Aspects of embodiments of the present disclosure are generally related to relays and contactors.
Relays and contactors are used extensively in electrical power switching applications. These devices operate with a fairly low power signal and may be capable of switching high levels of power. The principle of operation of these devices is a magnetic circuit that actuates a moving contact and closes the path of the current. The magnetic force may be generated via a coil, and is applied to the moving contact to close the conduction path.
One method of actuating a contact is using the linear displacement force of the magnetic field to move a ferromagnetic material. When the coil is energized, it generates a magnetic force that attracts a ferromagnetic plunger, which is connected to the moving contact. The moving contact is pulled toward and makes intimate contact with stationary contacts, thus closing the conduction path and allowing the current to flow through the device.
Contactors and relays that are designed for critical applications, such as aerospace applications, have stringent requirements for their operating characteristics, which limit acceptable levels of shock and chatter. Chattering is referred to a behavior of the contacts of a relay/contactor that open and close momentarily. Prolonged chattering may have an adverse effect on the contact material and causes their rapid erosion.
The above information disclosed in this Background section is only for enhancement of understanding of the present disclosure, and therefore it may contain information that does not form the prior art that is already known to a person of ordinary skill in the art.
Aspects of embodiments of the present disclosure are directed to a system and method for eliminating or substantially reducing chatter of contacts of a contactor device.
According to some embodiments of the present disclosure, there is provided a contactor including: a first actuator; a compressive element moveably coupling the first actuator to a rigid portion of the contactor; a shaft configured to move toward the rigid portion when the contactor is in an energized state and to move away from the rigid portion when the contactor is in a de-energized state, the shaft being moveable with respect to the first actuator; a second actuator fixedly coupled to the shaft and spaced from the first actuator; and a common contact extending between the first actuator and the second actuator, the common contact being moveable with respect to a first contact, wherein the compressive element is configured to press the first actuator against the common contact, and wherein the first actuator is configured to electrically connect the common contact and the first contact when the contactor is in the de-energized state, and the second actuator is configured to electrically disconnect the common contact and the first contact when the contactor is in the energized state.
In some embodiments, the shaft is engaged with, and not attached to, the first actuator.
In some embodiments, the first and second actuators are parallel plates extending in a direction crossing an extension direction of the shaft.
In some embodiments, the first contact is a normally-closed contact and includes a first pair of contacts configured to conduct electrical current when the contactor is in the de-energized state.
In some embodiments, the first actuator is configured to maintain a physical and electrical connection between the common contact and the first contact in the presence of vibration of the shaft within a set range.
In some embodiments, the set range is 6 to 8 Grms (root mean square acceleration) at 5 Hz to 2000 Hz vibration levels.
In some embodiments, the contactor further includes: a second contact spaced from the first contact, wherein the contact is between the first contact and the second contact along an extension direction of the shaft.
In some embodiments, the common contact extends between, and contacts at least one of, the first and second actuators.
In some embodiments, the first and second contacts are electrically isolated from one another.
In some embodiments, the first actuator is configured to electrically disconnect the common contact and the second contact when the contactor is in the de-energized state, and the second actuator is configured to electrically connect the common contact and the second contact when the contactor is in the energized state.
In some embodiments, the second contact is a normally-open contact and includes a second pair of contacts configured to conduct electrical current when the contactor is in the energized state.
In some embodiments, the first and second contacts are auxiliary contacts of the contactor and are configured to replicate conduction states of main contacts of the contactor and to indicate the conduction states of the main contacts to a host system.
In some embodiments, the rigid portion is a housing of the contactor.
In some embodiments, the contactor further includes: a shaft driver configured to drive the shaft toward the rigid portion, when the contactor is in the energized state, and to retract the shaft away from the rigid portion when the contactor is in the de-energized state.
In some embodiments, the shaft driver includes: a moveable core coupled to the shaft; and an electromagnetic coil configured to induce a movement in the moveable core in response to a control signal, the control signal being an open or close signal.
According to some embodiments of the present disclosure, there is provided a contactor including: a first actuator; a compressive element moveably coupling the first actuator to a rigid portion of the contactor; a shaft configured to move toward the rigid portion when the contactor is in an energized state and to move away from the rigid portion when the contactor is in a de-energized state, the shaft being moveable with respect to the first actuator; a second actuator fixedly coupled to the shaft and spaced from the first actuator; and a common contact extending between the first actuator and the second actuator, the common contact being between a first contact and a second contact and being moveable with respect to the first and second contacts, wherein the compressive element is configured to press the first actuator against the common contact, and wherein the first actuator is configured to electrically connect the common contact to the first contact and to electrically disconnect the common contact and the second contact when the contactor is in the de-energized state, and the second actuator is configured to electrically disconnect the common contact and the first contact and to electrically connect the common contact to the second contact when the contactor is in the energized state.
In some embodiments, the shaft is engaged with, and not attached to, the first actuator.
In some embodiments, the first actuator is configured to maintain a physical and electrical connection between the common contact and the first contact in the presence of vibration of the shaft within a set range.
In some embodiments, the set range is from 6 to 8 Grms (root mean square acceleration) at 5 Hz to 2000 Hz vibration levels.
In some embodiments, the first and second contacts are auxiliary contacts of the contactor and are configured to replicate conduction states of main contacts of the contactor and to indicate the conduction states of the main contacts to a host system.
The accompanying drawings, together with the specification, illustrate example embodiments of the present disclosure, and, together with the description, serve to explain the principles of the present disclosure.
The detailed description set forth below is intended as a description of example embodiments of a system and method for defect detection, provided in accordance with the present disclosure, and is not intended to represent the only forms in which the present disclosure may be constructed or utilized. The description sets forth the features of the present disclosure in connection with the illustrated embodiments. It is to be understood, however, that the same or equivalent functions and structures may be accomplished by different embodiments that are also intended to be encompassed within the scope of the disclosure. As denoted elsewhere herein, like element numbers are intended to indicate like elements or features.
Referring to
In some embodiments, the first and second contacts 114 and 116 and the common (COM) contact 112 may be arranged along a first direction D1, which corresponds to the extension direction of the shaft 104. The first and second contacts 114 and 116 are stationary (e.g., relative to the rigid portion 102) and the common contact 112 is moveable between, and capable of coming into physical and electrical contact with, either of the first and second contacts 114 and 116, based on the position of the first and second actuators 106 and 108. According to some embodiments, the first contact 114, which may be further away from the rigid portion 102 than the second contact 116, is a normally closed (N.C.) contact, and the second contact 116 is a normally open (N.O.) contact. The common contact 112 and the first and second contacts 114 and 116 may be made of a suitable conductive material, such as silver tin oxide (AgSnO2), and/or the like. In some embodiments, the common contact 112 includes a pair of common contacts 112a and 112b that are electrically shorted each other, the first contact 114 includes a pair of first contacts 114a and 114b, and the second contact 116 includes a pair of second contacts 116a and 114b. The pairs 112a and 112b, 114a and 114b, and 116a and 116b are arranged at opposite sides of the shaft 104 (e.g., along the second direction D2 crossing the first direction D1). When the common contact 112 (e.g., the pair of common contacts 112a and 112b) comes into contact with the first contact 114 or the second contact 116, an electrical short is created between the pair of first contacts 114a and 114b or between the pair of second contacts 116a and 116b, respectively, thus allowing a current I to pass through the corresponding contact.
According to some embodiments, unlike the second actuator 108, which is fixedly mounted to (or attached to) the shaft 104, the first actuator 106 is not fixedly connected to (e.g., not attached to) but engaged by the shaft 104 and may freely move along the length of the shaft 104 (e.g., along the first direction D1). In some examples, the shaft 104 may pass through an opening (e.g., through hole) in the first actuator 106. The first actuator 106 is held in place by the compressive element 110, which may surround a portion of the shaft 104 and may exert a restoring force on the first actuator 106 to push it toward the common contact 112 when compressed. With this scheme, the initial movement of the shaft 104 is not transferred to the first actuator 106. As such, vibrations of the shaft 104 relative to the rigid portion 102 within a particular range may not affect (e.g., may not reduce) the pressure on the common contact 112, thus preventing or substantially reducing chatter. Such particular range may be about 6 to about 8 Grms (root mean square acceleration) at about 5 Hz to about 2000 Hz vibration levels. When a gap G exists between the second actuator 108 and the common contact 112 in the de-energized state, any vibrational displacement of the shaft 104 with respect to the rigid portion 102 that is less than the gap G may not result in any chatter.
The movement of the shaft 104 along the direction D1 may be driven by the shaft driver 120 in response to a control signal from a controller 130. In an energized state, the shaft driver 120 drives the shaft 104 toward the rigid portion 102, and in a de-energized state, the shaft 104 is retracted toward the shaft driver and away from the rigid portion 102.
Thus, by detaching and moveably coupling the top actuator and the shaft, and utilizing a spring between the top actuator and the rigid member, the contactor according to embodiments of the present invention is capable of eliminating or substantially eliminating chatter during vibration in at least the de-energized state for a desired margin of vibration movements.
Tests conducted with a comparative example illustrate the effectiveness of the contactor, according to embodiments of the invention, in substantially reducing or eliminating contact chatter. The test was conducted with a 115/230 Vac, 3-pole single throw (3PST) switch /contactor rated for 450 A, with eight single-pole double-throw (SPDT) auxiliary contacts. In a comparative example that does not use a compressive element 110 and has a first actuator that is attached to the shaft, all of the normally closed (N.C.) auxiliary contacts chattered when subjected to 6 gRMS (20 Hz.-2 kHz). The same contactor fitted with the compressive element 110 and utilizing a first actuator that is moveably coupled to the shaft, according to some embodiments of the present invention, exceeded 7 gRMS without chatter. Based on the test results, the contactor according to embodiments of the present invention exhibited no chattering in the de-energized and energized states. The comparative example suffered from chattering due to the movement of the top actuator directly connected to the shaft. The contactor according to embodiments of the present invention allows slight shaft movement without causing the movement in the top Actuator, thus mitigating the chatter of the contacts (e.g., auxiliary contacts) in at least their normally closed position.
The contacts illustrated in
Referring to
Generally, in any power distribution system utilizing contactors with auxiliary contacts, the integrity of the auxiliary signals generated by the auxiliary contacts may be very critical to system performance, as their incorrect reporting could result in critical, or even catastrophic failures. To assure their compliance with the position of the main contact, the auxiliary contacts are generally driven by the same shaft that actuates the main contacts. Similarly, in the example of the contactor 100-1 illustrated in
However, as illustrated in
In the examples, illustrated in
Further, by eliminating or substantially reducing chatter on contacts, embodiments of the present invention also prevent or substantially prevent arcing, which can improve (e.g., extend) the life of contacts. Generally, when contacts are opened under load (e.g., as a result of chatter) the electron flow across the contacts may be enough to ionize the air molecules across a minimal gap, thus forming an electric arc. The generated plasma may have a low enough electrical resistance to sustain electron flow even with the separation distance between the contacts steadily increasing. The arcing may result in pitting and fretting of the contact material, which in turn results in increased contact resistance and reduced life. However, embodiments of the present invention can readily alleviate this problem, thus improving system reliability and reducing the cost of deploying contactors in power distribution systems.
According to some examples, the contactor 100/100-1 may be a solenoid type contactor, and the shaft 104 may be a part of, or be coupled to, a moveable core (also referred to as a plunger) 122 of a magnet in the shaft driver 120. When an electromagnetic coil 124 of the shaft driver 120 is energized (e.g., in response to the control signal received from the controller 130), the electromagnetic coil 124 generates an electromagnetic force that pushes the movable core toward the rigid portion 102 and away from the stationary core 126. This causes the second actuator 108/108-1, which is mounted to the shaft, to move up and press the common contact 112/112-1 against the second contact 116/116-1, thus closing (e.g., electrically shorting) the second pair of contacts 116a/116a-1 and 116b/116b-1 (e.g., the normally open contacts) and allowing the second contact 116/116-1 to conduct current I. At the same time, the first contact 114/114-1 (e.g., the normally closed contacts) open, thus breaking the electrical connection between the first pair of contacts 114a/114a-1 and 114b/114b-1. When the electromagnetic coil 124 is de-energized, the shaft 104 returns to its normal/relaxed position (i.e., retracts toward the stationary core 126, which causes the electrical connection between the second pair of contacts 116a/116a-1 and 116b/116-1 to be broken and the electrical connection between the first pair of contacts 114a/114a-1 and 114b/114b-1 to be reestablished.
While
While the illustrated embodiments of the present invention utilize both a first contact 114/114-1 (e.g., the normally closed contact) and a second contact 116/116-1 (e.g., the normally open contact), embodiments of the present invention are not limited thereto, and the contactor 100/100-1 may utilize only the first contact 114/114-1 and still benefit from the chatter reducing/eliminating benefits described above with respect to
The terminology used herein is for the purpose of describing particular embodiments and is not intended to be limiting of the inventive concept. As used herein, the singular forms “a” and “an” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “include”, “including”, “comprises”, and/or “comprising”, when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items. Expressions such as “at least one of”, when preceding a list of elements, modify the entire list of elements and do not modify the individual elements of the list. Further, the use of “may” when describing embodiments of the inventive concept refers to “one or more embodiments of the inventive concept”. Also, the term “exemplary” is intended to refer to an example or illustration.
It will be understood that, although the terms “first”, “second”, “third”, etc., may be used herein to describe various elements, components, and/or sections, these elements, components, and/or sections should not be limited by these terms. These terms are used to distinguish one element, component, or section from another element, component, or section. Thus, a first element, component, or section discussed below could be termed a second element, component, or section, without departing from the scope of the inventive concept.
It will be understood that when an element is referred to as being “connected to” or “coupled to ” another element, it can be directly connected to or coupled to the other element, or one or more intervening elements may be present. When an element is referred to as being “directly connected to” or “directly coupled to” another element, there are no intervening elements present.
As used herein, the terms “use”, “using”, and “used” may be considered synonymous with the terms “utilize”, “utilizing”, and “utilized”, respectively.
The controller and/or any other relevant devices or components according to embodiments of the present disclosure described herein may be implemented by utilizing any suitable hardware, firmware (e.g., an application-specific integrated circuit), software, or a suitable combination of software, firmware, and hardware. For example, the various components of the independent multi-source display device may be formed on one integrated circuit (IC) chip or on separate IC chips. Further, the various components of the controller may be implemented on a flexible printed circuit film, a tape carrier package (TCP), a printed circuit board (PCB), or formed on the same substrate. Further, the various components of the controller may be a process or thread, running on one or more processors, in one or more computing devices, executing computer program instructions and interacting with other system components for performing the various functionalities described herein. The computer program instructions are stored in a memory which may be implemented in a computing device using a standard memory device, such as, for example, a random access memory (RAM). The computer program instructions may also be stored in other non-transitory computer-readable media such as, for example, a CD-ROM, flash drive, or the like. Also, a person of skill in the art should recognize that the functionality of various computing devices may be combined or integrated into a single computing device, or the functionality of a particular computing device may be distributed across one or more other computing devices without departing from the scope of the exemplary embodiments of the present disclosure.
While this disclosure has been described in detail with particular references to illustrative embodiments thereof, the embodiments described herein are not intended to be exhaustive or to limit the scope of the disclosure to the exact forms disclosed. Persons skilled in the art and technology to which this disclosure pertains will appreciate that alterations and changes in the described structures and methods of assembly and operation can be practiced without meaningfully departing from the principles, and scope of this disclosure, as set forth in the following claims and equivalents thereof.
This application claims priority to, and the benefit of, U.S. Provisional Application No. 62/755,077 (“SYSTEM AND METHOD FOR REDUCING CHATTERING ON CONTACTS DURING VIBRATION”), filed on Nov. 2, 2018, the entire content of which is incorporated herein by reference.
Number | Name | Date | Kind |
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2444157 | Dries | Jun 1948 | A |
3418608 | Angel | Dec 1968 | A |
3684986 | Nagamoto | Aug 1972 | A |
4216452 | Arnoux | Aug 1980 | A |
9543102 | Tachikawa | Jan 2017 | B2 |
20100026427 | Moeller | Feb 2010 | A1 |
Number | Date | Country | |
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20200144011 A1 | May 2020 | US |
Number | Date | Country | |
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62755077 | Nov 2018 | US |