoke 405 to one side of the actuator circuit 415. The interactions of the trip yoke magnetic circuit 431 and the coil actuator magnetic circuit 432 flowing in opposite directions through the actuator assembly, reduces the magnetic hold force on the actuator assembly keeping the moveable contact 406 closed. Once this hold force drops below the opposing force of the high-strength plunger spring, the plunger spring rapidly drives the moveable contact open, interrupting the fault current. This passive process occurs inherently within the system’s magnetic and mechanical structure, requiring no external control or intervention.

[0045] For further explanation, FIG. 5 sets forth a flow chart illustrating a method of passively interrupting a fault current in a high-voltage circuit using a contactor.

[0046] The method of FIG. 5 includes energizing 502 an actuator circuit of the contactor to generate a magnetic hold force that maintains a moveable contact in a closed position against a spring mechanism during normal operation. The step of energizing 502 the actuator circuit may be carried out by supplying electrical current to the coil of the actuator circuit to establish a magnetic circuit through the actuator assembly. In various embodiments, the energizing step magnetizes a plunger or other portion of the actuator assembly, generating a magnetic hold force that overcomes the bias of the spring mechanism and maintains the movable contact in the closed position during normal operation.

[0047] The method of FIG. 5 also includes conducting 504 current through the high-voltage circuit, the current generating magnetic flux in a region of a base plate shaped to conduct magnetic flux toward a trip yoke. As this current flows, magnetic flux is produced and guided through the shaped ferromagnetic region of the base plate, concentrating the flux toward the trip yoke for passive fault-responsive operation.

[0048] In addition, the method of FIG. 5 includes intercepting 506, with the trip yoke, magnetic flux produced by the current in the high-voltage circuit. Magnetic flux may be intercepted 506 by positioning the trip yoke so that flux produced by the high-voltage current naturally couples into its ferromagnetic structure. In some embodiments, the trip yoke geometry' and placement are selected to efficiently capture a sufficient portion of the faultgenerated magnetic field to initiate the passive response mechanism.

[0049] The method of FIG. 5 includes redirecting 508 the intercepted flux into an actuator assembly in a direction opposing magnetic flux generated by the actuator circuit. By routing the flux in an opposing direction, the redirected flux interferes with the coil-generated magnetic field and weakens the magnetic hold force acting on the actuator assembly.

[0050] In addition, the method of FIG. 5 includes reducing 510, during a fault condition, the magnetic hold force on the actuator assembly as a result of the redirected flux. Reduction of the magnetic hold force 510 may occur as the redirected flux increases the magnetic reluctance wi thin the actuator assembly and disrupts the continuity of the coil-generated magnetic circuit. During a fault condition, this reduction develops automatically when the fault current induces sufficient flux into the trip yoke to overcome the holding capability of the energized actuator circuit.

[0051] The method of FIG. 5 includes allowing 512 the spring mechanism to drive the moveable contact to an open position when the magnetic hold force falls below a spring force of the spring mechanism, thereby interrupting the fault current without external sensing or control. Allowing 512 the spring mechanism to drive the movable contact to an openposition may be carried out by permitting the plunger spring within the actuator assembly to extend once the magnetic hold force becomes insufficient to counteract its stored mechanical energy. In certain embodiments, this spring-driven motion pulls the movable contact away from the high-voltage terminals, mechanically opening the circuit and interrupting the fault current without requiring any external sensing or control signals.

[0052] For further explanation, FIG. 6 sets forth a flow chart illustrating another method of passively interrupting a fault current in a high-voltage circuit using a contactor.

[0053] The method of FIG. 6 includes selecting 602 a geometry of the region of the base plate configured to conduct magnetic flux to set a threshold fault current at which the moveable contact opens. Selecting 602 a geometry of the region of the base plate configured to conduct magnetic flux may be carried out by adjusting dimensions such as the width, thickness, or cross-sectional profile of the ferromagnetic portion that channels flux toward the trip yoke. In various embodiments, these geometric adjustments determine the amount of magnetic flux coupled into the trip yoke during a fault, thereby setting the threshold fault current at which the movable contact opens.

[0054] In addition, the method of FIG. 6 also includes selecting 604 a thickness of the trip yoke to tune a threshold fault current. Selecting 604 a thickness of the trip yoke may be carried out by increasing or decreasing the cross-sectional thickness of the ferromagnetic material used to form the trip yoke so as to control the amount of magnetic flux it can intercept and redirect. In various embodiments, modifying this thickness adjusts the magnetic coupling between the high-voltage circuit and the actuator assembly, thereby tuning the threshold fault current at which the movable contact opens.

[0055] The flowchart and block diagrams in the figures illustrate the architecture, functionality, and operation of possible implementations of systems, apparatuses, and methods, according to various embodiments of the present invention. In this regard, each block in the flowchart or block diagrams may represent a module, segment, or portion of instructions, which comprises one or more instructions for implementing the specified logical function(s). In some alternative implementations, the functions noted in the block may occur out of the order noted in the figures. For example, two blocks shown in succession may, in fact, be executed substantially concurrently, or the blocks may sometimes be executed in the reverse order, depending upon the functionality involved.

[0056] Advantages and features of the present disclosure can be further described by the following statements:

[0057] 1. A contactor with passive fault response, comprising: a moveable contact configured to selectively connect and disconnect a high-voltage circuit; an actuator assembly coupled to the moveable contact and biased toward an open position by a spring mechanism; an actuator circuit configured, when energized, to generate a magnetic hold force that maintains the moveable contact in a closed position; a ferromagnetic base plate having a region shaped to conduct magnetic flux generated by current in the high-voltage circuit; and a ferromagnetic trip yoke positioned to intercept magnetic flux from the high-voltage circuit and redirect the intercepted flux into the actuator assembly in a direction opposing a magnetic flux produced by the actuator circuit; wherein the redirected flux reduces the magnetic hold force during a fault condition, and wherein, when the magnetic hold force falls below a spring force of the spring mechanism, the spring mechanism opens the moveable contact to interrupt the fault current without external sensing or control.

[0058] 2. The contactor of statement 1, wherein the region of the base plate configured to conduct magnetic flux comprises a shaped ferromagnetic portion of the base plate that channels magnetic flux generated by current in the high-voltage circuit toward the trip yoke.

[0059] 3. The contactor of statement 1 or 2, wherein the base plate includes a reluctance gap positioned to direct magnetic flux intercepted by the trip yoke into a portion of the actuator circuit.

[0060] 4. The contactor of any of statements 1-3, wherein a geometry of the region of the base plate configured to conduct magnetic flux is selected to tune a fault-current threshold at which the moveable contact opens.

[0061] 5. The contactor of any of statements 1-4, wherein the trip yoke comprises an upper ferromagnetic member positioned above the moveable contact.

[0062] 6. The contactor of any of statements 1-5, wherein the actuator assembly includes a plunger and a plunger shaft mechanically coupled to the moveable contact.

[0063] 7. The contactor of any of statements 1-6, wherein the spring mechanism comprises a plunger spring configured to bias the plunger toward the open position.

[0064] 8. The contactor of any of statements 1-7, wherein the actuator circuit comprises a single-sided coil yoke.

[0065] 9. The contactor of any of statements 1-8, wherein the actuator circuit comprises a two-sided coil yoke.

[0066] 10. The contactor of any of statements 1 -9, further comprising ferromagnetic plates positioned on opposite sides of the trip yoke and configured to guide magnetic flux from the high-voltage circuit into the trip yoke.

[0067] 11. The contactor of any of statements 1-10, further comprising a non-ferromagnetic sealing plate coupled to the base plate and configured to direct magnetic flux through the region of the base plate configured to conduct magnetic flux.

[0068] 12. The contactor of any of statements 1-11, wherein the contactor operates without an electronic controller configured to command opening of the moveable contact in response to the fault condition.

[0069] 13. A method for passively interrupting a fault current in a high-voltage circuit using a contactor, the method comprising: energizing an actuator circuit of the contactor to generate a magnetic hold force that maintains a moveable contact in a closed position against a spring mechanism during normal operation; conducting current through the high-voltage circuit, the current generating magnetic flux in a region of a base plate shaped to conduct magnetic flux toward a trip yoke; intercepting, with the trip yoke, magnetic flux produced by the current in the high-voltage circuit;redirecting the intercepted flux into an actuator assembly in a direction opposing magnetic flux generated by the actuator circuit;reducing, during a fault condition, the magnetic hold force on the actuator assembly as a result of the redirected flux; and allowing the spring mechanism to dnve the moveable contact to an open position when the magnetic hold force falls below a spring force of the spring mechanism, thereby interrupting the fault current without external sensing or control.

[0070] 14. The method of any of statement 13, further comprising selecting a geometry of the region of the base plate configured to conduct magnetic flux to set a threshold fault current at which the moveable contact opens.

[0071] 15. The method of any of statements 13-14, further comprising selecting a thickness of the trip yoke to tune a threshold fault current.

[0072] 16. The method of any of statements 13-15, wherein magnetic flux redirected by the trip yoke opposes magnetic flux from the actuator circuit within the actuator assembly.

[0073] 17. The method of any of statements 13-16, wherein the region of the base plate configured to conduct magnetic flux comprises a shaped ferromagnetic portion of the base plate that channels magnetic flux generated by current in the high-voltage circuit toward the trip yoke.

[0074] 18. The method of any of statements 13-17, wherein the base plate includes a reluctance gap positioned to direct magnetic flux intercepted by the trip yoke into a portion of the actuator circuit.

[0075] 19. The method of any of statements 13-18, wherein the actuator circuit comprises a single-sided coil yoke.

[0076] 20. The method of any of statements 13-19, wherein the actuator circuit comprises a two-sided coil yoke.

[0077] It will be understood from the foregoing description that modifications and changes may be made in various embodiments of the present disclosure without departing from its true spirit. The descriptions in this specification are for purposes of illustration only and are not to be construed in a limiting sense.

Claims

CLAIMSWhat is claimed is:1 . A contactor with passive fault response, comprising: a moveable contact configured to selectively connect and disconnect a high-voltage circuit; an actuator assembly coupled to the moveable contact and biased toward an open position by a spring mechanism; an actuator circuit configured, when energized, to generate a magnetic hold force that maintains the moveable contact in a closed position; a ferromagnetic base plate having a region shaped to conduct magnetic flux generated by current in the high-voltage circuit; and a ferromagnetic trip yoke positioned to intercept magnetic flux from the high-voltage circuit and redirect the intercepted flux into the actuator assembly in a direction opposing a magnetic flux produced by the actuator circuit; wherein the redirected flux reduces the magnetic hold force during a fault condition, and wherein, when the magnetic hold force falls below a spring force of the spring mechanism, the spring mechanism opens the moveable contact to interrupt the fault current without external sensing or control.

2. The contactor of claim 1. wherein the region of the base plate configured to conduct magnetic flux comprises a shaped ferromagnetic portion of the base plate that channels magnetic flux generated by current in the high-voltage circuit toward the trip yoke.

3. The contactor of claim 1. wherein the base plate includes a reluctance gap positioned to direct magnetic flux intercepted by the trip yoke into a portion of the actuator circuit.

4. The contactor of claim 1 , wherein a geometry of the region of the base plate configured to conduct magnetic flux is selected to tune a fault-current threshold at which the moveable contact opens.

5. The contactor of claim 1 , wherein the trip yoke comprises an upper ferromagnetic member positioned above the moveable contact.

6. The contactor of claim 1. wherein the actuator assembly includes a plunger and a plunger shaft mechanically coupled to the moveable contact.

7. The contactor of claim 6. wherein the spring mechanism comprises a plunger spring configured to bias the plunger toward the open position.

8. The contactor of claim 1, wherein the actuator circuit comprises a single-sided coil yoke.

9. The contactor of claim 1 , wherein the actuator circuit comprises a two-sided coil yoke.

10. The contactor of claim 1. further comprising ferromagnetic plates positioned on opposite sides of the trip yoke and configured to guide magnetic flux from the high- voltage circuit into the trip yoke.

11. The contactor of claim 1. further comprising a non-ferromagnetic sealing plate coupled to the base plate and configured to direct magnetic flux through the region of the base plate configured to conduct magnetic flux.

12. The contactor of claim 1, wherein the contactor operates without an electronic controller configured to command opening of the moveable contact in response to the fault condition.

13. A method for passively interrupting a fault current in a high-voltage circuit using a contactor, the method comprising: energizing an actuator circuit of the contactor to generate a magnetic hold force that maintains a moveable contact in a closed position against a spring mechanism during normal operation; conducting current through the high-voltage circuit, the current generating magnetic flux in a region of a base plate shaped to conduct magnetic flux toward a trip yoke; intercepting, with the trip yoke, magnetic flux produced by the current in the high- voltage circuit; redirecting the intercepted flux into an actuator assembly in a direction opposing magnetic flux generated by the actuator circuit; reducing, during a fault condition, the magnetic hold force on the actuator assembly as a result of the redirected flux; and allowing the spring mechanism to drive the moveable contact to an open position when the magnetic hold force falls below a spring force of the spring mechanism, thereby interrupting the fault current without external sensing or control.

14. The method of claim 13, further comprising selecting a geometry of the region of the base plate configured to conduct magnetic flux to set a threshold fault current at which the moveable contact opens.

15. The method of claim 13, further comprising selecting a thickness of the trip yoke to tune a threshold fault current.

16. The method of claim 13, wherein magnetic flux redirected by the trip yoke opposes magnetic flux from the actuator circuit within the actuator assembly.

17. The method of claim 13, wherein the region of the base plate configured to conduct magnetic flux comprises a shaped ferromagnetic portion of the base plate that channels magnetic flux generated by current in the high-voltage circuit toward the trip yoke.

18. The method of claim 13, wherein the base plate includes a reluctance gap positioned to direct magnetic flux intercepted by the trip yoke into a portion of the actuator circuit.

19. The method of claim 13, wherein the actuator circuit comprises a single-sided coil yoke.

20. The method of claim 13, wherein the actuator circuit comprises a two-sided coil yoke.

Images