Wireless arc detection in an electrical system

Abstract

An electrical device includes a movable contact configured to selectively open / close an electrical circuit. The contactor device also includes a sensing element that includes a receiver, such as an antenna, disposed proximate, but spaced from the electrical circuit. In examples, the sensing element may be disposed to wirelessly detect a change in an electromagnetic field associated with the electrical circuit via one or more antennas. For example, an arcing event may produce a detectable change in an electromagnetic field.

Description

WIRELESS ARC DETECTION IN AN ELECTRICAL SYSTEMFIELD OF THE TECHNOLOGY

[0001] The subject disclosure relates to electrical switching devices, such as contactor devices and electrical fuse devices, and more particularly to improved switching device systems adapted to detect switch levitation and / or arcing.BACKGROUND OF TECHNOLOGY

[0002] Many conventional devices are known to selectively power on or off electrical devices. Electrical contactors, e.g., high-voltage DC contactors, and fuses, e.g., electrical fuses and / or pyrotechnic fuses, are conventionally available and used in electrical systems. Contactors may be configured to either interrupt or complete a circuit to control electrical power to and / or from a device.

[0003] In many conventional systems, a contactor is configured as a switch, e.g., to selectively allow / disallow current flow. In some examples, one or more movable contacts may be coupled to a shaft. In these examples, the shaft may be movable, e.g., by an actuator, to selectively move the movable contact(s) into and out of contact with one or more fixed contacts. In some examples, the shaft (and the movable contact(s)) may be biased away from the fixed contact(s), e.g., to “open” the contactor and prevent current flow through the contactor.

[0004] When a current flows through the movable contact a magnetic field is generated. The strength of this field increases with the square of the current. In contactors like those just described, the field will cause a repulsive force at a contact of the fixed contacts and the movable contact. In normal operation, this repulsive force is less than a force applied on the movablecontact to maintain the movable contact in contact with the fixed contacts. However, during high load scenarios, the repulsive force can overcome the contact force, e.g., at a levitation limit. At the levitation limit, the movable contact separates from the fixed contacts and an arc may be formed. During arcing, the contacts may be welded together and / or the switching device can be thermally destroyed. In pressurized, gas filled devices, if the overcurrent is substantially greater than the current limit, the free-burning arc may generate such a strong pressure in the contact chamber that the enclosure can burst, causing an explosion.

[0005] Accordingly, there is a need in the art for improved sensing systems that are capable of detecting arcing and / or levitation conditions.SUMMARY OF THE TECHNOLOGY

[0006] The subject technology relates to improved electrical devices and sensing systems and methods associated with such devices. In examples, aspects of this disclosure relate to receiver-based sensing systems configured to wirelessly detect anomalous operation of electrical systems, including arcing and / or levitation events. For example, aspects of this disclosure can relate to a contactor device that incorporates a sensing system to detect arcing in the contactor device. In other examples, the sensing system may be used with any electrical device for which detecting arcing may be beneficial or desired. For example the sensing systems described herein can include one or more antennas that are configured to generate data (e.g., as signals) in response to elevated electrical fields and / or magnetic fields.BRIEF DESCRIPTION OF THE DRAWINGS

[0007] So that those having ordinary skill in the art to which the disclosed systems and techniques pertain will more readily understand how to make and use the same, reference may be had to the following drawings.

[0008] FIG. 1 is a perspective, section view of an electrical device, including a housing and electrical components, in accordance with aspects of this disclosure.

[0009] FIG. 2A is a partial cross-sectional view of portions of the electrical device of FIG. 1, with the electrical device in a first, closed configuration, in accordance with aspects of this disclosure.

[0010] FIG. 2B is a partial cross-sectional view corresponding to the portions of the electrical device shown in FIG. 2A, with the electrical device experiencing an arcing event, in accordance with aspects of this disclosure.

[0011] FIG. 3 is a schematic representation of aspects of a sensing element, in accordance with aspects of this disclosure.

[0012] FIG. 4 is a flowchart illustrating a process for monitoring aspects of an electrical device, in accordance with aspects of this disclosure.

[0013] FIGS. 5 and 6 are graphs illustrating aspects of arc detection using the systems describe herein, in accordance with aspects of this disclosure.DETAILED DESCRIPTION

[0014] As noted above, when a current flows through a conductor, a magnetic field is generated. In a contactor, the magnetic field creates a repulsive force. In high load scenarios, the repulsive force can overcome the contact force, e.g., at the levitation limit. At loads above the levitation limit, the repulsive force forces the movable contact away from the fixed contacts, creating an arcing event. The arcing event can lead to destruction of, or promote premature failure of, the contactor. Accordingly, it may be desirable to identify arcing events.

[0015] Some conventional test methods to evaluate the ability of a contactor to withstand a short- circuit event have utilized operator interpretation of an oscilloscope trace to output binary Pass / Fail attribute data. In practice, this data has been collected statistically through destructive testing of many contactors, generally at a high cost, in both destroyed or compromised contactors and / or operator time. Other conventional test methods may measure an open / closed resistance of a contactor and / or a temperature associated with the contactor. Some conventional contactors have associated IV (current voltage) curves that correspond to operation until the resistance is out of specification. Some conventional techniques may use these curves, along with IV measurements and / or the number of contactor switching cycles, to decrement a counter. For example, in these systems, when the counter reaches zero, the contactor is assumed end of life, and the contactor must be replaced. However, the cost of each contactor may be significant as may be the cost to warranty of such contactors, if they are being replaced too early.

[0016] Aspects of this disclosure provide improved systems and techniques for determining attributes of contactors. For example, the systems and techniques described herein may include using a sensing element to identify arcing events. Also in some examples, aspects of this disclosurecan include using data generated by the sensing element to determine if a levitation event has occurred and / or a state-of-health of the contactor.

[0017] Specifically, aspects of this disclosure may relate to sensing elements configured to measure aspects indicative of arcing events. For instance, arcing events, e.g., caused by high loads, may produce a broad frequency emission comprising both an electric and a magnetic field. Sensing elements described herein may be embodied as a small electronic circuit that integrates one or more methods for wirelessly measuring the arc and / or current flowing through the contactor. In examples, the circuit can be the sensing elements described herein may be externally retrofitted to a contactor, e.g., for production testing and / or monitoring. In other examples, the sensing elements described herein may be integrated into the product design.

[0018] In brief summary, the subject technology provides improved systems and techniques for monitoring electrical devices. These systems and techniques may improve performance and / or the functional life of electrical devices. In examples, systems described herein can include a

[0019] While aspects of this disclosure may be particularly useful in certain applications, like DC contactors for use in high voltage electrical systems, the systems and techniques described herein may be useful with any electrical systems that may be damaged by or otherwise be susceptible to arcing events.

[0020] Aspects of the disclosure will now be explained in more detail with reference to the Figures.

[0021] FIG. 1 is a cross-sectional view of an electrical device 100. In examples of this disclosure, the electrical device 100 may be a switch or contactor assembly, such as a DCcontactor. In other examples, the electrical device may be a hybrid device, e.g., that includes a fuse or disconnect (such as a pyrotechnic disconnect). As will be appreciated from this disclosure, aspects of this disclosure may be used with any switching device that incorporates one or more movable contacts that are selectively placed into contact with one or more fixed contacts.

[0022] In the illustrated example, the electrical device 100 includes an electrical device housing 102. The housing 102 includes a housing base 104 disposed between an upper housing portion 106 and a lower housing portion 108. In the example of FIG. 1, the upper housing portion 106 is configured to cooperate with the housing base 104. In examples, the switch assembly housing base 104 and portions of the upper housing portion 106 may be metal parts, e.g., steel parts, welded to each other. The upper housing portion 106 defines, at least in part, an upper housing volume 110. In some examples, the upper housing volume 110 may be an arc chamber. The upper housing volume 110 may be a hermetically-sealed volume. An electronegative gas may be contained in the upper housing volume 110. This hermetically sealed configuration can help mitigate or prevent electrical arcing between adjacent conductive elements, and in some embodiments, helps provide electrical isolation between conductive contacts, as detailed further herein. In some examples, the upper housing volume 110 can be under vacuum conditions, and can be hermetically sealed using known means of generating hermetically sealed electrical devices.

[0023] Features of the electrical device 100 are disposed in the upper housing volume 110.For example, the view of FIG. 1 shows two fixed contacts 112 coupled to the upper housing portion 106. The fixed contacts 112 are disposed partially in the upper housing volume 110 and are configured to electrically connect internal components (detailed further herein) of the electrical device 100 to external circuitry, for example, to an electrical system or device. For example, the fixed contacts 112 may be terminals configured to facilitate connection of first electrical leads (notshown) from a voltage source to second electrical leads (also not shown) associated with a load to be powered by the voltage source, the fixed contacts 112, e.g., as fixed, or stationary contacts.

[0024] The electrical device 100 also includes a movable contact 114. As detailed further herein, the movable contact 114 is movable between a first position spaced from the fixed contacts 112 and a second position contacting the fixed contacts 1 12. The first position is shown in FIG. 1 , and the movable contact 114 may be moved upward (in the orientation of FIG. 1) from the illustrated position to the second position. In the illustrated example, the movable contact 114 is a generally elongate member that, in the second position, not illustrated but just described, can simultaneously contact both of the fixed contacts 112. Accordingly, the movable contact 114 can selectively couple the two fixed contacts 112, to facilitate current flow between the fixed contacts 112 and thus through the electrical device 100.

[0025] The electrical device 100 also includes an actuator assembly 116 configured to, among other functions, facilitate selective opening and closing of the electrical device 100, e.g., by facilitating selective movement of the movable contact 114 into and out of contact with the fixed contacts 112. In examples, the actuator assembly 116 can include the movable contact 114 and / or may be operatively coupled to the movable contact 114.

[0026] As illustrated in FIG. 1., the actuator assembly 116 is illustrated as including a shaft 118, a coupler 120, and a plunger 122.

[0027] In the example, the shaft 118 is disposed such that a first end 124 (e.g., an upper end in the orientation of FIG. 1) is positioned in the upper housing volume 110 defined by the upper housing 106 and the base 104. The first end 124 is coupled to the movable contact 114, e.g., via the coupler 120. An opposite, second end 126 of the shaft 118 extends through the base 104into a lower housing volume 128 defined at least in part by the lower housing portion 108. The second end 126 of the shaft 118 is coupled to the plunger 122.

[0028] In more detail, FIG. 1 shows that the coupler 120 that includes a base 130 and opposing spaced sides 132 extending upward (in the orientation of FIG. 1) from the base 130. In this example, the opposing sides 132 define openings 134 through which portions of the movable contact 114 extend. Specifically, the movable contact 114 is a substantially elongate or bar-shaped member extending from a first end 136 to a second end 138. The movable contact 114 extends through the openings 134 in the spaced sides 132 such that the first end 136 and the second end 138 are disposed on opposite sides of the spaced sides 132 of the coupler 120 (and generally aligned vertically with the fixed contacts 112).

[0029] In the illustrated example, the base 130 of the coupler is secured to the first end 124 of the shaft 118. In examples, the base 130 may be molded onto the first end 124 of the shaft 118. For instance, the base 130 may be a polymeric material formed on the shaft 118 via an overmolding process or the like. In examples, the polymeric material may configure the base to electrically isolate the movable contact 114 from the remaining actuator components (e.g., the shaft 118) and / or portions of the housing 102 (e.g., the base 104).

[0030] In the illustrated examples, the sides 132 of the coupler 120 may be integrated with the base 130. For example, the base 130 may be overmolded over a bottom portion of the sides 132. However, the sides 132 may be otherwise coupled, secured, or attached to the base 130 in other examples. In the illustrated example, the sides 132 may approximate an inverted U-shape to define the openings 134 which provide clearance for the ends 136, 138 of the movable contact114, as noted above. The movable contact 1 14 may be movable in the openings 134 relative to the sides 132 and the base 130.

[0031] In the example of FIG. 1, a biasing spring 140 is disposed between the base 130 and the movable contact 114. More specifically, the biasing spring 140 biases the movable contact 114 away from the shaft 1 18 and against a top edge of the openings 134 in the sides 132. Thus, in the illustrated example, the shaft 118 is secured to the coupler 120 (e.g., to the base 130 of the coupler 120) and the biasing spring 140 biases the movable contact 114 against the top edge of the openings 134 in the sides 132 of the coupler 120. Accordingly, movement of the shaft 118, e.g., along an axis 141 of the shaft 118, will cause corresponding movement of the coupler 120, the biasing spring 140, and the movable contact 114. For example, when the shaft 118 is caused to move downward in the orientation of FIG. 1, the movable contact 114 moves away from the fixed contacts 112. Alternatively, when the shaft 118 is caused to move upward in the orientation of FIG. 1, the movable contact 114 is moved toward, and eventually into contact with, the fixed contacts 112. Continued movement of the shaft 118 in the upward direction (in the orientation of FIG. 1) when the movable contact 114 contacts the fixed contacts 112, can result in continued travel of the coupler 120 relative to the movable contact 114, e.g., resulting from compression of the biasing spring 140. In this example, the biasing spring 140 can compensate for overtravel of the shaft 118, e.g., to prevent destructive contact of the movable contact 114 with the fixed contacts 112. In other examples, the biasing spring 140 may not be included.

[0032] As also illustrated in FIG. 1, the base 130 of the coupler 120 includes a tapered protrusion 142. In examples, the protrusion 142 may be provided to help maintain positioning and / or orientation of the biasing spring 140. For example, an outer diameter of the protrusion 142may be similar to or slightly smaller than an inner diameter of the biasing spring 140, e.g., to limit or prevent lateral movement of the biasing spring 140 relative to the coupler 120.

[0033] FIG. 1 also shows a lower yoke 144 disposed below and in contact with the movable contact 114. In examples, the lower yoke 144 may be a metal component configured to enhance or control an electromagnetic field generated by current passing through the movable contact 114.

[0034] FIG. 1 also shows an arc shield member 148. The arc shield member 148 may be a polymeric or other insulative material that acts as an insulator or barrier, e.g., in case of arcing in the upper housing volume 110 or the like. In the illustrated example, the arc shield 148 is disposed on the housing base 104 and defines an opening that generally surrounds a portion of the actuator assembly 116, e.g., the coupler 120.

[0035] The configuration of FIG. 1 is provided for example only. For example, modifications to the actuator assembly 116 are contemplated and will be appreciated by those having ordinary skill in the art with the benefit of this disclosure. For example, the lower yoke 144 may be omitted and / or one or more additional yokes may be provided. Also, in some examples, aspects of the coupler 120 may be omitted.

[0036] As also shown in FIG. 1, the shaft 118 extends through the base plate 104, such that the second end 126 of the shaft 118 is disposed in the lower volume 128, defined at least in part by the lower housing portion 108. In the illustrated example, an opening 150 or hole is formed in the base 104, and the shaft 118 extends through the opening 150. In the illustrated example, the opening 150 is sized to have a diameter smaller than an outer extent of the coupler 120 (e.g., the base 130 of the coupler 120) such that the coupler 120 contacts the base 104 and does not pass through the opening 150. Also in the illustrated example, an alignment plug 152 is disposed atleast partially in the opening 150. The alignment plug 152 may be configured for fitting into the opening 150, e.g., via a press fit. When present, the alignment plug 152 also defines an opening through which the shaft 118 extends.

[0037] When used, the alignment plug 152 may facilitate locating one or more additional components of the electrical device 100. For example, the alignment plug 152 extends from the opening 150 (and the base 104) into the lower volume 128. In the illustrated example, a distal end (e.g., spaced from the base 104) of the alignment plug 152 is sized to extend into a plunger tube 154. For example, an inner diameter of the plunger tube 154 and an outer diameter of the alignment plug 152 may be sized to allow for the alignment plug 152 to be disposed in the plunger tube 154. In some examples, the alignment plug 152 can be press fit into the plunger tube 154 (or the plunger tube 154 can be press fit over the alignment plug 152). As detailed further below, the plunger tube 154 can house or otherwise retain the plunger 122.

[0038] As also illustrated in FIG. 1, the alignment plug 152 may also define a bore 156. The shaft 118 passes through the bore 156. Moreover, the bore 156 is sized to receive at least a portion of a return spring 158. In the example, the return spring 158 is a compression spring extending from a first end disposed in the bore 156 (and contacting an inner, bottom surface of the bore 156) of the alignment plug 152 to a second end spaced from the first end along an axis of the return spring 158. The second end of the return spring 158 contacts an upper surface 160 of the plunger 122. In the illustrated example, because the alignment plug 152 is fixed to the base 104 of the housing 102, the return spring 158 biases the plunger 122 away from the base 104, e.g., in a downward direction in the orientation of FIG. 1. Moreover, because the second (e.g., lower) end of the shaft 118 also is coupled to the plunger 122, the return spring 158 biases the shaft 118 and the movable contact 114, e.g., away from the fixed contacts 112.

[0039] The actuator assembly 116 is driven by a coil 162, e g., a DC coil. The coil 162 may be selectively energized. For example, and as shown in FIG. 1, the coil 162 is disposed proximate the plunger tube 154. In examples, the coil 162 is a cylindrical coil that is disposed around the plunger tube 154. The plunger 122 is disposed in the plunger tube 154, and the plunger 122 is movable relative to the plunger tube 154. In examples, the plunger tube 154 may be fixed relative to the coil 162 and the plunger 122 is free to move axially relative to the plunger tube 154 (and the coil 162) in response to activation / deactivation of the coil 162. As detailed above, the plunger 122 is coupled to the second end 126 of the shaft 118. The return spring 158 is positioned on the shaft 118 between the upper surface 160 of the plunger 122 and a lower surface of the housing base 104 (e.g., the alignment plug 152 in FIG. 1). The return spring 158 biases the plunger 122 (and thus the shaft 118) away from the base 104, e.g., in a downward direction in FIG. 1 along the axis 141. Accordingly, when the coil 162 is not charged, the return spring 158 biases the shaft 118 (via the plunger 122) to distance the movable contact 114 from the fixed contacts 112.

[0040] The example of FIG. 1 shows a normally open contactor, e.g., such that the return spring 158 biases the movable contact 114 away from the fixed contacts 112, and the plunger is actuated against a biasing force of the return spring 158 to close the circuit (e.g., by contacting the movable contact 114 to the fixed contacts 112). Aspects of this disclosure may also be applied to other contactor constructions, including normally closed contactors. In a normally closed contactor, the return spring 158 may bias the movable contact toward the fixed contacts 112 and the plunger is actuated against the biasing force of the return spring 158 to open the circuit (e.g., by separating the movable contact 114 from the fixed contacts 112).

[0041] The electrical device 100 is also illustrated as including a sensing element 164. As detailed herein, the sensing element 164 may be configured to sense attributes of the electricaldevice 100. The sensing element 164 is also configured to generate corresponding sensor data 166. In examples, the sensor data 166 may include one or more signals associated with or related to a magnetic field and / or an electrical field in which the sensing element 164 is disposed. Without limitation, the sensor data 166 may include a voltage generated by the sensing element 164. The voltage may be related to a strength of an electrical field and / or a magnetic field generated by the current passing through the movable contact 114.

[0042] In the example of FIG. 1, the sensing element 168 is configured to communicate with a computing system 168. For example, FIG. 1 shows two electrical leads 170 extending between the sensing element 164 and the computing system 168. In some examples described herein, each of the leads 170 may be associated with a different receiver of the sensing element 164. Thus, for example, each of the leads 170 may be associated with a different channel, e.g., carrying different sensor data. Although two instances of the electrical leads 170 are illustrated, more or fewer instances of the leads 170 may be provided. Moreover, although the electrical leads 170 are illustrated as extending from the sensing element 164 between the fixed contacts 112, this arrangement is for example only. The electrical leads 170 may extend from any direction, e.g., based on design requirements, or the like. In at least some examples, additional elements may be provided between the fixed contacts 112, e.g., a pyrotechnic element and / or other elements. Such additional elements may necessitate a different positioning and / or orientation of the sensing element 164 and / or the electrical leads 170. Moreover, although the leads 170 are shown in FIG. 2, in other examples the sensing element 164 and the computing system 168 may communicate wirelessly. In still further examples, the sensing element 164 and the computing system 168 may be integrated into a sensing device in which additional leads may not be required. For instance, the sensing element 164 may be directly coupled to the computing system 168 (or aspects thereof).

[0043] The computing system 168 includes a number of processing components configured to perform the processes and techniques detailed herein. The processing components include a data processing component 172, an arc determination component 174, a current determination component 176, and a health determination component 178. The processing components are illustrated as discreet modules, which may be memory modules storing executable instructions, e.g., executable by one or more processors, to perform certain functions. The processing components are represented as discreet modules for ease of explanation and understanding only. The layout, arrangement, and functionality may vary, as will be appreciated by those having ordinary skill in the art with the benefit of this disclosure.

[0044] In examples, the processing components may include logically-connected computing blocks and / or computer and / or electrical components. For instance, various of the illustrated blocks and / or other aspects of the computing system 168 may be implemented as circuitry and / or an intelligent hardware device, e.g., a central processing unit (CPU), a microcontroller, an application specific integrated circuit (ASIC), or may be implemented as part of a reconfigurable device. In at least some examples, the computing system 168 can include a circuit board, such as a printed circuit board (PCB) on which components of the computing system 168 are disposed and / or to which the components of the computing system 168 are otherwise coupled. Aspects of the computing system 168 can include random access memory (RAM) and / or read-only memory (ROM) which may include instructions that are configured to, when executed (or when compiled and executed), cause aspects of the computing system 168 to perform various functions described herein. Various components of the computing system 168 may be implemented using one or more separate CPUs or ASICs, for example, and the components may, individually or collectively, be implemented with one or more ASICs adapted to perform some orall of the applicable functions in hardware. Each of the noted components may be a means for performing one or more functions related to operation of the system.

[0045] The data processing component 172 includes functionality to receive and / or process the sensor data 166. For example, when the sensor data 166 comprises a signal, the data processing component 172 can perform one or more of amplifying, filtering, smoothing, converting (e.g., analog to digital converting), and / or the like. Moreover, in some examples, the data processing component 172 can be configured to sample one or more data channels, e.g., channels associated with different sensor outputs.

[0046] The arc determination component 174 includes functionality to determine an arcing event. As used herein, an arcing event may be a high load event, e.g., a surge or overcurrent event, in an electrical system. As detailed above, the arcing event may result from an electromagnetic field, e.g., associated with the movable contact 114, increasing in magnitude due to increased current through the movable contact 114. The arcing event may cause a levitation condition in which the movable contact 114 separates from the fixed contacts 112, although such is not required. In other aspects of this disclosure, an arcing event may describe a high load event that results in an increase in a levitation force, but in which levitation or separation does not occur. For example, an arcing event may correspond to an increase in a magnitude of a magnetic field and / or current, which may or may not result in arcing.

[0047] In some examples, the arc determination component 174 may be configured to compare aspects of the sensor data 166 to one or more thresholds that correspond to an arcing event. For instance, when the sensor data 166 comprises a signal, the arc determination component 174 may compare a voltage of the signal to one or more threshold voltage values to determinewhether the signal indicates an arcing event. For example, if the sensed voltage is equal to or exceeds the threshold voltage, the arc determination component 172 may determine that the device 100 has experienced an arcing event.

[0048] The current determination component 176 includes functionality to determine a current associated with the arcing event. For instance, the current determination component 176 can include functionality to calculate a current flowing through the movable contact 114 during the arcing or levitation event. For instance, the current determined by the current determination component 176 may be a magnitude of an overcurrent causing the arcing event.

[0049] The health determination component 178 includes functionality to determine a health or suitability of the electrical device 100. For example, the health determination component 178 can include functionality to evaluate an effect of an arcing event on a suitability of the electrical device 100. Without limitation, the health determination component can consider a magnitude of an arcing event, a duration of an arcing event, a number of arcing events, and / or other features of arcing event(s) detected by the arc determination component 174 to determine a health or suitability of the device 100. In some examples, the arc determination component 174 can also receive or otherwise access information about the electrical device to determine the health of the device 100. Such information can include, but is not limited to, an age of the device, a number of cycles of the device, information about components of the device, or other information. In some instances, the heath determination component 178 can be configured to generate a score or metric, e.g., as a health metric, that relates to a suitability of the device, e.g., for continued use.

[0050] FIGS. 2A and 2B illustrate an example implementation of the electrical device 100 and use of the sensing element 164. More specifically, FIG. 2A shows a portion of the electricaldevice 100 when the electrical device 100 is configured in a closed state (e.g., with the movable contact 114 contacting the fixed contacts 112). FIG. 2B shows the same portion of the electrical device 100 when the electrical device 100 has experienced an arcing event. In FIGS. 2A and 2B, the same reference numerals used in FIG. 1 are used to identify the same features.

[0051] In more detail, the view of FIG. 2A shows that the electrical device 100 is in a closed state in which the movable contact 114 contacts the fixed contacts 112 to allow the movable contact 114 to conduct a load current, h, through the device 100. As illustrated, a contact force, Fcomact, is exerted on the movable contact 114 to maintain the movable contact 114 against the fixed contacts 112. The contact force may be applied by the actuator assembly 116 and / or by a biasing force associated with the spring 140.

[0052] As also shown in FIG. 2A, a levitation force, Filiation, acts on the movable contact in a direction opposite the contact force, Fcomact. As described herein, the levitation force results from the load current passing through the movable contact 114. More specifically, the load current passing through the movable contact 114 generates an electromagnetic field that includes a repulsion force perpendicular to the flow of electricity. In the illustrated example, during application of a normal load current the levitation force is less than the contact force, so the device remains closed. Also in the example of FIG. 2A, the magnetic field has an overall field strength, Bi.

[0053] Also shown schematically in FIG. 2A, the sensing element 164 is disposed proximate the movable contact 114 to sense aspects of the magnetic field, e.g., to generate the sensor data 166. In some examples, the sensing element may include one or more antennas configured to generate one or more first voltage signals, VI, which may be related, at least in part,to the magnetic field strength Bl . In the illustrated example, the sensing element 164 is positioned outside the housing 102, e.g., on a top of a cover of the housing. In other examples, the sensing element 164 may be disposed in the housing 102, e.g., in a hermetically sealed volume. However, in some examples, because the sensing element 164 may be configured to generate sensor data wirelessly, e.g., by detecting electrical and / or magnetic fields, the sensing element 164 may be disposed anywhere, e.g., in proximity of the movable contactor 114, that facilitates sensing of the field(s).

[0054] In FIG. 2B, the load on the electrical device 100 has increased, e.g., such that an overload current, , is conducted through the device 100. As with the example of FIG. 2A, the contact force, Fcontact, is exerted on the movable contact 114 to maintain the movable contact 114 against the fixed contacts 112. While the contact force is the same in the example of FIG. 2B as in the example of FIG. 2A. the levitation force, Fievitation, is higher because the overload current, h, is higher than the load current, h, applied in FIG. 2A. In this example, the levitation force is greater than the contact force, e.g., such that the movable contact 114 separates from the fixed contacts 112, as illustrated. As also illustrated schematically, one or more arcs 202 may form between the fixed contacts 112 and the movable contact 114.

[0055] As also illustrated in FIG. 2B, as a result of the increased load current, the magnetic field also increases, and has an overall field strength, B2, which is greater than the field strength, Bi, of FIG. 2A. As noted above, the sensing element 164 is disposed proximate the movable contact 114 to sense aspects of the magnetic field, e.g., to generate the sensor data 166. In some examples, the sensing element may include one or more antennas configured to generate one or more second voltage signals, V2, e.g., as the sensor data 166. The voltage V2 may be related, at least in part, to the magnetic field strength B2. In the illustrated example, the second voltage V2may be greater than the first voltage VI . As detailed herein, the sensor data 166 associated with the arcing event may be used, e.g., by the computing system 168, to determine that the arcing event has occurred.

[0056] In the illustrated examples of FIGS. 1, 2A and 2B, the sensing element 164 is positioned between the fixed contacts 112, proximate a top of the device 100. While such an arrangement may be preferred in some instances, e.g., because the sensing element 164 may be directly disposed between the fixed contacts 112 and in proximity of the movable contact 114, this disclosure is not limited to such an arrangement. For instance, in some examples additional elements may be provided between the fixed contacts 112, e.g., a pyrotechnic element and / or other elements, such that placement of the sensing element 164 is not practical or possible. Any positioning and / or arrangement in which the sensing element 164 is arranged to detect aspects of the magnetic field may be used. Without example, the sensing element 164 may be disposed on a side or bottom of the arc chamber, e.g., depending on integration and potential restrictions due to creepage and clearance requirements.

[0057] FIG. 3 is a schematic representation of an example sensing system 300. For example, the sensing system 300 is illustrated as including a sensing element 302 and a computing system 304. Without limitation, the sensing element 302 may correspond to the sensing element 164 described above and / or the computing system 304 may correspond to aspects of the computing system 168.

[0058] As shown in FIG. 3, the sensing element 302 includes a first antenna 306 and a second antenna 308. Although the two antennas 306, 308 are illustrated, other implementations can include only a single instance of the antennas 306, 308. In one non-limitingexample, the sensing element 302 may include only the first antenna 306 or only the second antenna 308. In still further examples, the sensing element 302 can include additional antennas. In some examples, however, it may be desirable to have both of the antennas 306, 308. For instance, two (or more) antennas may be preferred in electromagnetically noisy environments - such as in an electric vehicle, due to the inverter. Using two antennas can help to eliminate false positives that might occur in the real world and / or during compliance testing. The use of multiple antennas may also allow for the making of some logical assumptions. For example, if there is no current flowing then arcing cannot occur, therefore if an arc is detected, e.g., by the first antenna 306 but there is no current flow, per the second antenna 308, then a false positive can be identified.

[0059] In the illustrated example, the antennas 306, 308 are formed on a substrate 310. The substrate 310 may be a circuit board, such as a printed circuit board. In the example illustration, the first antenna 306 is formed from a first trace 312 disposed on the substrate 310, and the second antenna 308 is formed from a second trace 314 disposed on the substrate 310. Although the example of FIG. 1 shows the first and second antennas 306, 308 as being formed on the same substrate 310, in other examples the first antenna 306 can be formed on a first substrate and the second antenna 308 can be formed on a second substrate.

[0060] The antennas 306, 308 are configured to produce first data 316 and second data 318, respectively. For example, the first data 316 and the second data 318 may correspond to the sensor data 166 discussed above. Without limitation, the first data 316, 318 may include a signal, e.g., a voltage signal, corresponding to an electrical and / or magnetic field in which the antenna(s)306, 308 are disposed.

[0061] The first antenna 306 and / or the second antenna 308 may be configured to operate at relatively high frequencies. For example, the first antenna 306 and / or the second antenna 308 may be configured to operate at frequencies equal to or above about 3 MHz. The first antenna 306 and / or the second antenna 308 may be configured to operate at frequencies equal to or below about 3 GHz. In at least some examples, the first antenna 306 and / or the second antenna 308 may be configured to operate in the high frequency and / or the ultra-high frequency bands.

[0062] In the illustrated example of FIG. 3, the first trace 312 is laid out as a plurality of parallel segments. In the example, a spacing between the parallel segments of the first trace 312 may control a roll-off / decay curve of a detection pulse. The first trace 312 may be designed and / or formed such that this spacing is selected based on one or more desired attributes of the sensing element 302. The first antenna 306 may be configured to detect arcing events, for example, by detecting changes in an electrical field. Although the example of FIG. 3 uses the first trace 312 for the first antenna 306, the first trace 312 is for example only. In other examples, the first antenna 306 may be embodied as a monopole antenna, a dipole antenna, a patch antenna, and / or any other antenna configured to detect an arcing event, e.g., by determining a change in an electrical field.

[0063] In contrast, the second trace 314 is laid out as a coil or spiral. In examples, the second antenna 308 may be configured to detect current changes and / or to detect arcing events. A diameter of the second trace 314, e.g., of the coil or loop, may be proportional to a sensitivity of the magnetic field sensing. Without limitation, a relatively wider diameter loop will pick up more magnetic field lines than a relatively smaller diameter loop.

[0064] The patterns of the traces may be configured to detect changes in particular frequency bands, as discussed above. For example, a line length, e.g., of a segment of the traces312, 314 may be proportional to the frequency. Of course, the illustrated layouts of the traces 312, 314 are for example only. Other patterns may be appreciated by those having ordinary skill in the art, with the benefit of this disclosure. Moreover, although the examples illustrate that the antennas 306, 308 are formed as traces on the substrate 310, other antenna types, such as patch antennas or the like may be used in aspects of this disclosure. For example, the sensing element 302 can include any antenna design that is configured to wirelessly determine aspects (e.g., changes) in an electromagnetic field generated by an electrical circuit.

[0065] The computing system 304 is illustrated as including electronic circuitry 320 for processing the data. Without limitation, the circuitry 320 may be configured to implement aspects of one or more of the data processing component 172, the arc determination component 174, the current determination component 176, and / or the health determination component 178.

[0066] The circuitry 320 is illustrated schematically as including a comparator 322 (which may a comparator circuit). In examples, the comparator 322 may be configured to receive the first data 316 and / or the second data 318 and compare that data to one or more thresholds. Without limitation, the comparator 322 can compare a voltage signal in the first data 316 and / or in the second data 318 to a threshold voltage determined to be associated with an arcing event. If the voltage signal is equal to or greater than the threshold voltage, the comparator 322 will identify an arcing event.

[0067] The circuitry 320 also is illustrated as including a signal processing circuit 324 embodied as an amplifier, a filter, and an analog-to-digital converter, arranged in series. For example, the signal processing circuit 324 can include functionality to sample the first data 316 and the second data 318 to determine an arcing event, as well as to determine a health of theelectrical device due to the measured characteristics of the arc. For example, the signal processing circuit 324 can enable additional signal processing that allows for determination of additional, e.g., more detailed information about the arcing event.

[0068] FIG. 4 is a flowchart illustrating a process 400 for determining arcing events in an electrical device, such as the electrical device 100. Although aspects of FIG. 4 will be discussed in the context of the electrical device 100, the process 400 is not limited to use with the electrical device 100. For example, aspects of the process 400 may be useful to determine arcing events at any point in an electrical system. Moreover, the electrical device 100 need not incorporate the process 400.

[0069] At an operation 402, the process 400 includes configuring a sensing element in proximity of an electrical device. In examples described herein, a sensing element can include one or more antennas or other receivers configured to generate a signal in response to an electrical field and / or a magnetic field. As sensing elements according to this disclosure, like the sensing elements 164, 300 can be configured to operate wirelessly, e.g., in the high frequency and / or high frequency bands, the sensing elements may be placed in any number of positions so long as the sensing element is positioned in a field, such as an electromagnetic field, of a conductor in an electrical circuit. In examples, the operation 402 can include integrating the sensing element into an electrical device, e.g., by placing the sensing element in an arcing chamber, in a housing, or the like, e.g. at the time of manufacture and / or testing of the device. In still further examples, the operation 402 can include retrofitting an existing electrical device and / or electrical system with the sensing element.

[0070] At an operation 404, the process 400 includes receiving sensor data from the sensing element. As detailed herein, a computing device, such as the computing system 168 may be configured to receive sensor data. The sensor data may be, or include, signals generated by the sensing element 164, 300. In some examples, the operation 404 may include sampling one or more sensing elements to receive the sensor data. Moreover, and as detailed herein, in some examples of this disclosure the sensing element may have more than one receiver and / or may generate more than one data type or value. In examples, the operation 404 can include receiving various sensor types or streams of data, e.g., as signals or the like.

[0071] At an operation 406, the process 400 includes determining whether the sensor data indicates an arcing event. As detailed herein, arcing events can occur when a current flowing through a conductor, such as the movable contact 114 discussed above, cause a levitation force to exceed a contact force. In this example, the movable contact 114 will separate from the associated fixed contacts 112, resulting in arcing at the separation. In this high load or overcurrent scenario, there is an appreciable change in an electromagnetic field generated by current passing through the movable contact 114. Aspects of this disclosure include detecting this change via the sensor data. For example, the sensor data received at the operation 404 can include a voltage value and the operation 406 can compare the voltage value to a threshold voltage value. In this example, if the measured voltage value is equal to or exceeds the threshold voltage value, the operation 406 can determine that an arcing event has occurred.

[0072] In other examples, the operation 406 can include determining, from the sensor data, a value of the current passing through movable contact 114. In examples, the operation 406 can include comparing the current determined from the sensor data to a threshold current, e.g., associated with an arcing event.

[0073] If, at the operation 406 it is determined that the sensor data does not indicate an arcing event (e.g., “No” at the operation 406), the process 400 returns to the operation 404 to continue monitoring the sensor data for arcing / levitation events.

[0074] Alternatively, if, at the operation 406, it is determined that the sensor data does indicate an arcing event (e.g., “Yes” at the operation 406), the process 400 includes determining a suitability of the electrical device. For example, at the operation 406, the health determination component 176 can determine a health metric associated with the electrical device. As detailed herein, the health determination component 176 can determine suitability or health of a device based on a number of factors, including factors associated with the arcing event, factors associated with the device, factors associated with (historical) use of the device, and / or the like.

[0075] As will be appreciated from the foregoing, aspects of this disclosure relate to the use of a sensing element to wirelessly monitor aspects of an electrical device, e g., to detect arcing events in the device. The systems and techniques described herein can provide a different or supplemental means to determine overcurrent events and / or the severity of such events. Also in examples, the systems and techniques described herein can better quantify an expected life for devices. This wireless method is distinct from some conventional designs that require expensive high voltage isolation capacitors. Moreover, sensing elements and systems according to this disclosure can be retrofitted to existing electrical components and / or systems.

[0076] FIGS. 5 and 6 are graphs illustrating detection of arcing events using the systems and techniques described herein.

[0077] More specifically, FIG. 5 is a graph 500 representative of a first test case in which a voltage spike is applied to a conductor of an electrical circuit at a time 0 (measured along the x-axis). The voltage is shown by a line 502 and a line 504 represents the corresponding change in current. Also in FIG. 5, a line 506 shows a signal generated by a first antenna, e.g., the first antenna 306 in the sensing element 302, and a line 508 shows a signal generated by a second antenna, e.g., the second antenna 308 in the sensing element 302. As shown in FIG. 5, the second antenna (represented by the line 508) has a robust response to the arcing event. The first antenna (represented by the line 506) has a smaller response. FIG. 5 generally shows that the sensing elements, and in particular the second antenna 508, described herein can act as a wireless current sensor.

[0078] FIG. 6 is a graph 600 representative of a second test case in which a series of voltage spikes are applied to a conductor of an electrical circuit at discrete times (measured along the x- axis). In FIG. 6, the voltage is shown by a line 602 and a line 604 represents the corresponding change in current. Also in FIG. 6, a line 606 shows a signal generated by a first antenna, e.g., the first antenna 306 in the sensing element 302, and a line 608 shows a signal generated by a second antenna, e.g., the second antenna 308 in the sensing element 302. As shown in FIG. 6, both the first antenna (represented by the line 606) and the second antenna (represented by the line 608) have robust responses to the arcing events. FIG. 6 also shows that the second antenna (represented by the line 608) also allows for robust current detection.

[0079] While the subject technology has been described with respect to preferred embodiments, those skilled in the art will readily appreciate that various changes and / or modifications can be made to the subject technology without departing from the spirit or scope of the subject technology. For example, each claim may depend from any or all claims in a multiple dependent manner even though such has not been originally claimed.

Claims

WHAT IS CLAIMED IS:

1. An electrical system comprising: a switching device comprising: one or more fixed contacts, a movable contact movable between a first position spaced from the one or more fixed contacts and a second position contacting the one or more fixed contacts to conduct electricity through the switching device, and an actuator assembly biasing the movable contact toward the second position; and a sensing element comprising a receiver spaced from the movable contact and the one or more fixed contacts, the sensing element being configured to generate an electrical signal in response to an arcing event at the switching device.

2. The electrical system of claim 1, wherein: the sensing element comprises at least one antenna configured to generate the electrical signal in response to at least one of an electrical field or a magnetic field generated by the arcing event.

3. The electrical system of claim 2, wherein the at least one antenna is configured to operate in frequency bands between about 3 MHz and about 3 GHz.

4. The electrical system of claim 2, wherein the at least one antenna comprises a first antenna configured to measure a current associated with the arcing event and a second antenna configured to measure arcing.

5. The electrical system of claim 2, wherein the at least one antenna comprises a printed antenna disposed on a printed circuit board.

6. The electrical system of claim 2, wherein the at least one antenna comprises a patch antenna.

7. The electrical system of claim 2, wherein the at least one antenna comprises a coil or spiral antenna.

8. The electrical system of claim 2, further comprising a control system in communication with the sensing element, the control system being configured to perform operations comprising: receiving sensor data from the sensing element; and determining, based at least in part on the sensor data, an occurrence of the arcing event .

9. The electrical system of claim 8, wherein the operations further comprise: determining, based at least in part on the sensor data, a magnitude of a current associated with the arcing event.

10. The electrical system of claim 8, wherein the determining the occurrence of the arcing event comprises: comparing a value associated with the sensor data to a threshold value associated with arcing events; and determining, based at least in part on the value meeting or exceeding the threshold value, the occurrence of the arcing event.

11. The electrical system of claim 8, wherein: the sensing element comprises a first antenna configured to generate first data and a second antenna configured to generate second data; and the control system is configured to sample the first data and the second data and the determining the occurrence of the arcing event is based at least in part on the sampling.

12. The electrical system of claim 8, wherein the operations further comprise: determining one or more characteristics of the arcing event; and determining, based at least in part on the one or more characteristics of the arcing event, a health metric associated with the switching device.

13. An electrical system comprising: a sensing element comprising: a first antenna configured to generate first data associated with at least one of an electrical field or a magnetic field;a second antenna configured to generate second data associated with the at least one of the electrical field or the magnetic field; and a current carrying element, wherein the sensing element is spaced from the current carrying element to wirelessly generate the first and the second data in response to a change in a characteristic of the current carrying element.

14. The electrical system of claim 13, wherein the first antenna and the second antenna are printed antennas disposed on a printed circuit board.

15. The electrical system of claim 14, further comprising: a control system associated with the sensing element, wherein the control system is configured to perform operations comprising: receiving sensor data from the sensing element; and determining, based at least in part on the sensor data, an occurrence of an arcing event associated with the current carrying element.

16. The electrical system of claim 15, the operations further comprising: determining, based at least in part on the sensor data, a magnitude of a current associated with the arcing event.

17. The electrical system of claim 15, wherein the determining the occurrence of the arcing event comprises:comparing a value associated with the sensor data to a threshold value associated with arcing events; and determining, based at least in part on the value meeting or exceeding the threshold value, the occurrence of the arcing event.

18. The electrical system of claim 16, the operations further comprising: sampling the first data and the second data, wherein the determining the occurrence of the arcing event is based at least in part on the sampling.

19. The electrical system of claim 15, the operations further comprising: determining one or more characteristics of the arcing event; and determining, based at least in part on the one or more characteristics of the arcing event, a health metric associated with a component of the electrical system.

20. The electrical system of claim 15, the operations further comprising: generating an alert associated with the arcing event.

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