Patent Publication Number: US-11664180-B2

Title: Zero crossing contactor and method of operating

Description:
CROSS REFERENCE TO RELATED APPLICATION(S) 
     This application is a continuation of U.S. patent application Ser. No. 16/394,347, filed Apr. 25, 2019, now granted as U.S. Pat. No. 11,189,449, issued on Nov. 30, 2021, which claims priority to and the benefit of British Patent Application No. 1806782.7 filed Apr. 25, 2018, now granted as U.S. Pat. No. 2,573,139, issued on Jun. 23, 2021, both of which are incorporated in their entirety by reference. 
    
    
     BACKGROUND 
     In electrical power systems, there is often a need to electrically switch on and switch off the power system or portions thereof. In alternating current (AC) systems, the current periodically reverses direction, varying between a positive and negative voltage in a sinusoidal cycle. At the change between directions, the voltage is zero. Traditional AC contactors will switch at any point during the AC cycle, without regard to the current or voltage. Switching a contactor in this manner can lead to voltage or current spikes, voltage surges, contact wear at the contactor and other stresses, noise, arcing, and deposition from arcing. 
     BRIEF DESCRIPTION 
     In one aspect, the disclosure relates to a method of operating a contactor, the method comprising receiving, in a controller module, at least two operational characteristics of the contactor, with each operational characteristic representative of a delay time, determining, in the controller module, a contactor time delay for at least one of disconnecting or connecting a power supply by the contactor, the contactor time delay being a summation of a set of delay timings based on the delay time of each operational characteristic, and initiating, by the controller module, the at least one of disconnecting or connecting of the power supply by the contactor at an initiation time prior to a zero-crossing voltage of an alternating current (AC) waveform of the power supply, wherein the initiation time anticipates the zero-crossing voltage based upon the contactor time delay. 
     In another aspect, the disclosure relates to a method of operating a contactor, the method comprising receiving, in a controller module, at least two operational characteristics of the contactor, with each operational characteristic representative of a delay time, determining, in the controller module, a total contactor time delay defined by a timing estimation to operably disconnect or connect a power supply and an electrical load, based on the delay time of each operational characteristic, determining a contactor initiation time based on at least one delay time and an alternating current (AC) waveform of the power supply, such that an expiration of the total contactor time delay coincides with a zero-crossing voltage of the AC waveform, and initiating, by the controller module, a toggling of the power supply by the contactor at the contactor initiation time. 
     In another aspect, the disclosure relates to a method of operating a contactor, the method comprising receiving, in a contactor assembly comprising a contactor switch selectably connecting an input with an output, a contactor coil operably coupled to the contactor switch and configured to actuate the contactor switch, at least two sensors configured to measure an operational characteristic of the contactor assembly, and a controller module configured to receive at least two electrical signals from the at least two sensors, with each electrical signal representative of a delay time, determine a contactor time delay as a summation of a set of delay timings based upon the at least two electrical signals, and initiate at least one of a disconnecting or connecting of the input and the output by the contactor switch at an initiation time prior to a zero-crossing voltage of an alternating current (AC) waveform of a power supply wherein the initiation time is based upon the contactor time delay. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       In the drawings: 
         FIG.  1    is a top down schematic view of an aircraft and power distribution system in accordance with aspects described herein. 
         FIG.  2    is a schematic view of an electrical circuit forming a portion of the power distribution system of  FIG.  1    including a contactor assembly, in accordance with aspects described herein. 
         FIG.  3    is a graph plotting an alternating current waveform for the electrical circuit of  FIG.  2   , including a total delay prior to a zero-crossing point, in accordance with aspects described herein. 
         FIG.  4    is a block diagram illustrating a method of operating the contactor assembly of  FIG.  2   , in accordance with aspects described herein. 
     
    
    
     DETAILED DESCRIPTION 
     The disclosure is related to a zero-crossing contactor assembly and method of operating, which can be used, for example, in a power distribution system for an aircraft. While this description is primarily directed toward a power distribution system for an aircraft, it is also applicable to any environment utilizing an alternating current electrical system, such as any power distribution system in non-aircraft implementations. 
     As used herein, the term “upstream” refers to moving in a direction toward an inlet or beginning position, or a component being relatively closer to the inlet or beginning position as compared to another component. The term “downstream” refers to a direction toward an outlet or end position or being relatively closer to the outlet or end position as compared to another component. Furthermore, the terms “upstream” or “downstream” can be used as a reference relative to a current direction for an alternating current circuit, which can reverse direction periodically, defining the meaning of the terms “upstream” or “downstream” based upon the current direction for the circuit. Furthermore, as used herein, the term “set” or a “set” of elements can be any number of elements, including only one. 
     All directional references (e.g., radial, axial, proximal, distal, upper, lower, upward, downward, left, right, lateral, front, back, top, bottom, above, below, vertical, horizontal, clockwise, counterclockwise, upstream, downstream, forward, aft, etc.) are only used for identification purposes to aid the reader&#39;s understanding of the present disclosure, and do not create limitations, particularly as to the position, orientation, or use of aspects of the disclosure described herein. Connection references (e.g., attached, coupled, connected, and joined) are to be construed broadly and can include intermediate members between a collection of elements and relative movement between elements unless otherwise indicated. As such, connection references do not necessarily infer that two elements are directly connected and in fixed relation to one another. The exemplary drawings are for purposes of illustration only and the dimensions, positions, order and relative sizes reflected in the drawings attached hereto can vary. 
     Additionally, while terms such as “voltage”, “current”, and “power” can be used herein, it will be evident to one skilled in the art that these terms can be interchangeable when describing aspects of the electrical circuit, or circuit operations. 
     Also as used herein, while sensors can be described as “sensing” or “measuring” a respective value, sensing or measuring can include determining a value indicative of or related to the respective value, rather than directly sensing or measuring the value itself. The sensed or measured values can further be provided to additional or separate components. Such a provision can be provided as a signal, such as an electrical signal, to said additional or separate components. For instance, the measured value can be provided to a controller module or processor, and the controller module or processor can perform processing on the value to determine a representative value or an electrical characteristic representative of said value. 
     As used herein, a “system” or a “controller module” can include at least one processor and memory. Non-limiting examples of the memory can include Random Access Memory (RAM), Read-Only Memory (ROM), flash memory, or one or more different types of portable electronic memory, such as discs, DVDs, CD-ROMs, etc., or any suitable combination of these types of memory. The processor can be configured to run any suitable programs or executable instructions designed to carry out various methods, functionality, processing tasks, calculations, or the like, to enable or achieve the technical operations or operations described herein. The program can include a computer program product that can include machine-readable media for carrying or having machine-executable instructions or data structures stored thereon. Such machine-readable media can be any available media, which can be accessed by a general purpose or special purpose computer or other machine with a processor. Generally, such a computer program can include routines, programs, objects, components, data structures, etc., that have the technical effect of performing particular tasks or implement particular abstract data types. 
     As used herein, a controllable switching element, or a “switch” is an electrical device that can be controllable to toggle between a first mode of operation, wherein the switch is “closed” intending to transmit current from a switch input to a switch output, and a second mode of operation, wherein the switch is “open” intending to prevent current from transmitting between the switch input and switch output. In non-limiting examples, connections or disconnections, such as connections enabled or disabled by the controllable switching element, can be selectively configured to provide, enable, disable, or the like, an electrical connection between respective elements. 
     The disclosure can be implemented in any electrical circuit environment having a switch, electrical switch, or switching element. A non-limiting example of an electrical circuit environment that can include aspects of the disclosure can include an aircraft power system architecture, which enables production of electrical power from at least one spool of a turbine engine, preferably a gas turbine engine, and delivers the electrical power to a set of electrical loads. In one non-limiting example, the electrical switch or switching element can include at least one solid state switch, such as a solid state power controller (SSPC) switching device. One non-limiting example of the SSPC can include a silicon carbide (SiC) or Gallium Nitride (GaN) based, high power switch. SiC or GaN can be selected based on their solid state material construction, their ability to handle high voltages and large power levels in smaller and lighter form factors, and their high speed switching ability to perform electrical operations very quickly. Additional switching devices or additional silicon-based power switches can be included. 
     As illustrated in  FIG.  1   , an aircraft  10  is shown having at least one gas turbine engine, shown as a left engine system  12  and a right engine system  14 . Alternatively, the aircraft  10  can have fewer or additional engine systems. The left and right engine systems  12 ,  14  can be substantially identical, and can further include at least one electric machine, such as a generator  18 . The aircraft  10  is shown further including a plurality of power-consuming components, or electrical loads  20 , for instance, an actuator load, flight critical loads, and non-flight critical loads. The electrical loads  20  are electrically coupled with at least one of the generators  18  via a power distribution system  22 . 
     In the aircraft  10 , the operating left and right engine systems  12 ,  14  generates mechanical energy which can be extracted via a spool, to provide a driving force for the generator  18 . The generator  18 , in turn, delivers the power to the electrical loads  20  via the power distribution system  22  for load operations. Additional power sources for providing power to the electrical loads  20 , such as emergency power sources, ram air turbine systems, or starter/generators, are envisioned. It will be understood that while the power distribution system  22  is shown in an aircraft environment, the power distribution system is not so limited and has general application to electrical power systems in non-aircraft applications, such as other mobile applications and non-mobile industrial, commercial, and residential applications. 
     Referring now to  FIG.  2   , an electrical circuit  30  can form at least a portion of the power distribution system  22  having the contactor assembly  32 . It should be understood that the electric circuit  30  is merely one example aspect of an electrical network or power distribution system  22 , or subcomponents thereof, for ease of understanding. Further non-limiting examples of the disclosure can be included or contained as a portion of a printed circuit board, field programmable gate array (FPGA), or the like. 
     The contactor assembly  32  can form a portion of the circuit  30 , positioned between a power supply input  34 , such as the generator  18  (not shown), and a power supply output  36  connected with a power consuming device, such as the electrical load  20  (not shown). In non-limiting examples, the power supply input  34  can include a voltage input and the power supply output  36  can include a voltage output. The contactor assembly  32  can further include a contactor  38  schematically shown to include a switch  40  and a contactor coil  42 . The switch  40  can be configured to move between a first opened condition or state and a second closed condition or state. In the opened condition, the contactor  38  or switch  40  prevents, disconnects, or otherwise disables current conduction between the power supply input  34  and the power supply output  36 , while in the closed condition, the contactor  38  or switch  40  permits, allows, connects, or otherwise enables current conduction between the power supply input  34  and the power supply output  36 . The switch  40  can be operable between the first opened condition or the second closed condition by selective energization of the contactor coil  42 . For example, the application of a voltage or power to the coil can effectively or operably close the switch, while the lack of a voltage or power to the coil can effectively or operably open the switch. One non-limiting example for the contactor assembly  32  can include a solenoid, while any suitable element or component configured to actuate or be energized to actuate the switch  40  within the contactor  38  is contemplated. 
     The circuit  30  can further include a coil switch  48  connected to the contactor coil  42  at a first end  44  of the contactor coil  42 . The coil switch  48  can be operable between a first opened condition or state and a second closed condition or state, In the first opened condition, a voltage or power is prevented, disconnected, or otherwise disabled across the coil switch  48 , while in the second closed states, a power or voltage is permitted, allowed, connected, or otherwise enabled across the coil switch  48 . In one non-limiting example, a contactor coil energizing supply  50  can include a power supply or a power source that electrically and selectively couples to the coil switch  48 , selectively providing a voltage or power to the coil switch  48 . The circuit  30  can further include a ground  52  provided at a second end  46  of the contactor coil  42 , opposite of the coil switch  48 , electrically grounding the contactor coil  42 . 
     The contactor assembly  32  can further include a controller module  60  electrically couple within the circuit  30 . The controller module  60  can include at least one processor  64  and memory  66 , and can be configured to run any suitable program or executable instructions designed to carry out operation of the circuit  30 , the contactor assembly  32 , or portions thereof. The controller module  60  can be controllably connected with the coil switch  48 , such that the controller module  60  can generate, send, or otherwise provide a control signal  54  (shown as a dotted arrow) to selectively control the switching between the first and second states of the coil switch  48 . 
     A command controller  62  can be further communicably coupled with the controller module  60 , and can be configured to provide a command, such as an instruction to open or close a switch, or operate a portion of the circuit  30 . The command controller  62  can also include at least one processor and memory (not shown), and can be configured to run any suitable program or executable instruction. While shown adjacent the controller module  60 , the command controller  62  can be located remotely from the controller module  60 , and adapted to send a signal or instruction to the controller module  60  relating to the contactor assembly  32  or the circuit  30 . 
     A set of sensors  70  can be included with the contactor assembly  32 , and can include a contactor coil operational characteristic sensor  72 , a waveform sensor  74 , and a temperature sensor  78 . The set of sensors  70  can be communicatively and operatively couple with the controller module  60 , such that the set of electrical signals can be generated, provided, supplied to, or otherwise received by the controller module  60 . The contactor coil operational characteristic sensor  72  can be configured to generate a signal representative of a voltage, current, or otherwise, which can be representative of an operational characteristic of the contactor coil energizing supply  50 . Non-limiting examples of operational characteristics can include an “on” characteristic or an “off” characteristic, for example, as well as an “active,” “inactive,” “closed,” or “opened” in additional non-limiting examples. Additionally, the set of sensors  70  is further shown including an optional output voltage sensor  76 . While shown as four sensors, it is contemplated that the set of sensors  70  can include additional or fewer sensors. The contactor coil operational characteristic sensor  72  can couple to the circuit  30  between the contactor coil energizing supply  50  and the coil switch  48 . In one non-limiting example, the waveform sensor  74  can couple to the circuit  30  between the power supply input  34  and the switch  40  and can be configured or adapted to sense or measure a waveform frequency for the AC current passing across the switch  40  from the power supply input  34  to the power supply output  36 . The waveform sensor  74  can be configured to generate a signal representative of an alternating current (AC) waveform supplied by the power supply input  34 . Such a waveform can be substantially sinusoidal, represented as a reversing current direction over a period of time. In another non-limiting example, the output voltage sensor  76  can couple the circuit  30  between the switch  40  and the power supply output  36 , and can be configured or adapted to sense or measure a voltage downstream of the switch  40 , between the contactor assembly  32  and the power supply output  36 . The output voltage sensor  76  can be configured to generate a signal representative of a voltage, such as a voltage transmitted by way of the contactor assembly  32  when the switch  40  is in the second closed position. The temperature sensor  78  can be positioned to measure a temperature of the contactor coil  42 , and configured to generate a signal representative of a temperature of the contactor coil  42 . 
     During operation, the contactor assembly  32  or contactor  38  operates to selectively enable or disable conduction of power supplied to the power supply input  34  to the power supply output  36 . The selective enabling or disabling can be operably or effectively controlled by way of the controller module  60 . In one non-limiting example, the command controller  62 , or another controlling component, can supply or provide a demand, desire, or instruction to the controller module  60  to connect or disconnect the power supply input  34  from the power supply output  36  by way of the contactor coil  42 , the coil switch  48 , the control signal  54 , and the contactor coil energizing supply  50 , or a combination thereof. Such an instruction can be based on a schedule or can be on demand. Based upon said instruction, the controller module  60  operably or effectively supplies the control signal  54  to the coil switch  48 , instructing or controlling the coil switch  48  to toggle to the closed state, energizing the contactor coil  42  with the contactor coil energizing supply  50 . Therefore, operation of the switch  40  of the contactor  38  is controlled by way of selectively powering the contactor coil  42  in response to the control signal  54  from the controller module  60 . Thus, the controller module  60  can effectively operate the contactor assembly  32 . 
     Operation of the contactor assembly  32  can further be based on a number of operation characteristics. For example, the operational characteristics can include at least one of a frequency of the electric current supplied to the power supply input  34 , a coil temperature, a coil operational characteristic, an error correction, or a combination thereof. The frequency of the electrical circuit can be representative of a sinusoidal electrical frequency for the alternating electrical current passing from the power supply input  34 . In one non-limiting example, the determination of the frequency of the electrical circuit from the power supply input  34  can include sensing the frequency, or a characteristic of the frequency such as a zero-crossing voltage, with the waveform sensor  74 , and generating and providing a signal representative of the waveform or waveform characteristic to the controller module  60 . 
     The contactor coil temperature can be representative of a temperature of the contactor coil  42  both when the contactor coil  42  is energized and is not energized. In one non-limiting example, the determination of the coil temperature can be determined by sensing the temperature of the contactor coil  42  with the temperature sensor  78 , and generating and providing a signal representative of the temperature of the contactor coil  42  to the controller module  60 . 
     The coil operational characteristic can include an “on” or an “off” characteristic, such as the time it takes to open or close the coil switch  48 . Such a coil operational characteristic can be determined by sensing an electrical characteristic of the coil switch  48  or the contactor coil energizing supply  50  by way of the contactor coil operational characteristic sensor  72 . A signal representative of the coil operational characteristic can be generated and provided by the contactor coil operational characteristic sensor  72  to the controller module  60 . 
     An error correction can include a measurement indicative of or representative of an error measurement of the circuit  30 , that is, a difference in expected operation of the circuit  30 , the contactor  38 , or the contactor assembly  32 , compared with the actual operation of the circuit  30 , the contactor  38 , or the contactor assembly  32 . 
     The controller module  60  can store at least a subset of the signals received from the set of sensors  70  in the memory  66 . The controller module  60 , receiving or storing the electrical signals from the set of sensors  70 , can utilize the processor  64  to incorporate the electrical signals as values to initiate disconnecting or connecting of the power supply from the power supply input  34  and the power supply output  36 . While aspects of the disclosure are described with respect to “disconnecting” the power supply from the power supply input  34  from the power supply output  36 , it will be understood that the disclosure is also applicable to any connecting, or any toggle or toggling of the contactor between a disconnecting and connecting operation. More specifically, the controller module  60  can determine a disconnection, connection, or contactor time delay based upon the values of the electrical signals from the set of sensors  70 . For example, the temperature value of the contactor coil  42  provided by the temperature sensor  78  can be representative of a first time delay such as a coil temperature delay time. As used herein the contactor coil  42  temperature delay time is representative of a delay in timing in the contactor coil  42  operably effecting the switch  40  to toggle between opened and closed states, due to the temperature of the contactor coil  42 . For example, the temperature of the contactor coil  42  affects the operation of the coil, wherein a higher temperature generally causes an increased delay in toggling the switch  40 , whereas a lower temperature of the contactor coil  42  generally causes a reduced delay in toggling the switch  40 . 
     A contactor coil operational characteristic provided by the contactor coil operational characteristic sensor  72  can be representative of a second time delay such as a coil operational characteristic delay time, which is representative of the expected delay in sufficiently energizing the contactor coil  42  by way of the contactor coil energizing supply  50  and the coil switch  48 . The contactor coil operational characteristic can include, or be at least partially based on, the supply voltage of the contactor coil energizing supply  50 , the time delay in operating the coil switch  48  after receiving a control signal  54 , or a combination thereof. The time for providing a signal across the circuit  30  can be representative of a third time delay such as an electrical signal delay time, based on the specific configuration of the circuit signal traces. An error correction value can be representative of a fourth time delay based on a difference in expected operation of the circuit  30 , the contactor  38 , or the contactor assembly  32 , compared with the actual operation of the circuit  30 , the contactor  38 , or the contactor assembly  32 . In one non-limiting example, the error correction characteristic can include sensing or measuring the voltage at the power supply output  36 , by the output voltage sensor  76 . In this example, the output voltage sensor  76  can generate and provide a signal representative of the voltage, such as when the voltage increases, decreases, or the like, to the controller module  60 . In response, the controller module  60  can compare an actual timing of the signal representative of the voltage from the output voltage sensor  76 , and compare the timing with the expected, estimated, calculated timing of the circuit  30  operations. For instance, if the controller module  60  initiates a “disconnect” or “connect” command to operably toggle the switch  40  of the contactor  38  to disable or enable supplying power to the power supply output  36 , the controller module  60  can receive a signal indicating when the voltage at the power supply output  36  falls (e.g. when the power is disconnected or connected), by way of the output voltage sensor  76 . A difference in compared or expected timing can result in a determined error correction characteristic. In one non-limiting example, it will be understood that a calculated, compared, or determined error correction characteristic can be represented as an “error delay time,” and accounted for in the following or a subsequent connection or disconnection cycle. 
     Referring to  FIG.  3   , a graph  90  includes a plot showing a sinusoidal alternating current (AC) waveform  92  representing an amplitude for an alternating current passing along the circuit  30  over a period of time. In one non-limiting example, the AC waveform  92  can be representative of a signal provided to the controller module  60  from the waveform sensor  74 . The AC waveform  92  includes a set of zero-crossing points  94 , representative of a zero voltage or current as the alternating current reverses direction. Such zero-crossing points  94  can be determined by the controller module  60  based upon a consistent frequency for the current, such that the controller module  60  can accurately predict a schedule for future zero-crossing points  94 . It is beneficial to operate the contactor assembly  32  such that the effective connecting, disconnecting, enabling, or disabling of the contactor assembly  32  coincides with the zero-crossing point. However, as described above with respect to the delays, the initial decision or initiation of operation of the contactor assembly  32  does not effectively or instantaneously result in the opening or closing of the switch  40 , as set of operational delays can be intervening. Thus, non-limiting aspects of the disclosure can be included wherein the controller module  60  can determine a total contactor time delay, that is, an estimated, predicted, or otherwise determined summated time delay between initiating a disconnection or connection command, instruction, or control signal, and the actual or effective disconnection or connection of the power conducted via the contactor  38 , and initiate the disconnection or connection such that the effective disconnection or connection coincides with the zero-crossing points  94 . While the specific example of initiating a “disconnect” is described, non-limiting aspects of the disclosure are also applicable and included wherein the controller module  60  can determine a total contactor time delay and initiate the connecting or supplying of the power conducted via the contactor  38 , and such that the effective connecting coincides with the zero-crossing points  94 . 
     A total delay time  80  can include the summation of a set of delay timings, including but not limited to, the coil temperature delay time  82 , the coil operational characteristic delay time  84 , the electrical signal delay time  86 , and the error delay time  88 , as described above. As illustrated, the controller module  60  can determine a total time delay  80  of the aforementioned delays, or determine individual delays for each respective delay, which can be summated in a subsequent step. Additionally, it is contemplated that the aforementioned delay times  82 ,  84 ,  86 ,  88  and any other delay between initiating a disconnecting or connecting of the power supply by the contactor  38  in anticipation of a zero-crossing voltage of the AC waveform  92 , and the effective disconnecting or connecting of the power supply, can be utilized in determining a total delay time  80 . While shown as four delays as  82 ,  84 ,  86 ,  88 , any number of intervening, determined, calculated, or comparison delays is contemplated, as any system component or operational function contributing to total delay time  80 , which results in a delay of time between initiating an instruction to open the switch  40  and effectively disconnecting or connecting the power supply input  34  and the power supply output  36 . Additionally, while the set of time delays are illustrated as approximately the same length of time (e.g. the same time delay) the example delays are for purposes of illustration only and the time delays for the collective set of time delays, or the relative delay timings can vary. 
     The processor  64  in the controller module  60  can calculate the total time delay  80  based upon the signals received from the contactor coil operational characteristic sensor  72 , the output voltage sensor  76 , and the temperature sensor  78 , or optionally including any other time delay or sensor input, and determine a schedule, estimation, prediction, or the like, for a subsequent or upcoming zero-crossings for the AC waveform  92  from the signal provided by the waveform sensor  74 . The controller module  60  can then calculate an initiation time  96 . The initiation time  96  can be a time calculated as an anticipated zero-crossing point  94  minus the total delay time  80 . Still referring to  FIG.  3   , the initiation time  96  is determined prior to a zero-crossing point  94  by the total delay time  80  as the sum of the time delays  82 ,  84 ,  86 ,  88 . 
     The controller module  60  can initiate operation of the switch  40  at the initiation time  96  to coincide with the zero-crossing point  94  of the AC waveform  92  to effectively disconnect or connect the switch  40  at the zero-crossing point  94 . In this manner, the contactor assembly  32  can utilize the set of sensors  70  and the controller module  60  to effectively calculate an operational delay for the contactor assembly  32 , and can operate the switch  40  to coincide with the zero-crossing point  94  for the AC waveform. 
     Similarly, the controller module  60  can utilize the output voltage sensor  76  to continuously determine the error delay time  88  based upon a voltage between the switch  40  and the power supply output  36 . ‘Continuously’ as used herein can mean at an operation of the contactor assembly  32 . Alternatively, the output voltage sensor  76  can make an on-demand measurement, such as when a predicted, calculated, determined, or estimated total delay time  80  is found to be outside an expected range or threshold of operation, such as a predetermined tolerance. If such a measured voltage is not zero, the delay for the error delay time  88  can be updated after operation of the contactor assembly  32 , and input into the controller module  60  to update the total delay time  80  for future operations of the contactor assembly  32 . Therefore, as the contactor assembly  32  changes over time, such as degradation due to age or other environmental factors, the output voltage sensor  76  can provide for updating the error delay time  88 . As such, an accurate zero-crossing switch can be consistently achieved, particularly over time. 
     Referring now to  FIG.  4   , a flow chart demonstrates a method  100  of operating a contactor  32  can include receiving, in a controller module  60 , an electrical signal representative of an alternating current (AC) waveform  92  of a power supply or power supply input  34 , at  102 . The method  100  can further include receiving, in the controller module  60 , a temperature value representative of a temperature of a contactor coil  42 , at  104 . Alternatively, the method  100  could include receiving, in the controller module  60 , the temperature of the contactor coil  42  energizable to disconnect or connect the power supply from an electrical load, at  104 . The method  100  can further include receiving, in the controller module  60 , a contactor coil operational characteristic, or a contactor coil energizing supply characteristic, at  106 . 
     The method  100  can also include determining, in the controller module  60 , a total time delay or a contactor time delay  80  for disconnecting or connecting the power supply  34 , by the contactor  32 , with the contactor time delay  80  being the summation of a set of delay timings  82 ,  84 ,  86  based on the electrical signal, the temperature value, and the contactor coil operational characteristic, at  108 . Alternatively, the method  100  can include determining, in the control module  60 , a total contactor time delay  80  defined by a timing estimation to operably disconnect or connect the power supply  34  and the electrical load or power supply output  36 , based on the coil temperature delay time  82  and the coil operational characteristic delay time  84 , at  108 . 
     Optionally, the method  100  can include determining an initiation time or a contactor initiation time  96  based on the total contactor time delay  80  and the AC waveform  92  of the power supply, such that the expiration of the total contactor time delay  80  coincides with a zero-crossing point  94  of the AC waveform  92 , at  110 . 
     The method  100  can further include initiating, by the controller module  60 , the disconnecting or connecting of the power supply  34  by the contactor  32  at an initiation time  96  prior to a zero-crossing point  94  in the AC waveform  92 , wherein the initiation time  96  anticipates the zero-crossing point  94  based upon the contactor time delay  80 , at  112 . Alternatively, the method  100  can include initiating, by the controller module  60 , the disconnecting or connecting of the power supply  34  by the contactor  32  at the contactor initiation time  96 , at  112 . 
     In a non-limiting example, the effective disconnecting or connecting of the power supply can coincide with the zero crossing point  94  of the AC waveform  92 . In another non-limiting example, the determining is further based on estimating the contactor time delay  80 . In yet another example, the determining is further based on predicting the contactor time delay  80 . In another example, the determining the contactor time delay  80  is further based on the summation of the set of delay timings  82 ,  84 ,  86  and an error delay time or error correction value  88  defined by a difference between an effective disconnecting or connecting of the power supply  34  and the zero-crossing point  94  of the AC waveform  92  of at least one previous contactor  32  disconnection or connection. In yet another non-limiting example, the error correction value  88  is based upon a difference in a voltage measured at an effective disconnecting or connecting of the power supply  34  and a zero value for the voltage. In another non-limiting example, the error correction value is further based upon the measured voltage at the effective disconnecting or connecting, and the AC waveform  92  of the power supply  34 . In yet another non-limiting example, the initiating further includes energizing a solenoid contactor coil  42  with a contactor coil energizing supply  50  to operably disconnect or connect the power supply  34 . In yet another non-limiting example, initiating further includes closing a coil switch  48  to provide the contactor coil energizing supply  50  to the solenoid contactor coil  42 . In another example, initiating can further include energizing the contactor coil  42  with the contactor coil energizing supply  50  at the contactor initiation time  96 . 
     The sequence depicted is for illustrative purposes only and is not meant to limit the method  100  in any way as it is understood that the portions of the method can proceed in a different logical order, additional or intervening portions can be included, or described portions of the method can be divided into multiple portions, or described portions of the method can be omitted without detracting from the described method. 
     Therefore, it should be appreciated that the contactor assembly  32  as described herein can provide for accurate zero-crossing voltage for a switch  40 . Such accuracy can provide for decreasing contact wear at the switch  40  itself, leading to increased component lifetime and reduced maintenance. Furthermore, reduction of contact deposition at zero current and voltage can be achieved. Electromagnetic noise along the power supply is reduced and can eliminate spikes to a much higher level. Stress on upstream and downstream electrical loads can be reduce, as well as reducing the occurrence of spikes and surges on said electrical loads. Overall a cleaner power consumption is achieved, which can lead to an overall reduction in power consumption. 
     The aspects disclosed herein provide a method and apparatus for operating a contactor assembly. The technical effect is that the above described aspects enable the disconnecting or connecting of the contactor after determining a total contactor time and initiating the disconnection or connecting of the power supply by the contactor at the total contactor time or delay such that the effective disconnection or connection occurs or coincides with a zero-crossing voltage of the input power AC waveform, as described herein. The circuit and contactor assembly as described herein can be suitable for different or all types of power supplies, powered electronics or circuit boards, or any suitable electrical power distribution system. It should be appreciated that the contactor assembly provides for effectively disconnecting or connecting an AC circuit at a zero-crossing point where the current for the AC circuit is at or near zero. Utilizing one or more sensors, measurements of the contactor assembly can be provided to a controller module. The controller module can determine a set of actual, predicted, or estimated time delay values defining a time between the contactor assembly operably connecting or disconnecting an input with an output, after receiving a command or instruction to do so. Utilizing the determined time delay, as described herein, the contactor assembly can initiate disconnection or connection of the power supply prior to, ahead of, or in anticipation of a zero-crossing point on the AC waveform for the AC circuit, such that the power supply is effectively disconnected or connected at or near the zero-crossing point. Therefore, effectively disconnecting or connecting the power supply at the zero-crossing point can be accurately and consistently achieved. Disconnecting or connecting at the zero-crossing point can reduce contact wear and contact deposition, which can increase lifetime of the contactor assembly and reduce maintenance. Furthermore, stress on upstream and downstream electrical loadings can be reduced, as well as reducing the occurrence of voltage spikes and surges. Overall power consumption can be cleaner, reducing total power consumption. Noise generated by the contactor assembly is also reduced, and can reduce spikes surges resultant of the reduced noise. 
     To the extent not already described, the different features and structures of the various features can be used in combination as desired. That one feature is not illustrated in all of the aspects of the disclosure is not meant to be construed that it cannot be, but is done for brevity of description. Thus, the various features of the different aspects described herein can be mixed and matched as desired to form new features or aspects thereof, whether or not the new aspects or features are expressly described. All combinations or permutations of features described herein are covered by this disclosure. 
     This written description uses examples to detail the aspects described herein, including the best mode, and to enable any person skilled in the art to practice the aspects described herein, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the aspects described herein are defined by the claims, and can include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims.