Abstract:
A method and apparatus for identifying the health status of a contactor include the steps of counting the number of operations performed by the contactor, identifying a closing time of the contactor, using the number of operations and the closing time to assess the health status of the contactor and, where the health of the contactor is a first health status, reporting the health status of the contactor.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     Not applicable. 
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
     Not applicable. 
     BACKGROUND OF THE INVENTION 
     The present invention relates to contactor health and more specifically to a system and method that can be customized by a user for predicting the health of contactors and the remaining life of contactors. 
     Contactors are generally used in motor starter applications to switch on/off a load as well as to protect a load, such as a motor, or other electrical devices, from current overloading. As such, a typical contactor has one or more contact assemblies—a contact assembly for each phase or pole required for the electrical device. Each contact assembly, in turn, includes a pair of stationary contacts and a pair of moveable contacts. One stationary contact will be a line side contact and the other stationary contact will be a load side contact. The moveable contacts are controlled by an actuating assembly comprising a contact carrier and an armature magnet assembly which is energized by a coil to move the moveable contacts to form a bridge between the stationary contacts. When the moveable contacts are engaged with both stationary contacts, current is allowed to travel from the power source or line to the load or electrical device. When the moveable contact is separated from the stationary contacts, an open circuit is created and the line and load are electrically isolated from one another. 
     Since contactors and motor starters are important components of both automation and control systems, monitoring their remaining useable life, or “health”, to predict impending faults before occurrence is essential. Un-predicted failures of contactors not only cause costly work stoppages, but also can cause damage to a load and other related systems and equipment. In contrast, over-cautious approaches to contactor monitoring and replacement increase maintenance costs and slow or delay usage of the motor/load. 
     Currently, most methods for estimating the working life of contactors rely upon the manufacturer&#39;s life test data or guidelines. That is, most commercially available contactors have a designated number of operations or cycles (e.g., 100,000 to 2,500,000 operations) after which the manufacturer recommends replacement to avoid failure in use. Thus, many systems and methods for predicting failure simply count the number of operations that a contactor completes. However, each contactor will not necessarily operate for the same number of cycles before failure. Exacerbating matters, the causes of failures vary among contactors as well as the conditions which lead to possible failure issues. How a contactor is operated, the conditions under which a contactor is used, and the characteristics of the environment in which a contactor is used cause even more variation in the number of operations a contactor might undergo before failure. Therefore, to be useful, counting methods must be overly cautious in setting replacement schedules, or risk contactor failures while in use. In addition, some types of loads, or one time events such as faults, can drastically change the expected life of a contactor which reinforces the usefullness of a real time monitoring system such as the one proposed in this ‘User Customizable Contactor Prognostics System’. 
     In addition, different applications have different consequences when contactors fail. For this reason, the conditions under which contactors should be replaced may vary between applications. For example, in the case of an auto manufacturer, a failed contactor may result in severe and expensive damage to manufacturing robots while a failed contactor in a transfer line associated with a machine vision system may simply mean that a part is not imaged properly and no physical damage may result. Here, the auto manufacturer would likely have a lower tolerance for contactor failure than the manufacturer employing the machine vision system. 
     Thus, it would be desirable to have a system and method capable of estimating the remaining useable life of a contactor and impending faults thereof. It would also be advantageous if the system and method were customizable by a user to accommodate different application requirements and user preferences. 
     BRIEF SUMMARY OF THE INVENTION 
     It has been recognized that a contactor prognostics method and apparatus can be provided that is more accurate than previous methods and apparatuses where the method accounts for both operation count and closing time of a contactor when assessing health status. It has also been recognized that methods and apparatus can be provided that are customizable by system operators to suit particular applications and user/operator preferences. To this end, in at least some embodiments an operator may be able to define different combinations of contactor operating count and closing time durations to be associated with different contactor health statuses. In some embodiments an operator may be able to define different operation count variables and/or closing time variables and their relative definitions where those variables are then used together to assess health status. 
     Consistent with the above comments, at least some embodiments include a method for identifying the health status of a contactor, the method comprising the steps of counting the number of operations performed by the contactor, identifying a closing time of the contactor, using the number of operations and the closing time to assess the health status of the contactor and where the health of the contactor is a first health status, reporting the health status of the contactor. In some cases the step of identifying a closing time of the contactor includes identifying a most current closing time of the contactor. 
     In some cases the step of using the number of operations and the closing time to assess health status includes setting an operation count variable to one of a plurality of different operation count variables as a function of the number of times the contactor has been operated and setting a closing time variable to one of a plurality of different closing time variables as a function of the identified closing time and using the operation count variable and the closing time variable to assess the health status. In some cases the contactor has a maximum contactor count value and is characterized by a maximum contactor closing time value and wherein the step of setting an operation count variable includes setting the operation count variable as a function of the percent of the maximum contactor count value represented by the current number of operations performed and the step of setting a closing time variable includes setting the closing time variable as a function of the percent of the maximum contactor closing time value represented by the most recent closing time of the contactor. 
     In some cases the step of setting the operation count variable includes setting the operation count variable to New, Young, Middle, Old and Aged when the current number of operations is between substantially zero and substantially 20%, substantially twenty and substantially 40%, substantially forty and substantially 60%, substantially sixty and substantially 80% and substantially eighty and substantially 100% of the designed life operations value, respectively, and, wherein, the step of setting a closing time variable includes setting the closing time variable to Good, Normal and Bad when the most recent closing time is less than substantially 80% of the maximum designed closing time, between substantially 80 and substantially 110% of the maximum designed closing time and greater than substantially 110% of the maximum designed closing time, respectively, and wherein the step of using the number of operations and the closing time to assess health status includes applying health status rules to the operation count variable and the closing time variable to assess health status of the contactor. In some cases the step of using the number of operations and the closing time to assess the health status of the contactor includes applying a set of health status rules to the number of operations and the closing time to determine the health status, the method further including the step of enabling a system operator to modify the set of health status rules. 
     In some cases the step of enabling a system operator to modify the set of health status rules includes providing an interface for the operator to use to modify the health status rules. In some cases the step of enabling an operator to modify the set of health status rules includes enabling the operator to identify different combinations of the operation count variables and the closing time variables that comprise the first health status. In some cases all health statuses are indicated. 
     In some embodiments the method further includes the steps of enabling an operator to modify definitions of at least one of the operating count variables and the closing time variables for subsequent use. 
     Other embodiments include an apparatus for identifying the health status of a contactor, the apparatus comprising a processor programmed to perform the steps of counting the number of operations performed by the contactor, identifying a closing time of the contactor, using the number of operations and the closing time to assess the health status of the contactor and where the health of the contactor is a first health status, reporting the health status of the contactor. 
     In some cases the step of identifying a closing time of the contactor includes identifying a most current closing time of the contactor. In some cases the processor performs the step of using the number of operations and the closing time to assess health status by setting an operation count variable to one of a plurality of different operation count variables as a function of the number of times the contactor has been operated and setting a closing time variable to one of a plurality of different closing time variables as a function of the identified closing time and using the operation count variable and the closing time variable to assess the health status. In some cases the contactor has a maximum contactor count value designed life operations value and is characterized by a maximum contactor closing time value and wherein the processor performs the step of setting an operation count variable by setting the operation count variable as a function of the percent of the maximum contactor count value represented by the current number of operations performed and the step of setting a closing time variable by setting the closing time variable as a function of the percent of the maximum contactor closing time value represented by the most recent closing time of the contactor. 
     In some cases the processor performs the step of setting the operation count variable by setting the operation count variable to New, Young, Middle, Old and Aged when the current number of operations is between substantially zero and substantially 20%, substantially twenty and substantially 40%, substantially forty and substantially 60%, substantially sixty and substantially 80% and substantially eighty and substantially 100% of the designed life operations value, respectively, and, performs the step of setting a closing time variable by setting the closing time variable to Good, Normal and Bad when the most recent closing time is less than substantially 80% of the maximum designed closing time, between substantially 80 and substantially 110% of the maximum designed closing time and greater than substantially 110% of the maximum designed closing time, respectively, and wherein the processor performs the step of using the number of operations and the closing time to assess health status by applying health status rules to the operation count variable and the closing time variable to assess health status of the contactor. 
     In some cases the processor performs the step of using the number of operations and the closing time to assess the health status of the contactor by applying a set of health status rules to the number of operations and the closing time to determine the health status, the processor further programmed to perform the step of enabling a system operator to modify the set of health status rules. In some cases the processor performs the step of enabling a system operator to modify the set of health status rules by providing an interface for the operator to use to modify the health status rules. 
     In some cases the processor performs the step of enabling an operator to modify the set of health status rules by enabling the operator to identify different combinations of the operation count variables and the closing time variables that comprise the first health status. In some cases all health statuses are indicated. 
     In some embodiments the processor is further programmed to perform the steps of enabling an operator to modify definitions of at least one of the operating count variables and the closing time variables for subsequent use. 
     Other embodiments include a method for determining a contactor life left value for a contactor, the method comprising the steps of specifying a maximum contactor operations count for the contactor, counting the number of contactor operations for the contactor, identifying the average number of contactor operations per unit of time for the contactor and mathematically combining the average number of operations per unit of time with the number of contactor operations and the maximum contactor operations count to identify the contactor life left value. 
     In some cases the step of identifying the average number of contactor operations per unit time includes counting the number of days that the contactor is operated and dividing the number of contactor operations by the number of days that the contactor is operated. In some cases the step of mathematically combining includes dividing the difference between the maximum contactor count value and the number of contactor operations by the average number of contactor operations per unit of time for the contactor. 
     To the accomplishment of the foregoing and related ends, the invention, then, comprises the features hereinafter fully described. The following description and the annexed drawings set forth in detail certain illustrative aspects of the invention. However, these aspects are indicative of but a few of the various ways in which the principles of the invention can be employed. Other aspects, advantages and novel features of the invention will become apparent from the following detailed description of the invention when considered in conjunction with the drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
         FIG. 1  is a schematic illustrating a system including a customizable contactor prognostics subsystem that is consistent with at least some aspects of the present disclosure; 
         FIG. 2  is a schematic illustrating an exemplary health status rules database that may be included in the  FIG. 1  system; 
         FIG. 3  is a table illustrating an exemplary operation count variable definition database that may be included in the rules database of  FIG. 2 ; 
         FIG. 4  is a table illustrating an exemplary closing time variable definition database that may be included in the rules database of  FIG. 2 ; 
         FIG. 5  is a schematic illustrating an exemplary contactor health status definition database that may be included in the rules database of  FIG. 2 ; 
         FIG. 6  is a schematic illustrating exemplary digital logic that is consistent with the health status information shown in  FIG. 5 ; 
         FIG. 7  is a schematic illustrating a flow chart of a method consistent with at least some embodiments of the present disclosure; 
         FIG. 8  is a schematic illustrating an exemplary screen shot that may be presented via the display shown in  FIG. 1  when a processor performs a customization program whereby a system operator can specify or modify health status rules according to at least some aspects of the present disclosure; 
         FIG. 9  is similar to  FIG. 8 , albeit illustrating the screen shot at a different time during a customization process; 
         FIG. 10  is similar to  FIG. 8 , albeit illustrating the screen shot at a different time during a customization process; 
         FIG. 11  is similar to  FIG. 8 , albeit illustrating a different screen shot where a tool bar includes additional tools; 
         FIG. 12  is similar to  FIG. 11 , albeit showing a screen shot with an additional sub-window opened for specifying operation count status definitions; and 
         FIG. 13  is a schematic illustrating a customization process that may be performed by the processor of  FIG. 1 . 
     
    
    
     While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof have been shown by way of example in the drawings and are herein described in detail. It should be understood, however, that the description herein of specific embodiments is not intended to limit the invention to the particular forms disclosed, but on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention as defined by the appended claims. 
     DETAILED DESCRIPTION OF THE INVENTION 
     The various aspects of the subject invention are now described with reference to the annexed drawings, wherein like reference numerals correspond to similar elements throughout the several views. It should be understood, however, that the drawings and detailed description hereafter relating thereto are not intended to limit the claimed subject matter to the particular form disclosed. Rather, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the claimed subject matter. 
     As used herein, the terms “component,” “system” and the like are intended to refer to a computer-related entity, either hardware, a combination of hardware and software, software, or software in execution. For example, a component may be, but is not limited to being, a process running on a processor, a processor, an object, an executable, a thread of execution, a program, and/or a computer. By way of illustration, both an application running on a computer and the computer can be a component. One or more components may reside within a process and/or thread of execution and a component may be localized on one computer and/or distributed between two or more computers or processors. 
     The word “exemplary” is used herein to mean serving as an example, instance, or illustration. Any aspect or design described herein as “exemplary” is not necessarily to be construed as preferred or advantageous over other aspects or designs. 
     Furthermore, the disclosed subject matter may be implemented as a system, method, apparatus, or article of manufacture using standard programming and/or engineering techniques to produce software, firmware, hardware, or any combination thereof to control a computer or processor based device to implement aspects detailed herein. The term “article of manufacture” (or alternatively, “computer program product”) as used herein is intended to encompass a computer program accessible from any computer-readable device, carrier, or media. For example, computer readable media can include but are not limited to magnetic storage devices (e.g., hard disk, floppy disk, magnetic strips . . . ), optical disks (e.g., compact disk (CD), digital versatile disk (DVD) . . . ), smart cards, and flash memory devices (e.g., card, stick). Additionally it should be appreciated that a carrier wave can be employed to carry computer-readable electronic data such as those used in transmitting and receiving electronic mail or in accessing a network such as the Internet or a local area network (LAN). Of course, those skilled in the art will recognize many modifications may be made to this configuration without departing from the scope or spirit of the claimed subject matter. 
     Referring specifically to  FIG. 1 , the present invention will be described in the context of an exemplary system  10  including a power source  12 , a contactor  14 , a load  16 , a contactor controller  18 , a network  20  and a computer or workstation  21 . Power source  12  provides power to load  16  (e.g., a motor) via contactor  14  where the contactor  14  can be opened and closed to provide power to and cut power off from load  16 . Here, contactor  14  may be a medium voltage contactor such as the 400 Amp 1502 Vaccuum Contactor manufactured by Allen-Bradley that is suitable for all types of AC loads such as, for instance, motors, transformers, power capacitors and resistive heating loads. These contactors are used in various starter and drive configurations such as, for instance, full voltage non-reversing, full voltage reversing, two speed, reduced voltage, synchronous, drive input/output and bypass applications. The 1502 Vaccuum Contactors are designed for use with the IntelliVac™ control module manufactured by Allen-Bradley. 
     Referring still to  FIG. 1 , contactor controller  18  controls opening and closing operations of contactor  14 . To this end, controller  18  may include one of the control modules, such as those manufactured by Allen-Bradley. Controller  18  includes a processor  26  and a database  28 . Processor  26  is linked to contactor  14  for opening and closing the contactor during contactor operations. Processor  26  is also linked to database  28  to access programs and data stored therein and to store and update data therein. 
     Database  28  includes, among other things, programs  30 , health status rules  36 , an operation count value  38 , a closing time value  40 , a maximum contactor count and a maximum contactor closing time. The programs  30  include a health status program  34  that processor  26  runs to assess the health status of contactor  14  during operation. While performing health status program  34 , processor  26  applies the health status rules  36  to assess contactor health status. In at least some embodiments when contactor health status has deteriorated sufficiently, processor  26  provides notice or an indication that contactor  14  should be replaced or at least maintained. 
     In at least some embodiments, processor  26  provides notice by transmitting a signal via network  20  (e.g., via the Ethernet, the Internet, etc.) to computer terminal  21  which can present a contactor maintenance or replacement warning or report to a system operator. To this end, computer  21  includes a display screen  22  and a keyboard  24  or other input device (not illustrated). Maintenance or replacement notices may be presented via text on display  22 . In some embodiments, processor  26  may simply set a warning flag (i.e., change the flag from an off value to an on value) to indicate a warning condition and some other program may recognize the set bit as a warning indicator and provide a notice message to the operator via computer  21 . In still other embodiments, where a contactor warning signal is generated, the system associated with contactor  14  may be fully or partially shut down. 
     Referring still to  FIG. 1 , the health status rules  36  may include several different types of rules. In at least some embodiments, the health status rules  36  will take into account operating characteristics of contactor  14  when determining the health status of the contactor where the operating characteristics include an operation count value and a closing time value. Here, the phrase “operation count”, as the label implies, is simply a count value indicating the number of times contactor  14  has been closed and reopened. Contactors are designed to achieve or reach, in general, a maximum contactor count (MCC) where, after the maximum count has occurred, likelihood of failure substantially increases. Thus, as the operation count  38  increases and approaches the designed maximum contactor count, likelihood of contactor failure increases. 
     The phrase “closing time” refers to the amount of time required for the contactor  14  to change from an open state to a closed state after a close command has been provided to the contactor  14  by processor  26 . Contactors are manufactured and designed to have a maximum contactor closing time where, as the closing time approaches and exceeds the maximum closing time, the likelihood of failure increases. Thus, as the duration of the contactor closing time approaches and then exceeds the maximum contactor closing time, the duration can be used as an indicator of the likelihood of contactor failure. In  FIG. 1 , both the maximum contactor count  41  and the maximum contactor closing time  43  are stored in database  28 . 
     Referring now to  FIG. 2 , an exemplary health status rules database  36  is illustrated that includes three separate sub-databases including an operation count variable value definition database  50 , a closing time variable value definition database  52  and a contactor health status variable value definition database  54 . Referring to  FIG. 3 , an exemplary operation count variable value definition database  50  is illustrated in table format. Here, it should be appreciated that while database  50  is shown in table format to simplify this explanation, database  50  may be stored in other formats know in the art. Database  50  includes an operation count (OC) variable column  58  and a value definition column  60 . The operation count variable column  58  includes an exemplary list of operation count variables including OC-New, OC-Young, OC-Middle, OC-Old and OC-Aged where the New, Young, Middle, Old and Aged qualifiers indicate relative operation count. Thus, variable OC-New indicates that an associated contactor is relatively new while variable OC-Aged indicates that an associated contactor is relatively old and is at or is likely approaching the end of its useful life. 
     Value definition column  60  provides a separate definition for each of the operation count variables in column  58  and indicates how a separate flag associated with each one of the variables in column  58  should be set as a function of an instantaneous operation count. Thus, for example, the value definition for the operation count variable OC-New indicates that where the operation count is less than 20% of the designed maximum contactor count, the OC-New variable should be equal to true and, under all other circumstances, the OC-New variable should be equal to false. Similarly, column  60  indicates that when the operation count is between twenty and 40% of the maximum contactor count, is between 40 and 60% of the maximum contactor count, is between 60 and 80% of the designed maximum contactor count and is greater than 80% of the designed maximum contactor count, the OC-Young, OC-Middle, OC-Old and OC-Aged variables should be set equal to true, respectively, and under all other circumstances, those variables should be set equal to false. Thus, at any time during the life of a contactor  14 , only one of the operation count variables OC-New, OC-Young, OC-Middle, OC-Old and OC-Aged will be set equal to true and the other variables will be set equal to false. 
     Referring now to  FIG. 4 , an exemplary closing time variable value definition database  52  is illustrated. Here, again, database  52  is shown in table format to simplify this explanation and it should be recognized that database  52  may take any other known database form. Database  52  includes a closing time (CT) variable column  66  and a value definition column  68 . Closing time variable column  66  includes three different closing time variables including a CT-Good status, a CT-Normal and a CT-Bad status. Here the qualifiers Good, Normal and Bad indicate relative closing time durations. Column  68  provides a value definition for each one of the variables in column  66 . For example, column  68  indicates that when the closing time is less than 80% of the maximum contactor closing time for contactor  14 , the CT-Good variable should be set equal to true and at all other times the CT-Good variable should be set equal to false. Similarly, column  68  indicates that when the closing time contactor  14  is between 80% and 110% of the maximum designed closing time for the contactor, the CT-Normal variable should be set equal to true and at all other times the CT-Normal variable should be set equal to false and indicates that when the closing time is greater than 110% of the maximum design closing time the CT-Bad variable should be set equal to true and at all other times the CT-Bad variable should be set equal to false. 
     Referring now to  FIG. 5 , an exemplary contactor health status variable value definition database  54  is illustrated. Once again, database  54  is shown in table format to simplify this explanation and it should be realized that the database  54  may be provided in any of several other different forms known in the art. Database  54  includes two columns including a closing time variable column  80  and an operation count variable column  90 . The closing time variable column  80  includes each of the three closing time variables described above with respect to  FIG. 4  including the CT-Good variable  96 , the CT-Normal variable  98  and the CT-Bad variable  100 . Operation count variable column  90  includes five separate sub-columns corresponding to the five separate operation count variables described above with respect to  FIG. 3 . Thus, the sub-columns include an OC-New sub-column  84 , an OC-Young sub-column  86 , an OC-Middle sub-column  88 , an OC-Old sub-column  92  and an OC-Aged sub-column  94 . The table  54  includes a separate field corresponding to each combination of a closing time variable and an operation count variable and indicates a relative health status for an associated contactor  14 . Thus, for example, field  85  corresponds to the CT-Good variable  96  and the OC-New variable  84  and indicates that when the associated closing time and count variables occur, the health status of the contactor  14  is excellent. Thus, referring to  FIGS. 3 ,  4  and  5 , field  85  indicates that when the operation count is less than 20% of the maximum contactor count (see  FIG. 3 ) and the most recent closing time is less than 80% of the maximum contactor closing time (see  FIG. 4 ), the contactor health status will be excellent (see  FIG. 5 ). As another example, field  87  corresponds to the CT-Bad variable  100  and the OC-Aged variable  94  and indicates that when those two variables occur, the health status of the contactor associated therewith is particularly bad (i.e., the indicator in field  87  indicates HS-Worst). As yet one other example, field  89  indicates that the health status of an associated contactor is normal when the closing time variable is CT-Good and the operation count variable is OC-Middle. 
     In the illustrated example the health statuses include Excellent, Good, Normal, Worse and Worst indicating relative contactor health status. Exemplary definitions of the health status variables are shown in Table 1 below. 
     
       
         
               
               
             
           
               
                 TABLE 1 
               
               
                   
               
               
                 Health Status 
                   
               
               
                 (HS)Variables 
                 Value Definitions 
               
               
                   
               
             
             
               
                 HS-Excellent 
                 New contactor is functioning normally. 
               
               
                 HS-Good 
                 Contactor has possibly been run for certain time, but 
               
               
                   
                 still functioning normally. 
               
               
                 HS-Normal 
                 Contactor is possibly over half its life span, but still 
               
               
                   
                 functioning normally. 
               
               
                 HS-Worse 
                 Contactor is possibly close to the malfunction stage and 
               
               
                   
                 needs special maintenance or repair operations. In 
               
               
                   
                 some embodiments a warning flag will be set to 
               
               
                   
                 indicate this state. 
               
               
                 HS-Worst 
                 Contactor is likely close to malfunction stage and needs 
               
               
                   
                 special maintenance, repair or replacement operations. 
               
               
                   
                 In some embodiments a fault sign will be set to indicate 
               
               
                   
                 this state. 
               
               
                   
               
             
          
         
       
     
     Referring still to  FIG. 5  and now also to  FIG. 6 , an exemplary digital logic representation  102  of the information presented in  FIG. 5  is shown in  FIG. 6  where a plurality of AND gates  104  and OR gates  106  represent the  FIG. 5  information. To this end, representation  102  includes  15  AND gates collectively identified by numeral  104  where each of the AND gates represents a different one of the closing time variable and operation count variable combinations shown in  FIG. 5 . Thus, for instance, AND gate  85   a  corresponds to field  85  in database  54  where the variable inputs are OC-New and CT-Good and the logic output indicates that the contactor health status is excellent. Similarly, AND gates  87   a  and  89   a  correspond to fields  87  and  89  in  FIG. 5 . The OR gates  106  each simply “OR” together the outputs of all of the AND gates corresponding to an associated health status of the contactor. For example, OR gate  95  “ORs” together the outputs of all three AND gates associated with the good contactor health status. 
     Referring once again to  FIG. 1  and also to  FIG. 7 , an exemplary process  110  that is consistent with the system described above and that may be performed by processor  26  is illustrated in  FIG. 7 . At block  112 , a maximum contactor count MCC value and a maximum contactor closing time MCCT value are provided to processor  26  which stores those values in database  26  (see  41  and  43  in  FIG. 1 ). At block  114 , health status rules  36  are provided to processor  26  which stores those rules in database  28 . At block  116 , an operation counter or count (OC) is set equal to zero prior to the initial time a contactor to be monitored is operated. 
     Referring still to  FIGS. 1 and 7 , at decision block  118 , during normal operation of system  10  wherein contactor  14  may be operated, processor  26  determines whether or not contactor  14  is operated. Once contactor  14  is operated, control passes to process block  120  where the operation count (OC) is incremented by one and then to block  122  where the closing time for the contactor  14  is identified and stored in database  28  (see  40  in  FIG. 1 ). Continuing, at block  124 , processor  26  applies the health status rules  36  to set the operation count variable and the closing time variable. To this end, in the present example, processor  26  applies the definitions from databases  50  and  52  as shown in  FIGS. 3 and 4 , respectively, to set the operation count variable and closing time variable (i.e., to set one of the closing time variables and one of the operation count variables equal to one while all other variables remain zero). 
     At block  126 , processor  26  applies the health status rules  36  to the operation count and closing time variables to determine a contactor health status. In the present example, processor  26  applies the rules specified in  FIG. 5  to assess contactor health status. At block  128 , in at least some embodiments, where the health status of the contactor  14  is “worse” or “worst” as specified by database  54  in  FIG. 5 , control passes to block  130  where the “worse” or “worst” health status is reported or indicated (e.g., via display  22 ). After block  130 , control passes back up to block  118  where the process described above continues. Referring again to block  128 , where the health status is not “worse” or “worst”, in the illustrated example, control passes from block  128  back up to block  118  where the process described above continues. 
     In at least some embodiments, consistent with the description above, operation count variable definitions and closing time variable definitions as well as the health status definitions may be pre-defined by a contactor manufacturer and a system operator may not be able to modify those definitions. In other embodiments it is contemplated that system  10  (see again  FIG. 1 ) may enable a system operator to modify operation count variable, closing time variable and health status definitions or at least subsets thereof to accommodate specific applications or operator preferences. Thus, for example, referring again to  FIG. 5 , in at least some embodiments a system operator may want to change the health status corresponding to field  89  to be “worse” instead of “normal”. As another example, referring to  FIG. 3 , an operator may want to change the percentages in the value definition column  60  corresponding to one or more of the operation count variables in column  58 . For instance, the operator may want to entirely eliminate the OC-Young count variable and have the OC-New variable correspond to all operation counts that are less than 40% of the maximum contactor count. Many other health status rule modifications are contemplated. 
     Referring once again to  FIG. 1 , in at least some embodiments, to enable an operator to modify health status rules to be applied by processor  26 , the database programs  30  may include a customization program  32 . While various types of customization programs  32  are contemplated by this disclosure, one particularly useful customization program will be described in some detail. To this end, also referring to  FIG. 8 , an exemplary customization program screen shot  140  is illustrated. Here, screen shot  140  includes a logic specifying workspace  141  and a tool bar  144 . In at least some embodiments it is contemplated that where operation count variables and closing time variables are predefined, a separate AND gate  142  corresponding to each one of the operation count variable and closing time variable combinations may be provided. In  FIG. 8 , the AND gates  142  include  15  separate AND gates corresponding to each one of the combinations shown in  FIG. 5 . 
     Referring still to  FIG. 8 , tool bar  144  includes an AND icon  148 , an OR icon  150 , a connector line icon  152 , health status indicators collectively identified by numeral  154  and a compile icon  156 . Here, AND icon  148  can be selected via a mouse controlled cursor  146  or the like to cause an instance of an AND gate to appear in workspace  141 . Once a gate is placed within workspace  141 , the cursor  146  can be used to select the gate and move the gate around within workspace  141  to a desired location. 
     Referring still to  FIG. 8 , instances of OR gates may also be added to workspace  141  by selecting OR gate icon  150 . The OR gates can be moved around within space  141  to desired locations. Once one or more gates is added to space  141 , a system operator can select the connector line icon  151  to be able to add lines to space  141  and connect the gates added by the operator. Thus, for instance, referring to  FIG. 9 , gate  147  has been added to space  141  and AND gates  149  and  151  have been connected to OR gate  147  via lines while gate  153  is in the process of being connected to OR gate  147  thereby specifying health status rules logic. Referring to  FIG. 10 , a completed set of logic is illustrated in space  141 . 
     The health status indicators  54  may each be separately selected and moved within space  141  to associate each of the indicators with at least one output of one of the gates within space  141 . In at least some embodiments, when a health status indicator is moved to a location adjacent the output of one of the gates in space  141 , the indicator will be automatically associated therewith. While all five of the health status indicators described above are shown in space  141 , in at least some embodiments less than all of the indicators may need to be added to the logic. In  FIG. 10 , in addition to the five indicators described above, two additional indicators are provided that are identified collectively by numeral  169 . Here, it is contemplated that a system operator may want to specify more than five indicators and the indicators  169  can be used for this purpose. In some embodiments, the labels used for the indicators  154  may be modified by, after adding one of the indicators to space  141 , double clicking on the indicator and then typing in a replacement label or the like. 
     Referring now to  FIG. 11 , another exemplary screen shot  200  that may be presented via display  22  in  FIG. 1  is illustrated where tool bar  144  includes four additional mouse selectable icons including a DEFINE OC VARIABLE DEFINITION icon  202 , a DEFINE CT VARIABLE DEFINITION icon  204 , a SET MCCT icon  206  and a SET MCC icon  208 . In at least some embodiments it is contemplated that when icon  202  is selected, referring to  FIG. 12 , a sub-window  213  may be opened where a table similar to the table described above with respect to  FIG. 3  is presented that includes an operation count variable column and a value definition column. Here, percentages in the value definition column are shown as underlined fields that can be selected so that the values therein can be altered. For example, a field  210  corresponds to the percentage in the definition associated with the OC-New variable while percentage fields are collectively identified by numeral  212  for the definition corresponding to the OC-Young variable. In this case, the system operator may select any one of the percentage fields within window  213  and modify the percentages therein to change the value definition for any one of the operation count variables. 
     In a similar fashion, operation count variables may be eliminated from the database by simply deleting definitions from the definition column. In some embodiments it is contemplated that other variables may be added to the database using tools similar to conventional table editing tools used in other standard software packages (e.g., via row insertion and entry of new variable names and definition in the field). How sophisticated the database defining tools are is a matter of designer choice and many more sophisticated defining options and tools are contemplated. 
     Referring again to  FIG. 11 , similarly, although not illustrated, a system operator may select icon  204  to modify the closing time variable definitions, may select icon  206  to modify the maximum contactor closing time (MCCT) value and may select icon  208  to modify the maximum contactor count (MCC) value used by the health status program. In each of these cases, when one of icons  204 ,  206  or  208  is selected, a window similar to window  213  described above with respect to  FIG. 12  would be opened to enable the operator to modify definitions or maximum values. 
     Referring now to  FIG. 13 , a customization program process  180  that may be performed by the processor  26  shown in  FIG. 1  is illustrated. At block  182 , processor  26  provides an interface for the system operator to specify or customize health status rules. At block  184 , the system operator specifies logic via the interface that defines the health status rules or modifies those rules. At block  186 , processor  26  monitors the interface for a command from the system operator indicating that the rules have been completely specified. To this end, referring again to  FIG. 8 , after rules have been completely specified, the system operator can select COMPILE icon  156  to cause processor  26  to complete the health status rules specifying process and to store the rules as appropriate. Referring again to  FIG. 13 , if specifying has not been completed, control passes back up to block  184  where processor  26  continues to receive logic. At block  186 , once the specifying process has been completed, the process ends. 
     In accordance with another aspect of the present disclosure, a method for estimating the contactor life left using contactor usage statistics is contemplated. To this end, the contactor controller includes a power up or on time counter T on  that represents the accumulation of power up time of a relay in units of days. Here, the processor  26  of  FIG. 1  may be programmed to estimate a contactor life left in units of days of operation by solving the following equation: 
                     T     left   ⁡     (   days   )         =       MCC   -   OC       CPD   ave               Eq   .           ⁢   1               
where OC is the current operations count for the contactor and CPD ave  is the average operations count per diem for the contactor and is determined by solving the following equation:
 
                     CPD   ave     =     OC     T   on               Eq   .           ⁢   2               
The T left  value may be reported to a system operator via display  22  routinely or whenever the value T left  drops below some threshold value (e.g., 10 days).
 
     The particular embodiments disclosed above are illustrative only, as the invention may be modified and practiced in different but equivalent manners apparent to those skilled in the art having the benefit of the teachings herein. Furthermore, no limitations are intended to the details of construction or design herein shown, other than as described in the claims below. It is therefore evident that the particular embodiments disclosed above may be altered or modified and all such variations are considered within the scope and spirit of the invention. Accordingly, the protection sought herein is as set forth in the claims below. 
     Thus, the invention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention as defined by the following appended claims. For example, instead of using the most recent contactor closing time to set the closing time variable, processor  26  may be programmed to use a rolling average of closing times over a series (e.g.,  20 ) of contactor operations to set the closing time variable. As another example, a database of contactor maximum closing times and maximum contactor count is contemplated where a system operator may access the database on-line and download maximum values for specific contactor types to be used by the health status software. Here the database could be for contactors manufactured by one company or could include data corresponding to multiple manufacturers. In addition, in some embodiments contactor health may only be determined once within a period (e.g., once every day) or periodically (e.g., every 1200 th  contactor operation). Moreover, other systems are contemplated where operating characteristics other than OC and closing time may be combined in a customizable fashion to assess contactor health. For example, one other operating characteristic that may be monitored includes a contactor open time as well as the proposed close time. 
     To apprise the public of the scope of this invention, the following claims are made: