Abstract:
An improved electrical equipment housing which includes an oil sample valve and a gas port assembly which are contained within the electrical equipment housing, yet are separated from electrical contacts and may be accessed without exposure to the electrical contacts.

Description:
TECHNICAL FIELD OF THE INVENTION 
       [0001]    The present invention is generally directed towards an apparatus to allow a user to safely obtain a fluid sample from oil-filled electrical equipment. 
       BACKGROUND ART OF THE INVENTION 
       [0002]    Large industrial electrical equipment, such as oil-filled pad mounted transformers, load tap changers, and the like, contain contacts and other parts which can wear out over time. Since these parts are located inside an oil-filled tank, it is very difficult to visually inspect them. Instead, dissolved gas analysis is often used to measure the level of “fault gases” in the oil. The level of fault gases may be used to estimate the condition of the equipment. However, dissolved gas analysis requires an oil sample to be taken from the transformer tank. Typically, the oil sample would be taken from a valve located on the tank within the transformer cabinet. Because the valve is inside the cabinet, alongside exposed electrical contacts, the transformer would need to be de-energized before the sample was taken to avoid the risk of injury or death to the person taking the sample. De-energizing a transformer is costly. What is needed is an apparatus that will allow a user to safely obtain an oil sample from electrical equipment without having to de-energize the equipment. The apparatus is preferably also tamper resistant. 
       SUMMARY 
       [0003]    Problems with prior art oil sampling are solved by providing an improved electrical equipment housing which includes an oil sample valve and a gas port assembly which are contained within the electrical equipment housing, and are separated from electrical contacts and may be accessed without exposure to the electrical contacts. The improved electrical equipment housing preferably comprises: a tank containing electrical equipment and a liquid; electrical contacts extending through a wall of the tank; a liquid sample port; an enclosure surrounding the electrical contacts and the liquid sample port; a cavity containing the liquid sample port, wherein the cavity is configured to substantially physically isolate the liquid sample port from the electrical contacts; and an opening in the enclosure configured to provide access to the cavity while maintaining substantial physical isolation of the liquid sample port from the electrical contacts. 
         [0004]    In one embodiment, the electrical equipment housing further comprises a lockable cover configured to selectively close the opening. 
         [0005]    In another embodiment, the electrical equipment housing further comprises a second opening, the second opening allowing access to the electrical contacts. 
         [0006]    In another embodiment, the electrical equipment housing further comprises a gas and a remote gas port contained in the cavity. 
         [0007]    Also provided is a remote sample kit for an electrical equipment housing comprising: a drain connector configured to connect to a drain valve of a tank; a remote sample port; a sample line connecting the drain connector to the remote sample port; and a remote housing containing the remote sample port and configured to attach to a wall of the electrical equipment housing. 
         [0008]    In another embodiment, the remote sample kit further comprises: a remote gas port; a gas connector configured to connect to a gas port of the tank; and a gas line connecting the remote gas port to the gas connector. 
         [0009]    In another embodiment, the remote housing also contains the remote gas port. 
         [0010]    In another embodiment, the remote sample kit further comprises an opening in the remote housing to allow access to the remote sample port through the wall of the electrical equipment housing. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]    For a more complete understanding of the present invention and for further advantages thereof, reference is now made to the following Description of the Preferred Embodiments taken in conjunction with the accompanying Drawings in which: 
           [0012]      FIG. 1  is a perspective view of a pad-mounted transformer with an embodiment of the present invention; 
           [0013]      FIG. 2A  is a view of a typical transformer cabinet. 
           [0014]      FIG. 2B  is a view of a typical transformer cabinet including an embodiment of the present invention; 
           [0015]      FIG. 3A  is a detailed view of a gas port assembly. 
           [0016]      FIG. 3B  is a detailed view of a gas port assembly configured for use in an embodiment of the present invention. 
           [0017]      FIG. 4A  is a detailed view of a drain valve. 
           [0018]      FIG. 4B  is a detailed view of a drain valve configured for use in an embodiment of the present invention. 
           [0019]      FIG. 5  is a detailed view of a remote collection station for use in an embodiment of the present invention. 
           [0020]      FIG. 6A  is view of a transformer cabinet with a remote collection station in a closed position. 
           [0021]      FIG. 6B  is view of a transformer cabinet with a remote collection station in an open position. 
           [0022]      FIG. 7  is a back view of a remote collection station. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0023]    Referring to  FIG. 1 , reference number  10  indicates a housing for electrical equipment used in electricity distribution. The equipment shown and discussed herein is a pad-mounted transformer, although the disclosed invention may be used in connection with other electrical equipment. Transformer  10  comprises a cabinet  12 , a tank  14 , and radiator  16 . Cabinet  12  comprises main doors  102  and a remote collection station  50 . Main doors  102  and remote collection station  50  are shown in a closed configuration. In this configuration, main doors  102  and remote collection station  50  are preferably locked to restrict access to components (shown in  FIG. 2 ) within cabinet  12 . 
         [0024]      FIG. 2A  shows the inside of cabinet  12  without the improvements of the disclosed invention. A number of items are attached to a back wall  202  of transformer cabinet  12 , including low-voltage contacts  204 , high voltage contacts  206 , and a tank thermometer  208 . Low-voltage contacts  204  and high voltage contacts  206  are conductively connected to electrical equipment such as transformer windings (not shown) in tank  14 . Near a top of back wall  202  is a gas port assembly  30  (discussed in connection with  FIGS. 3A and 3B ). Near the bottom of back wall  202  is a drain valve  40  (discussed in connection with  FIGS. 4A and 4B ). 
         [0025]      FIG. 2B  shows the inside of cabinet  12  including an embodiment of the present invention. Cabinet  12  further comprises remote collection station  50 , a gas line  222 , and an oil sample line  224 . Gas line  222  and oil sample line  224  are discussed in more detail below. To minimize clutter and the risk of hose damage, gas line  222  and oil sample line  224  are preferably secured to back wall  202  by clips, zip ties, or the like. 
         [0026]      FIG. 3A  is a closer view of a typical gas port assembly  30  found in transformer cabinets. Gas port assembly  30  includes a pressure-vacuum gauge  302 . Pressure-vacuum gauge  302  indicates the pressure within tank  14 . To avoid contamination, tank  14  must have a positive internal pressure before drain valve  40  may be opened to obtain a sample. Gas port assembly  30  also comprises a pressure-relief valve  304  which vents gasses from inside tank  14  if the internal pressure exceeds a predetermined level. 
         [0027]      FIG. 3B  is a closer view of gas port assembly  30  configured for use in an embodiment of the disclosed invention. A T-junction  322  is installed between pressure-relief valve  304  and back wall  202 . T-junction  322  includes a first hose barb  324 . Gas line  222  attaches at one end to the first hose barb  324  and at an opposite end to a remote gas assembly  502  (discussed below in connection with  FIG. 5 ). Pressure-vacuum gauge  302  in  FIG. 3A  is shown in  FIG. 3B  as removed and replaced by T-junction  322  with first hose barb  324  attached. Alternatively, first hose barb  324  could replace pressure-relief valve  304 . First hose barb  324  is preferably a ¼″ hose barb. Gas line  222  may be secured to first hose barb  324  using a hose clamp (not shown). Alternatively to using a hose barb and hose clamp, other methods of connecting gas line  222  to the gas port assembly  30  are known and may be used. Alternatively to connecting the gas line  222  to gas port assembly  30 , a dedicated port (not shown) for connecting the gas line  222  may be provided during construction of tank  14  or may be added to tank  14  after construction by defining a hole in tank  14  and adding a threaded adaptor, hose barb, or the like to tank  14 . Alternative gas line connection ports should be located sufficiently high on tank  14  so that the connection ports are above the oil level in tank  14 . 
         [0028]      FIG. 4A  is a closer view of a typical drain valve  40 . Drain valve  40  comprises a control handle  402  configured to open and close drain valve  40 . Drain valve  40  also comprises a sample device  404 . Sample device  404  allows a technician to remove an oil sample from tank  14 . Typically, the sample is removed using a syringe (not shown). 
         [0029]      FIG. 4B  is a closer view of a drain valve  40  configured for use in the present invention. In  FIG. 4B , drain plug  426  has been removed, and second hose barb  424  is installed in its place, along with a reducer  428 . Alternatively, sample device  404  may be removed and replaced with a second hose barb  424 . An oil sample line  224  (see  FIG. 2B ) preferably connects at one end to drain valve  40  via second hose barb  424  and at an opposite end to a remote sample assembly  540  (discussed below in connection with  FIG. 5 ). Second hose barb  424  is preferably a ⅝″ hose barb. Oil sample line  224  may be secured to second hose barb  424  using a hose clamp (not shown). Alternatively to using a hose barb and hose clamp, many other methods of connecting oil sample line  224  to drain valve  40  are known and may be used. Alternatively to connecting oil sample line  224  to drain valve  40 , a dedicated port (not shown) for connecting the oil sample line  224  may be provided during construction of tank  14  or may be added to tank  14  after construction by defining a hole in tank  14  and adding a threaded adaptor (not shown), hose barb, or the like to tank  14 . The alternative oil sample line connector ports, if used, are preferably located near the bottom of tank  14 . 
         [0030]      FIG. 5  shows a closer view of remote collection station  50 . Remote collection station  50  comprises a mounting flange  502  which is configured to attach to a side wall  602  of cabinet  12 . Mounting flange  502  preferably comprises steel sheet metal. Remote collection station  50  comprises a cover  512  that is attached to mounting flange  502  by hinge  514 . Preferably, hinge  514  is a type that is tamper-resistant when closed. A lock receiver  522  is permanently attached to mounting flange  502 . Lock receiver  522  is configured to protrude through a lock receiver hole  524  defined in cover  512 . Once cover  512  is closed, lock receiver  522  may be twisted  90  degrees to hold cover  512  in a closed position. Remote collection station  50  may be secured by inserting a lock  604  (shown in  FIG. 6A ) through lock receiver  522  when cover  512  is in a closed position. Remote collection station  50  also preferably includes a weather shield  558 , attached to mounting flange  502 . Whether shield  558  is configured to at least partially shield remote collection station  50  from precipitation. Weather shield  558  is preferably integrally constructed from the same piece of metal as mounting flange  502 . 
         [0031]    Inside remote collection station  50  are remote gas assembly  530  and remote sample assembly  540 . Remote gas assembly  530  preferably comprises a pressure gauge  532 . Pressure gauge  532  allows a user to easily verify that a positive pressure exists in tank  14  before taking an oil sample. Remote gas assembly  530  also preferably comprises an inlet port  534 , through which a user may apply a gas (not shown), such as nitrogen or dry air, to increase the pressure in tank  14 , if necessary. Remote sample assembly  540  comprises a shutoff valve (not shown) which is operated by valve handle  542 . Remote sample assembly  540  also comprises remote sample device  544 . Remote sample device  544  is preferably a typical sample device as is known in the prior art. However, remote sample device  544  may be any device capable of allowing a user to remove an oil sample from tank  14  without excessive contamination of the sample. 
         [0032]    Back wall  550  and a remote collection station side wall  552  define a cavity  556 . Cavity  556  preferably contains remote gas assembly  530  and remote sample assembly  540 . Cavity  556  is configured to physically isolate remote gas assembly  530  and remote sample assembly  540  from other components within cabinet  12 , such as low voltage contacts  204  and high voltage contacts  206 . This physical separation reduces the risk of death or injury to technicians from arcing while taking samples. To further increase safety, back wall  550  and remote collection station side wall  552  preferably comprise a conductive material, such as steel, and are conductively connected to side wall  602 . Preferably, cavity  556  is configured so that remote gas assembly  530  and remote sample assembly  540  are separated from low voltage contacts  204  and high voltage contacts  206  by a substantially continuous partition composed of one or more of back wall  550 , remote collection station side wall  552 , mounting flange  502  and side wall  602 . 
         [0033]      FIGS. 6A and 6B  show a side view of cabinet  12 . Cabinet  12  includes side wall  602 , which comprises remote collection station  50 . In  FIG. 6A , the remote collection station  50  is shown in a closed configuration. In the closed configuration, the interior of the remote collection station  50  is inaccessible. Preferably, remote collection station  50  includes a lock  604  configured to restrict unauthorized access to the interior of remote collection station  50  and render its components tamper resistant.  FIG. 6B  shows a side view of cabinet  12  with remote collection station  50  in an open configuration, allowing access to remote gas assembly  530  and remote sample assembly  540 . Although remote gas assembly  530  and remote sample assembly  540  are accessibly, access to other components is blocked by back wall  550  and remote collection station side wall  552 . 
         [0034]      FIG. 7  shows a rear view of remote collection station  50 . Mounting studs  506  are seen extending through side wall  602 . Mounting studs  506  are preferably 1″ long threaded rods which are welded to mounting flange  502  and are secured to side wall  602  by mounting nuts  714 . Portions of remote gas assembly  530  and remote sample assembly  540  are seen extending through back wall  550 . Remote gas assembly  530  and remote sample assembly  540  preferably include threaded portions and may be secured to a back wall  550  of the remote collection station  50  by ½″ nuts  712 . Remote gas assembly  530  and remote sample assembly  540  preferably comprise hose attachments  704  for connecting gas line  222  to remote gas assembly  530  and connecting oil sample line  224  to remote sample assembly  540 . Gas line  222  and oil sample line  224  are preferably secured to hose attachments  704  by hose clamps  706 . 
         [0035]    In one embodiment, the improvement disclosed herein may be offered as a kit comprising remote collection station  50 , remote gas assembly  530 , remote sample assembly  540 , gas line  222 , sample line  224 , T-junction  322 , first hose barb  324 , and second hose barb  424 . The kit may be used to improve safety for existing electrical equipment. The kit is preferably installed by first defining a hole (not shown) in side wall  602  using a knockout punch or a hole saw. Next, remote collection station  50  is temporarily placed in the hole, remote collection station  50  is leveled, and mounting holes locations are marked. Next mounting holes (not shown) are defined in side wall  602 , using a drill. Next, mounting studs  506  are positioned in the mounting holes and mounting nuts  714  are installed. Then, T-junction  322  and first hose barb  324  are added to gas port assembly  30 . Next, second hose barb  424  is attached to drain valve  40 . Next, gas line  222  and sample line  224  are cut to the desired length. Then, gas line  222  is connected to first hose barb  324  and sample line  224  is attached to second hose barb  424 . Next, gas line  222  and sample line  224  are secured to back wall  202  or side wall. After sample line  424  is attached, drain valve  40  should be opened. 
         [0036]    Although the invention has been described with reference to specific embodiments, this description is not meant to be construed in a limiting sense. Various modifications of the disclosed embodiments, as well as alternative embodiments of the inventions, will be apparent to persons skilled in the art upon reference to the description of the invention. It is, therefore, contemplated that the appended claims will cover such modifications that fall within the scope of the invention.