Abstract:
An apparatus and method for optimizing power factor in single-phase home power electrical systems. Advantages associated with the achievement of this objective include reduced electrical consumption and cost and prolonged equipment life. A capacitor circuit is connected with a circuit breaker to the home main power panel. The correct capacitance to optimize the power factor is determined prior to installation of the apparatus.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    The instant invention relates to an apparatus and method for optimizing power factor in dwelling electrical installations, and in particular to a home unit and method of termination to optimize power factor.  
           [0003]    2. Background of the Invention  
           [0004]    Optimization of inductive loads is well known in the prior art. An inductive load is an electric current that results from a magnetic current. The magnetic current may be produced by an electric current passing through coils in an inductor, a transformer or the like, or the magnetic current may be produced by an electro magnet. Whatever its source, the inductive load always flows in an opposite direction to any change in the magnetic field. As the inductive load always acts in opposition to any change in the magnetic field, the inductive load is also known as a counter voltage or counter electromotive force (cemf). The inductive loads draw a combination of kilowatts (real power) and kilovars (apparent power).  
           [0005]    The term “power factor” is used by persons of skill in the art to denote the equation: “real power divided by apparent power.” Some benefits associated with the optimization of power factor include increased equipment life due to lower operating temperature, protection against electrical surges such as those caused by lightning, and increased capacity at the electrical panel.  
           [0006]    Capacitors are a static source of kilovars/capacitive power. Capacitors installed at equipment that have inductive loads provide a number of benefits: reduced electrical energy consumption, reduced line current, increased voltage at the load, better voltage regulation and lower losses. These benefits are accomplished by installing sufficient capacitors/kilovars at the load to bring the power factor to just under unity.  
           [0007]    Inductive equipment that would benefit from power factor optimization include air conditioners, heat pumps, refrigeration equipment, irrigation pumps, pool pumps, etc. Other inventors have taken power factor correction technology to more complicated inductive equipment.  
           [0008]    There are two types of power factor correction discussed in the prior art. The first type of power factor correction focuses on fluorescent lamps. Fluorescent lamps require large amounts of energy to ionize the gas contained therein, resulting in the production of light. The power factor optimization of fluorescent lamps focuses on preventing the harmonic interference introduced in the lamp circuit. Examples of fluorescent lamp power factor correction are provided in U.S. Pat. No. 5,095,253 to Brent; U.S. Pat. No. 5,498,936 to Smith; and U.S. Pat. App. No. 2002/00111801 A1 to Chang.  
           [0009]    The second type of power factor correction is the application of capacitors to induction motors. Once again, there are several prior art references that address this issue.  
           [0010]    U.S. Pat. No. 4,271,386 to Lee discloses an electronic controller for regulating power applied by an alternating current (AC) supply to an AC induction motor. Lee&#39;s electronic controller improves the power factor of the motor over a wide range of varying mechanical loads. Lee utilizes a thyristor switch, a transformer, resistors, and a capacitor. Lee limits his invention to AC induction motors.  
           [0011]    U.S. Pat. No. 4,554,502 to Rohatyn discloses a power factor correcting system. Rohatyn states that some disadvantages with the use of capacitors to correct power factor are the resulting surge or spike the system experiences when the capacitor is switched and capacitor fuse blowing, which causes wattage loss. Rohatyn utilizes a fixed ratio series transformer, a variable autotransformer, a capacitor and a fuse. Rohatyn only discloses the use of his power factor correcting system for inductive loads.  
           [0012]    The loads served by electric utility companies are generally primarily resistive (such as incandescent light bulbs) or primarily inductive (such as induction motors). The present invention steps back from the prior art focus on power factor correction in individual equipment. The present inventors have discovered that in small residential installations, the power factor of the entire house may be optimized at the house&#39;s main electrical breaker panel. In large residential, commercial and industrial settings, the power factor of individual components may be optimized at the load side of the component&#39;s switching device. Unfortunately, capacitors are not used to optimize load factor as widely as they might be. One reason for this has been the lack of a simple apparatus and method to optimize power factor. Utility company engineers have the technical background to size capacitors to correct power factor for electric utility companies, but in general, no such capability exists in the residential areas. As a result, more electrical energy than is necessary is used to power inductive loads, resulting in higher electricity bills.  
         SUMMARY OF THE INVENTION  
         [0013]    Accordingly, it is an object of this invention to provide an apparatus and method to optimize power factor in single-phase installations of the home. Invention features allowing the accomplishment of this object include a single-phase home unit and a simple method of termination. Advantages associated with these achievements include reduced electrical consumption, reduced electric bills, and prolonged equipment life.  
           [0014]    It is still another object of the present invention to provide an apparatus and method of termination to optimize power factor whereby the required capacitance has been predetermined. Invention features allowing this object to be achieved include a large sampling of applications to determine a best-fit capacitance for the average dwelling. Advantages associated with this accomplishment include reduced electrical consumption, reduced electric bills, and prolonged equipment life. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0015]    The invention, together with the other objects, features, aspects and advantages thereof will be more clearly understood from the following in conjunction with the accompanying figures.  
         [0016]    [0016]FIG. 1 is a front isometric view of a single-phase home unit.  
         [0017]    [0017]FIG. 2 is an electrical schematic of a single-phase home unit depicting the recommended termination method to optimize power factor in the home.  
         [0018]    [0018]FIG. 3 is circuit diagram of one embodiment of the present invention. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0019]    The terms “single-phase home power factor correction unit,” “single-phase home unit” and “home unit” are used interchangeably throughout this specification.  
         [0020]    The terms “dwelling,” “home,” “house,” and “residential facility” are used interchangeably throughout this specification.  
         [0021]    The term “load” refers to anything plugged into or connected to power lines.  
         [0022]    The present invention provides a means to optimize the power factor of an entire house by terminating the home unit to the main electric power supply of a house. The novelty of the present invention lies in correcting many pieces of inductive equipment at one time, rather than, as in the prior art, attaching power factor correction equipment to each piece of equipment. The means for optimizing the power factor of an entire house include any of the prior art circuits utilized to correct power factor and installed at the main electric power supply of the house. However, the preferred embodiment of the present invention is provided in the following figures and their detailed description.  
         [0023]    [0023]FIG. 1 is a front isometric view of a single-phase home unit  2 . The home unit  2  of FIG. 1 is shown as a three-dimensional square. However, one of ordinary skill in the art would realize that the invention could be practiced utilizing any shape as long as the internal components were protected. Additional shapes include, but are not limited to, circular, cylindrical, rectangular and the like.  
         [0024]    First single-phase lead  26 , second single-phase lead  28  and ground lead  30  connect one or more capacitors to the electrical load whose power factor is being optimized. The electrical load whose power factor is being optimized can include residential, commercial and industrial facilities. In the preferred embodiment, the home unit  2  described herein is used on residential facilities. The leads are comprised of material suitable for their surroundings. The home unit  2  is constructed of materials suitable and safe for adverse weather conditions.  
         [0025]    A light  34  is visibly lighted when the home unit  2  is energized and also acts as a bleed-down resistor when the home unit  2  is disconnected from service. The light  34  can be any color and located anywhere on the home unit  2 .  
         [0026]    Most of the single-phase home unit  2  components are contained within enclosure  24 , with the leads  26 ,  28 ,  30  and the light  34 , discussed above, being the only components located on the outside of the home unit enclosure  24 . Of course, the home unit  2  may include warnings standard in the field, as is depicted in FIG. 1. Also, based on the physical and geographic location of the home unit  2 , the home unit enclosure  24  may be designed to withstand weather conditions, such as snow, wind, rain and the like, possibly by the inclusion of vents or slats. The home unit enclosure  24  is made of materials suitable to the climate in which it is located. For example, a home unit enclosure  24  located outside the home in a tropical environment may be made of sealed concrete to prevent the growth of mold and fungus. A home unit enclosure  24  located outside the home in New England may be made of galvanized metal. Whereas a home unit enclosure  24  located inside the home may be made of stainless steel. The materials of which the home unit enclosure  24  is made are not limited to those disclosed herein. One of ordinary skill in the art would be able to adapt the material of the home unit enclosure  24  to best suit its environment.  
         [0027]    [0027]FIG. 2 is an electrical schematic of a single-phase home unit  2  connected to a dwelling main power panel  40 . As shown in FIG. 2, the home unit  2  is adjacent to the dwelling main power panel  40 . However, one of ordinary skill in the art would be able to locate the home unit  2  anywhere and utilize leads  26 ,  28  and  30  to connect the home unit  2  to the dwelling main power panel  40 . As discussed above, the home unit  2  may be located inside or outside the home.  
         [0028]    Single-phase home unit  2  comprises a single-phase capacitor  20 . Single-phase capacitor  20  can be one or more capacitors connected in series, in parallel or in series-parallel. Each individual capacitor in the single-phase capacitor  20  can be passive; aluminum electrolytic, film, power film, metallized polyester, film/foil polyester metallized polypropylene, polypropylene film with double sided electrodes or solid tantalum; radial-metal can, axial-metal can, surface mount, metal can, surface mount, epoxy molded case, axial-tapewrap, radial-dip, or radial-box; comprising a capacitance range of 0.5 kVAR to 200 kVAR; and a voltage range of 110 VAC to 600 VAC. In the preferred embodiment utilized on a residential dwelling, any capacitor or combination of capacitors with the proper capacitance value as determined by one of ordinary skill in the art can be used as the single-phase capacitor  20 .  
         [0029]    The single-phase capacitor  20  is electrically connected to a first single-phase capacitor terminal  4  and a second single-phase capacitor terminal  6 . This electrical connection is usually part of the capacitor design. However, the present invention is not limited to such design and any method of connection known in the art may be utilized. The capacitor terminals,  4  and  6 , of the present invention comprise at least two connection points. First single-phase capacitor terminal  4  is electrically connected to first single-phase lead  26  and to first single-phase light lead  52 . The second single-phase capacitor terminal  6  is electrically connected to second single-phase lead  28  and to second single-phase light lead  50 .  
         [0030]    A light  34  is electrically connected by first and second single-phase light leads  50  and  52 . Ground lead  30  is electrically connected to the enclosure  48  and electrically connected to the main power panel ground terminal  46 .  
         [0031]    Although never intended, on occasion electronic circuitry experiences overload. This occurs when the electric load present in the circuitry is larger than the circuitry was designed to handle. The present invention may include an overload protection device  44 , which is electrically connected between first single-phase lead  26  and first single-phase line bus  54 . The overload protection device  44  of the present invention electrically isolates the first single-phase lead  26  from the first single-phase line bus  54  in case of an overload condition in first single-phase lead  26 . An overload protection device  44  may also be electrically connected between second single-phase lead  28  and second single-phase line bus  56 . Again, the overload protection device  44  electrically isolates the second single-phase lead  28  from the second single-phase line bus  56  in case of an overload condition in second single-phase lead  28 . Non-limiting examples of overload protection devices include fuses or circuit breakers.  
         [0032]    In one preferred embodiment of the present invention, there is one single-phase capacitor  20 , having a capacitance value of 80 microfarads and a working voltage rating of 440 VAC. The overload protection device  44  is a 20 amp circuit breaker. Enclosure  24  is made of metal.  
         [0033]    [0033]FIG. 3 provides the circuit diagram for another embodiment of the present invention. In this embodiment, the light  34  and the capacitor  20  are connected in parallel. Both are located within enclosure  24 . The optional overload protection device  44  is provided as a two-pole circuit breaker.  
       Termination of Single-phase Kilo VAR home Unit  2   
       [0034]    [0034]FIG. 2 shows single-phase home unit  2  connected to a dwelling main power panel  40  to optimize the power factor in the single-phase power panel  40 .  
         [0035]    In the field of electronics, termination means to electrically connect to each other. In the present invention, the home unit  2  is connected to the main power panel of a house. The preferred method of termination for single-phase home unit  2  is as follows:  
         [0036]    A. open single-phase overload protection device  44 , such as a circuit breaker;  
         [0037]    B. electrically connect first single-phase lead  26  to first single-phase circuit breaker terminal  36 ;  
         [0038]    C. electrically connect second single-phase lead  28  to second single-phase circuit breaker terminal  38 ;  
         [0039]    D. electrically connect ground lead  30  to power panel ground bus  46 ;  
         [0040]    E. close single-phase overload protection device  44 ; and  
         [0041]    F. observe indicator light  34  illumination indicating proper operation.  
         [0042]    The following table provides the average monthly cost and kilowatt usage in a residential dwelling before and after installation of one embodiment of the present invention. It is interesting to note that the number of people living in the dwelling actually increased, and therefore it can be extrapolated that power consumption increased, after installation of one embodiment of the present invention. However, the utility bill after installation is over fifteen percent (15%) lower than prior to installation.  
                                                     TABLE 1                                   Average                       Monthly               KiloWatts   Temperature   Average Monthly       Month   Year   Used   (° F.)   Cost                                August   2001   2261   83   214.77       September   2001   2042   81   194.93       October   2001   1556   75   150.92       November   2001   1071   69   106.99           Average   1732.5   77   166.90       March   2002   823   67   83.10       May   2002   1548   77   134.91       June   2002   1910   81   164.34       August   2002   1969   83   172.68           Average   1562.5   77   138.76       BEFORE       1732.5   77   166.90       AFTER       1562.5   77   138.76           Difference   170       28.14           Savings at   $13.60           $0.08 kwh                  
 
         [0043]    Table 2 provides a comparison of the utility bill for August before and after installation of the present invention for the same household. Again, although this household experienced an increase in the number of residents, the present invention provided almost a twenty percent (20%) reduction in utility costs.  
                                                                 TABLE 2                                           Kilo-       Ave.                   Watts   Average Monthly   Monthly           Month   Year   Used   Temperature (F.)   Cost                                    BEFORE   August   2001   2261   83 F.   214.77       AFTER   August   2002   1969   83 F.   172.68               Difference   292       42.09               Savings at   $23.36               $0.08 kwh                  
 
         [0044]    While preferred embodiments of the present invention have been illustrated herein, it is to be understood that changes and variations maybe made by those skilled in the art without departing from the spirit and scope of the appending claims.