Abstract:
An apparatus configured to selectively supply power among a plurality of electrical devices, includes a plug configured to be electrically connected to a power source, a first outlet selectively connected to the plug, a first sensor connected to the first outlet, a first switch disposed between the first outlet and the plug, a second outlet selectively connected to the plug, a second sensor connected to the second outlet, a second switch disposed between the second outlet and the plug, and a processing unit in electrical communication with the first and second switches and the first and second sensors. The processing unit being configured to selectively open and close the first and second switches based on parameters sensed by the first and second sensors.

Description:
RELATED APPLICATIONS 
       [0001]    This application relates to and claims priority benefits from U.S. Provisional Patent Application No. 60/760,719 entitled “Switching Apparatus for Operating Multiple High-Current Devices From One Electrical Circuit,” filed Jan. 20, 2006, which is hereby incorporated by reference in its entirety 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    Embodiments of the present invention generally relate to a system and method for operating multiple electrical devices, and more particularly, to a switching system and method for operating multiple high-current devices from a single electrical source. 
         [0003]    Various electrical devices draw a current from a power source that is more than half of the allowable capacity for the power source. For example, a 1000 watt heater may draw 8.3 amps, while a 1500 Watt heater may draw 12.5 amps. The maximum current for a standard electrical circuit may only be, however, 15 amps. Thus, the current draw for either of the electrical devices is such that only a single device may be operated at any given time. If multiple devices are to be used, the additional devices typically are plugged into separate sources of electrical power, which may require installation of extra circuits or long extension cords. 
         [0004]    Some electrical devices, such as water deicers, are designed to run intermittently. For example, a typical 1500 Watt deicer may be used to keep ice from forming in a 100 gallon livestock tank. The deicer may activate when the water temperature drops below a certain cool temperature, such as 40° F. When the water drops below that temperature, the deicer activates and heats the water to a particular heated temperature, such as 55° F. When the water temperature is heated to the heated temperature, the deicer deactivates. The deicer then remains deactivated until the water temperature dips below the cool temperature again, at which point the cycle is repeated. 
         [0005]    The duty cycle for a typical deicer (i.e., the percentage of time that the deicer is activated) is typically less than 50%. Thus, even though a deicer may draw more than half of the allowable current from a power source, the deicer is operating less than half the time. Nevertheless, in order to provide power to separate deicers, each deicer is typically connected to a separate source of electrical power. 
         [0006]    Thus, a need exists for a system and method of efficiently delivering electrical power to multiple electrical devices that are intermittently activated. 
       SUMMARY OF THE INVENTION 
       [0007]    Certain embodiments of the present invention provide an apparatus configured to selectively supply power among a plurality of electrical devices. The apparatus may include a plug configured to be electrically connected to a power source, a first outlet selectively connected to the plug, a first sensor connected to the first outlet, a first switch disposed between the first outlet and the plug, a second outlet selectively connected to the plug, a second sensor connected to the second outlet, a second switch disposed between the second outlet and the plug, and a processing unit in electrical communication with the first and second switches and the first and second sensors. The processing unit is configured to selectively open and close the first and second switches to complete and break first and second circuits based on parameters sensed by the first and second sensors. 
         [0008]    The processing unit may be configured to close one of the first and second switches to complete a first circuit or second circuit, respectively, based on whether a device attempts to draw current through one of the first and second outlets. Alternatively, the processing unit may be configured to close one of the switches to complete a circuit based on a sensed change of resistance at one of the outlets. 
         [0009]    The processing unit may be configured to close the first switch to complete a first circuit when the processing unit determines that a first device is attempting to draw current through the firs t outlet. The processing unit may simultaneously open the second switch to break a second circuit. The processing unit may also be configured to open the first switch to break the first circuit when the processing unit determines that the first device is no longer attempting to draw current through the first outlet. 
         [0010]    The apparatus may also include a thermometer in electrical communication with the processing unit. The processing unit may open both the first and second switches to break the first and second circuits when the thermometer detects a temperature above a predetermined threshold. 
         [0011]    Certain embodiments of the present invention also provide a system that includes a power source, such as a standard wall outlet, a switching apparatus connected to the power source, a first deicer connected to the power source through the switching apparatus, and a second deicer connected to the power source through the switching apparatus. 
         [0012]    The switching apparatus may include a plug electrically connected to the power source, a first outlet selectively connected to the plug through a first circuit, such that the first deicer is connected to the switching apparatus through the first outlet, a first sensor connected to the first outlet, a first switch disposed within the first circuit, a second outlet selectively connected to the plug through a second circuit, such that the second deicer is connected to the switching apparatus through the second outlet, a second sensor connected to the second outlet, a second switch disposed within the second circuit, and a processing unit in electrical communication with the first and second switches and the first and second sensors. The processing unit may be configured to selectively open and close the first and second switches based on parameters sensed by the first and second sensors. 
         [0013]    Certain embodiments of the present invention also provide a method of selectively supplying power to first and second deicers connected to a power source through a switching apparatus. The switching apparatus connects to the power source through a plug, and the first and second deicers are positioned within first and second water receptacles, respectively. The method includes sensing a parametric change, selectively completing and breaking a first electrical circuit between the plug and the first deicer based on the sensing step, and selectively completing and breaking a second electrical circuit between the plug and the second deicer based on the sensing step. 
         [0014]    The second electrical circuit is broken when the first electrical circuit is completed, and the first electrical circuit is broken when the second electrical circuit is completed. The parametric change may be a change of current in at least one of the first and second electrical circuits. Optionally, the parametric change may be a change in resistance in at least one of the first and second circuits. 
     
    
     
       BRIEF DESCRIPTION OF SEVERAL VIEWS OF THE DRAWINGS 
         [0015]      FIG. 1  illustrates a simplified top plan view of multiple electrical devices connected to a single source of electrical power according to an embodiment of the present invention. 
           [0016]      FIG. 2  illustrates a schematic diagram of a switching apparatus according to an embodiment of the present invention. 
           [0017]      FIG. 3  illustrates a flow chart of a method of supplying electrical power to multiple electrical devices according to an embodiment of the present invention. 
       
    
    
       [0018]    The foregoing summary, as well as the following detailed description of certain embodiments of the present invention, will be better understood when read in conjunction with the appended drawings. For the purpose of illustrating the invention, there is shown in the drawings, certain embodiments. It should be understood, however, that the present invention is not limited to the arrangements and instrumentalities shown in the attached drawings. 
       DETAILED DESCRIPTION OF THE INVENTION 
       [0019]      FIG. 1  illustrates a simplified top plan view of multiple electrical devices  10  and  12  connected to a single source  14  of electrical power according to an embodiment of the present invention. The electrical devices  10  and  12  may be deicers positioned within water receptacles  16  and  18 , respectively. The electrical source  14  may be a standard 120 volt electrical outlet. The water receptacles  16  and  18  may be, for example, livestock water troughs or birdbaths. 
         [0020]    Each electrical device  10  and  12  may be electrically connected to the source  14  through electrical cords  20  and  22 , respectively. The cords  20  and  22  electrically connect to the source  14  through a switching apparatus  24  that plugs into the electrical source  14 . The switching apparatus  24  also includes multiple outlets  26  and  28 . The cord  20  plugs into the outlet  26 , while the cord  22  plugs into the outlet  28 . While  FIG. 1  shows a switching apparatus  24  having two outlets  26  and  28 , the apparatus  24  may include more outlets than those shown to accommodate additional electrical devices. 
         [0021]      FIG. 2  illustrates a schematic diagram of the switching apparatus  24  according to an embodiment of the present invention. The switching apparatus  24  includes a main housing  30  that may be formed of insulated plastic or the like. One side of the apparatus  24  includes an electrical plug  32  that is configured to plug into the electrical source  14  (shown in  FIG. 1 ), which may be a standard electrical outlet. The opposite side of the apparatus  24  includes the outlets  26  and  28 , which are configured to receive plugs of the cords  20  and  22  (shown in  FIG. 1 ). Additional outlets may be positioned at various points within the apparatus  24 . 
         [0022]    The outlets  26  and  28  are electrically connected to sensors  34  and  36 , respectively. The sensors  34  and  36  are connected to wires  47  and  43 , which are, in turn, connected to the outlets  26  and  28 , respectively. The sensors  34  and  36  are also electrically connected to a processing unit  38 , such as a microprocessor, or various other types of processors. Switches  40  and  42  are disposed between the plug  32  and each outlet  26  and  28 , respectively. Switch  40  is disposed between wires  45  (connected to the plug  32 ) and  47  (connected to the outlet  26 ), while switch  42  is disposed between wires  41  (connected to the plug  32 ) and  43  (connected to the outlet  28 ). 
         [0023]    Referring to  FIGS. 1 and 2 , in operation, the processing unit  38  is configured to determine when one of the electrical devices  10  and  12  attempts to draw current from the electrical source  14 . The processing unit  38  may, for example, monitor the current in the wires leading to each outlet  26  and  28  through the sensors  40  and  42 . Optionally, the processing unit  38  may monitor the resistance of the devices  10  and  12  and determine when the resistance drops from infinity, thereby indicating the devices  10  and  12  have been activated. When one device  10  or  12  attempts to draw current from the power source  14 , the processing unit  38  enables an electrical path (i.e., completes a circuit) from the power source  14  to that device  10  or  12 , while it disables the electrical path (i.e., “breaks” connection within a circuit) from the power source  14  to the other device  10  or  12 , as discussed below. 
         [0024]    Power to each of the outlets  26  and  28  is switched on or off by the apparatus  24  through the processing unit  38 . The processing unit  38  determines when one of the devices  10  or  12  activates, and then acts to deactivate the other device  10  or  12 . For example, when the device  10  attempts to draw current from the power source  14  (i.e., when the device  10  is to be activated), the processing unit  38  sends a signal to move the switch  42  into the off position, and sends a signal to move the switch  40  into the on position. Thus, an electrical path is formed between the electrical source  14 , the plug  32 , wires  41 , the switch  42 , the wires  43 , and the outlet  28 . At the same time, the electrical path that previously existed between the plug  32 , wires  45 , the switch  40 , the wires  47 , and the outlet  26  is broken due to the switch  40  being moved into the off position. As such, power is cut off from the outlet  28 , and therefore the device  12 , while power is supplied to the outlet  26 , and therefore, the device  10 . 
         [0025]    Power to the device  12  remains cut off until the device  10  is deactivated (such as when the water in the receptacle  16  reaches a certain heated temperature). When the processing unit  38  senses that the device  10  is no longer drawing power, the processing unit  38  moves the switch  42  into the on position, and moves the switch  40  into the off position, such that power is supplied to the outlet  28 , and therefore the device  12 , while power is cut off from the outlet  26 , and therefore the device  10 . The cycle repeats itself as the devices  10  and  12  are deactivated (such as by heating the water within the receptacles  16  and  18  to certain heated temperatures). That is, as one device  10  or  12  deactivates, the processing unit  38  acts to cut off the power supply to that device  10  or  12 , and switch on the power supply to the other of the devices  10  or  12 . Optionally, when one of the devices  10  or  12  deactivates, the processing unit  38  may be configured to enable an electrical path to the next device  10  or  12  that attempts to draw current from the electrical source  14 . 
         [0026]    Also, alternatively, the apparatus  24  may be configured to automatically cut off power to a device  10  or  12  after a set period of time. For example, the processing unit  38  may be configured to allow the device  10  to draw current for a first predetermined time period. After the first predetermined time period, the apparatus  24  cuts off power to the device  10  and provides power to the device  12  for a second predetermined time period, which may be the same as the first predetermined time period. After the second predetermined time period, the apparatus  24  switches so that power is supplied to the device  10  and cut off from the device  12 . The cycle may then repeat. As such, the apparatus  24  may force the devices  10  and  12  to share the available power. 
         [0027]      FIG. 3  illustrates a flow chart of a method of supplying electrical power to multiple electrical devices according to an embodiment of the present invention. At  50 , the processing unit determines whether a first electrical device is attempting to draw current from a power source. If the first device is attempting to draw current, the processing unit enables an electrical path (i.e., completes a circuit) to the first device and disables an electrical path (i.e., breaks a circuit), if not already disabled, to the second device at  52 . If the first device is not attempting to draw current, the processing unit acts to maintain the electrical path to the second device (if the second device is drawing current), while the electrical path to the first device remains disabled at  54 . 
         [0028]    At  56 , if the first device is still drawing current, the electrical path to the first device is maintained at  58 . If, however, the first device is no longer drawing current, the electrical path to the first device is disabled at  60 . 
         [0029]    At  62 , the processing unit then determines if the second device is attempting to draw current. If the second device is not attempting to draw current, the electrical paths to both devices are disabled until one of the devices attempts to draw current at  64 . Optionally, the electrical path to the first device may be enabled. 
         [0030]    If, however, the second device is attempting to draw current, the processing unit enables the electrical path to the second device at  66 . At  68 , the processing unit then determines if the second device is still drawing current. If it is, the electrical path to the second device is maintained, while the electrical path to the first device remains disabled at  54 . If, however, the processing unit determines that the second device is no longer drawing current, then the electrical path is disabled at  64 . 
         [0031]    Referring to  FIGS. 1-3 , if the devices  10  and  12  are deicers, the apparatus  24  may be configured so that the devices  10  and  12  take turns drawing power from the source  14 . Because a high powered deicer typically operates at less than 50% duty cycle, the two water receptacles  16  and  18  may be kept ice free using one 15 amp circuit even though the two devices  10  and  12  would previously have used two separate circuits. Even on very cold days, when the devices  10  and  12  would normally operate at much higher duty cycles, the devices  10  and  12  can still effectively heat the water within the respective water receptacles  16  and  18 . For example, a first deicer may heat water within a first tank, thereby providing drinking water for livestock, while the second tank freezes over. After a set amount of time, the switching apparatus  24  switches power to the second deicer, so that the water within the frozen tank melts, while water within the first tank freezes. The process continues with each deicer being activated and deactivated after set periods of time. 
         [0032]    In situations where both devices  10  and  12  attempt to turn on at the same time, the processing unit  38  may sense that the devices  10  and  12  are attempting to activate before power is actually supplied to either device  10  and  12 . At this point, the processing unit  38  may simply choose which device  10  or  12  to activate based upon a predetermined algorithm. Alternatively, a reduced amount of current may be supplied to each device  10  and  12  until the processing unit  38  determines which device  10  or  12  to fully activate. 
         [0033]    Additionally, the apparatus  24  may be configured so that neither device  10  or  12  receives power when the sensed temperature exceeds a certain threshold. For example, the apparatus  24  may include a thermometer (in electrical communication with the processing unit  38 ) configured to measure outside air temperature. If the outside temperature exceeds the freezing point, the electrical paths to each device  10  or  12  may be disabled. 
         [0034]    Thus, embodiments of the present invention provide a system and method of efficiently delivering electrical power to multiple electrical devices that are intermittently activated. 
         [0035]    While the invention has been described with reference to certain embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from its scope. Therefore, it is intended that the invention not be limited to the particular embodiments disclosed, but that the invention will include all embodiments falling within the scope of the appended claims.