Patent Publication Number: US-11651918-B2

Title: Sensing properties of switching devices using back EMF measurements

Description:
BACKGROUND 
     The present disclosure relates generally to switching devices, and more particularly to operation and configuration of the switching devices. Switching devices are generally used throughout industrial, commercial, material handling, process and manufacturing settings, to mention only a few. As used herein, “switching device” is generally intended to describe any electromechanical switching device, such as mechanical switching devices (e.g., a contactor, a relay, air break devices, and controlled atmosphere devices) or solid-state devices (e.g., a silicon-controlled rectifier (SCR)). More specifically, switching devices generally open to disconnect electric power from a load and close to connect electric power to the load. For example, switching devices may connect and disconnect three-phase electric power to an electric motor. 
     As the switching devices open or close, electric power may be discharged as an electric arc and/or cause current oscillations to be supplied to the load, which may result in torque oscillations. Over time, the switching devices begin to operate slightly differently due to contact wear and other conditions. As such, systems and methods for monitoring changes in the operations of the switching devices may be useful. 
     This section is intended to introduce the reader to various aspects of art that may be related to various aspects of the present techniques, which are described and/or claimed below. This discussion is believed to be helpful in providing the reader with background information to facilitate a better understanding of the various aspects of the present disclosure. Accordingly, it should be understood that these statements are to be read in this light, and not as admissions of prior art. 
     BRIEF DESCRIPTION 
     A summary of certain embodiments disclosed herein is set forth below. It should be understood that these aspects are presented merely to provide the reader with a brief summary of these certain embodiments and that these aspects are not intended to limit the scope of this disclosure. Indeed, this disclosure may encompass a variety of aspects that may not be set forth below. 
     In one embodiment, a system may include a switching device. The switching device may include an armature that may move between a first position that electrically couples the armature to a first contact and a second position that electrically couples the armature to a second contact. The switching device may also include a coil that may receive a voltage that magnetizes a core, thereby causing the armature to move from the first position to the second position. The system may also include a control system that may monitor a voltage waveform associated with the coil during an open operation of the switching device. 
     In another embodiment, a method may include receiving, via circuitry, a first back electromotive force (EMF) waveform associated with a coil of a switching device during an open operation. The method may also include determining, via the circuitry, a change in the first back EMF waveform based on a second back EMF waveform. The method may then involve sending, via the circuitry, a notification indicative of an operating condition of the switching device to a computing device in response to the change being greater than a threshold. 
     In yet another embodiment, a non-transitory computer-readable medium comprising computer-executable instructions that, when executed, may cause at least one processor to perform operations that may include receiving coil voltage data associated with a coil of a switching device during an open operation. The operations may also include determining an open timing interval based the coil voltage data and sending one or more control signals to one or more components based on the open timing interval. 
    
    
     
       DRAWINGS 
       These and other features, aspects, and advantages of the present disclosure will become better understood when the following detailed description is read with reference to the accompanying drawings in which like characters represent like parts throughout the drawings, wherein: 
         FIG.  1    is a diagrammatical representation of a set of switching devices to provide power to an electrical load, in accordance with an embodiment; 
         FIG.  2    is a similar diagrammatical representation of a set of switching devices to provide power to an electrical motor, in accordance with an embodiment; 
         FIG.  3    is a similar diagrammatical representation of a set of switching devices to provide power to an electrical motor, in accordance with an embodiment; 
         FIG.  4    is a system view of an example single-pole, single current-carrying path relay device, in accordance with an embodiment; 
         FIG.  5    is a circuit diagram for providing monitoring coil voltage data (e.g., back electromotive force data) associated with a coil of a switching device, in accordance with an embodiment; 
         FIG.  6    is a coil voltage/current/flux-time graph that depicts a coil voltage, a coil current, and a coil&#39;s magnetic flux of a coil in a switching device during a switching operation, in accordance with an embodiment; 
         FIG.  7    is a voltage-time graph that depicts the voltage across two coils of two switching devices during a switching operation, in accordance with an embodiment; 
         FIG.  8    is a block diagram of a control system that may be used to monitor a coil voltage, in accordance with an embodiment; 
         FIG.  9    is a method for controlling components based on changes to coil voltage properties over time, in accordance with an embodiment; 
         FIG.  10    illustrates a voltage over time graph that depicts a relationship between measured back electromotive force (EMF) properties of a switching device during a switching operation over a number of cycles of operations, in accordance with an embodiment; and 
         FIG.  11    illustrates a graph that presents changes in measured back EMF properties for a switching device over a number of cycles, in accordance with an embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     One or more specific embodiments of the present disclosure will be described below. In an effort to provide a concise description of these embodiments, all features of an actual implementation may not be described in the specification. It should be appreciated that in the development of any such actual implementation, as in any engineering or design project, numerous implementation-specific decisions must be made to achieve the developers&#39; specific goals, such as compliance with system-related and business-related constraints, which may vary from one implementation to another. Moreover, it should be appreciated that such a development effort might be complex and time consuming, but would nevertheless be a routine undertaking of design, fabrication, and manufacture for those of ordinary skill having the benefit of this disclosure. 
     When introducing elements of various embodiments of the present disclosure, the articles “a,” “an,” “the,” and “said” are intended to mean that there are one or more of the elements. The terms “comprising,” “including,” and “having” are intended to be inclusive and mean that there may be additional elements other than the listed elements. 
     As described above, switching devices are used in various implementations, such as industrial, commercial, material handling, manufacturing, power conversion, and/or power distribution, to connect and/or disconnect electric power from a load. For example, a number of switching devices may be used to control operations, monitor conditions, and perform other operations related to various equipment in an industrial automation system. As such, the switching devices may be used to coordinate operations across a number of device. 
     With the foregoing in mind, it should be noted that the open operation of the switching device generally depends on a coil current and a core flux of a coil that induces a magnetic field in the switching device. Over time (e.g., cycles of operation), the back electromotive force (EMF) waveform or coil voltage may change as the contacts of the switching devices wear, as a core of the coil saturates, as hysteresis effects increase, and the like. In some embodiments, a system for monitoring the change in the back EMF of the switching device during open operations may provide insight into the wear or life of the switching device. In addition, the measured back EMF may also provide insight into how much time that the switching device may take to open. As such, a number of switching devices may be coordinated in a such a fashion to precisely open or change states within microseconds of desired times. Additional details with regard to coordinating the operations and monitoring of open operations in switching devices will be described below with reference to  FIGS.  1 - 10   . 
     By way of introduction,  FIG.  1    depicts a system  10  that includes a power source  12 , a load  14 , and switchgear  16 , which includes one or more switching devices that may be controlled using the techniques described herein. In the depicted embodiment, the switchgear  16  may selectively connect and/or disconnect three-phase electric power output by the power source  12  to the load  14 , which may be an electric motor or any other powered device. In this manner, electrical power flows from the power source  12  to the load  14 . For example, switching devices in the switchgear  16  may close to connect electric power to the load  14 . On the other hand, the switching devices in the switchgear  16  may open to disconnect electric power from the load  14 . In some embodiments, the power source  12  may be an electrical grid. 
     It should be noted that the three-phase implementation described herein is not intended to be limiting. More specifically, certain aspects of the disclosed techniques may be employed on single-phase circuitry and/or for applications other than power an electric motor. Additionally, it should be noted that in some embodiments, energy may flow from the source  12  to the load  14 . In other embodiments energy may flow from the load  14  to the source  12  (e.g., a wind turbine or another generator). More specifically, in some embodiments, energy flow from the load  14  to the source  12  may transiently occur, for example, when overhauling a motor. 
     In some embodiments, operation of the switchgear  16  (e.g., opening or closing of switching devices) may be controlled by control and monitoring circuitry  18 . More specifically, the control and monitoring circuitry  18  may instruct the switchgear  16  to connect or disconnect electric power. Accordingly, the control and monitoring circuitry  18  may include one or more processors  19  and memory  20 . More specifically, as will be described in more detail below, the memory  20  may be a tangible, non-transitory, computer-readable medium that stores instructions, which when executed by the one or more processors  19  perform various processes described. It should be noted that non-transitory merely indicates that the media is tangible and not a signal. Many different algorithms and control strategies may be stored in the memory and implemented by the processor  19 , and these will typically depend upon the nature of the load, the anticipated mechanical and electrical behavior of the load, the particular implementation, behavior of the switching devices, and so forth. 
     Additionally, as depicted, the control and monitoring circuitry  18  may be remote from the switchgear  16 . In other words, the control and monitoring circuitry  18  may be communicatively coupled to the switchgear  16  via a network  21 . In some embodiments, the network  21  may utilize various communication protocols such as DeviceNet, Profibus, Modbus, and Ethernet, to mention only a few. For example, to transmit signals between the control and monitoring circuitry  18  may utilize the network  21  to send make and/or break instructions to the switchgear  16 . The network  21  may also communicatively couple the control and monitoring circuitry  18  to other parts of the system  10 , such as other control circuitry or a human-machine-interface (not separately depicted). Additionally, the control and monitoring circuitry  18  may be included in the switchgear  16  or directly coupled to the switchgear, for example, via a serial cable. 
     Furthermore, as depicted, the electric power input to the switchgear  16  and output from the switchgear  16  may be monitored by sensors  22 . More specifically, the sensors  22  may monitor (e.g., measure) the characteristics (e.g., voltage or current) of the electric power. Accordingly, the sensors  22  may include voltage sensors and current sensors. These sensors may alternatively be modeled or calculated values determined based on other measurements (e.g., virtual sensors). Many other sensors and input devices may be used, depending upon the parameters available and the application. Additionally, the characteristics of the electric power measured by the sensors  22  may be communicated to the control and monitoring circuitry  18  and used as the basis for algorithmic computation and generation of waveforms (e.g., voltage waveforms or current waveforms) that depict the electric power. More specifically, the waveforms generated based on input the sensors  22  monitoring the electric power input into the switchgear  16  may be used to define the control of the switching devices, for example, by reducing electrical arcing when the switching devices open or close. The waveforms generated based on the sensors  22  monitoring the electric power output from the switchgear  16  and supplied to the load  14  may be used in a feedback loop to, for example, monitor conditions of the load  14 . 
     As described above, the switchgear  16  may connect and/or disconnect electric power from various types of loads  14 , such as an electric motor  24  included in the motor system  26  depicted in  FIG.  2   . As depicted, the switchgear  16  may connect and/or disconnect the power source  12  from the electric motor  24 , such as during startup and shut down. Additionally, as depicted, the switchgear  16  will typically include or function with protection circuitry  28  and the actual switching circuitry  30  that makes and breaks connections between the power source and the motor windings. More specifically, the protection circuitry  28  may include fuses and/or circuit breakers, and the switching circuitry  30  will typically include relays, contactors, and/or solid-state switches (e.g., SCRs, MOSFETs, IGBTs, and/or GTOs), such as within specific types of assembled equipment (e.g., motor starters). 
     More specifically, the switching devices included in the protection circuitry  28  may disconnect the power source  12  from the electric motor  24  when an overload, a short circuit condition, or any other unwanted condition is detected. Such control may be based on the un-instructed operation of the device (e.g., due to heating, detection of excessive current, and/or internal fault), or the control and monitoring circuitry  18  may instruct the switching devices (e.g., contactors or relays) included in the switching circuitry  30  to open or close. For example, the switching circuitry  30  may include one (e.g., a three-phase contactor) or more contactors (e.g., three or more single-pole, single current-carrying path switching devices). 
     Accordingly, to start the electric motor  24 , the control and monitoring circuitry  18  may instruct the one or more contactors in the switching circuitry  30  to close individually, together, or in a sequential manner. On the other hand, to stop the electric motor  24 , the control and monitoring circuitry  18  may instruct the one or more contactors in the switching circuitry  30  to open individually, together, or in a sequential manner. When the one or more contactors are closed, electric power from the power source  12  is connected to the electric motor  24  or adjusted and, when the one or more contactors are open, the electric power is removed from the electric motor  24  or adjusted. Other circuits in the system may provide controlled waveforms that regulate operation of the motor (e.g., motor drives, automation controllers, etc.), such as based upon movement of articles or manufacture, pressures, temperatures, and so forth. Such control may be based on varying the frequency of power waveforms to produce a controlled speed of the motor. 
     In some embodiments, the control and monitoring circuitry  18  may determine when to open or close the one or more contactors based at least in part on the characteristics of the electric power (e.g., voltage, current, or frequency) measured by the sensors  22 . Additionally, the control and monitoring circuitry  18  may receive an instruction to open or close the one or more contactors in the switching circuitry  30  from another part of the motor system  26 , for example, via the network  21 . 
     In addition to using the switchgear  16  to connect or disconnect electric power directly from the electric motor  24 , the switchgear  16  may connect or disconnect electric power from a motor controller/drive  32  included in a machine or process system  34 . More specifically, the system  34  includes a machine or process  36  that receives an input  38  and produces an output  40 . 
     To facilitate producing the output  40 , the machine or process  36  may include various actuators (e.g., electric motors  24 ) and sensors  22 . As depicted, one of the electric motors  24  is controlled by the motor controller/drive  32 . More specifically, the motor controller/drive  32  may control the velocity (e.g., linear and/or rotational), torque, and/or position of the electric motor  24 . Accordingly, as used herein, the motor controller/drive  32  may include a motor starter (e.g., a wye-delta starter), a soft starter, a motor drive (e.g., a frequency converter), a motor controller, or any other desired motor powering device. Additionally, since the switchgear  16  may selectively connect or disconnect electric power from the motor controller/drive  32 , the switchgear  16  may indirectly connect or disconnect electric power from the electric motor  24 . 
     As used herein, the “switchgear/control circuitry”  42  is used to generally refer to the switchgear  16  and the motor controller/drive  32 . As depicted, the switchgear/control circuitry  42  is communicatively coupled to a controller  44  (e.g., an automation controller. More specifically, the controller  44  may be a programmable logic controller (PLC) that locally (or remotely) controls operation of the switchgear/control circuitry  42 . For example, the controller  44  may instruct the motor controller/driver  32  regarding a desired velocity of the electric motor  24 . Additionally, the controller  44  may instruct the switchgear  16  to connect or disconnect electric power. Accordingly, the controller  44  may include one or more processor  45  and memory  46 . More specifically, the memory  46  may be a tangible non-transitory computer-readable medium on which instructions are stored. As will be described in more detail below, the computer-readable instructions may be configured to perform various processes described when executed by the one or more processor  45 . In some embodiments, the controller  44  may also be included within the switchgear/control circuitry  42 . 
     Furthermore, the controller  44  may be coupled to other parts of the machine or process system  34  via the network  21 . For example, as depicted, the controller  44  is coupled to the remote control and monitoring circuitry  18  via the network  21 . More specifically, the automation controller  44  may receive instructions from the remote control and monitoring circuitry  18  regarding control of the switchgear/control circuitry  42 . Additionally, the controller  44  may send measurements or diagnostic information, such as the status of the electric motor  24 , to the remote control and monitoring circuitry  18 . In other words, the remote control and monitoring circuitry  18  may enable a user to control and monitor the machine or process  36  from a remote location. 
     Moreover, sensors  22  may be included throughout the machine or process system  34 . More specifically, as depicted, sensors  22  may monitor electric power supplied to the switchgear  16 , electric power supplied to the motor controller/drive  32 , and electric power supplied to the electric motor  24 . Additionally, as depicted, sensors  22  may be included to monitor the machine or process  36 . For example, in a manufacturing process, sensors  22  may be included to measure speeds, torques, flow rates, pressures, the presence of items and components, or any other parameters relevant to the controlled process or machine. 
     As described above, the sensors  22  may feedback information gathered regarding the switchgear/control circuitry  42 , the motor  24 , and/or the machine or process  36  to the control and monitoring circuitry  18  in a feedback loop. More specifically, the sensors  22  may provide the gathered information to the automation controller  44  and the automation controller  44  may relay the information to the remote control and monitoring circuitry  18 . Additionally, the sensors  22  may provide the gathered information directly to the remote control and monitoring circuitry  18 , for example via the network  21 . 
     To facilitate operation of the machine or process  36 , the electric motor  24  converts electric power to provide mechanical power. To help illustrate, an electric motor  24  may provide mechanical power to various devices. For example, the electric motor  24  may provide mechanical power to a fan, a conveyer belt, a pump, a chiller system, and various other types of loads that may benefit from the advances proposed. 
     As discussed in the above examples, the switchgear/control circuitry  42  may control operation of a load  14  (e.g., electric motor  24 ) by controlling electric power supplied to the load  14 . For example, switching devices (e.g., contactors) in the switchgear/control circuitry  42  may be closed to supply electric power to the load  14  and opened to disconnect electric power from the load  14 . 
     By way of example, the switching device may include a relay device  100  that is composed of components illustrated in  FIG.  4   , some of which correspond to the components of the switching device described above. As shown in  FIG.  4   , the relay device  100  may include an armature  102  that is coupled to a spring  104 . The armature  102  may have a common contact  106  that may be coupled to a part of an electrical circuit. The armature  102  may electrically couple the common contact  106  to a contact  108  or to a contact  110  depending on a state (e.g., energized) of the relay device  100 . For example, when a relay coil  112  of the relay device  100  is not energized or does not receive voltage from a driving circuit, the armature  102  is positioned such that the common contact  106  and the contact  108  are electrically coupled to each other. When the relay coil  112  receives a driving voltage, the relay coil  112  magnetizes and attracts the armature  102  to itself, thereby connecting the contact  110  to the common contact  106 . 
     The electrical connections between the common contact  106  and the contacts  108  and  110  are made via contacts  114  and  116  and contacts  118  and  120 , respectively. Over time, as the contacts  114  and  116  and the contacts  118  and  120  strike against each other, the conductive material of the contacts  114 ,  116 ,  118 , and  120  may begin to wear. 
     Moreover, the relay coil  112  may include a core that maintains a core flux during the operation of the relay device  100 . That is, as the armature  102  moves between connecting to the contact  108  and the contact  110 , and vice-versa, a magnetic flux may be generated in a core of the relay coil  112  and/or the armature  102 . This magnetic flux may be related to the core flux of the relay coil  112  and may change over time as the relay device operates. 
     With this in mind,  FIG.  5    illustrates an example circuit  130  of the relay device  100  described above. Referring to  FIG.  5   , the circuit  130  may include a voltage source  132  that may be used to drive the relay coil  112 . The voltage source  132  may output a voltage that causes the relay coil  112  to magnetize and thus generates a force to move the armature  102 . In some embodiments, a control system  136  may provide a gate signal to a switching device  138  (e.g., transistor), which may couple a gate of a switching device  140  to ground, thereby causing the switching device  140  to close. As a result, the relay coil  112  may be energized via the voltage source  132 . 
     In some embodiments, a Zener diode  142  may be coupled between to the gate of the switching device  140 , as shown in  FIG.  5   . The Zener diode  142  may be a semiconductor device that permits current to flow in a forward or reverse direction. In addition, the Zener diode  142  may clamp or limit the voltage provided to a resistor  144 . In same manner, a Zener diode  146  may be used to clamp or limit a voltage provided to the relay coil  112 . 
     As shown in  FIG.  5   , when the relay coil  112  is energized (e.g., on), the switching device  140  closes and current conducts from the voltage source  132  to the relay coil  112  via the switching device  140 . On the other hand, when the relay coil  112  opens (e.g., off), the switching device  140  opens and current dissipates through the relay coil  112  and the Zener diode  146 . 
     With this in mind,  FIG.  6    illustrates a graph  160  that illustrates various properties of the relay coil  112  during an open operation. At time t 0 , a coil voltage  162  (e.g., measured at node  148 ) may decrease rapidly due to the switching device  140  opening and the flux changing with the moving armature  102 . In addition to the coil voltage  162  decreasing, a coil current  164  decreases as well. In an ideal relay coil  112 , the coil voltage recovers as shown in line  166 , which represents the flux decay when the armature  102  is held closed. However, due to the presence of residual flux in the core of the relay coil  112 , the measured coil voltage  162  may not recover as predicted by the line  166 . That is, at time t 1 , when the coil current  164  collapses to zero, a flux density  168  of the core of the relay coil  112  is still changing. As a result, a lag is observed between the coil current reaching zero and the flux density  168  reaching zero. This lag causes the measured coil voltage  162  to decrease at time t 2  before recovering like the line  166 . In other words, hysteresis and/or eddy currents generated in the core material of the relay coil  112  may cause the residual flux density  168  to remain when a magnetizing force (e.g., coil current  164 ) in the relay coil  112  is removed. The flux density  168  coupled with a mechanical movement of the armature  102  generates the voltage dip illustrated at time t 2 . 
     In this way, the flux density  168  influences the movement of the armature  102 . Moreover, as contacts erode, the time in which the armature  102  starts to move and change the timing of when the contacts  114  and  118  changes states changes. As such, monitoring the timing of the movement of the armature  102  and the contacts  1114  and  118  may be directly related to the wear of various mechanical components (e.g., contacts, armature, spring) of the relay device  100 . Moreover, by monitoring the voltage properties of the relay coil during an open operation, different relay devices may be calibrated to provide a more consistent open operation across various relay devices. 
     For example,  FIGS.  7  and  8    illustrate a graph  180  and a graph  190  that tracks voltage over time during an open operation for two relay devices. The graph  190  depicts the voltage over time properties of the two relay devices in a more detail at a more granular scale as compared to the graph  180 . Referring to the graph  190 , a first relay voltage  192  associated with a first coil voltage (e.g., at node  148 ) or back EMF voltage of the first relay device  192  and a second relay voltage  194  associated with a second coil voltage (e.g., at node  148 ) or back EMF voltage of the second relay device  194  during open operations may be closely analyzed. As shown in  FIG.  8   , the second relay voltage  194  may have a lower maximum value and a lower minimum value during a portion of the time that the respective coil voltages stabilize, as compared to the first relay voltage  192 . That is, after the open operation is performed by the respective relay device, a control system may track each respective coil voltage until it changes its trajectory (e.g., rising or falling) to measure its maximum voltage value and its minimum voltage value and the correspond times at which those voltages were recorded. 
     Based on maximum and minimum voltage values, the control system  136  or any suitable control system may coordinate the operations of different relay devices, such that the detected maximum voltage values, the detected minimum voltage values, or both occur at the same time. For example, the control system  136  may incorporate a slight delay when performing an open operation for the second relay device represented in  FIG.  8    to cause the second relay voltage  194  to reach its maximum value (e.g., during the transition period after the open operation) at substantially the same time as the first relay voltage  192  reaches its maximum value. By incorporating this time delay, the control system  136  may better equip the first relay device  192  and the second relay device  194  to open at the same time, thereby reducing chances that equipment controlled by the relay devices operate asynchronously. 
     With the foregoing in mind, it should be noted that the control system  136  may include any suitable computing system, controller, or the like. By way of example,  FIG.  9    illustrates certain components that may make up the control system  136 . The control system  136  may include a communication component  202 , a processor  204 , a memory  206 , a storage  208 , input/output (I/O) ports  210 , a display  212 , and the like. The communication component  202  may be a wireless or wired communication component that may facilitate communication between different components within the industrial automation system, the relay device  100 , or the like. 
     The processor  204  may be any type of computer processor or microprocessor capable of executing computer-executable code. The processor  204  may also include multiple processors that may perform the operations described below. The memory  206  and the storage  208  may be any suitable articles of manufacture that can serve as media to store processor-executable code, data, or the like. These articles of manufacture may represent computer-readable media (e.g., any suitable form of memory or storage) that may store the processor-executable code used by the processor to perform the presently disclosed techniques. The memory  206  and the storage  208  may represent non-transitory computer-readable media (e.g., any suitable form of memory or storage) that may store the processor-executable code used by the processor to perform various techniques described herein. It should be noted that non-transitory merely indicates that the media is tangible and not a signal. 
     The I/O ports  210  may be interfaces that may couple to other peripheral components such as input devices (e.g., keyboard, mouse), sensors, input/output (I/O) modules, and the like. The display  212  may operate to depict visualizations associated with software or executable code being processed by the processor. In one embodiment, the display may be a touch display capable of receiving inputs from a user. The display may be any suitable type of display, such as a liquid crystal display (LCD), plasma display, or an organic light emitting diode (OLED) display, for example. Additionally, in one embodiment, the display  212  may be provided in conjunction with a touch-sensitive mechanism (e.g., a touch screen) that may function as part of a control interface. It should be noted that the components described above with regard to the control system  136  are exemplary components and the control system  136  may include additional or fewer components as shown. 
     As discussed above, opening (e.g., breaking) and closing (e.g., making) relay devices or any type of switching device may cause certain properties of the switching devices to change over time. For example, after a number of open and close cycles, the contacts that are used to make and break electrical connections for the switching device may wear over time, weld together, and the like. With this in mind, the control system  136  may monitor the wear of the contacts and the operations of the switching device based on how the back EMF properties or coil voltage properties change over time.  FIG.  10    illustrates a method  220  for controlling operations of other switching devices, monitoring wear of the switching device, and the like based on the back EMF properties of the respective switching device. 
     Before discussing the method  220 , it should be noted that although the method  220  will be described as being performed by the control system  136 , it should be understood that the method  220  may be performed by any suitable control system or computing device. In addition, although the method  220  is described in a particular order, it should be noted that the method  220  may be performed in any suitable order. 
     Referring now to  FIG.  10   , at block  222 , the control system  136  may receive initial coil voltage data for a switching device. The initial coil voltage data may correspond to a voltage waveform (e.g., back EMF waveform) during an open or close operation. In some embodiments, the initial coil voltage data may be acquired during commissioning of the switching device, during acceptance testing at an industrial system, after manufacturing, or any suitable time. In any case, the initial coil voltage data may be used as a reference to gauge how the operating characteristics of the switching device changes over time. The initial coil voltage may be stored in the storage  208 , a database, or any suitable storage component. By way of example, the coil voltage data may be measured at the node  148  of the example circuit  130  presented above in  FIG.  5   . 
     At block  224 , the control system  136  may determine an open timing interval for the switching device based on the initial coil voltage data. The opening timing interval may correspond to an amount of time between a time in which the switching device initiates an open operation and after the armature of switching device moves to an open position. In one embodiment, the armature may complete its motion after the coil voltage stabilizes and remains at a relatively constant level (e.g., within 5%) over a period of time. By way of example, the coil voltage  162  depicted in the graph  160  of  FIG.  6    may stabilize at time t 3 . 
     After determining the open timing interval for the switching device, the control system  136  may, at block  226 , adjust the timing of control signals used for other switching devices based on the open timing interval. That is, if other switching devices are expected to open and/or close synchronously or according to a coordinated schedule with respect to the switching device being evaluated, the control system  136  may adjust the times in which control signals are sent to the other switching devices or to other control systems that control operations of the other switching devices based on the open timing interval of the switching device evaluated at block  222 . For instance, if the open timing interval indicates that the switching device takes an additional 2-5 ms to open as compared to other switching devices, the control system  136  may add a 2-5 ms delay in sending control signals to the other switching devices to ensure that each of the switching devices operate in a synchronous fashion. In some embodiments, the timing adjustment may be implemented for the switching device being evaluated at block  224  based on the open timing interval of other switching devices. 
     At block  228 , the control system  136  may receive updated coil voltage data for the switching device evaluated at block  222 . The updated coil voltage data may be received at any suitable time after receiving the initial coil voltage data at block  222 . In some embodiments, the updated coil voltage data may be received after an expiration of a certain amount of time (e.g., hours, days, weeks, years), after a number of operation cycles (e.g., 100, 1,000, 10,000, etc.) performed by the switching device, and the like. 
     In any case, after receiving the updated coil voltage data, the control system  136  may determine whether a change in the updated coil voltage data and the initial coil voltage data is greater than some threshold. The comparison between the two coil voltage data may include a comparison of two voltage waveforms associated with the open operations. As mentioned above, the coil voltage data or voltage waveforms during an open operation may change over time. The threshold may be related to differences between the respective waveforms, differences in maximum values, differences in minimum values, amount of time to stabilize, and the like. 
     For instance,  FIG.  11    illustrates a graph  250  that presents how changes in measured back EMF properties (e.g., coil voltages) for a switching device over 890,000 cycles. Referring briefly to  FIG.  11   , back EMF waveform  252  corresponds to the operation of the switching device during its first opening operation or cycle. As shown in the graph  250 , over time the back EMF waveform  252  changes to back EMF waveform  254  after 400,00 cycles. By way of operation, as the switching device operates over an initial period of time, the contacts may conform to each other&#39;s shape in such a manner to cause the movement of the armature of the switching device to change. As such, the peak voltage of the back EMF waveform  254  may be greater than the back EMF waveform  252  during the transition period of open operations that take place over a number of cycles of operation. After more cycles are performed, the back EMF waveform  254  may change again to the back EMF waveform  256 . As shown in the back EMF waveform  256 , after the initial period of operation (e.g., 400,000 cycles), the maximum back EMF value and minimum back EMF value may decrease. This decrease may be related to the wearing of the contact surface, changes in the magnetic properties of a core, and the like. In any case, the change of the back EMF waveforms or the coil voltage, as illustrated in  FIG.  11   , may trend in such a way that the maximum and minimum voltages may increase over time along with the times in which those voltages occur. As such, the change in the back EMF waveforms or the coil voltage may be representative of an amount of wear of the switching device. 
     Referring back to block  230 , if the change between the initial coil voltage data and the updated coil voltage data is less than the threshold, the control system  136  may return to block  228  and receive updated coil voltage data at a later time, after a number of cycles, or the like. However, if the change in the coil voltage data is greater than or equal to the threshold, the control system  136  may proceed to block  232 . 
     At block  232 , the control system  136  may determine an open time drift for the switching device. That is, the control system  136  may determine a change in an amount of time for the switching device to open. That is, the control system  136  may compare the open timing interval determined at block  224  with an updated open timing interval to determine an amount of drift between the two amounts of time. In some embodiments, the open time drift may be related to a number of open operation cycles performed by the switching device. 
     At block  234 , the control system  136  may determine a state of the contacts of the switching device. The state of the contacts may include an indication that the contacts are worn, such that conductive material deposited on the contacts has been reduced to limit the conductive properties between the contacts. In addition, the state of the contacts may include a determination as to whether the contacts are welded together. That is, by monitoring the coil voltage data, the control system  136  may determine that the contacts of the switching device are welded together if the coil voltage data (e.g., back EMF) does not change during the open operation. 
     After determining the open time drift, the state of the contacts, or both, the control system  136  may send control signals to other components at block  236 . The control signals may correspond the devices controlled with adjusted timing signals described at block  226 . In addition, the control system  136  may adjust the control signals sent to other components based on the state of the contacts. For example, if the state of the contacts indicates that the contacts are worn, the control system  136  may send a control signal to an auxiliary device or fail-safe device to ensure that the appropriate signals are transmitted to other devices. 
     In any case, at block  238 , the control system  136  may send a status notification to a computing device, a database, a server, a cloud-computing system, or the like. The status notification may cause a visualization to be generated to provide details with regard to the change in the coil voltage data, the open time drift, the state of the contacts, and the like. In some embodiments, the status notification may include a determination of an amount of life expectancy for the switching device, an indication that the contacts are welded together, and the like. The life expectancy may be determined based on the minimum value, the maximum value, an average value, and other values associated with the back EMF waveform measured during the transition period of an open operation for the coil of the switching device. For example, as the maximum value of the back EMF waveform decreases, the life expectancy of the switching device may decrease. 
     In some embodiments, a historical record of the back EMF waveform for the life of another switching device or a baseline switching that corresponds to the switching device being evaluated may be stored in a database or the like. As such, the control system  136  may compare the updated coil voltage data (e.g., back EMF waveform) to other back EMF waveforms for the respective switching device to determine a current life expectancy of the respective switching device. That is, the historical record may track the back EMF waveform for the life of the switching device. As such, the control system  136  may determine a life expectancy of the switching device by tracking the recently acquired coil voltage data with the historical record. In the same manner, a historical record of maximum values and minimum values associated with the back EMF waveforms during open operations may be stored, such that the control system  136  may determine a state or condition of the switching device, the contacts of the switching device, or the like based on the updated coil voltage data. 
     In some embodiments, the status notification may cause the recipient computing device to automatically execute or open an application, such that the notification or any generated visualization is presented for viewing to a user. In addition, the status notification may cause the application or program stored on the recipient computing device to output or produce a visual alert (e.g., flashing light, home screen visualization), an audible alert, or the like in response to the life expectancy of the respective switching device being less than a threshold amount of time. 
     Technical effects of the embodiments described herein include increasing the monitoring capabilities of switching devices without adding additional hardware. That is, since the coil voltage data may be measured at the node  148  of the example circuit  130  presented above in  FIG.  5   , additional sensors for monitoring the armature position within the switching device may be avoided. As a result, the switching device may include more monitoring features without adding additional components that may increase the size of the switching device. 
     It should be noted that some switching or relay devices may include more than one coil. For example, some relay devices may have two coils, such that both coils may be used to control the movement of an armature. In these types of relay devices, one of the coils may be used to hold the armature in place after it moves to a particular position. It should be understood that the present embodiments described herein may be implemented on the deactivated coil to measure the flux or the back EMF of the relay. In this way, the additional coil that is not being used may provide an indication of the life of the relay. 
     It should also be noted that although certain embodiments described herein are described in the context or contacts that are part of a relay device, it should be understood that the embodiments described herein may also be implemented in suitable contactors and other switching components. Moreover, it should be noted that each of the embodiments described in various subsections herein, may be implemented independently or in conjunction with various other embodiments detailed in different subsections to achieve more efficient (e.g., power, time) and predictable devices that may have a longer lifecycle. It should also be noted that while some embodiments described herein are detailed with reference to a particular relay device or contactor described in the specification, it should be understood that these descriptions are provided for the benefit of understanding how certain techniques are implemented. Indeed, the systems and methods described herein are not limited to the specific devices employed in the descriptions above. In addition, although the monitored operations are described herein with respect to open operations, the presently disclosed techniques may also be implemented for close operations. 
     While only certain features of the disclosure have been illustrated and described herein, many modifications and changes will occur to those skilled in the art. It is, therefore, to be understood that the appended claims are intended to cover all such modifications and changes as fall within the true spirit of the disclosure.