Abstract:
A conversion kit for providing a sealed environment for containing a remote monitoring system transmitter and providing electrical connections between the transmitter and an existing environmentally sealed cable harness. The existing cable harness is terminated by a boot adapted to surround a cylindrical structure for environmental sealing contact therewith. The conversion kit includes an adaptor cable harness having terminations at a first end for mating with the terminations of the existing cable harness and terminations at a second end for mating with connectors of the transmitter. The conversion kit also includes an enclosure for containing the transmitter. The enclosure is formed with cylindrical structure at an open end thereof which is surroundable by the boot.

Description:
BACKGROUND OF THE INVENTION 
   This invention relates to a remote monitoring system transmitter for use in an underground utility vault and, more particularly, to a conversion kit whereby the type of transmitter can be changed without changing the existing transmitter cabling, even though the transmitter cable terminations are different. 
   The need for remote monitoring capability of operating conditions existing at individual transformers in an underground vault of an underground network power distribution system is well known in the art. Ideally, information such as three phase load currents on transformers, status of network protectors, oil temperatures of transformers in excess of specified limits, water levels, fuse status, and surrounding environmental concerns such as vault access, air temperatures, etc., are required so that critical decisions can be made regarding network switching, problem analysis, peak load analysis, contingency studies, etc. 
   For example, the Remote Monitoring System manufactured by BAE Systems is typical of the current approach to meeting these requirements. This apparatus is a power line carrier system designed specifically to use network distribution feeders as the communications medium between network distribution transformers, located in underground vaults, and the substation. The system consists of a transmitter and sensors installed at the distribution transformer to be monitored and a receiver located at the network substation. The sensors provide input data, such as transformer load currents and network protector position, to the transmitter, which periodically transmits the information, including vault identification, by power line carrier signal over the distribution feeder to the substation receiver. Coupling of the signal to the feeder is accomplished by direct connection to the low voltage side of the network distribution transformer. At the substation, the signal is magnetically detected from the feeder by means of a pick-up coil attached to the feeder cable. Direct electrical connection to the feeder is not required. The substation receiver decodes the signal information and stores the data for presentation on demand. The receiver is microprocessor controlled. In addition to cross referencing data to the actual vault identification, the receiver produces the data in numerous “by exception” formats controlled by command inputs. Network protector status and transformer loading prior to and following feeder outages, are available, thereby reducing the need for feeder patrols. Peak period transformer loading data is instantly available for the whole network simultaneously for more accurate planning than was previously possible with manual measurements, which are not concurrent. Monitoring of spot networks, local areas, and critical locations for maintenance work can be achieved remotely without the need for field crews to be on-site to check status. 
   Up to now, the above-described transmitter, identified as Model 2391, has been in the form of a sealed cylindrical tube, having connectors on a first end for connection to complementary terminations at a first end of an otherwise environmentally sealed cable harness. The cable harness is connected at its second end to the network distribution transformer in the vault. To protect the transmitter connectors and cable harness terminations from the environment in the vault, which may be wet, the cable harness is equipped with a boot at its first end. After the cable harness terminations are mated to the transmitter connectors, the boot is slipped over the first end of the cylindrical transmitter and environmentally sealed thereto by means of a large hose, or ribbon, clamp. 
   Due to technological advances and the need for additional monitoring features, the transmitter has been redesigned, and may be identified as Model 2777. With this redesign, the transmitter is no longer in the form of a cylindrical tube, but instead now has a generally rectilinear and boxlike configuration. Additionally, the connectors on the new transmitter are different from the connectors on the old transmitter. Thus, if an old transmitter is to be replaced by a new transmitter, the new transmitter cannot be connected directly to the existing cable harness. It would be desirable to be able to connect the new transmitter to the existing cable harness because this would obviate the need to change internal wiring of the associated transformer, an arduous and time consuming task. 
   The environment in the underground vault requires that the transmitter and its connections be environmentally sealed. Since the new transmitter design is boxlike instead of cylindrical, the old manner of sealing the transmitter/cable connections is not possible. It would therefore be desirable to be able to provide a sealed environment for the new transmitter design and the transmitter/cable connections. 
   SUMMARY OF THE INVENTION 
   According to the present invention, there is provided a conversion kit for providing a sealed environment for containing a remote monitoring system transmitter and providing electrical connections between the transmitter and an existing environmentally sealed cable harness, wherein the existing cable harness is terminated by a boot adapted to surround a cylindrical structure for environmental sealing contact therewith. The conversion kit comprises an adaptor cable harness having at least one termination at a first end for connecting to the existing cable harness and having at least one termination at a second end for connecting to the transmitter. The conversion kit further comprises an enclosure for containing the transmitter, the enclosure having an open end formed as the cylindrical structure surroundable by the boot. 
   In accordance with an aspect of this invention, the enclosure includes a hollow structure sized to accept the transmitter therein and having first and second open ends, with the second open end of the hollow structure being formed as the cylindrical structure surroundable by the boot. A cover piece is adapted to seal the first open end of the hollow structure. 
   In accordance with another aspect of this invention, the kit further includes at least one spacer element adapted for insertion between the transmitter and the interior of the hollow structure. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The foregoing will be more readily apparent upon reading the following description in conjunction with the drawings in which like elements in different figures thereof are identified by the same reference numeral and wherein: 
       FIG. 1  is a perspective view of the prior art cylindrical tube transmitter, showing the connectors on one end; 
       FIG. 2  is a perspective view showing the transmitter of  FIG. 1  connected to the environmentally sealed cable harness and having the transmitter/cable connections environmentally sealed by a boot which is part of the cable harness; 
       FIG. 3  is a perspective view showing the new transmitter design; 
       FIG. 4  is a perspective view showing an adaptor cable harness according to the present invention; 
       FIGS. 5A ,  5 B and  5 C are perspective views showing exemplary pieces which may be utilized to together form an enclosure for the transmitter, according to the present invention; 
       FIG. 6  is a cross-sectional view showing an assembled exemplary enclosure formed from the pieces shown in  FIGS. 5A ,  5 B and  5 C; and 
       FIG. 7  is a perspective view showing the assembled enclosure with the transmitter, spacer elements and adaptor cable harness contained therein, with the adaptor cable harness connected between the transmitter and the existing cable harness and with the existing cable harness boot sealing the enclosure, according to the present invention, wherein the enclosure and the boot are shown in phantom (broken lines). 
   

   DETAILED DESCRIPTION 
   Referring to the drawings,  FIG. 1  shows the Model 2778 cylindrical tube transmitter, designated generally by the reference numeral  10 , which is installable in an underground utility vault of an underground network power distribution system as part of a remote monitoring system. On the end  12  of the transmitter  10  are the connectors  14  and  16 , which connect to terminations  18  and  20 , respectively, ( FIG. 7 ) at a first end of the cable harness  22  ( FIG. 2 ). The cable harness is sealed against the environment by encasing its wires in an outer protective rubber or plastic covering. The other end (not shown) of the cable harness  22  is connected to the network distribution transformer in the vault and enters the transformer casing through a sealed opening, as is known in the art. The first end of the cable harness  22  is provided with a boot structure  24  surrounding the terminations  18 , 20  and sealingly connected to the outer protective covering of the cable harness  22 . As shown in  FIG. 2 , the boot  24  is slipped over the end  12  of the transmitter  10  (after the cable terminations  18 , 20  are connected to the connectors  14 , 16 ) and is then securely attached thereto by means of the large hose, or ribbon, clamp  26 . This provides a protective sealed environment for the connectors  14 , 16  and the terminations  18 , 20 . 
     FIG. 3  shows a transmitter, designated generally by the reference numeral  30 , which was designed to replace the transmitter  10 . Instead of the cylindrical configuration of the original transmitter  10 , the replacement transmitter  30  is generally rectilinear, or boxlike. In addition, the connectors  32  and  34  of the replacement transmitter  30  are markedly different from the connectors  14  and  16  of the original transmitter  10 . It is therefore apparent that the existing cable harness  22  used with the original transmitter  10  cannot be used with the replacement transmitter  30 , either to make electrical connections thereto or to provide a sealed environment for the connectors  32 , 34 . As will be described in full detail hereinafter, according to this invention, there is provided a conversion kit which provides connections between the replacement transmitter  30  and the existing cable harness  22  and also provides a sealed environment for the replacement transmitter  30 . Because the existing cable harness  22  is not disturbed when the original transmitter  10  is replaced by the transmitter  30  and the inventive conversion kit is utilized, there is no need to perform any rewiring of the transformer to which the existing cable harness  22  is connected. 
     FIG. 4  shows an adaptor cable harness  36  which is part of the inventive conversion kit. At a first end of the adaptor cable harness  36  are terminations  38 , 40  for mating engagement with the terminations  18 , 20 , respectively, of the existing cable harness  22 . Thus, the termination  38  emulates the connector  14  of the original transmitter  10  and the termination  40  emulates the connector  16  of the original transmitter  10 . At the other end of the cable harness  36  are terminations  42 , 44  for mating engagement with the connectors  32 , 34 , respectively, of the replacement transmitter  30 . As will be described hereinafter, after installation, the adaptor cable harness  36  is within a sealed environment, so there is no need to provide it with its own outer protective covering, in contrast to the existing cable harness  22 . 
     FIGS. 5A ,  5 B and  5 C show exemplary pieces which may be utilized to together form the enclosure of the inventive conversion kit. Illustratively, those pieces are PVC pipe fittings manufactured by Plastic Trends, Inc. of Shelby Township, Mich. Thus, the piece  46  is a reducer coupling, the piece  48  is a fitting cleanout adaptor and the piece  50  is a threaded plug. The sizes of the pieces  46 , 48 , 50  are determined by the size of the transmitter, which fits inside the pieces  46 , 48 , 50  when they are assembled to form an enclosure, as shown in  FIG. 6 . The piece  48  is hollow and is generally cylindrical with first and second open ends  52 , 54 , respectively. Illustratively, the transmitter  30 , when viewed from its end  31 , is approximately 4⅝ inches wide and 5⅝ inches high, so the exemplary piece  48  is selected as Plastic Trends part number P1508 with an inner diameter of slightly more than nine inches. 
   The cover piece  50  is a generally planar disc having external peripheral threads  56  for engaging the internal threads  58  at the first open end  52  of the piece  48 . The cover piece  50  also has a central boss  60  with a plurality (illustratively four) of flat sides  62  which may be gripped by a wrench, or the like, to turn the cover piece  50  for attachment to the piece  48 . Illustratively, the exemplary cover piece  50  is selected as Plastic Trends part number P1158. 
   The piece  46  is a hollow piece with first and second open ends  64 , 66 , respectively, and is made up of three sections. The first section  68  includes the open end  64  and is generally cylindrical so that it can telescopically surround the open end  54  of the piece  48 , as best seen in  FIG. 6 . The second section  70  includes the open end  66  and is also generally cylindrical. The diameter of the second section  70  is substantially the same as that of the original cylindrical transmitter  10  so that the boot  24  can be placed snugly thereover. The third section  72  is a transitional section between the first and second sections  68 , 70  and is therefore of frusto-conical shape to account for the diametric difference between the first and second sections  68 , 70 . Illustratively, the exemplary piece  46  is selected as Plastic Trends part number P608-4. 
   The inventive conversion kit also includes two spacer elements  74 , 76  ( FIG. 7 ) which are formed of resilient material, such as a urethane foam. The spacer elements  74 , 76  can be cut from a cylindrical piece of foam so that they each have a planar side which can contact a side of the transmitter  30  and an opposing side which conforms substantially to the interior of the enclosure piece  48 . Alternatively, each spacer element  74 , 76  can be a sheet of foam material which is rolled up and inserted between a respective side of the transmitter  30  and the interior of the enclosure piece  48 . 
   To use the inventive conversion kit to replace the original cylindrical transmitter  10  by the box transmitter  30 , first the end  64  of the enclosure section  46  is slid over the end  54  of the enclosure section  48  and the two sections are secured to each other by glue. Next, the clamp  26  is loosened, the boot  24  is removed from the end of the transmitter  10  and the cable terminations  18 , 20  are separated from the connectors  14 ,  16 . The adaptor cable harness  36  is then connected to the box transmitter  30  by mating the cable terminations  42 , 44  to the transmitter connectors  32 , 34 . The assembly of the adaptor cable harness  36  and the box transmitter  30  is then placed inside the combined enclosure sections  46 , 48 . The spacer elements  74 , 76  are then inserted each between a respective opposed side of the box transmitter  30  and the interior of the enclosure section  48 . The spacer elements  74 , 76  help protect the box transmitter  30  from vibration and/or shock damage. Next, the free end of the adaptor cable harness  36  is routed through the open end  66  of the reduced diameter section  70  of the enclosure piece  46  and the terminations  38 , 40  at the free end of the adaptor cable harness  36  are mated to the cable terminations  18 , 20 , respectively, of the existing cable harness  22 . The boot  24  is then slid over the reduced diameter section  70  of the enclosure piece  46  and secured thereto by the clamp  26 . Anti-seizing compound is applied to the threads  56  of the cover piece  50  and to the threads of the enclosure piece  48 , and the cover piece  50  is screwed into the end  52  of the enclosure piece  48 . A wrench may be used to grip a pair of opposed flat sides  62  of the boss  60  in order tighten the connection of the cover piece  50  to the enclosure piece  48 .  FIG. 7  shows the completed assembly. 
   Accordingly, there has been disclosed a conversion kit whereby a cylindrical transmitter can be replaced by a box transmitter while utilizing an existing cable harness and preserving environmental protection of the cable terminations and the transmitter connectors. While an illustrative embodiment of the present invention has been disclosed, it will be apparent to those of skill in the art that various adaptations and modifications of the described embodiment are possible. It is therefore intended that this invention be limited only by the scope of the appended claims.