Electrical device with switch state detection

Abstract

A contactor device includes a movable contact configured to selectively open / close an electrical circuit. The contactor device also includes an auxiliary coil and sensing element that move relative to each other when the movable contact is moved to open / close the electrical circuit. The relative movement of the coil and the sensing element effects a measurable change in a characteristic of the coil that indicates whether the circuit is open or closed.

Description

ELECTRICAL DEVICE WITH SWITCH STATE DETECTIONBy: Fernanda V. Ortega, Michael J. SangermanoFIELD 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 contactor devices with an auxiliary coil to detect a state of the switching device.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 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. For example, a return spring may bias the shaft to an open position. For safety and / or other purposes, it may be desirable to know a status of the contactor, e.g., whether the contactor is open or closed.

[0004] Accordingly, there is a need in the art for improved switching devices that are capable of providing information about whether the switching device is open or closed. There also is a need in the art for improved devices with increased life spans and / or reduced complexity and / or cost.SUMMARY OF THE TECHNOLOGY

[0005] The subject technology relates to improved electrical devices and methods of making and using those devices. In examples, aspects of this disclosure relate to improved switching devices with features for easily and / or repeatedly determining whether the device is open or closed. For example, aspects of this disclosure can relate to a contactor device that includes an auxiliary coil that is monitored to detect changes in the contactor state. For example a magnet can be moved relative to the coil to effect changes in a current in the coil or a core or second coil can be moved relative to the coil to effect changes in the inductance. Measured changes in characteristics of the auxiliary coil (e.g., inductance, current) can indicate whether the device is open or closed.BRIEF DESCRIPTION OF THE DRAWINGS

[0006] 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.

[0007] FIG. 1 is a perspective, section view of an electrical device, including a housing and electrical components, in accordance with aspects of this disclosure.

[0008] FIG. 2A is a partial cross-sectional view of portions of the electrical device ofFIG. 1, with the electrical device in a first, open configuration, in accordance with aspects of this disclosure.

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

[0010] FIG. 3 is a flowchart illustrating a process for detecting a state of an electrical switching device, in accordance with aspects of this disclosure.DETAILED DESCRIPTION

[0011] The subject technology overcomes many of the prior art problems associated with electrical devices. In brief summary, the subject technology provides improved electrical devices including a contactor design that may have improved performance and / or longer functional life compared to other conventional electrical devices. In examples, the electrical device may have two discrete operation states, including a first operating state and a second operating state. In the first operation state, the device is open, e.g., such that no voltage or current flows through the device. In the second operating state, the device is closed. In examples, the electrical device can include a coil that is energized to cause one or more movable contacts to move into contact with one or more fixed or stationary contacts, thereby completing a circuit, e.g., to configure the device in the second operating state. In the second operating state, current, e.g., from a high voltage source, may flow through the device.

[0012] In aspects of this disclosure, the electrical device can include an auxiliary coil, e.g., separate from the coil or other device that drives the movable contact(s). The auxiliary coil is configured for use in detecting whether the electrical device is open or closed. For example, in some aspects of this disclosure, a sensing element is positioned to move relative to the auxiliary coil. For instance, when the movable contact is spaced from the fixed contacts, the sensing element is spaced from the auxiliary coil, and when the movable contact contacts the fixed contacts, the sensing element is in close proximity of the auxiliary coil. In examples, the position of the sensing element relative to the auxiliary coil will impact one or more characteristics of the auxiliary coil. For example, depending on the composition of the sensing element, the sensing element can alter a current passing through the coil and / or an inductance of the coil.

[0013] In some aspects of this disclosure, the auxiliary coil is disposed outside an inner volume or an arc chamber defined by a housing. For example, the inner volume may house a portion of the fixed contacts and the movable contact. The volume may be hermetically sealed in some examples. Although the auxiliary coil is disposed outside the volume, the sensing element can be coupled to the movable contact and may also be disposed in the volume. A sensing element mount may extend from the movable contact in some examples. The sensing element may be secured to the sensing element mount at a position spaced from the movable contact. The sensing element mount is configured to cause the sensing element to move with the movable contact, e.g., such that the spaced positioning of the sensing element is maintained at different positions of the movable contact.

[0014] In operation, when the movable contact is spaced from the fixed contacts, e.g., when the circuit is open, the sensing element is similarly spaced from the auxiliary coil. When the circuit is closed, e.g., when the movable contact is moved into contact with the fixed contacts, thesensing element is arranged proximate the auxiliary coil. This proximity effects a change in a characteristic of the auxiliary coil that is detectable. For example, one or more leads may be electrically coupled to the auxiliary coil and one or more characteristics of the auxiliary coil may be monitored via the lead(s).

[0015] In some examples, the auxiliary core may be substantially circular or cylindrical, although other shapes and constructions also are contemplated. For example, the auxiliary coil can define a central, cylindrical opening. When the sensing element is disposed in proximity of the auxiliary coil, the sensing element may be disposed at least partially in the opening. Also in examples, the auxiliary coil be formed about an axis, and the axis may be generally aligned with a direction of travel of the movable contact. In some examples, in which a shaft is used to move the movable contact, the axis of the auxiliary coil may be substantially coaxial with an axis of the shaft.

[0016] In some aspects of this disclosure, the sensing element may be a magnet. When the magnet is moved into proximity of the coil, e.g., into the opening defined by the coil, into a position surrounding the coil, or the like, the magnet induces a current through the coil, e.g., according to Faraday -Lenz’s Law. This change in current may be measurable, e.g., to confirm the position of the magnetic sensing element, and thus of the movable contact. In examples, a magnetic field generated by the current, e.g., high voltage current, passing through the movable contact (and the fixed contacts), may not induce a current in the auxiliary coil if the magnetic field is perpendicular to the axis of the auxiliary coil and / or if the sensing element is substantially distanced from the movable member.

[0017] In additional aspects of this disclosure, the sensing element may be a core. For example, the core may be a ferromagnetic core or a core made of some other material that is magnetically permeable. The core may be selected to have a higher magnetic permeability than the atmosphere of the arc chamber of the electrical device. Accordingly, depending on whether the core is inserted into or spaced from the opening of the coil, the coil will have a different selfinductance. Thus, by measuring the inductance, aspects of this disclosure can determine a position of the sensing element and a corresponding position of the movable contact.

[0018] In still further aspects of this disclosure, the sensing element may be a second coil. For example, the auxiliary coil may be a first coil and the sensing element may be a second coil configured to move into and out of proximity of the first coil. In some examples, it may be possible that a ferromagnetic core used as the sensing element may be magnetically saturated by the current passing through the closed electric circuit, e.g., through the movable contact. This magnetic saturation may reduce the efficacy of the core to facilitate the change in inductance described above. A coil, e.g., a second auxiliary coil may not be saturated. When the secondary coil is placed in proximity of the auxiliary coil, a total inductance of the auxiliary coil increases due to the mutual inductance between the two coils, which adds to the total inductance. Thus, by measuring the inductance, aspects of this disclosure can determine a position of the sensing element and a corresponding position of the movable contact.

[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 devices that incorporate movable contact members.

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

[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 DC contactor. 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 additional components, for example, ceramic components may also be disposed in the upper housing portion 106 and may at least partially define the 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 portion106. 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 (not shown) 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 112. 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 shaft118, 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 104 into 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 sides132. 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 contact 114, as noted above. The movable contact 114 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 118 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 ofthe shaft 118, e.g., to prevent destructive contact of the movable contact 114 with the fixed contacts112. 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 142 may 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 1150 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 at least 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 ofthe 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 themovable 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 state detection system 164. As detailed herein, the state detection system 164 is configured to determine a state of the electrical device 100. More specifically, the state detection system 164 is configured to identify whether the movable contact 114 is spaced from the fixed contacts 112 (e.g., an open state) or whether the movable contact 114 is in contact with the fixed contacts 112 (e.g., a closed state). As illustrated in FIG. 1, the state detection system 164 includes a coil 166 and a sensing element 168.

[0042] The coil 166 may be an electromagnetic coil. In some examples, the coil 166 may be an auxiliary coil. The coil 166 may have a cylindrical shape, e.g., extending along an axis and defining an opening. In other examples, the coil 166 may be other than cylindrical. As will be appreciated, the coil 166 may include a number of windings, e.g., of copper or other conductive wire, or the like. As illustrated in FIG. 1, the coil may be connected to or otherwise include electrical leads 170. As detailed further herein, the electrical leads 170 may be connected to a computing device that is configured to monitor or sample one or more attributes of the coil 166. For example, the electrical leads 170 may be used to determine a current in the coil 166 and / or an inductance of the coil 166, as detailed further herein.

[0043] In the illustrated example, the sensing element 168 is coupled to the movable contact 114 by a sensing element mount 172. The sensing element mount 172 maintains thesensing element 168 at a distance from the movable contact member 114. When the movable contact 114 moves, the sensing element 168 also moves, correspondingly. As detailed further herein, a proximity of the sensing element 168 to the coil 166 will vary one or more characteristics of the coil 166, which can be sensed via the electrical leads 170, as noted above.

[0044] FIGS. 2 A and 2B illustrate an example implementation of the use of the state detection system 164. More specifically, FIG. 2A shows a portion of the electrical device 100 when the electrical device 100 is configured in an open state (e.g., with the movable contact 114 spaced from the fixed contacts 112), and FIG. 2B shows the same portion of the electrical device 100 when the electrical device 100 is configured in a closed state (e.g., with the movable contact 114 contacting the fixed contacts 112). In FIGS. 2A and 2B, the same reference numerals used in FIG. 1 are used to identify the same features.

[0045] In more detail, the view of FIG. 2A shows that coil 166 is secured or coupled to an upper portion 202 of the upper housing 106. More specifically, FIG. 2A shows that a receptacle or channel 204 is formed in a top surface of the upper portion 202. The coil 166 is disposed in the channel 204. In examples, the channel 204 may be an annular channel or receptacle configured to receive (and retain) the coil 166. As will be appreciated, the configuration of the channel 204 may vary based on the comigration of the coil 166. For example, if the coil 166 is other than cylindrical, the channel 204 may have a corresponding non-cylindrical shape.

[0046] As also shown, the electrical device 100 can also include a cap 206 disposed on the upper portion 202. The cap 206 can be configured to cover the coil 166 and / or the channel 204.The cap 206 may also have one or more openings through which the electrical leads 170 extends.In other examples, the cap 206 can be configured as a connector, e.g., to receive a plug or adapter,for connecting to the electrical leads 170. In still further examples, the cap 206 may be otherwise formed or omitted entirely.

[0047] As also shown in FIG. 2A, a bore 208 is formed in a bottom surface of the upper portion 202 of the upper housing 106. The bore 208 may be a circular or cylindrical bore and that is coaxial with the channel 204 discussed above. Although illustrated as being cylindrical, the bore may be differently shaped in other examples. In examples, the bore 208 extends into an opening defined by the coil 166. Stated differently, at least a portion of the coil 166 may be wrapped around the bore 208. As detailed further herein, the bore may be sized to receive a portion of the sensing element 168 therein.

[0048] As noted above, the sensing element 168 is coupled to the movable contact 114 by the sensing element mount 172. FIG. 2A shows that the sensing element mount 172 includes an elongate body 210 and a flanged head 212. The elongate body 210 may be cylindrical and extends from an upper surface of the movable contact 114. Although illustrated as cylindrical, the elongate body 210 may have any shape that facilitates positioning of the sensing element 168 as described herein. In the illustrated example, the movable contact member 114 includes a hole 214, and the elongate body 210 extends through the hole 214 to a position spaced from an upper surface (in the illustrated orientation) of the movable contact member 114. The flanged head 212 has a diameter or outer extent larger than the hole 214 and contacts a lower surface (in the illustrated orientation) of the movable contact member 114. In the illustrated example, the flanged head 212 is sandwiched or otherwise disposed between the movable contact member 114 and the lower yoke 144. With the illustrated arrangement, the sensing element mount 172 is coupled to the movable contact member 114 such that the sensing element mount 172 moves with the movable contact member 114.

[0049] FIG. 2A is not to be understood to be limiting. For example, the sensing element mount 172 may be otherwise coupled to the movable contact member. Without limitation, instead of including a flanged head, the sensing element mount 172 may have threads configured to mate with threads in the hole 214 of the movable contact 114. In other examples, the movable contact member 114 and the sensing element mount 172 may be coupled via a press or interference fit. In still further examples, the sensing element mount 172 may be integrated into the shaft 118, e.g., by elongating the shaft 118 to extend upward through the movable contact member 114. Generally, any configuration in which the sensing element mount 172 retains the sensing element 168 to move with the movable contact member 114 may be used.

[0050] In the illustrated example, the sensing element 168 may be embedded into the sensing element mount 172. For example, and without limitation, the sensing element mount 172 may be a molded part, e.g., made via injection molding or the like, that is molded over the sensing element 168. In other examples, however, the sensing element 168 may be otherwise coupled to or retained by the sensing element mount 172. Generally, any arrangement or configuration in which the sensing element 168 is retained to move with the movable contact member 114 may be used.

[0051] FIG. 2A also shows, schematically, that the electrical leads 170 are in communication with a monitoring system 216. In examples, the monitoring system 216 may include a computing system or device in electrical communication with the electrical leads 170. The monitoring system 216 can include one or more modules or components for determining attributes of the coil 166 by monitoring the electrical leads 170 coupled to the coil 166. In examples, the monitoring system 216 may include functionality to sample attributes of the coil166 via the electrical leads 170.

[0052] As noted above, FIG. 2A shows an open configuration, e.g., in which the movable contact member 114 is spaced from the fixed contact members 112. In this example, the sensing element 168 is spaced from the coil 166. In the open position, the coil 166 may have one or more characteristics or attributes. For instance, the monitoring system 216 can determine a current, h, associated with the coil 166 in the open configuration, an inductance, Li, associated with the coil 166 in the open configuration, and / or one or more other attributes of the coil 166.

[0053] FIG. 2B shows the same elements as FIG. 2A, but in FIG. 2B the electrical device 100 is in a closed state, e.g., such that the movable contact 114 contacts the fixed contacts 112. As shown, with the movable contact 114 advanced toward the fixed contacts 112, the sensing element 168 also has moved. Specifically, the sensing element 168 has moved into proximity of the coil 166. In the illustrated example, the sensing element is at least partially disposed in the bore 208. Accordingly, the sensing element 168 is at least partially disposed in the coil 166, e.g., in the opening defined by the coil 166.

[0054] With the sensing element 168 in (closer) proximity with the coil 166, characteristics of the coil 166 are altered. For example, FIG. 2B shows that the monitoring system 216 senses or determines a current, h, associated with the coil 166 in the closed configuration, an inductance, L2, associated with the coil 166 in the closed configuration, and / or one or more other attributes of the coil 166 in the closed configuration. In these examples, the current, h, associated with the coil 166 in the closed configuration may be measurably different from the current, h, associated with the coil 166 in the open configuration. Moreover, the inductance, L2, associated with the coil 166 in the closed configuration may be measurably different from the inductance, Li, associated with the coil 166 in the open configuration. The monitoring system can also measure other characteristics and identify differences between the states.

[0055] In some examples, in addition to determining one or more characteristics of the coil 166, the monitoring system 216 can also include functionality to determine a state of the electrical device 100 based on the characteristic(s). For example, the monitoring system 216 can compare a value of the measured characteristic(s) to an expected value for the characteristic(s) in the open state and / or in the closed state. For example, and without limitation, the expected value(s) may be determined empirically, mathematically, and / or otherwise. Accordingly, when the measured value corresponds to a value or range of values expected in the open state, the monitoring system 216 may determine that the device is open. Alternatively, when the measured value corresponds to a value or range of values expected in the closed state, the monitoring system 216 may determine that the device is closed.

[0056] The altered characteristic measured by the monitoring system 216 may vary based on the composition and / or configuration of the sensing element 168. In a first example, the sensing element 168 may be a magnet. When the magnet is moved into proximity of the coil 166, e.g., into the bore 208 or the opening defined by the coil 166, the magnet induces a current through the coil, e.g., according to Faraday-Lenz’s Law. The monitoring system 216 may detect this change in current as the current h. As will be appreciated, the current, e.g., a high voltage current, passing through the fixed contacts 112 and the movable contact 114 will create a magnetic field, but that field will not induce a current in the auxiliary coil 166 because the generated magnetic field is perpendicular to the axis of the auxiliary coil 166 and / or because the auxiliary coil 166 is sufficiently distanced from the fixed contacts 112 and the movable contact 114.

[0057] In other example implementations, the sensing element 168 may be a core, such as a ferromagnetic core or other magnetically permeable core. The core may be selected to have a higher magnetic permeability than the atmosphere of the arc chamber, e.g., in the volume 110 ofthe electrical device 100. Accordingly, depending on whether the core is inserted into the coil 166 (as in FIG. 2B) or spaced from the opening of the coil 166 (as in FIG. 2 A), the coil 166 will have a different self-inductance, L. Thus, by measuring the inductance, L, aspects of this disclosure can determine a position of the sensing element 168 and a corresponding position (open or closed) of the movable contact 114.

[0058] In yet another example, the sensing element 168 may be a second coil. For example, the auxiliary coil 166 may be a first coil and the sensing element 168 may be a second coil configured to move into and out of proximity of the first coil 166. For example, when a ferromagnetic core or some other core made of some other material that is magnetically permeable is used as the sensing element 168, the sensing element 168 may be magnetically saturated by the current passing through the closed electric circuit, e.g., through the movable contact 114. This magnetic saturation may reduce the efficacy of the core to facilitate the change in inductance described above. Implementing the sensing element 168 as a coil, e.g., a second auxiliary coil, will prevent this saturation. When the secondary coil is placed in proximity of the auxiliary coil, a total inductance of the auxiliary coil 166 increases due to the mutual inductance between the two coils, which adds to the total inductance. Thus, by measuring the inductance, L, aspects of this disclosure can determine a position of the sensing element and a corresponding position of the movable contact.

[0059] FIG. 3 is a flowchart illustrating a process 300 for determining a state of an electrical device, such as the electrical device 100. Although aspects of FIG. 3 will be discussed in the context of the electrical device 100, the process 300 is not limited to use with the electrical device 100, and the electrical device 100 need not incorporate the process 300.

[0060] At an operation 302, the process 300 includes configuring a contact device in an open state or a closed state. As detailed herein, aspects of this disclosure may be useful in a contactor or other electrical switching device that can be configured in an open state and a closed state. For example, the operation 302 may include causing the movable contact 114 to move into or out of contact with the fixed contacts 112 to complete a circuit that facilitate current / voltage flow between the fixed contacts 112 via the movable contact 114.

[0061] At an operation 304, the process 300 includes monitoring a characteristic of an auxiliary coil. As detailed herein, the electrical device 100 can include an auxiliary coil 166. In examples, the auxiliary coil 166 can be disposed outside a volume in which the movable contact 114 is disposed. As described herein, placing the auxiliary coil 166 outside the volume may help to increase electrical insulation between the low voltage (associated with the coil 166) and the high voltage current flowing through the contacts 112, 114. The monitoring system 216 can be electrically coupled to the coil 166, e.g., via the one or more electrical leads 170. The monitoring system 216 can be configured to monitor the current and / or inductance of the coil 166.

[0062] At an operation 306, the process 300 includes determining a value for the monitored characteristic of the auxiliary coil. For example, at the operation 306 the monitoring system 216 can determine or quantify a current, I, of the coil 166 and / or an inductance, , of the coil 166. In other examples, the process 300 can include quantifying any characteristic that may be altered in response to the sensing element 168 moving relative closer to or farther from the coil 166, as detailed herein.

[0063] At an operation 308, the process 300 includes determining whether the measured value corresponds to the open or closed configuration. In some examples, the operation 308 caninclude comparing the value determined at the operation 306 to expected values or ranges of values associated with the open / closed states of the electrical device 100. For example, when the electrical device 100 is in the open state, the auxiliary coil 166 may have an expected first current (or lack of current) flowing therethrough or the auxiliary coil 166 may have an expected first inductance (or lack of inductance). In contrast, when the device 100 is in the closed state, because the sensing element 168 is in closer proximity to the coil 166, the auxiliary coil 166 will have a second, different current and / or the auxiliary coil 166 will have a second, different inductance.

[0064] If, at the operation 308, the measured value corresponds to the open / closed configuration, at an operation 310, the process 300 can include confirming a state of the device 100. For example, if at the operation 302 the contactor device is instructed to be closed and the operation 308 confirms that the measured value of the coil 166 corresponds to a value expected with the contactor closed, the operation 310 can confirm the correct state (closed) of the device. In examples, the operation 310 can include generating and / or transmitting a signal corresponding to the agreement of the state with the expected configuration. In other examples, the operation 310 may be independent of the operation 302. For example, the operation 310, using the information from the comparison at the operation 308 can determine whether the device is in an open or closed state and generate a signal associated with the detected state.

[0065] Alternatively, if at the operation 308 it is determined that the measured value does not correspond to the open / closed configuration, at an operation 312, the process 300 can signal a fault. In examples, if the operation 302 comprises configuring the device in the closed state (or the open state), but the comparison of the operation 308 indicates that the device is in an open state (or the closed state), the operation 312 can include generating a fault. The fault may indicate that the device 100 is working incorrectly, for example.

[0066] As will be appreciated from the foregoing, aspects of this disclosure relate to the use of an auxiliary coil to monitor a state of an electrical device, e.g., by monitoring a current and / or inductance of the auxiliary coil. This non-contact monitoring method is distinct from some conventional designs that use a physical or mechanical contact that may be directly connected to the contactor’s moving parts to determine state. Moreover, because the auxiliary coil can be disposed outside the arc chamber of the device, aspects of the present disclosure can provide increased electrical insulation between the auxiliary and high-voltage circuits. In addition, the auxiliary coil may provide a reduced number of components and / or obviate the need for a hermetic seal through which the leads 170 pass, e g., because the coil is outside the chamber. Moreover, when compared to conventional mechanical sensors, the present disclosure may provide fewer moving and contacting parts, which can reduce points of failure, thereby increasing contactor life.

[0067] As detailed above, FIGS. 1, 2A and 2B show an example of a contactor or switching electrical device that incorporates the coil 166 and the sensing element 168 to determine a state of the device 100. Modifications to the example are contemplated. For example, and without limitation, although the coil 166 is illustrated as being disposed outside the volume 110, in other examples the coil 166 could be disposed in the volume. The illustrated position may be desirable to obviate the need for passing the lead(s) 170 out of the volume 110, but in other examples the coil 166 may be at least partially in the volume 110. Similarly, although the sensing element 168 is illustrated as being disposed in the volume 110, in other examples the mount 172 may be configured to dispose the sensing element 168 at least partially outside the volume 110.

[0068] Moreover, although the illustrated example shows the sensing element 168 as being coupled to the movable contact 114 and the coil 166 as being fixed to the housing 102, in other examples the coil 166 may be coupled to the movable contact 114 and the sensing element 168may be fixed. For example, and without limitation, the coil 166 may be disposed inside the volume 110 and configured to move with the movable contact 114. In this example, the sensing element 168 may extend into the volume, e.g., in a fixed orientation, or the sensing element 168 may be disclosed partially or completely outside the volume 110. In this example, the coil 166 may move over the sensing element when the movable contacts move into contact with the fixed contacts. This arrangement also is for example only. Any arrangement in which a relative movement of the coil 166 and the sensing element 168 corresponds to movement between the open and closed configurations may be used.

[0069] Moreover, although aspects of this disclosure contemplate the core 166 defining a central opening in which the sensing element 168 is disposed wen the device is closed, this disclosure is not limited to that example. For instance, in some examples the sensing element may define an opening into which a portion of the coil extends. Any arrangement in which a relative movement of the coil 166 and the sensing element 168 corresponds to movement between the open and closed configurations may be used.

[0070] Other modifications also are contemplated. For example, and without limitation, although the coil 166 and the sensing element 168 are illustrated as being generally aligned along the axis 141 of the shaft 118, other arrangements, including off-axis arrangements, also are contemplated. Any configuration in which the coil 166 and the sensing element 168 are moved relative to each other to effect a measurable change in the coil 166 may be used in accordance with this disclosure.

[0071] While the subject technology has been described with respect to preferred embodiments, those skilled in the art will readily appreciate that various changes and / ormodifications 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. A switching device comprising: a housing defining a volume; one or more fixed contacts disposed at least partially in the volume defined by the housing; a movable contact disposed in the volume, the movable contact being movable between a first position spaced from the one or more fixed contacts and a second position contacting the one or more fixed contacts; a coil; and a sensing element coupled to the movable contact, wherein, moving the movable contact between the first position and the second position causes the sensing element to move relative to the coil such that a characteristic of the coil changes.

2. The switching device of claim 1, wherein: the coil is disposed outside the volume; and the sensing element is disposed inside the volume.

3. The switching device of claim 1 or claim 2, wherein: the coil defines an opening; and the sensing element is disposed at least partially in the opening with the movable contact in the second position.

4. The switching device of claim 3, wherein: the sensing element is a magnet; and moving the movable contact to the second position causes the magnet to induce a current in the coil.

5. The switching device of claim 3, wherein: the sensing element is a magnetically permeable core; and moving the movable contact to the second position causes a change in an inductance of the coil.

6. The switching device of claim 3, wherein: the coil is a first coil; the sensing element comprises a second coil; and moving the movable contact to the second position causes a change in an inductance of the first coil.

7. The switching device of any one of claim 1 through claim 6, further comprising: one or more electrical leads coupled to the coil.

8. The switching device of any one of claim 1 through claim 7, further comprising: a sensing element mount coupled to the movable contact and configured to retain the sensing element.

9. The switching device of claim 8, wherein: the sensing element mount extends from a surface of the movable contact; and the sensing element is disposed in the sensing element mount at a distance from the surface of the movable contact.

10. An electrical device comprising: a housing defining a volume; fixed contacts coupled to the housing and configured for coupling to a power source or a load; a movable contact disposed in the housing and movable between a first position spaced from the fixed contacts and a second position contacting the fixed contacts; a coil; and a sensing element, wherein movement of the movable contact between the first position and the second position positions the sensing element relatively closer to the coil to change a characteristic of the coil.

11. The electrical device of claim 10, wherein the sensing element comprises at least one of a magnet, a magnetically permeability core, or a second coil.

12. The electrical device of claim 10 or claim 11, wherein: the coil is fixed relative to the housing; and the sensing element is coupled to the movable contact.

13. The electrical device of claim 12, wherein: the coil is disposed outside the housing; and the sensing element is disposed inside the housing.

14. The electrical device of claim 10 or claim 11, wherein: the sensing element is fixed relative to the housing; and the coil is coupled to the movable contact.

15. The electrical device of claim 14, wherein: the sensing element is disposed outside the housing; and the coil is disposed inside the housing.

16. The electrical device of any one of claim 10 through claim 15, wherein: the coil defines an opening; and the sensing element is disposed at least partially in the opening with the movable contact in the second position.

17. The electrical device of any one of claim 10 through claim 16, further comprising: one or more electrical leads coupled to the coil and extending to a position outside the housing, the one or more electrical leads facilitating monitoring the characteristic of the coil.

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