Abstract:
A transfer switch system includes a normal power supply and an emergency power supply. A set of linked switches select between these power supplies. A breaker seperates the power supplies from loading circuit. The switches and the breaker are mounted within an enclosure having an exterior handle. The exterior handle controls the selection between the normal and emergency power supplies.

Description:
FIELD OF THE INVENTION  
         [0001]    The invention relates generally to a transfer switch, and more particularly to system for reverting to an alternative electric source during a power failure.  
         BACKGROUND OF THE INVENTION  
         [0002]    The reliable supply of electricity is important for businesses and homes. Indeed, virtually every business and home relies upon the continuous supply of electricity to refrigerate food, to operate heating and cooling systems and many other appliances.  
           [0003]    In some applications, the uninterrupted supply of electricity is absolutely critical. For example, computer systems generally require a virtually perfect power supply. Even a momentary glitch can disrupt their operation. Consequently, where the supply of electricity is unreliable, back-up power sources commonly referred to uninterrupted power supplies are used. These usually include a power detection and filtering circuit. If the main power fails, the back-up power source immediately detects the failure and switches to a battery or other back-up source. In more sophisticated systems, the back-up power source will switch to an alternative power supply such as a generator if the main power remains off line.  
           [0004]    Although these types of systems are effective even for the most demanding of applications, they are also expensive. The circuitry required to monitor the main power supply and associated battery back up are relatively complex. Moreover, this type of uninterrupted power supply is not necessary for many applications. For example, many businesses or homes can tolerate a short interruption in their power supply. Interruptions of only a few minutes have little affect on heating or cooling systems. Critical applications such as a computer can depend upon a local back-up power supply. If the main power supply continues to fail, a local generator can be started to provide backup power.  
           [0005]    The installation of a back-up generator requires that it is connected into the loading circuits in a manner that does not interfere with the normal delivery of power from a local utility company. The back-up generator must be disconnected when the local utility company provides power to prevent large flows of electricity between the two sources. In most conventional home or business settings, the internal wiring is connected directly to the local utility company through a power meter and breaker switches. The power meter is used to monitor usage for billing purposes. The breaker switches are used to prevent excessive flow of current through any loading circuit.  
           [0006]    The addition of an auxiliary generator to a conventional home or business requires significant changes to the internal wiring, and typically requires the addition of an auxiliary cabinet. This cabinet houses switches and the additional wiring required to accommodate the generator.  
           [0007]    For an existing structure, the installation of an additional cabinet and associated wiring requires significant modifications. The cabinet must be mounted and, depending upon the installation, generally cannot be mounted flush with the surface of the wall. In addition, for external conduit generally is required to house the additional wiring. These external additions are cumbersome at best. Accordingly, an improved method of installing an auxiliary generator is desired.  
         SUMMARY OF THE INVENTION  
         [0008]    According to one preferred aspect of the invention, a transfer switch system is especially suited for connecting loading circuits to a normal power source and to an emergency power source. The transfer switch system includes an enclosure, an electrical power meter, a normal power switch, an emergency power switch, and a handle. The enclosure has a front face and a plurality of side walls. The front face of the enclosure defines a circular hole sized to fit an electrical power meter. The side walls of the enclosure define holes for passing wires that carry electrical power from a normal power source and an emergency power source and at least one hole for passing wires that carry electrical power to loading circuits. The electrical power meter is mounted within the enclosure and extends through the circular hole in the front face. The electrical power meter is electrically connected with the normal power source to measure the electrical power flowing from the normal power source. The normal power switch is mounted within the enclosure and electrically connected to the normal power source and to the loading circuits. The normal power switch is configured to connect the normal power source to the loading circuits in an on position and to disconnect the normal power source from the loading circuits in an off position. The emergency power switch also is mounted within the enclosure proximate the normal power switch. The emergency power switch is electrically connected to the emergency power source and the loading circuits and configured to connect the emergency power source to the loading circuits in an on position and to disconnect the emergency power source from the loading circuits in an off position. The handle is mounted on the front face of the enclosure proximate the normal power switch and the emergency power switch. The handle includes a bracket extending into the interior of the enclosure to engage the normal power switch and the emergency power switch. Operation of the handle to a normal position places the normal power switch in the on position and the emergency power switch in the off position; operation of the handle to the emergency position places the normal power switch in the off position and the emergency power switch in the on position.  
           [0009]    According to further aspects of the invention, the normal power switch comprises a pair of circuit breakers with one circuit breaker on a positive and one circuit breaker on a negative path of the normal power source and configured to automatically disconnect when the current therethrough exceeds a predetermined level. Likewise, the emergency power switch comprises a pair of circuit breakers with one circuit breaker on a positive and one circuit breaker on a negative path of the emergency power source and configured to automatically disconnect when the current therethrough exceeds a predetermined level.  
           [0010]    According to further aspects of the invention, the transfer switch system includes an emergency power terminal mounted within the enclosure and having a positive terminal electrically connected with the positive path and a negative terminal electrically connected with the negative path of the emergency power source. The emergency power source is removeably connected with the emergency power terminal.  
           [0011]    According to a further aspect of the invention, the transfer switch system includes a meter socket configured to receive the electric power meter. The meter socket is electrically connected between the normal power source and the normal power switch.  
           [0012]    According to a further aspect of the invention, the transfer switch system includes a pair of load breaker switches electrically connected with the loading circuits. The pair of load breakers are configured to control the flow of electrical current so that when the breaker switches are in an off position the loading circuits are disconnected from the normal power source and the emergency power source, and when the breaker switches are in an on position the loading circuits are connected to one of the normal power source or the emergency power source depending upon the position of the normal power switch and the emergency power switch. The load breaker switches each include a terminal removeably connected with the loading circuits.  
           [0013]    According to a further aspect of the invention, the interior of the enclosure is divided into an upper chamber that houses the electrical power meter and a lower chamber that houses the normal power switch and the emergency power switch. The holes for passing wires that carry electrical power from a normal power source enter the upper chamber and the at least one hole for passing wires that carry electrical power to loading circuits enters the lower chamber. The front face of the enclosure is substantially rectangular in shape and is divided into an upper portion that covers the upper chamber and a lower portion hingedly attached to the upper portion that covers the lower chamber. The upper portion defines the circular hole for the electrical power meter and the lower portion mounts the handle.  
           [0014]    According to a further aspect of the invention, the bracket of the handle includes an emergency push plate and a normal push plate. The emergency push plate engages the emergency power switch so that movement of the handle from the normal position to the emergency position causes the emergency push plate to move the emergency power switch from the off position to the on position. Likewise, the normal push plate engages the normal power switch so that movement of the handle from the emergency position to the normal position causes the normal push plate to move the normal power switch from the off position to the on position.  
           [0015]    According to a further aspect of the invention, the emergency power switch and the normal power switch further comprise a linking arm positioned therebetween so that movement of the emergency power switch from the off position to the on position simultaneously moves the normal power switch from the on position to the off position. Likewise, movement of the normal power switch from the off position to the on position simultaneously moves the emergency power switch from the on position to the off position through the linking arm.  
           [0016]    According to another aspect of the invention, a power meter and switch box are especially suitable for selecting between a utility power supply and an auxiliary power supply. The combination includes an enclosure, a meter, an auxiliary power terminal, a breaker switch, a set of power switches, and a handle. The enclosure has a first chamber and a second chamber. The meter is electrically connected with a utility power supply and configured to determine the amount of electrical power that has been used from the utility power supply. The meter is mounted within the first chamber of the enclosure. The meter includes a display that extends through a hole defined by the enclosure so that the amount of electrical power that has been used from the utility power supply can be readily determined. The auxiliary power terminal is configured to removeably connect with an auxiliary power supply. The auxiliary power terminal is mounted within the second chamber of the enclosure. The breaker switch is configured to removeably connect with a loading circuit. The breaker switch is mounted within the second chamber of the enclosure. The set of power switches is connected between the meter and the breaker switch and between the auxiliary power terminal and the breaker switch and are configured to operate in tandem. When the set of power switches forms an electrical connection between the meter and the breaker switch, the electrical power switches disconnect the auxiliary power terminal from the breaker switch. Likewise, when the set of power switches forms an electrical connection between the auxiliary power terminal and the breaker switch, the electrical power switches disconnect the meter from the breaker switch. The set of power switches are mounted in the second chamber. The handle engages the set of power switches and has a normal and an auxiliary position. Operation of the handle to the normal position causes the set of power switches to form an electrical connection between the meter and the breaker switch. Operation of the handle to the auxiliary position causes the set of power switches to form an electrical connection between the auxiliary power terminal and the breaker switch.  
           [0017]    According to a further aspect of the invention, the combination includes a linking arm positioned between the pair of meter breaker switches and the pair of auxiliary breaker switches. Movement of the meter breaker switches to an on position forces the auxiliary breaker switches to an off position and movement of the auxiliary breaker switches to an on position forces the meter breakers switches to an off position by operation of the linking arm.  
           [0018]    According to a further aspect of the invention, the handle is mounted proximate the second chamber and positioned with an outward orientation for access by an operator. The handle includes a bracket that extends into the second chamber to engage the set of switches so that operation of the handle causes the bracket to move the set of switches.  
           [0019]    According to a further aspect of the invention, the handle includes a bracket that extends into the enclosure and engages the set of switches. The bracket includes a first and a second u-shaped plate and a flat plate. The first u-shaped plate defining a pair of slots. The flat plate extends through the pair of slots in the first u-shaped plate so that the flat plate is free to move along a first axis but is restricted from moving in any other direction by the confines of the pair of slots. Movement of the handle moves the flat plate along the first axis. The second u-shaped plate extends from the flat plate and is positioned so that the set of switches are confined between the walls of the u-shaped plate. Thus movement of the flat plate causes the u-shaped plate to operate the set of switches. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0020]    [0020]FIG. 1A is a front view of one preferred enclosure  100  including a power switch handle  102  having a normal and an emergency position.  
         [0021]    [0021]FIG. 1B is a side view of enclosure  100  including a face cover  120  shown in a closed position, and in an open position by phantom lines.  
         [0022]    [0022]FIG. 1C is a top view of enclosure  100  including a conduit adapter  130 .  
         [0023]    [0023]FIG. 2 is a front view of enclosure  100  shown with face cover  120  removed. Enclosure  100  houses meter socket  202 , transfer breakers  204  and transfer breakers  206 .  
         [0024]    [0024]FIG. 3A is a partial, exploded, cross-sectional view of enclosure  100 , transfer breakers  204  and transfer breakers  206 . Handle  102  connects with transfer breakers  204  and transfer breakers  206  through bracket  302 .  
         [0025]    [0025]FIG. 3B is a partial, exploded, perspective view of handle  102 , bracket  302  and transfer breakers  204  and  206 .  
         [0026]    [0026]FIG. 4 is a front view of transfer breakers  204  and transfer breakers  206 , including a link  402 .  
         [0027]    [0027]FIG. 5A is a top view of one preferred bracket  500  for connecting a handle to linked normal and emergency breaker switches.  
         [0028]    [0028]FIG. 5B is a front view of the bracket  500  shown in FIG. 5A.  
         [0029]    [0029]FIG. 5C is a side view of the bracket  500  shown in FIG. 5A.  
         [0030]    [0030]FIG. 6 is a circuit diagram showing connections between meter  602 , generator  612 , and loading circuits. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0031]    Turning to FIG. 1A, the front cover  120  of enclosure  100  is divided into an upper panel  104  and a lower panel  106 . The upper panel defines a circular hole  108  configured to fit around a standard electricity meter. Such meters are widely used and commercially available. Handle  102  is mounted on the lower panel  106 . As further described below, it is positioned proximate breaker switches that are housed within enclosure  100 . Handle  102  connects with such breaker switches through a bracket. Handle  102  has two positions: normal and emergency. Movement of the handle  102  from one position to the other, changes the position of the breaker switches. The operation of the breaker switches will be further described below.  
         [0032]    The upper panel  104  and the lower panel  106  are both rectangular in shape. The bottom edge of upper panel  104  joins with the top edge of lower panel  106 . The two panels are held together by a pair of hinges  110 . The top of upper panel  104  fits beneath top cover  112 . The bottom of lower panel  106  defines a slot that engages a tab  114  extending from enclosure  100 . When the top of upper panel  104  is positioned beneath top cover  112 , and the tab  114  extends through the slot in the lower panel  106 , the front cover is held in place. Tab  114  defines a hole so that the front cover may be locked in place by securing a lock through the hole.  
         [0033]    Turning to FIG. 1B, front cover includes wrap-around sides  122  that extend from upper panel  104 , and wrap-around sides  124  that extend from lower panel  106 . The wrap-around sides  122  and  124  overlap with side walls  126  of enclosure  100 . Front cover is shown in place and in phantom lines as it is removed. Alternatively, the lower panel  106  may be lifted while the upper panel  104  remains substantially in place. This permits access to the breaker switches behind lower panel  106 . A standard power meter  126  is also shown in phantom lines. It extends through hole  108  defined by enclosure  100 .  
         [0034]    Turning to FIG. 1C, the top cover  112  is shown. It substantially defines a rectangle with a slight extension  132  at its front corners to accept the wrap around sides  122  of the front cover. Conduit adapter  130  extends above top cover  112 . It provides an interface for engaging a conduit housing the normal power supply wires. Enclosure  100  also includes a number of phantom holes positioned in the sides and back. Depending upon the placement of the enclosure, the auxiliary generator and the load circuits, the nearest phantom holes are removed to pass associated wires.  
         [0035]    Turning to FIG. 2, one preferred transfer switch is shown. The transfer switch is housed within enclosure  100 , which is shown without the front cover. Meter socket  202  is mounted in the upper portion of the enclosure  100 . The meter socket  202  includes four sockets  208  for receiving the plugs from a standard meter. Electric power is received through the top sockets and passes through the meter to the lower sockets. The lower sockets are electrically connected to breaker switches  204 . The meter socket  202  is positioned so that when a meter is plugged into the socket, the meter will align with the hole defined in the upper panel  104 . The meter&#39;s face then faces outward so that it can be read easily.  
         [0036]    Breaker switches  706  are configured to receive power through auxiliary terminals  224 . These terminals are wired to an auxiliary generator. In the event of a power failure on the normal power supply, the auxiliary generator is activated. Breaker switches  206  are turned on and power flows from auxiliary terminals  224  through breaker switches  206 .  
         [0037]    Depending upon the application, the breaker switches  204  will have a pre-determined set level. When the current through the breaker switches  204  exceeds the pre-determined set level, then the breaker switches  204  automatically disconnect. This acts to break any circuit therethrough.  
         [0038]    Likewise, the breaker switches  206  will also have a pre-determined set level, preferably the same as breaker switches  204 . The sets of breaker switches  204  and  206  operate in tandem to select between the normal power supply which is provided through the meter circuit, and an emergence power supply. Either source is connected to a load through breaker switches  220 .  
         [0039]    More specifically, when power is provided from the normal power source, it flows through the meter circuit and through breaker switches  204 . The breaker switches  204  are in a connected or on position. Consequently, power flows through the breaker switches to terminals  222 . From terminals  222  it passes through wire connections to an on-off breaker  220 . The on-off breaker connects with the loading circuits. It provides a single point for disconnecting the loading circuits from both the normal and auxiliary power supplies.  
         [0040]    Terminals  222  are positioned between breaker switches  206  and breaker switches  206 . Terminals  222  make electrical connections with both of the sets of breaker switches  204  and  206 . Acting in tandem, the breaker switches  204  are in an on position, only when the breaker switches  206  are in an off position. Likewise, breaker switches  206  are in an on position, only when the breaker switches  204  are in an off position. The operation of these two sets of breaker switches  204  and  206  is coordinated by bracket  302  and link  402 , described below with reference to FIGS. 3 and 4, respectively.  
         [0041]    The interior of enclosure  100  is separated into two compartments by divider  226 . The upper compartment houses the meter  126  and socket  202 . The lower compartment houses breaker switches  204  and  206 . Grounding bar  230  connects the two compartments.  
         [0042]    Turning to FIG. 3, bracket  302  connects with handle  102 . Handle  102  extends from the front face of the enclosure. The handle  102  has two positions: normal and emergency. Movement of the handle  102  between these positions moves pin  304  on the inside of the enclosure about an arc. Bracket  302  translates this arc movement into vertical movement. When the handle  102  is in the normal position, bracket  302  is in a lower position. This forces breaker switches  204  into an on position. When handle  102  is in the emergency position, bracket  302  is in an upper position (shown in phantom lines). This forces breaker switches  206  into an on position.  
         [0043]    When breaker switches  204  are in the on position, then the normal power source is connected to the loading circuits. When breaker switches  206  are in the on position, then the emergency power source is connected to the loading circuits. To avoid connecting the normal power source to the emergency power source, one must be disconnected when the other is connected. In other words, when the normal power source is connected to the loading circuit, then the emergency power source must be disconnected, and vice versa.  
         [0044]    Turning to FIG. 4, link  402  forces breaker switch  206  into the off position when breaker switch  204  is moved to the on position. Likewise, link  402  forces breaker switch  204  into the off position when breaker switch  206  is moved to the on position.  
         [0045]    Link  402  is formed of a body  404  that narrows at each end into blades  406  and  408 . Breaker switches  204  are positioned adjacent one another so that they may be switched on and off together. Blade  406  extends between breaker switches  204 . The shoulder formed between blade  406  and body  404  rests against the bottom surface of breaker switches  204 . Movement of link  402  in an upward direction forces the shoulder of body  404  against the breaker switches  204  and switches them into an off position. Likewise, breaker switches  206  are positioned adjacent one another so that they may be switched on and off together. Blade  408  extends between breaker switches  206 . The shoulder formed between body  404  and blade  408  rests against the top of surface of breaker switches  408 . Movement of link  402  in a downward direction forces the other shoulder of body  404  against the breaker switches  206  and switches them into an off position.  
         [0046]    Together, bracket  302  and link  402  permit an operator to switch from normal to emergency power. The bracket  302  and link  402  operate to move breaker switches  204  and  206  so that only one is in an on position at any time.  
         [0047]    In addition, the breaker switches  204  and  206  are selected so that they disconnect before reaching the midpoint between their on and off positions. This ensures that they two circuits are not temporarily connected as the switches move from one state to the other.  
         [0048]    Turning to FIGS. 5A, 5B, one preferred bracket  500  is shown in more detail. It essentially consists of three pieces: a base  502 , a plate  504  and a switch bracket  506 . The base  502  is formed of a single piece of bent sheet metal. It forms a U-shape. The upper side  508  and the lower side  510  each define a slot  511  through which plate  504  passes. The slots permit vertical movement of plate  504 , only.  
         [0049]    Switch bracket  506  attaches to plate  504 . It is also formed into a U-shape. The upper side  512  meets breaker switch  204  (shown in FIG. 3) along an inner side. The lower side  514  meets breaker switch  206  (also shown in FIG. 3) also along an inner side. Switch bracket  506  also defines a horizontal slot  516  that extends through its middle. Slot  516  also extends through plate  504 . Pin  518  of handle  102  extends through this slot.  
         [0050]    In operation, movement of handle  102  between the normal and emergency positions moves pin  518  about an arc. Slot  516  translates that movement into vertical movement of switch bracket  506 . This, in turn, operates breaker switches  204  and  206 . More specifically, movement of switch bracket  506  in a downward direction forces switch  204  into an off position. As described above, this forces switch  206  into an on position. Similarly, movement of switch bracket  506  in an upward direction forces switch  206  into an off position. As also described above, this forces switch  204  into an on position.  
         [0051]    Turning to FIGS. 6A and 6B, circuit diagrams of one preferred embodiment of the invention are described. Electrical power is delivered by a utility through meter  602 , which tracks and displays total consumption on its face panel. In the normal position, shown in FIG. 6A, electrical power passes through meter  602  to breaker circuit  604  (shown in the normal position). Breaker circuit  604  consists of two sets of breaker switches  606  and  608 , which are mechanically coupled through coupling  610 . When in the on position, the first set of breaker switches  606  connects meter  602  to loading circuits. Under normal conditions, power is supplied by the power utility to the loading circuits through breakers  614 .  
         [0052]    When power fails, breaker circuit  604  is switched to the emergency position, shown in FIG. 6B. This places breaker switches  606  in an off position and breakes switches  608  in an on position. Generator  612  provides emergency electrical power. When in the on position, electricity flows through breaker switches  608  to the loading circuits through breakers  614 .  
         [0053]    Although the invention has been described with reference to specific embodiments, those skilled in the art will appreciate that many variations, modifications and additions are possible without departing from the scope of the invention. All such variations, modifications and additions are intended to be encompassed within the scope of the following claims.