Abstract:
A transfer switch is provided for transferring the supply of electrical power to a load between a utility source and a generator that generates electrical power when started. The load is interconnected to the utility source through a first circuit breaker and to the generator through a second circuit breaker. Each circuit breaker is movable between an on position and an off position. The transfer switch includes a first arm movable between a first position and a second position wherein the first arm is engageable with the first circuit breaker for moving the first circuit breaker from the off position to the on position. A second arm is movable between a first position and a second position engageable with the second circuit breaker for moving the second circuit breaker from the off position to the on position. A control structure selectively urges the first and second arms to the second positions.

Description:
FIELD OF THE INVENTION 
   This invention relates generally to stand-by electrical generators, and in particular, to a transfer switch connectable to a circuit breaker panel for transferring the supply of electrical power to essential devices in a residential home between a utility source and a stand-by electrical generator. 
   BACKGROUND AND SUMMARY OF THE INVENTION 
   As is known, virtually all residential homes utilize electrical power received from a utility company. Typically, utility companies have an excellent record of providing uninterrupted or infrequently interrupted power to their customers at proper voltage levels and line frequency. However, due to the increasing demand for power, power outages have become more frequent. While power outages usually last only for a short duration, an extended power outage may cause more than simple aggravation for customers of the utility. A power outage may render a homeowner&#39;s appliances, such as the sump pump, refrigerator or freezer inoperable. If a power outage occurs during a rainstorm, the failure of the sump pump to operate may result in the flooding of the homeowner&#39;s basement. 
   In order to combat these occasional disruptions in service, many residential customers of the utility companies have equipped their homes with stand-by electrical generator systems. These stand-by electrical generator systems include internal combustion engines that drive electrical generators. If the commercial power from the utility company fails, the internal combustion engine of the stand-by electrical generator system is automatically started causing the electrical generator to generate electrical power. When the electrical power generated by the electrical generator reaches the proper voltage and frequency desired by the customer, a transfer mechanism transfers the load imposed by the homeowner from the commercial power lines to the electrical generator. 
   Typically, the transfer mechanism incorporates switches that isolate the electrical power supplied by the utility company from the generator. In a residential application, the switches are flipped either manually or automatically between the utility source and the generator in order to provide power to the electrical system of the home. These prior art transfer mechanisms often require a homeowner to transfer the entire electrical system of the home onto the generator. Such an arrangement does not provide the homeowner with the ability to decide which circuits of the home&#39;s electrical system are to be powered. It can be appreciated that the demands of the entire electrical system of the home can be quite significant. As a result, the generator must be of sufficient size to power the entire electrical system of the home. This, in turn, increases the overall cost of the stand-by electrical generator system for the homeowner. 
   Therefore, it is a primary object and feature of the present invention to provide a transfer switch that transfers the electrical power supplied to essential devices within a residential home between a utility source and stand-by electrical generator. 
   It is a further object and feature of the present invention to provide a transfer switch that automatically transfers the electrical power supplied to essential devices within a residential home from a utility source to a stand-by electrical generator in response to a power outage. 
   It is a still further object and feature of the present invention to provide a transfer switch for transferring the electrical power supplied to essential devices within a residential home between a utility source and a stand-by electrical generator that may be simply and easily installed. 
   In accordance with the present invention, a transfer switch is provided. The transfer switch transfers the supply of electrical power to a load between a utility source and a generator that generates electrical power when started. The load is interconnected to the utility source through a first circuit breaker and to the generator through a second circuit breaker. Each circuit breaker is movable between an on position and an off position. The transfer switch includes a first arm movable between a first position and a second position wherein the first arm is engageable with the first circuit breaker for moving the first circuit breaker from the off position to the on position. A second arm is movable between a first position and a second position engageable with the second circuit breaker for moving the second circuit breaker from the off position to the on position. A control structure selectively urges the first and second arms to the second positions. 
   A bar extends between the first and second circuit breakers. The bar moves the second circuit breaker to the off position when the first circuit breaker moves to the on position and moves the first circuit breaker to the off position when the second circuit breaker moves to the on position. 
   The control structure includes a rotatable arm selectively engageable with one of the first and second arms to move the one of the first and second arms to the second position. The rotatable arm is also axially movable between a retracted position and an extended position. The control structure includes a biasing structure for urging the rotating arm towards the extended position. The rotating arm includes a terminal end and a bearing rotatably mounted to the terminal end of the rotating arm. The bearing is engageable with the first and second arms. The control structure also includes a motor operatively connected to the rotatable arm for rotating the arm and a controller operatively connected to the generator. The controller actuates the motor in response to a command from the generator. The controller also includes first and second switches movable between off positions and on positions. The positions of the switches control actuation of the motor. 
   The control structure further includes a cam disk disposed between the rotating arm and the first and second switches. The cam disk has a first camming surface engageable with the first switch for actuating the first switch and a second camming surface engageable with the second switch for actuating the second switch. 
   In accordance with a further aspect of the present invention, a transfer switch is provided for transferring the supply of electrical power to a load between a utility source and a generator that generates electrical power when started. The load is interconnected to the utility source through a first circuit breaker and to the generator through a second circuit breaker. Each circuit breaker is movable between an on position and an off position. The transfer switch includes a first arm movable between a first position and a second position wherein the first arm is engageable with the first circuit breaker for moving the first circuit breaker from the off position to the on position. A second arm is movable between a first position and a second position engageable with the second circuit breaker for moving the second circuit breaker from the off position to the on position. A bar extends between the first and second circuit breakers. The bar moves the second circuit breaker to the off position when the first circuit breaker moves to the on position and moves the first circuit breaker to the off position when the second circuit breaker moves to the on position. 
   A rotatable arm is selectively engageable with one of the first and second arms to move the one of the first and second arms to the second position. In addition, the rotatable arm is axially movable between a retracted position and an extended position. A biasing structure urges the rotatable arm towards the extended position. The terminal end of the rotatable arm includes a bearing rotatably mounted thereto. The bearing is engageable with the first and second arms. 
   A motor is operatively connected to the rotatable arm for rotating arm and a controller is operatively connected to the generator. The controller actuates the motor in response to a command from the generator. The controller includes first and second switches movable between off positions and on positions. The positions of the switches control actuate the motor. A cam disk is disposed between the rotatable arm and the first and second switches. The cam disk includes a first camming surface engageable with the first switch for actuating the first switch and a second camming surface engageable with the second switch for actuating the second switch. 
   In accordance with a still further aspect of the present invention, a transfer switch is provided for transferring the supply of electrical power to a load between a utility source and a generator that generates electrical power when started. The load is interconnected to the utility source through a first circuit breaker and to the generator through a second circuit breaker. Each circuit breaker is movable between an on position and an off position. The transfer switch includes a first arm movable between a first position and a second position wherein the first arm is engageable with the first circuit breaker for moving the first circuit breaker from the off position to the on position. A second arm is movable between a first position and a second position engageable with the second circuit breaker for moving the second circuit breaker from the off position to the on position. A rotatable arm selectively engages one of the first and second arms to move the one of the first and second arms to the second position. A motor is operatively connected to rotatable arm for rotating the arm. A motor control is operatively connected to the motor for actuating the motor and an actuation element is operatively connected to the rotatable arm. The actuation element communicates with the motor control for controlling actuation of the motor. 
   A bar extends between the first and second circuit breakers. The bar moves the second circuit breaker to the off position when the first circuit breaker moves to the on position and moves the first circuit breaker to the off position when the second circuit breaker moves to the on position. The rotating arm is axially movable between a retracted position and an extended position. A biasing structure urges the rotating arm towards the extended position. The rotating arm also includes a terminal end and a bearing rotatably mounted to the terminal end of the rotating arm. The bearing is engageable with the first and second arms. First and second switches are operatively connected to the motor control and are movable between off positions and on positions. The positions of the switches control actuation of the motor. The actuation element includes at least one camming surface engageable with at least one switch for moving the at least one switch between the off position and the on position. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The drawings furnished herewith illustrate a preferred construction of the present invention in which the above advantages and features are clearly disclosed as well as others which will be readily understood from the following description of the illustrated embodiment. 
     In the drawings: 
       FIG. 1  is an isometric plan view of a circuit breaker panel incorporating a transfer switch in accordance with the present invention; 
       FIG. 2  is a partially exploded view of the circuit breaker panel and the transfer switch in accordance with the present invention; 
       FIG. 3  is an exploded view of the transfer switch of the present invention; 
       FIG. 4  is an exploded view of an actuator of the transfer switch of the present invention; 
       FIG. 5  is an isometric view of a cam for the actuator of the transfer switch of the present invention; 
       FIG. 6  is a bottom plan view of the cam of  FIG. 5 ; 
       FIG. 7  is a top plan view of the circuit breaker panel of  FIG. 1  showing the transfer switch in a first position; 
       FIG. 8  is a top plan view, partially in phantom, showing the transfer switch in the first position; 
       FIG. 9  is a top plan view of the circuit breaker panel of  FIG. 1  showing the transfer switch in a second position; 
       FIG. 10  is a top plan view, partially in phantom, showing the transfer switch in the second position; and 
       FIG. 11  is a schematic diagram of a circuit for the transfer switch of the present invention; and 
       FIG. 12  is a timing diagram for the circuit of  FIG. 11 . 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   Referring to  FIGS. 1-3 , a transfer switch in accordance with the present invention is generally designated by the reference numeral  10 . It is contemplated that transfer switch  10 . It is intended for transfer switch to be mounted on circuit breaker panel  12 . As is conventional, three utility service lines come into the upper portion of panel  12 . The three utility service lines include two “hot” lines and a neutral service line. The two hot lines are attached two-gang main circuit breaker that, in turn, are connected to first and second hot non-essential buss bars. The neutral service line is connected to a neutral buss bar. Circuit breaker panel  12  may also include a ground buss bar, interconnected to the neutral buss bar. A plurality of circuit breakers interconnect each hot non-essential buss bar to corresponding non-essential branch circuits of a building&#39;s electrical wiring. 
   In the present invention, it is contemplated to interconnect first and second hot non-essential buss bars to corresponding first and second essential hot buss bars  16  and  18 , respectively, disposed in lower portion  20  of panel  12  through two-pole circuit breaker  14 . Various individual branch circuits of the building&#39;s electrical wiring connected preferably to corresponding essential electrically powered devices are coupled to first and second essential hot buss bars  16  and  18 , respectively, through corresponding circuit breakers, e.g. circuit breakers  22  and  24 . In addition, the output of a conventional standby electrical generator (not shown) is interconnected to first and second essential hot buss bars  16  and  18 , respectively, disposed in lower portion  20  of panel  12  through two-pole circuit breaker  26 . The standby electrical generator monitors the power supplied by the utility source. In response to a power outage from the utility source, the standby electrical generator starts the engine of the generator. The starting of the engine causes the generator to generate electrical power at the output thereof, for reasons hereinafter described. 
   With circuit breaker  14  in the on position, electricity may flow from the utility, through the first and second non-essential hot buss bars and circuit breaker  14  to the first and second essential hot buss bars  16  and  18 , respectively. As a result, various essential branch circuits of the buildings electrical wiring may be supplied with electrical power from the utility source. With circuit breaker  14  in the off position, the first and second essential hot buss bars  16  and  18 , respectively, are isolated from the first and second non-essential hot buss bars, and hence, from the utility source. With circuit breaker  26  in the on position, electricity may flow from the standby electrical generator through circuit breaker  26  to the first and second essential hot buss bars  16  and  18 , respectively. As a result, various essential branch circuits of the buildings electrical wiring may be supplied with electrical power from the generator. With circuit breaker  26  in the off position, the first and second essential hot buss bars  16  and  18 , respectively, are isolated from the standby electrical generator. 
   As best seen in  FIGS. 2-3 , transfer switch  10  includes base  30  having first and second sides  32  and  34 , respectively, and first and second ends  36  and  38 , respectively. Sidewalls  40  and  42 , respectively, depend from corresponding first and second sides  32  and  34 , respectively, of base  30 , for reasons after described. First and second leg structures  44  and  46 , respectively, depend from corresponding first and second ends  36  and  38 , respectively, of base  30 . Leg structure  44  includes first and second generally flat walls  48  and  50 , respectively,  FIGS. 7 and 9 , interconnected by cross-support  52 . Feet  54  and  56  are provided on the terminal ends of corresponding walls  48  and  50  of leg structure  44 . Each foot  54  and  56  is generally perpendicular to walls  48  and  50 , respectively, and includes a corresponding aperture  58  and  60 , respectively, therethrough. Gussets  62  and  64  extend between the upper surfaces of feet  54  and  56 , respectively, and corresponding first and second walls  48  and  50 , respectively, of leg structure  44 . Leg structure  46  includes first and second generally flat walls  66  and  68 , respectively, interconnected by cross-support  70 . Feet  72  and  74  are provided on the terminal ends of corresponding walls  66  and  68  of leg structure  46 . Each foot  72  and  74  is generally perpendicular to walls  66  and  68 , respectively, and includes a corresponding aperture  76  and  78 , respectively, therethrough. Gussets  77  and  79  extend between the upper surfaces of feet  2  and  74 , respectively, and corresponding first and second walls  66  and  68 , respectively, of leg structure  46 . 
   Base  30  further includes recessed surface  80  in upper surface  82  thereof. Opening  84  extends through recessed surface  80  is dimensioned to rotatably support cam assembly  86  therein. First and second generally S-shaped operating arms  88  and  90 , respectively, are pivotally mounted to base  30 . As best seen in  FIGS. 7-10 , operating arm  88  includes central portion  92  having first and second opposite ends  94  and  96 , respectively. First leg  98  extends from first end  94  of central portion  92  of operating arm  88  and is defined by first and second sides  100  and  102 , respectively, which converge towards and interconnected by terminal end  104 . Second leg  106  extends from second end  96  of central portion  92  of operating arm  88  and is defined by first and second sides  108  and  110 , respectively, interconnected by a generally actuate terminal end  112 . Similarly, operating arm  90  includes central portion  114  having first and second opposite ends  116  and  118 , respectively. First leg  120  extends from first end  116  of central portion  114  of operating arm  90  and is defined by first and second sides  122  and  124 , respectively, which converge towards and interconnected by terminal end  126 . Second leg  128  extends from second end  118  of central portion  114  of operating arm  90  and is defined by first and second sides  130  and  132 , respectively, interconnected by a generally actuate terminal end  134 . First and second operating arms  88  and  90 , respectively, are pivotally connected to base  30  by corresponding pivot pins  136  and  138 . As best seen in  FIG. 3 , pivot pins  136  and  138  extend through corresponding apertures  140  and  142  in central portions  92  and  114  of first and second operation arms  88  and  90 , respectively, and into apertures  144  and  146  in base  30 . 
   Referring to  FIGS. 4-6 , cam assembly  86  includes cam disk  148  having upper surface  150  and lower surface  152  interconnected by outer periphery  154 . Arm  156  is supported on upper surface  150  of cam disk  148  is defined by upper and lower surfaces  158  and  160 , respectively, interconnected by first and second sides  162  and  164 , respectively. First and second sides  162  and  164 , respectively, are interconnected by first and second ends  166  and  168 , respectively. First end  166  of arm  156  is generally actuate and includes recess  170  formed therein. Recess  170  is dimensioned for receiving generally circular bearing  172  therein. Bearing  172  is rotatably supported on dowel pin  174  that extends through aperture  176  in arm  156  adjacent first end  166  and through central aperture  178  in bearing  172 . Second end  168  of arm  156  is generally actuate and includes recess  180  formed therein. Recess  180  is defined by sidewalls  182  and  184  interconnected by end wall  186 . Spring receipt passageway  188  is formed in end wall  186  and has a first end communicating with recess  180  and a second end communicating with oblong aperture  190  extending between upper and lower surfaces  158  and  160 , respectively, of arm  156 . 
   Arm  156  is interconnected to upper surface  150  of cam disk  148  by screw  192 . Screw  192  extends through oblong aperture  190  in arm  156  and into opening  194  in upper surface  150  of cam disk  148 . As a sample configuration, it can be appreciated that arm  156  is slideable along screw  192  between an extended position and a retracted position defined by the opposite ends of oblong aperture  190 . Spring  196  is disposed within spring receipt passageway  188  in arm  156  and includes first end  196   a  in engagement with screw  192  and second, opposite end  196   b  in engagement with wall  198  projecting vertically from upper surface  150  of cam disk  148 . Spring  196  urges arm  156  towards its extended position. 
   Cam disk  148  further includes a generally semi-circular aperture  200  extending between upper and lower surfaces  150  and  152 , respectively, thereof. Aperture  200  is adapted to receive drive shaft  202  of motor  204 . Lower surface  152  in cam disk  148  includes outer camming elements  206  and  208  projecting therefrom. Outer camming elements  206  and  208  are a predetermined radial distance from the center of cam disk  148  and are circumferentially spaced from each other. Outer camming element  206  includes first and second camming surfaces  210  and  212  projecting from lower surface  152  of cam disk  148  and converging toward each other. Camming surfaces  210  and  212  converge at and are interconnected by apex  214 . Similarly, camming element  208  includes first and second camming surfaces  216  and  218  extending from lower surface  152  of cam disk  148  and converging toward each other. Camming surfaces  216  and  218  converge at and are interconnected by apex  220 . 
   Outer surface  152  of cam disk  148  further includes an inner camming element  222 . Inner camming element  222  includes first and second sliding surfaces  224  and  226 , respectively, which extend from lower surface  152 . Camming surfaces  224  and  226  are circumferentially spaced from each other at a predetermined radial distance from the center of cam disk  148 . The radial distance of camming surfaces  224  and  226  from the center of cam disk  148  is less than the radial distance of camming elements  206  and  208  from the center of cam disk  148 . The terminal ends of camming surfaces  224  and  226  are interconnected by land  228 . Land  228  is partially defined by a generally C-shaped sidewall  230  extending from outer surface  152  of cam disk  148  at a predetermined radial distance. Outer periphery  154  of cam disk  148  and sidewall  230  partially define path  232  therebetween for switch  234 ,  FIG. 3 , as hereinafter described. Land  228  is further defined by sidewall  236  projecting from outer surface  152  of cam disk  148  at a predetermined radial distance. Sidewall  234  and inwardly directed surface  238  of camming element  206  partially define path  240  therebetween for switch  242 ,  FIG. 3 , for reasons hereinafter described. 
   Referring to  FIG. 2 , transfer switch  10  further includes bracket  244 . Bracket  244  is defined by an outer frame  246  having first and second sides  248  and  250 , respectively, and first and second ends  252  and  254 , respectively. Tabs  256  and  258  project the midpoints of corresponding ends  252  and  254 , respectively, toward the interior of frame  246 . In addition, tabs  260  and  262  project from the midpoints of sides  248  and  250 , respectively, toward the interior of frame  246 . Mounting tabs  264  and  266  project outwardly from side  248  of frame  246  and are positioned adjacent corresponding ends  252  and  254  of frame  246 . Apertures  264   a  and  266   a  extend through corresponding mounting tabs  264  and  266  to facilitate the mounting of bracket  244  to base  30 , which is hereinafter described. As best seen in  FIG. 2 , the terminal ends of tabs  256 ,  258 ,  260 , and  262  define an opening for receiving locking bar  268  therebetween. Locking bar  268  includes first and second switching elements  270  and  272  projecting therefrom for reasons hereinafter described. 
   In order to assemble transfer switch  10 , motor  204  is attached to the underside of base  130 . In addition, circuit board  280  having circuit  282  is interconnected to the underside of base  230  such that switches  234  and  242  project into opening  84  through recessed surface  80 . Thereafter, base  30  is positioned such that sidewall  42  abuts circuit breakers  14  and  26 . Feet  54  and  56  of leg structure  44  and feet  72  and  74  of leg structure  46  are interconnected to the upper portion of panel  12 . Bracket  244  is positioned over circuit breakers  14  and  26  such that tab  256  is disposed in between the first and second housing portions  282  and  284 , respectively, of circuit breaker  14  and such that tab  258  is disposed between first and second housing portions  286  and  288 , respectively, of circuit breaker  26 . Tabs  260  and  262  are disposed between circuit breakers  14  and  16 . Thereafter, fasteners, such as screws, extend through apertures  264   a  and  266   a  in corresponding tabs  264  and  266  and interconnect bracket  244  to upper surface  82  of base  30 . 
   With circuit breakers  14  and  26  in the off position, bar  268  is positioned between first and second housing portions  282  and  284  of circuit breaker  14  and between first and second housing portions  286  and  288 , respectively, of circuit breaker  26 . Switching elements  270  and  272  are spaced such that with actuator bar  14   a  of circuit breaker  14  in its on position, switching element  270  engages actuator bar  14   a  of circuit breaker  14 . In addition, switching element  272  of locking bar  278  maintains actuator bar  26   a  of circuit breaker  26  in its off position. When actuator bar  26   a  of circuit breaker  26  is moved to the on position, switching element  270  of locking bar  268  engages actuator bar  14   a  of circuit breaker  14  and moves actuator bar  14   a  to its off position. In such manner, circuit breakers  14  and  26  cannot be simultaneously in their on positions. 
   As described, with transfer switch  10  mounted to panel  12 , terminal end  112  of second leg  106  of operating arm  88  engages actuator bar  14   a  of circuit breaker  14 . Likewise, terminal end  134  of second leg  128  of operating arm  90  engages actuator bar  26   a  of circuit breaker  26 . It can be appreciated that by selectively pivoting operating arms  88  and  90  on corresponding pivot pins  136  and  138 , operating arms  88  and  90  selectively move corresponding actuator bars  14   a  and  26   a  of circuit breakers  14  and  26  to their on positions. 
   In order to selectively pivot operating arms  88  and  90  in order to actuate circuit breakers  14  and  26 , as hereinafter described, it is contemplated to utilize arm  156 . More specifically, as best seen in  FIGS. 7-10 , the rotation of cam disk  148  causes bearing  172  of arm  156  to sequentially engage first side  100  of first leg  98  of operating arm  88  and first side  122  of first leg  120  of operating arm  90 . As hereinafter described, actuation of motor  204 , and hence rotation of cam disk  148  and arm  156  attached thereto, is controlled by circuit  282  provided on circuit board  280 . 
   Referring to  FIGS. 11-12 , in its initial configuration, utility is connected to relay K 1  at terminals J 2  and J 3  of circuit  282 . Terminals J 4  and J 5  of circuit  282  are connected to motor  204  and terminals B− and B+ are connected to battery  284 . Terminals G 1  and G 2  of circuit  282  are connected to provide signals to a conventional standby electrical generator and terminal G 3  of circuit  282  is also connected to the standby electrical generator to receive signals therefrom. 
   With arm  156  in its initial state, at the 6 o&#39;clock position in  FIGS. 7-10 , circuit breaker  14  is in the on position and circuit breaker  26  is in the off position. With arm  156  in its initial state, switch  242 , line  289 , is closed by land  228  and switch  234  is in an open position. As a result, electricity flows from the utility, line  281 , though circuit breaker  14 , to first and second essential hot buss bars  16  and  18 , respectively. With the utility supplying electrical power, relay K 1  is energized thereby interconnecting terminals G 1  and G 2  of circuit  282 . In addition, relay K 2 -A, line  283 , is energized such that contacts K 2 -B, line  297 , are open so as to disconnect the standby generator from circuit  282  and such that contacts K 2 -C, line  285 , are closed so as to interconnect battery  284  to circuit  282 . 
   In response to a power outage at the utility at an initial time T 0 ,  FIG. 12 , relays K 1  and K 2  are de-energized such that the standby electrical generator receives a start signal, line  293 . In addition, contacts K 2 -B close so as to connect the standby electrical generator to circuit  282  at terminal G 3  and contacts K 2 -C open so as to disconnect battery  284  from circuit  282 . At a predetermined time T 1 , the standby electrical generator provides a signal, line  287 , at terminal G 3  of circuit  282  so as to actuate motor  204 , line  295 . As motor  204  rotates arm  156  and cam disk  148 , bearing  172  of arm  156  engages first side  122  of first leg  120  of operating arm  90  so as urge operating arm  90  counter-clockwise in  FIGS. 7-10 . 
   As motor  204  rotates cam disk  148 , camming element  206  engages and close switch  234 , line  291 , at time T 2 . Simultaneously, as operating arm  90  is urged counter-clockwise, terminal end  134  of second leg  128  of operating arm  90  engages actuator bar  26   a  of circuit breaker  26  and urges actuator bar  26   a  to the on position. In addition, locking bar  268  through switching elements  270  and  272  translates movement of actuator bar  26   a  to actuator bar  14   a  of circuit breaker  14  such than circuit breaker  14  is moved to the off position. As a result, first and second essential hot buss bars  16  and  18 , respectively, are disconnected from the utility and interconnected to the output of the standby electrical generator though circuit breaker  26 . 
   Motor  204  continues to rotate cam disk  148  such that land  228  disengages from switch  242  such that switch  242  opens at time T 3 . With switch  242  open, the signal from the standby electrical generator is isolated from circuit  282  so as to stop actuation of motor  204 . With motor  204  stopped, arm  156  is stopped at the 12 o&#39;clock position in  FIGS. 7-10  at time T 4 . As a result, standby electrical generator provides electricity to first and second essential hot buss bars  16  and  18 , respectively, through circuit breaker  26 . 
   In response to a return of power from the utility at time T 5 ,  FIG. 12 , relays K 1  and K 2  are energized such that the start signal to the standby electrical generator is terminated. In addition, contacts K 2 -B open so as to disconnect the standby electrical generator from circuit  282  at terminal G 3  and contacts K 2 -C close so as to interconnect battery  284  to circuit  282 . With battery  284  connected to circuit  282 , motor  204  rotates arm  156  and cam disk  148  such that bearing  172  of arm  156  engages first side  100  of first leg  98  of operating arm  88  so as urge operating arm  88  counterclockwise in  FIGS. 7-10 . At a predetermined time T 5 , the signal from the standby electrical generator at terminal G 3  of circuit  282  is terminated. 
   As motor  204  rotates cam disk  148 , camming element  208  engages and closes switch  234  at time T 6 . Simultaneously, as operating arm  88  is urged counterclockwise, terminal end  112  of second leg  106  of operating arm  88  engages actuator bar  14   a  of circuit breaker  14  and urges actuator bar  14   a  to the on position. In addition, locking bar  268  through switching elements  270  and  272  translates movement of actuator bar  14   a  to actuator bar  26   a  of circuit breaker  26  such than circuit breaker  26  is moved to the off position. As a result, first and second essential hot buss bars  16  and  18 , respectively, are disconnected from the standby electrical generator and are reconnected to the utility source though circuit breaker  14 . 
   Motor  204  continues to rotate cam disk  148  such that land  228  engages switch  242  such that switch  242  closes at time T 7 . Thereafter, camming element  208  disengages and opens switch  234  at time T 8 . With switch  234  open, the signal from the battery is isolated from circuit  282  so as to stop actuation of motor  204 . With motor  204  stopped, arm  156  is stopped at the 6 o&#39;clock position in  FIGS. 7-10 . Thereafter, the process can be repeated. 
   Various modes of carrying out the invention are contemplated as being within the scope of the following claims particularly pointing and distinctly claiming the subject matter that is regarded as the invention.