Abstract:
A submersible transformer assembly including a housing for holding an electrical transformer and having an aperture in a top panel of said housing for receiving a photocell assembly, the photocell assembly including a photocell positioned above the housing and electrically coupled with a socket held within the aperture by a socket retainer mounted to the underside of the housing top panel below the aperture. A transparent photocell cover or lens is mounted on top of the housing in covering and sealing relationship with the photocell and the aperture. The transformer positioned within the housing is electrically governed by the photocell which switches power to the transformer on and off in response to changes in ambient light conditions.

Description:
BACKGROUND OF THE INVENTION 
   The present invention relates to transformers for supplying power to lighting fixtures or other electrical equipment, such as fountains positioned in bodies of water, and which utilize photocells to control the power supplied by the transformer in response to changes in ambient light levels. 
   Transformers for providing electrical power to outdoor utilities or fixtures, including sub-grade or underwater lighting, are known in the prior art and include transformers for supplying low voltage power thereto. Photocells have been used to control electrical power supplied to fixtures associated with such transformers; however, they are typically separated by a length of conduit from the body of the transformer. While operable, such systems often require some on-site assembly and existing systems are not known to have been rated for submergence. The transformers used in such systems are typically maintained on shore or on a float associated with the lighting or other electrical equipment and are not specifically intended to be submerged. However, the current National Electric Code (2005) requires that electrical equipment and transformers that are maintained within a certain vertical distance relative to a normal level for specified types of bodies of water must be rated for submergence. 
   As used herein, the term “photocell” refers to a pre-assembled, photoelectric component existing in the prior art. A photocell typically includes a photodetector such as a photoresistor, photodiode, phototransistor or photovoltaic cell. Photocells, and associated circuitry and mounting hardware, may be used to regulate 120V or 240V electrical power such that power is allowed to flow through the regulated circuit when no or minimal light strikes the photocell, and power is not allowed to flow through the regulated circuit when light, of an intensity typically considered sufficient to constitute daylight, strikes the photocell. Most commonly, the photosensitivity of a photocell is provided by a cadmium sulfide photoresistor. 
   The term “transformer” is intended to have its ordinary meaning and generally refers to an electrical device that uses magnetic coupling to enable a primary circuit to induce a current in a secondary circuit. Typically, high voltage electrical power is provided to the transformer, in which lower voltage electrical power is thereby induced. 
   BRIEF SUMMARY OF THE INVENTION 
   A submersible power supply includes a transformer sealed within a waterproof housing and a photocell also sealed within the housing by a transparent or translucent cover such that light may pass through the cover to strike the photocell. The photocell regulates the transmission of low voltage current, provided by the transformer, to one or more low voltage electrical fixtures or appliances such as submerged lamps. 
   One embodiment of the submersible power supply includes a housing having a bottom, a peripheral sidewall and a top panel. A portion of the housing, typically the top panel, is removably securable to the rest of the housing a watertight seal to provide access to an interior of the housing in which the transformer is mounted. 
   An aperture extends through the top panel of the housing. A photocell socket is disposed within the housing and below and in general axial alignment with the top panel aperture. The photocell socket is retained in place by a socket retainer attached to the bottom of the housing top panel. Preferably, the electrical connections of the socket are rendered watertight by filling a portion of the socket retainer with an approved potting compound. 
   Electrical connectors (not shown) on the photocell are inserted into the socket through the aperture in the housing top panel to electrically couple the photocell to the socket. The photocell typically projects upward from the aperture so that it extends above the top panel of the housing. The photocell is protected, and the aperture fully closed and rendered watertight, by attaching a photocell cover, cap or lens to the housing top panel and over the photocell. The photocell cover is at least translucent and preferably substantially transparent. An appropriate photocell cover may be formed of clear acrylic plastic. The photocell cover includes a closed top end and a perimeter wall or side projecting downward from the top end. The bottom margin of the wall defines a bottom opening. A flange projects radially outward from the bottom margin of the wall to surround the bottom opening. The photocell cover is positioned over the photocell so that the photocell is enclosed by the wall and top end. Bolts or screws attach the photocell cover to the top panel of the housing, squeezing or compressing the gasket and forming a watertight seal. Typically the photocell cover, the photocell, the aperture in the housing top panel, the socket and the socket retainer are in substantial axial alignment with one another. 
   The transformer is positioned and retained within the housing by bosses projecting upward from the bottom of the housing and downward from the bottom surface of the top panel. The bosses cooperate to hold the transformer in place within the housing so that it does not shift when the power supply is moved. The transformer is in electrical engagement with the photocell so that electrical power provided by the transformer to electrical fixtures or appliances exterior to the housing is regulated by the photocell in response to ambient light levels. 

   
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
       FIG. 1  is a perspective view of a submersible power supply according to the present invention. 
       FIG. 2  is an exploded, perspective view of the submersible power supply of  FIG. 1 . 
       FIG. 3  is a partially schematic view showing all internal components of a submersible power supply in diagrammatical cross-section and in particular showing the photocell cover, photocell, photocell cover gasket, photocell socket and retainer, and cover sectioned along line  3 - 3  in  FIG. 1 . 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   As required, a detailed embodiment of the present invention is disclosed herein; however, it is to be understood that the disclosed embodiment is merely exemplary of the invention, which may be embodied in various forms. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a basis for the claims and as a representative basis for teaching one skilled in the art to variously employ the present invention in virtually any appropriately detailed structure. 
   Referring to the drawings, a submersible power supply  1  comprises an electrical transformer  4  (typically 120V or 240V AC primary voltage to 12V AC secondary voltage) mounted within an interior compartment  5  of a water tight housing  6  and a photocell assembly  8  mounted on and projecting upward from a cover or top panel  10  of the housing  6 . The photocell assembly  8  is electrically connected to a transformer circuit  13  as described in more detail hereafter and shown schematically in  FIG. 3 . 
   In the embodiment shown, in addition to the top panel  10 , the housing  6  includes a relatively planar bottom  15  and a continuous sidewall  16  extending upward from the bottom  15  to an open upper end  17 . The sidewall  16  is formed from four relatively planar side panels. The top panel  10  is removably securable to the upper end  17  of the sidewall  16 . Although the housing is shown with a removable top panel or cover  10  to provide access to the interior compartment  5  thereof, alternatively the bottom  15  or one or more of the side panels  16  could be removable to provide such access. The dimensions and shape of the housing and the sides, top panel and bottom thereof may be varied. 
   A sealing flange  20  is formed on and projects radially outward from the upper end  17  of sidewall  16 . The top panel or lid  10  of the housing is sized slightly larger than the sidewall sealing flange  20 . A gasket or other flexible sealant or sealing member  22  is positioned on the sealing flange  20  and beneath the outer periphery of the housing top panel  10  when it is positioned across the open upper end  17  of sidewall  16 . The top panel  10  is secured in place and drawn toward the sealing flange by bolts  24  and nuts  25 , or other appropriate fasteners, to form a water-tight seal around the margins of the sidewall upper end  17 . The housing  6  is typically formed via injection molding or via vacuum forming of polymeric plastic material. Other rigid, water impermeable materials may be used but reference should be made to appropriate laws or codes covering electrical fixtures, particularly fixtures for use when submerged in water, prior to selected materials. 
   An appropriate transformer  4  may be selected from devices in the prior art in consideration of power supply requirements of lighting units or other electrical devices to be powered by the transformer  4 . Preferably, the transformer  4  selected is manufactured to pool and spa specifications and can withstand submersion without creating a shock hazard should the housing  6  be damaged. The transformer  4  is positioned and retained within the housing  6 , typically by bosses  28  projecting upward from the bottom  15  of the housing  6  and downward from the lower surface of the housing top panel  10 . The bosses  28  are typically integrally formed in the housing bottom  15  and top panel  10 . 
   Line voltage (typically 120V or 240V which may be referred to as high voltage herein) is supplied to the transformer  4  through an inlet power supply cable (not shown) which is removably connectable to the transformer circuit  13  through a first submersible electrical connector  30  mounted on the housing sidewall  16 . A second submersible electrical connector  32  is also mounted on the housing sidewall  16  and connected to the transformer circuit  13  for distributing reduced voltage electricity (typically 12V which may be referred to as low voltage herein) through an outlet power supply cable (not shown) removably connectable thereto. Appropriate submersible electrical connectors  30  and  32  are to be rated IP  68  which facilitate formation of a watertight seal between the IP  68  connectors and the power supply cables (not shown) connected thereto. The IP (ingress protection) rating system is maintained by the International Electrotechnical Commission (IEC). An IP  68  device is completely sealed against infiltration by particulates and water. 
   Each submersible connector  30  and  32  is attached to and extends through an opening in the housing sidewall  16 . An epoxy  33  may be used to fill any voids between the connectors  30  and  32  and the sidewall  16  to form a watertight seal. 
   The photocell assembly  8  includes a photocell  35 , a photocell socket  37 , a socket retainer  39  and a photocell cover  41 . Referring to  FIG. 3 , an opening or aperture  45  is formed in the top panel  10  of the housing  6  through which the photocell assembly  8  extends and through which it is connected to the transformer circuit  13 . The socket retainer  39 , which is generally bowl shaped, is mounted to and extends below the housing top panel  10  around the aperture  45 . Typically, the socket retainer  39  is adhered to the bottom of the housing top panel  10  using an epoxy adhesive which forms a seal therebetween, however, it is to be understood that the socket retainer  39  could be integrally formed with the housing top panel  10 . 
   The photocell socket  37  is mounted in the socket retainer  39  with an upper surface of the socket extending flush with or above an upper surface of the housing top panel  10  or accessible through the aperture  45 . Screws  40  are passed through the socket  37  and the housing top panel  10  to engage bosses  42  projecting laterally from the retainer  39 . The photocell  35  includes male connectors (not shown) at a lower end thereof for connecting to receptacles (not shown) in the socket  37 . The photocell socket  37  is wired to the transformer circuit through an opening in a lower end of the socket retainer  39  as discussed in more detail below. 
   The photocell cover  41 , which may also be referred to as a water shield or water shield cover, a cap or a lens is made of translucent or transparent material to allow light to pass through the lens  41  and strike the photocell  35 . The lens  41  may be molded, for example, from an acrylic plastic. The photocell cover  41  as shown is generally cup shaped with a closed top  51 , a cylindrical sidewall  52 , and an open bottom end  54  with a mounting flange  56  extending radially outward from the open bottom end  54 . The photocell cover  41  is positioned over and in covering relationship with the photocell  35  and the socket  37 . A photocell cover sealing gasket  58 , or primary photocell seal, is positioned between the photocell cover mounting flange  56  and an upper surface of the housing top panel  10  around the aperture  45 . The photocell cover  41  is bolted to the housing top panel  10  with bolts  62  extending through the mounting flange  56  and the top panel  10  and secured in place with nuts  63 , with the gasket  58  forming a watertight seal therebetween. A socket sealing member or gasket  65 , or secondary photocell seal, may be positioned between the photocell socket  37  and the housing top panel  10  to form a seal between the socket  37  and the housing top panel  10 . Appropriate materials for forming the gaskets or seals  22 ,  58  and  65  include rubber, silicone, viton, neoprene, vinyl, nitrile, or urethane. A potting compound  68  is typically applied to the wiring for the photocell socket  37  in the socket retainer  39  to assure a water tight seal should the photocell cover ever become cracked or broken, or should the primary or secondary seals  58  and  65  fail. 
   The photocell  35  functions as a switch to selectively allow or disrupt the flow of high voltage electricity to the transformer  4  through the transformer circuitry  13 , thereby concomitantly allowing or interrupting the supply of lower voltage electricity to any devices operated off the transformer. 
   The transformer circuit  13  includes first and second line voltage leads  72  and  74  connecting the first connector  30  to the transformer  4 , with the second line voltage lead  74  connected through the photocell  35 . In particular, a first leg  75  of the second line voltage lead  74  extends from the first connector  30  to a first terminal (not shown) on the photocell socket  37 . A second leg  76  of the second line voltage lead  74  extends from a second terminal (not shown) on the photocell socket  37  to the transformer  4 . Branch wire  77  extends from a third terminal (not shown) on the photocell socket to the first line voltage lead  72  such that power is continuously supplied to the photocell  35  through a power line connected to the first connector  30 . First and second low voltage or reduced voltage leads  80  and  82  extend between the transformer  4  and the second, reduced voltage connector  32 . Because the photocell  35  is connected to one of the leads, lead  74 , extending between the first connector  30  and the transformer  4 , the photocell  35  operates to selectively supply power to or turn on and off the transformer  4 . 
   In accordance with the foregoing, when the photocell  35  is in an open state, high voltage electricity flows through the transformer  4  generating low voltage electricity which can be delivered to a selected electrical device through the second or low voltage electrical connector  32 . Typically, the photocell  35  is selected to maintain an open state when ambient light levels are low, as during night, and to maintain a closed state when ambient light levels are high, as during day. The photocell  35  is preferably of the type that may be used to regulate 120V or 240V electrical power supplied to the transformer such that power is allowed to flow through the transformer circuit  13  when no or minimal light strikes the photocell  35 , and power is not allowed to flow through the transformer circuit  13  when light, of an intensity typically considered sufficient to constitute daylight, strikes the photocell  35 . 
   By selecting appropriate, waterproof material for the lens gasket  58  and lid gasket  22  from the materials described above (or functional equivalents), polymer plastic materials such as PVC, ABS, GLV80 or equivalent material for the housing  6 , acrylic plastic or equivalent material for the lens  41 , and IP  68  rated electrical connectors  30  and  32 , and use of approved potting compounds  68 , the embodiment of the invention discussed above meets or exceeds standards set by the National Electric Code for resistance to water infiltration as an entire unit, including Articles 680.52(B)(2) and 682.10. In tests, the interior of the embodiment described remained dry after submergence to a depth of 5 feet for 24 hours. 
   It is to be understood that while certain forms of this invention have been illustrated and described, it is not limited thereto except insofar as such limitations are included in the following claims and allowable equivalents thereof.