Patent Publication Number: US-8988020-B1

Title: Motor operator system for a power switch with travel set with three positions for ground or double-throw type switch

Description:
BACKGROUND OF THE INVENTION 
     The invention relates to motor operators, such as for power switches of electrical utilities, and particularly to such operators for underground switches as well as switches in other locations, with a drive and control system that allows adjustment of motor travel settings resulting in the proper travel of the power switch. 
     Power switches, for example, disconnect and load break switches for distribution systems, are typically used in three main types of locations: overhead on a utility pole, in an underground vault, and pad mounted substantially at surface level. (Reference to “pad” or “pad mounted” herein, unless the context clearly indicates the contrary, is to be understood as mounted on an above ground pad.) It is of course the case that these switches can sometimes be mounted on a pad instead of being under ground. The switches can also be of different types. Unenclosed air break switches are often used on pole top installations. Enclosed, but not sealed, air break switches are often used at pad mounted installations. Enclosed and sealed switches, such as with vacuum or gas (e.g., SF6) insulation, are often used on or in locations, such as underground vaults, where the confined and sometimes flooded space makes air break switches inappropriate. 
     Switches in underground locations, and also in some pad installations, have motor operators located near the switches (in contrast, for example, to pole top air break switches that are mechanically coupled to motor operators on or near the ground). At one time power switches could be operated only by direct access to the switch or its operator. More recently, the power switch art has applied technology for remote, automated operation of a motor operator to close and open a power switch, (see, for example, Cleaveland/Price Bulletin DB-32BC04 (of 2004). During installation, however, the motor operator will need travel adjustment at the motor operator itself in order to operate the switch with the complete open or close position travel, which can be accomplished as disclosed in U.S. Pat. No. 7,122,986, issued on Oct. 17, 2006, to the present assignee, Cleaveland/Price Inc., said patent herein incorporated by reference in its entirety. 
     Extra danger to utility workers is encountered in tight locations such as underground vaults. For example, an enclosed switch may explode, due to heat buildup from arcing during a malfunction of the switch, subjecting workers to injury. 
     Motor operators for underground switch locations generally require a sealed enclosure to protect the operator from common flooding of the vault. For access to the interior of the enclosure for any reason, it has been necessary to have a port or panel of the enclosure that is removable and replaceable at the service location by a worker. In addition to the time needed to access the interior and to reseal the motor operator properly, perhaps dealing with up to thirty fasteners and a gasket, there is a risk the attempt to reseal is not successful and can lead to malfunction of the unit. The worker performing the field work is not equipped to test whether the seal is effective. Therefore, there is a need in the industry to adjust the travel of a sealed motor operator without disturbing the seal of the enclosure. 
     Generally, in the past, underground motor operators, required adjustment at the motor operator-power switch location to set the limits of travel of the motor in the motor operator which determine the travel limits of the power switch. This required accessing inside the sealed enclosure. For proper operation the motor drive unit (i.e., the motor itself and related gearing) needs to be able to move the power switch contacts to a definite closed position or a definite open position which requires adjustment of motor travel. 
     For final adjustment during installation and occasional readjustment over the life of the equipment, in the case of an underground switch, a worker would have to enter the vault where the switch and motor operator are located. Typically, limit switches to control the limits of travel of the motor operating shaft would need setting upon initial installation of the operator and switch and possible adjusting from time to time of the installation. The limit switches would have to be accessed by opening the enclosure containing the motor resulting in the risks mentioned above in the case of underground units, including at least at the risk to the integrity of the enclosure seal. While other locations, such as pad mounted at ground level, do not involve quite the same concerns for worker safety and motor operator integrity, the need for accessing the limit switches is at least an undesirable maintenance requirement. 
     Motor operators have been used or proposed having a switch actuator with a position-sensing feature between an output shaft of the motor of the operator and a lever that produces power switch opening and closing, for example, as in U.S. Pat. No. 5,552,647 issued to Ronald B. Tinkham on Sep. 3, 1996. Position sensing is shown by a potentiometer responsive to movement of a linear actuator to generate a signal indicating a position of a reference element on the actuator. The signal generated is communicated to control circuitry. The circuitry compares the signal to a standard to determine if the actuator travel is within limits determined by adjustable open-limit and closed-limit potentiometers. The arrangement is intended to improve on the prior limit switch assemblies which fail to provide sufficient accuracy and repeatability and tend to be complicated and costly. Such an actuator control is not one that avoids need for adjustment in the motor operator enclosure. The enclosure has an access hole specifically for adjustment of the open-limit potentiometer and the close-limit potentiometer. This adjustment requires a worker to enter the underground vault. 
     Other motor operators have been disclosed that also have a sensed position signal. U.S. Pat. No. 6,025,657, Feb. 15, 2000, is directed to a motor operator for either power on or manual operation without need for any decoupling or mode selection with a control system that receives signals indicating both the position of the drive output and the current drawn by the drive source. U.S. Pat. No. 6,215,263, Apr. 10, 2001, discloses a motor operator for overhead air break switches with a microcontroller subject to a variety of signals, including a position signal developed by a sensor that is a type of encoder. Some of the parameters relied on are temperature sensitive and require compensation. Some types of shaft position sensors, for example, including some encoders, depend on continuous power for a position signal to be reliably generated. Otherwise, after a power outage, the actual switch position would need to be observed and the motor travel limits reset. Such motor operators did not particularly address and respond to a need in the power switch art for avoiding needed travel limit adjustments in the enclosure of the motor, particularly important in underground sealed units. 
     As mentioned such motor operators will often need some adjustment at the motor operator itself in the case of a power switch having an open position and a dosed position, as disclosed in the aforesaid U.S. Pat. No. 7,122,986 B1. This patent discloses a power switch motor operator system which includes a first enclosure housing a motor with a motor shaft, a gear train running on the motor shaft, and an output shaft from the gear train having an end extending from the first enclosure to a movable contact of a power switch. A second enclosure is provided for containing a power supply and control assembly and a position switch panel that electrically communicates with the power supply and control assembly and includes switches for setting and adjusting travel limits for the motor shaft for the open switch position and the closed switch position using the signal from a potentiometer without requiring access to the first enclosure. 
     There has been a longstanding safety issue in the electric utility industry related to enclosed high voltage switch vaults and the need to operate the switch (without a person entering the vault) to a position which grounds the power circuit. The safest configuration for the vault mount switches is a GROUND position in addition to the OPEN and CLOSE positions. The GROUND position allows for the associated high voltage line to be grounded instead of merely open circuited. A grounded line assures the utility that any switching errors elsewhere on the system will not allow any voltage on the line that can injure or kill utility personnel. Additionally switch explosions in the vault caused by malfunctioning switch gear represent a fatal risk to any personnel in the vault. Currently in order to operate a power switch to the GROUND position requires electric utility personnel to enter the vault to perform the switching or the utility requires a complicated rope and pulley system to manually operate the switchgear to GROUND. Therefore it is an object of this invention to develop a power switch motor operator system that permits operation to and from the GROUND POSITION by remote electrical (non-manual) operation without the need for electric utility personnel to enter the vault or the need for a complicated rope and pulley system to manually operate the switchgear to GROUND. 
     SUMMARY OF THE INVENTION 
     The present invention provides a motor operator system for a power switch which allows electrical motor operation to the GROUND POSITION via TRAVEL SET electronics to ensure personnel safety but also allows operation to the ground position manually if so desired. The motor operator system of the present invention includes a position switch panel that allows a three position set travel with travel adjust function. The three positions are CLOSE, OPEN, and GROUND, or as an alternative arrangement, CLOSE OPEN CLOSE. 
     The power switch motor operating system includes switches and indication for selectively directing and adjusting the motor and power switch to a CLOSE position, OPEN position, and GROUND position or, in an alternative, a CLOSE position, OPEN position, and CLOSE position. This novel approach is accomplished by the position switch panel initiating clockwise or counterclockwise rotation of the motor based on the present position of the motor and recording the three positions utilizing a programmed microcontroller that has or is connected in circuit with a memory element. The CLOSE, OPEN, CLOSE switch configuration adapts the control electronics to allow for control of an auto-transfer style power switch that can feed power from one source to two loads or, alternatively, from two sources to one load. 
     In order to set positions, the present invention provides a combination of buttons of the position switch panel to be used to indicate to the electronics that a particular voltage that is developed by the potentiometer housed in the first enclosure is the desired set point. As with the power switch motor operating system disclosed in the above-mentioned U.S. Pat. No. 7,122,986 B1, a first enclosure, for example, houses a motor with a gear train for driving a shaft coupled to a power switch, which can be adjacent to it in an underground vault, with also a position sensor such as a potentiometer; preferably, a rotary potentiometer in the first enclosure that runs off the motor shaft. The rotary potentiometer (or “pot”, for simplicity) develops a voltage signal indicating the rotary position of the motor shaft. The motor operator system has a second enclosure for power supply and control elements that, in the case of an underground switch, is much more accessible, such as being at surface level, rather than the enclosure in the underground vault. The second enclosure can provide various automation functions, such as for remote switch operation via a radio and RTU, and also provide for local operation at the second enclosure. 
     The position signal from the pot is communicated to the microcontroller in the second enclosure that has or is connected in circuit with a nonvolatile memory for storing motor travel limits. A worker at the second enclosure can perform various functions at the second enclosure while merely observing or hearing the switch open or close or go to GROUND, such as through a manhole without the need to enter the vault where the switch and the first enclosure have been installed. Furthermore, even after total power outage, including lack of any back-up battery power, when the pot is re-energized an accurate signal of the present switch position is given to the controller. 
     With the use of the switch panel of the present invention in the second enclosure that receives the position signals, the worker can open or close or set to GROUND the switch, set an existing position as a set point, and adjust the set points of travel such that the motor moves between OPEN, CLOSE, GROUND, or, in the alternative, CLOSE, OPEN, CLOSE switch positions. Software running on the microcontroller controls all of these user functions. Simply using the position signal while selectively running the motor fully on for travel in the OPEN, CLOSE, GROUND, or CLOSE, OPEN, CLOSE direction allows a worker to set or adjust travel limits accurately. The only needed signal from the motor to the microcontroller is the shaft position signal. 
     These and other aspects of the present invention will be additionally illustrated and described in the accompanying drawings and the following text. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic block diagram of a motor operator system, with an underground power switch, showing an OPEN-CLOSE CONFIGURATION of the power switch according to the above-referenced U.S. Pat. No. 7,122,986 B1; 
         FIG. 2  is a schematic block diagram showing alternate power switch configurations of GROUND-OPEN-CLOSE and CLOSE-OPEN-CLOSE of the present invention with reference to  FIG. 1 ; 
         FIG. 3  is a schematic block diagram of another form of the innovative motor operator system of the present invention with a pad-mounted power switch; 
         FIG. 4  is a side elevation view, partly in section and partly broken away, of one form of a motor-gearbox applicable to the present invention; 
         FIG. 5  is an end elevation view, partly in section, of the motor-gearbox of  FIG. 4 ; 
         FIG. 6  is an enlarged view, partly in section, of part of the apparatus of  FIG. 4 ; 
         FIGS. 7 and 8  are front elevation views of different forms of control units for use with regard to the invention; 
         FIG. 9  is an enlarged front elevational view of part of the apparatus of  FIGS. 7 and 8  for setting travel limits; 
         FIG. 10  is a schematic diagram of the arrangement of the microcontroller of the invention and its associated switches and other devices; and, 
         FIG. 11  is a basic flow chart of the algorithm for the microcontroller with regard to the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring to  FIG. 1 , a power switch  10  and a motor operator system  20  are shown for an underground installation. The power switch configuration shown in  FIG. 1  is of the type described in the above-mentioned U.S. Pat. No. 7,122,986 B1 (hereinafter referred to “old switch configuration”). The switch  10 , in first enclosure  22 , is below ground level  12 , typically in an underground concrete vault (not shown) with a manhole for access. The first enclosure  22  may sometimes be referred to herein as the motor-gearbox. A second enclosure  24 , is located at or above ground level  12 . The second enclosure  24  may sometimes be referred to herein as the power and control box. 
     The old switch configuration power switch  10  included an enclosure  14  containing switch contacts  15  and  16  at least one of which,  15 , is movable relative to the other,  16 , a shown in  FIG. 1 . Switch  10  is, for example, a vacuum or gas insulated switch of prior art construction. Segments  17   a  and  17   b  of one phase of a power line are connected to the respective contacts  15  and  16 . ( FIG. 1  is to be taken as schematic for other arrangements including usually a power switch  10  with a set of contacts for each phase of a three-phase distribution system, all operable by a single motor operator). A movable contact  15  is mechanically coupled at a coupler or decoupler  19  via an undetailed operating mechanism  18 , to a shaft  38  from enclosure  22 . In  FIG. 2  alternate configurations for the power switch  10  relating to the present invention are shown. The difference from the old configuration switch is an additional switch point has been added; the first switch point connecting to segment  17   b  of a power line; the second switch point at  16  being OPEN; and, the third switch point connecting to segment  17   c  which may be to GROUND or to another power line. The mechanism  18  and contacts  15  and  16  can be arranged in any way, including those presently practiced, for operation by the output force of the motor operator system  20  including, for example, torsional and reciprocating versions. The mechanism  18  typically includes an energy storing element (e.g., a spring) that is loaded to a trigger point by the motor  30  actual switch contact movement occurs. A switch operation on release of the spring makes enough sound to be easily heard above ground. 
     Referring to  FIG. 4 , in enclosure  22 , there is shown a motor  30  with an output shaft  32 . A gear unit or gear train  34  and a rotary potentiometer  36  (sometimes referred to herein simply as the pot) are coupled with, and run off of, the shaft  32 . Through shaft  32  and gear unit  34 , the motor  30  drives the motor-gearbox output shaft  38  that goes to switch mechanism  18 . Of course other mechanisms besides a gear unit or gear train  34  are feasible for driving the gearbox output shaft  38 . 
     To help keep the terminology used in this description clear, the following is intended unless the context shows a different intent: The expression “motor-gearbox” refers to the whole of enclosure or box  22 . The “motor” in the enclosure  22 , likely to be a procured item for use by the maker of the system  20 , may (or may not) happen to have a gear or gears within the same enclosure  30  with an actual electric motor. In the case of an example motor  30  in the more specific embodiment of  FIG. 4 , such gears are present. The “motor  30 ” means the motor unit  30  including the motor with whatever gears are also present in the unit. The “motor shaft”  32  is the output shaft from the motor unit  30 , whether it is directly from a motor or is located to rotate as a result of gears in the unit  30 . The expression “gear train” or “gear unit”  34 , or the like, will refer to any one or more gears within the motor-gearbox  22  that are between the output shaft  32  at the motor  30  and the output shaft  38  of the box  22 . The expression “motor drive” may be used to encompass a combination of a motor, with gears (if any) either in a motor unit  30  or gear train  34  and an output mechanism such as the rotary shaft  38 . 
     In  FIG. 1  a more specific example of the motor-gearbox elements will be described later. For the present, it is seen that the system  20  has the elements of enclosure  22  next to or near the switch  10  location, underground in this example. The motor  30  and gear unit  34  are whatever meets the speed, torque and other mechanical requirements of the switch  10 . Because no adjustments in box  22  are contemplated after initial installation, it is unnecessary to have any access ports for a worker to set or reset anything. 
     The pot  36  is shown on motor shaft  32  in this example because that is a more direct and convenient location than is normally available on shaft  38 . It is also likely to produce more accurate readings. It is arranged with the shaft  32  to develop a voltage varying according to the motor shaft position, which allows the position of shaft  38  and the closed or open position of the switch  10  to be determined, as will be described. A signal line  37  schematically in  FIG. 1  represents an electrical connection from pot  36  to enclosure  24  carrying a switch position signal. 
     The second enclosure  24  of system  20  at the surface includes, in a first portion  40 , the power supply for the motor  30 , which depends on the motor requirements, e.g., AC line power, DC power developed from AC, DC battery power, or some combination. Single line  41  schematically represents an electrical power connection from the supply  40  to the motor  30 . Enclosure  24  normally does not need hermetic sealing as is desired for box  22  in an underground location. (If the enclosure  24  is also underground, then sealing is of course required.) 
     The second enclosure  24  also includes a control portion  42  that can have electronic circuitry such as that similar to the existing automated motor operators described in the above mentioned Bulletin, for control of power to the motor  30 , through power unit  40 . As in the units of the Bulletin and other such equipment, the control unit  42  may be arranged for both local and remote operation, the latter through a radio and a Remote Terminal Unit (RTU). The control unit  42  also is electrically connected with a position switch panel  44  in enclosure  24  by circuitry represented by a single line  45 . Panel  44  may sometimes be referred to as a “travel control panel”. (Contents of an enclosure such as  24  may be referred to herein collectively as a “control and power supply assembly”.) 
     One of the aspects of the arrangement of  FIG. 1  is that a position signal from the pot  36  at the underground location is communicated to the above ground enclosure  24 , here shown supplied by connection  37  to the position switch panel  44 . For convenience in implementation, this example has the position signal on line  37  go to switch panel  44  which has its own electronic signal processor or microcontroller  870  (e.g., if preferred to keep control block  42  the same as in prior designs). As an option, the circuitry for signal processing functions in parts  42  and  44  could be combined in a single package. 
     More description of examples of the workings of control  42  and position switch panel  44  will be found below.  FIG. 1  generally shows an arrangement of elements for a position signal from the pot  36  to be processed according to a worker&#39;s interaction at switch panel  44  to operate the motor  30 ; including the setting and adjusting of motor travel limits, without any need to access the underground enclosure  22 . As mentioned  FIG. 2  shows the alternate configurations of the power switch to which the present invention is applicable. The power switch configuration shown in  FIG. 1 , as mentioned, is applicable to the prior invention disclosed in the above-mentioned U.S. Pat. No. 7,122,986 B1 
     In the drawing figures, examples of elements of similar character will normally have reference numerals with the same last two digits.  FIG. 3  shows a pad mounted installation with a pad  105  on the ground  12  supporting a switch  110  and a motor operator system  120 . Switch  110  can be of a type like switch  10  but the above ground location often allows use of an enclosed air break switch, one not hermetically sealed. The internal elements of switch  110  are generally as described for switch  10  in  FIG. 2  with reference to the alternate switch configurations. 
     Motor operator system  120  could comprise two separate enclosures, like  22  and  24  in  FIG. 1 , but preferably has one enclosure  124  containing all the functional elements of the system  120 , i.e., such elements as are exemplified by those in both boxes  22  and  24  discussed above. For one embodiment, as shown, the enclosure  124  houses the elements of box  24 , and also, in a subenclosure  122  inside of box  124 , those of box  22 . 
     The apparatus depicted in  FIG. 3  is to make clear the system elements for an underground installation can be readily applied to the pad-mounted installation, particularly because power switches  10  and  110  likely to be used in the two cases often have similar speed and torque requirements for the motor operators  20  and  120 . It should still be appreciated that features of the invention, such as use of a rotary pot for generating a position signal that is used for setting or adjusting travel limits without accessing the enclosure  22  or  122 , are broadly applicable to a motor operator for a switch in any location. 
     A more specific example of a motor-gearbox, such as box  22  of  FIG. 1  or box  122  of  FIG. 3 , is shown in  FIG. 4  and  FIG. 5  which looks inside enclosure  22  as if a section is taken just past a sidewall on the side facing the viewer (i.e., element  22   d  of  FIG. 5 ).  FIG. 5  is a right end view taken just inside of the right cap (i.e., element  22   f  in  FIG. 4 ). The relation of the sectioned and unsectioned elements will be apparent from the following description. 
       FIGS. 4 and 5  show a motor  30  which may be one that is commercially procured as a unitary motor and gear set. The motor  30 , with whatever gearing accompanies it in the same unit from the motor manufacturer, may, but need not be one that by itself meets the mechanical requirements of a power switch it operates. For example, a motor  30  can be selected that can be coupled with a gear train  34  to achieve additional torsional output sufficient for power switches with which the motor-operator is to be used. The gear reduction of gearing  34  converts a higher speed, lower torque output of motor  30  on shaft  32  to a relatively lower speed, higher torque output on shaft  38 . In this particular example, the gearing  34  includes a spur gear  34   a  running off the motor shaft  32  and a mating spur gear  34   b  on the output shaft  38 . Each gear  34   a  and  34   b  has a tooth portion and a hub to the right of the tooth portion in  FIG. 4 . 
       FIG. 4  shows a rotary potentiometer  36  on the shaft  32  from motor unit  30  to develop the above-described motor position signal. The pot, in this embodiment, was selected to be a commercially available ten turn, I K. ohm potentiometer coupled to the shaft  32  by a slip clutch  50  to prevent damage that otherwise might occur if the pot reached its travel limits. The slip clutch  50  is further discussed in connection with  FIG. 6 . Also shown is a hexagonal coupler  60  and pointer  62 , seal  28 . A liquid tight cord grip  26  and a conduit  27  are provided for electrical conductors. 
       FIG. 5  also shows how the example motor unit  30  has its own housing of a substantially rectangular configuration. That is because it includes, in the example unit as procured, both a small DC permanent magnet motor and some gearing. The electric motor itself is not shown in  FIG. 5  but is within the right hand portion of the unit  30 . The shaft  32  ( FIG. 4 ) comes out of the unit  30  in the left portion and comes directly through the first gear  34   a  of the gear train  34  to the pot  36 . 
       FIG. 6  shows an enlarged view of an example pot  36  and slip clutch  50  that are assembled for use in a combination such as that of  FIGS. 4 and 5 . The rotary pot  36  requires a minimum force for accurate turning but has a certain stopper strength that may be exceeded by the torsion from the motor shaft  32 . In that case the pot  36  would likely be destroyed at its end limits of travel if it had a solid connection with the motor shaft  32 . The slip clutch  50  protects against such destruction. In the example of  FIG. 6 , a slip clutch  50  of simple parts and low expense is applied that serves the purpose well, although other forms of a slip clutch can also be used. A shaft  36   a  of pot  36  fits within a recess  32   a  of motor shaft  32  with O-rings  52  on the end of the pot shaft  36   a  and facing the wall of recess  32   a , with no direct contact, axially or laterally, between the pot shaft  36   a  and the motor shaft  32 . A spacer  53  helps keep O-rings  52  retained in alignment. For the particular case, the O-rings  52  are selected so the pot  36  turns steadily and safely for a predetermined number of turns, before slipping. 
     The pot  36  is mounted on a floating guide plate  54  by a nut  36   b  on a threaded part  36   c  surrounding the shaft  36   a . The pot shaft  36   a  passes through a hole (not shown) in plate  54  that allows free rotation. The guide plate  54  is joined with another plate  55 , sometimes called an anti-separation plate, which has apertures  55   a  and  55   b  for respective shafts  32  and  38 . The plate  55  is not secured to any wall of the enclosure. Its apertures  55   a  and  55   b  allow free running of the shafts  32  and  38  without requiring lubrication or bearings but the plate  55  contributes to maintaining accurate alignment of the parts which otherwise could become distorted due to torsional effects. The floating guide plate  54 , sometimes called a pot plate, is fastened to the other plate  55  by fasteners  56  and  57 ,  35  such as bolted standoff  57  from plate  55  with nuts  56 , securing the pot plate. The nuts  56  allow air space so guide plate  54  is not solidly joined with the other plate  55 . In this way, the shaft  32  is prevented from applying cantilevered forces that could cause undue wear or cause a change in the force to the pot resulting from the slip clutch  50 . 
     One advantage of an assembly as shown in  FIG. 5  and  FIG. 6  is that the slip clutch  50  can be easily varied in its force limits by varying the number and size of the O-rings  52 . That is, a design engineer may choose the motor  30  and pot  36  relatively independently and then devise a slip clutch  50  suitable for the choices made. In the illustrated example, four neoprene O-rings  52  are used in the slip clutch  50 . The slip clutch  50  accurately transfers up to ten motor shaft rotations to the rotary pot and only slips at the end of ten rotations. The characteristics can be varied by altering, for example, the number, size or material of the O-rings and the space they occupy between the pot shaft  36   a  and the shaft bore  32   a.    
       FIGS. 7 and 8  illustrate, respectively, representative examples for power and control box  24  of  FIG. 1  and the complete system box  124  of  FIG. 3  which can be used in conjunction with either power switch configuration depicted in  FIG. 2 . They show how there can be much in common in motor operator systems for both underground and pad mounted installations. Each has a power module  540 , in addition to a backup battery  580 , a control module  542 , and a position switch panel  544 . In these examples, the switch panel  544  has its own microcontroller  870 , as shown in  FIG. 10 , for processing position signals from the rotary pot in the motor-gearbox of the system. Both the units  24  and  124  are shown with a radio antenna  582  for a radio  583  and an RTU  584 , which can be provided for remote operation. Except for the position switch panel  544  in each enclosure  24  and  124 , and a motor gear box  122  as shown in  FIG. 8 , design for the mentioned elements can be substantially like prior technology, such as the automated motor operators described in the above mentioned Bulletin. Wiring for the elements in the units  24  and  124  in  FIGS. 7 and 8  is not fully shown. Each such unit will typically have additional elements not shown here, such as a thermostat controlled heater and fuses, as in the equipment in the Bulletin. Merely as examples, units  24  and  124  can each be of a size about 21 in. wide by 29 in. by 15 in. deep.  FIGS. 7 and 8  show units  24  and  124  without the usually present gasketed and lockable doors that provide weather resistance and security. 
     In  FIG. 7 , there is a conduit  527  through the bottom wall of the enclosure  24  for conductors  529  to an exterior motor-gearbox  22 , such as like that shown in  FIGS. 1 ,  4  and  5 , that could be at the underground location. In  FIG. 8 , the otherwise similar enclosure  124  has a motor-gearbox  122  on the back wall of the enclosure  124  for mechanical coupling to a pad-mounted power switch (like  110  in  FIG. 3 ).  FIG. 8  gives an idea of the convenience afforded by a compact motor-gearbox  122  that can be applied with some versatility for different applications. 
     The end view of motor gear box  122  in  FIG. 8  is the left end of the unit  22  in  FIG. 4 , showing a direct view of the hexagonal coupler  60  and pointer  62 . Also shown is a locking disk with a pair of stop bolts  63  that set the farthest limits of the movement of the output shaft, under either motor operation or manual operation. That can be important during a manual operation or if the motor operator malfunctions. 
       FIG. 9  shows an enlarged view of a position switch panel  544  suitable for use in  FIGS. 7 and 8 . Preliminarily, it is to be recognized the setting of travel limits with the present invention can achieve results like prior art arrangements, such as with limit switches, but in a much more convenient way and without concern about limit switch wear. In general, a worker performing hand operations at a switch panel  544  and seeing, hearing or otherwise being informed (such as by a co-worker) of a switch tripping to an open position or a dosed position, is highly effective, simple and convenient. The particular example only requires a sensor to give a position signal (without, for example, other sensors for motor current, speed, or other parameters, at least some of which are susceptible to variation due to temperature changes) and only requires a controller that needs to process that single sensed signal to effect a desired travel setting or adjustment to operate the power switch with complete travel. So the result in the particular example system is one that utilizes microprocessor technology in a simple, sure and dependable way with human judgment as a final determinant of achieving a desired result. Also, the particular technique is one that is equally effective whether or not the switch operating mechanism includes an energy storage spring, or the like. Even if the motor shaft  32  or output shaft  38  of  FIG. 4  is not producing any movement of a switch contact  15  of  FIG. 2  during part of its travel, while a spring is being wound, the worker just needs to determine (and the control to know in its memory) whether the result of the motor operation is successful in fully moving the power switch to its desired position. In the case of an enclosed switch, such as in an underground installation, it is helpful that the switch have a spring for a positive indication of when it trips to either the open or closed state. 
     In  FIG. 9 , the example position switch panel  544 , for use in either unit  24  of  FIG. 7  or unit  124  of  FIG. 8 , has a first switch  546  for switching between remote operation (shown here) and local operation. Panel  544  also has an OPEN-CLOSE toggle switch  547  which has an unlabeled center off position and also a GROUND-OPEN toggle switch  557  which also has an unlabeled center off position for the GROUND OPEN CLOSE CONFIGURATION of power switch  10  shown in  FIG. 2 . For the alternative CLOSE OPEN CLOSE CONFIGURATION of power switch  10  shown in  FIG. 2  the toggle switch  557  is CLOSE-OPEN and also has an unlabeled off position (this form of the toggle switch  557  is not shown in the drawings, but GROUND is simply replaced with a second CLOSE position). Indicator lights  547   a  and  547   b  are respectively shown by the labels of close and open positions for switch  547 . Typically, light  547   a  is red and light  547   b  is green. The switch  547  can be toggled to a desired position and then released. In a like manner the switch  557  can be toggled to GROUND where indicator light  557   a  is yellow, for example. When switch  557  is toggled to the open position the indicator light  547   b  is green. In addition, a SET TRAVEL portion of the panel  544  has a first push button switch  548   a  (e.g., with a red top), a second pushbutton switch  548   b  (e.g., with a green top), and a third pushbutton switch  549  (e.g., with a black top). By the dashed lines from each of switches  548   a  and  548   b  to the OPEN-CLOSE switch  547  and to switch  549  (referred to as the SET button), along with the displayed legends “ADJ CLOSE”, “ADJ OPEN”, “SET CLOSE”, and “SET OPEN”, a worker can readily see which switches are used together for travel limit settings and adjustments. Although not so labeled on  FIG. 11 , switches  548   a ,  548   b , and  549  may sometimes be referred to in the following description as the first CLOSE, OPEN, and SET pushbuttons, respectively. In addition, the SET TRAVEL portion of the panel  544  also has a fourth push button switch  558   a  (e.g., with a yellow top), a fifth pushbutton switch  558   b  (e.g., with a green top), and the third pushbutton switch  549  (e.g., with a black top) also works in conjunction with these switches. By the dashed lines from each of switches  558   a  and  558   b  to the GROUND-OPEN switch  557  and to switch  549  (referred to as the SET button), along with the displayed legends “ADJ GROUND”, “ADJ OPEN”, “SET GROUND”, and “SET OPEN”, a worker can readily see which switches are used together for travel limit settings and adjustments. Although not so labeled on  FIG. 9 , switches  558   a ,  585   b , and  549  may sometimes be referred to in the following description as the GROUND, OPEN, and SET pushbuttons, respectively. In the case GROUND is replaced with a SECOND CLOSE configuration for the non-grounded switch configuration shown in  FIG. 2  the “ADJ GROUND” switch  558   a  and “SET GROUND” designation would be changed to “ADJ CLOSE” and “SET CLOSE” respectively (not shown in the drawings). 
     The switches  546 ,  547 ,  548   a ,  548   b ,  549 ,  557 ,  558   a ,  558   b  and lights  547   a ,  547   b , and  557   a  are all interconnected behind the front of panel  544  with microcontroller  870  (shown schematically in  FIG. 10 ) that is further interconnected with the control module  542  of the units of  FIG. 7  or  8 . In addition MID-TRAVEL lights  550  and  551  are provided to indicate to the worker that the power switch  10  is in a MID-TRAVEL (when the light is on) position for respectively movement between GROUND AND OPEN and vice versa and between OPEN and CLOSE AND vice versa. These lights are also interconnected behind the front of panel  544  with the microcontroller  870  (shown schematically in  FIG. 10 ). The microcontroller  870  of panel  544  includes a circuit portion to convert an analog pot signal to a digital signal and to use the digital signal in a programmed microprocessor to process the pot signal in accordance with settings and other data of a memory element  891  (e.g., comparison of a present position with the last set position), all consistent with general microcontroller practice but here specifically programmed and arranged for operations and adjustments according to worker interaction with the switches on the panel  544 . The arrangement of such a microcontroller  870  of the present invention is shown in  FIG. 10  with a basic flowchart of the software algorithm of the microcontroller  870  shown  FIG. 11 . Microcontrollers with sufficient input and output connections for the panel  544  that include an analog to digital converter and an EEPROM type of memory are widely available and their programming and general methods of use are well known. 
     In order to set positions, a combination of buttons is used to indicate to the electronics that a particular voltage is developed by the potentiometer  36  of  FIG. 4  is the desired set point. For example, to set the OPEN position the worker would depress the SET TRAVEL button  549  and SET OPEN button  558   b  for approximately two seconds. The OPEN light  547   b  will blink indicating that the position has been set and this voltage set point is saved to non-volatile memory in the memory element  891 . This process is repeated for each set point. This novel approach is accomplished by the position switch panel  544  indicating clockwise or counterclockwise rotation of the motor  30  based on the present position and recording the four positions in memory element  891 . The set positions are only adjustable locally while the REMOTE/LOCAL switch  546  is in the LOCAL position. This prevents the points from being adjusted remotely while there is no personnel at the high voltage power switch location to confirm proper operation. The MIDTRAVEL lights  550 ,  551  indicate to the user locally at the display panel and remotely through supervisory control that the high voltage power switch is in between positions. This allows the worker to always know the position of the attached electric motor and switch. In order to retrofit present invention to the invention disclosed in the above-mentioned U.S. Pat. No. 7,122,986 B1, a change of all control electronics and motor is required in order to operate a different power switch that has a ground position or double-throw position. 
       FIG. 10  shows the arrangement schematically of a basic view of the microcontroller  870  of the present invention and its associated switches and devices including memory element  891 , position indicating lights i.e., light emitting diodes  557   a ,  551 ,  547   b ,  550 ,  547   a , also, switches  558   a ,  558   b ,  549 ,  548   b ,  548   a ,  546 ,  557 ,  547 , safety interlock logic  892 , power supply  893 , integrated circuits  894 , elementary circuit components  895 , oscillators  896 , and motor brake  897 . Additionally potentiometer  36  is shown and its connection to the microcontroller  870 . Not shown in detail is the additional safety interlock logic  892 , power supply  893 , oscillators  896 , integrated circuits  894 , motor brake  897 , and various elementary circuit components  895  required for a robust circuit design. As previously detailed the toggle switch for GROUND OPEN  557  and OPEN CLOSE  547  use both poles connected to the microcontroller  870 , as it is important to know when the switch is in either position. The REMOTE LOCAL  546  switch is only required to know if it is in either the REMOTE or LOCAL position, so only one connection is required to the microcontroller  870 . Each of the pushbutton switches for SET GROUND  558   a , SET OPEN  558   b , SET OPEN  548   b , SET CLOSE  548   a , and SET TRAVEL  549  are shown as single pole normally open pushbuttons each with individual connection to the microcontroller  870 . The status lights GROUND  557   a , OPEN  547   b , CLOSE  547   a , MID-TRAVEL GROUND  551 , and MID-TRAVEL CLOSE  550  are shown as individually connecting to the microcontroller  870 . 
       FIG. 11  is a basic flowchart of the software for the microcontroller  870  referred to in  FIG. 10  which includes in block  871  a Power-on detection state. In block  872  the variables/Timers/Analog Functions are initialized. In block  873  the data from the above-mentioned EEPROM is read. In block  874  a determination is made of whether or not the data indicates pre-defined setpoints. If Yes, in block  876  the setpoints are loaded into position data and position ranges for the power switch  10  are calculated. In block  877  the analog position of the motor  30  is monitored and correct status points are turned on. In block  878 , a determination is made as to whether a remote or local operation has been initiated, if No, a signal is again sent to block  877 . In block  879 , a determination is made as to whether a point Clear/reset has been performed, if yes block  875  determines if points have been manually set. If no, block  875  is activated again, if yes, block  876  is activated. Block  880 , determines if a point has been adjusted or reset, if yes, block  876  is activated, if no, block  877  is activated. Also, in block  878  if a remote or local operation has been initiated then block  881  determines if the operation is permissible. If no, block  877  is activated, if yes, block  882  is activated which Sends operation/monitors position/applies brake. 
     To perform functions at the panel  544 , in accordance with this example, a worker first needs to set the REMOTE/LOCAL switch  546  to LOCAL. Then various options are available. Operating just the switch  547  to OPEN or CLOSE will cause the motor  30  (as well as the motor-gearbox output shaft  38 ) to move from its current position to the corresponding position indicated on the toggle switch, according to the position settings in the memory of the microcontroller, for example. When a switch  10  and a motor operator system  20  or  120  are first installed and set up for operation, a suitable set up procedure can include: 
     Manually closing the switch  10 ; 
     Attaching the motor-gearbox  22  or  122  to the switch  10 ; applying battery power to the motor-gearbox, without any AC line power to the switch or its operator, resulting in a position signal to the controller indicating a closed position; 
     Setting the closed position as a travel limit at the panel  544 ; 
     Manually operating the motor-gearbox to move the switch to the open position; 
     Setting the open position as a travel limit at the panel  544 ; 
     Manually operating the motor-gearbox to move the switch to the ground position; 
     Setting the ground position as a travel limit at the panel  544 ; 
     Manually operating the motor-gearbox to move the switch back to the open position; and, 
     Setting the open position as a travel limit at the panel  544 . 
     Without any further manual operations at the switch location, the travel limits can be tested and adjusted as desired at the panel  544 . For example, the original set points upon completing an installation procedure as described above may be altered a little, to a more closed or more ground or more open position, if desired. That could prepare a spring loaded switch operating mechanism for more sure operation. 
     More specifically with respect to the particular panel  544 , in order to set a current location of the motor as the OPEN or CLOSE position, the worker holds down the SET pushbutton  549  while also pressing the corresponding OPEN push button on  548   b  or CLOSE push button  548   a  (briefly, e.g., 2-3 secs.). In either case, the corresponding light  547   a  or  547   b  will blink showing that the point has been set, i.e., recorded in the memory of the microcontroller of the panel  544  and the pushbuttons are released. Subsequent operation, either remote or local, will occur according to that position  10  until there is a further adjustment. 
     If the worker wants to adjust a present OPEN or CLOSE set point, either the OPEN button  548   b  or the CLOSE button  548   a  is held down while moving the switch  547  to the OPEN or CLOSE direction as the case may be, without operating the SET pushbutton  549 . If the worker wants to adjust a present GROUND or OPEN set point either the OPEN button  558   b  or the GROUND button  558   a  is held down while moving the switch  557  to the OPEN or GROUND directions as the case may be, without operating the SET pushbutton  549 . 
     The panel  544 , in this example, is programmed to effect a specific increment of motor motion (i.e., motor-gearbox output shaft) on each such operation. For example, the motor output shaft  38  of unit  22  will move 3 degrees toward a more open or more closed position. If the worker is then satisfied that the position reached is what is desired (e.g., by hearing or otherwise observing the switch  10  has opened or closed), and does not perform another operation, then the position reached will become the set position. Otherwise the worker  25  continues with one or more other ADJ OPEN or ADJ CLOSE operations or ADJ GROUND or ADJ OPEN operations. If the worker finds the predetermined increment is too much, a reverse operation is performed to back up. The MID-TRAVEL light  550  lights when the power switch  10  is between the OPEN-CLOSE setpoints and the MID-TRAVEL light  551  lights when power switch  10  is between the GROUND-OPEN setpoints. If the system hits a mechanical stop during adjustment in any direction and is unable to complete the increment of travel, the worker waits a few seconds while the microcontroller times out and the limit reverts to the last setting. In all these instances, the software running on the microcontroller produces the desired functions, in response to the worker&#39;s operation of the position switches, while taking advantage of the precise position signal produced by the potentiometer (e.g., pot  36 ) and recorded in the microcontroller. 
     By way of further example, the microcontroller of described panel  544  could be replaced by circuitry including discrete logic elements, counters, comparators, etc. The position switch panel  544  switches can all be varied in type and location, and their legends, as could the lights. For example, a worker could interact with the circuitry that receives the signal from the position sensor by some alphanumeric keyboard or by touching, directly or by a cursor on a computer video monitor, elements of a display. Furthermore, any or all such elements of a panel  544  or its alternatives can be more intimately combined, than shown in the illustrated embodiments, with elements that perform the functions of the power module  540  or  40  and the control module  542  or  42 . 
     Additional elements of a motor operator system with one or more features of the invention would normally include one or more brackets for physical support of the motor-gearbox with the switch so the unit stays in position despite the forces on it during switch operations. Also, a mechanical coupler-decoupler, indicated generally as element  19  in  FIG. 1 , is further provided for decoupling the motor-gear box output shaft from the power switch, such as for occasions for routine tests of the motor without disturbing the switch position. Such features can be provided in suitable forms in accordance with past practice and are not detailed further in this description. 
     In its broader aspects, use of a potentiometer for position signals may take other forms from that of a rotary pot and slip clutch on a motor shaft as shown here. The arrangement shown has simplicity and effectiveness. Other potentiometers are also suitable for achieving a motor position signal that is reliably renewed after a power outage. Shaft position encoders that are hall effect devices or optical sensors are not able to do so. That is also the case with other 2-phase encoders, sometimes referred to as relative position sensors, in contrast to absolute position sensors which in addition to a pot, include absolute encoders (mechanical or optical) and a “Selsyn” resolver, for example. 
     It is advantageous to have a position sensor that is of the type characterized by an ability to resume generating an accurate position signal upon restoration of power following a loss of power to the control circuit and motor drive. A loss of power to the device, in this context, means a total loss of power; both the AC line power and any backup (e.g., battery) power are out. The ability to resume generating an accurate position signal means the position signal from the position sensor indicates the actual position of the drive, regardless of any drive movement during the time the power is off. Absent that ability, a motor operator system faces a problem because, even with a nonvolatile memory in the controller storing predetermined travel limit, the motor operator may have moved during the power outage, such as by an actual, or a merely attempted, manual operation. Such movement makes the output from a relative position encoder, after power is restored, not accurate and not useful for the controller, so a repeat of a procedure like that used when the motor operator is first installed with the switch may be necessary. In the case of position sensors that have the described ability, e.g., potentiometers and absolute encoders, a signal is generated immediately upon power being restored that is accurate, even if such movement has occurred. The embodiments disclosed are merely some examples of the various ways in which the invention can be practiced. The present invention allows the travel set features to be applied to complex power switches that have a ground position contact or a double-throw contact.