US20140174171A1 - Portable self powered line mountable device for measuring and transmitting rainfall measurements - Google Patents

Abstract

A device for attaching to an electric power line conductor an electrically conductive housing with an opening for accepting the power line conductor. The housing is configured to be grounded to the power line conductor. At least one magnetic core is configured to surround the power line conductor and power a power supply electronics module. An infrared optical rain sensor measuring device is located within the housing.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS
• The application claims priority to U.S. Provisional Application No. 61/740, 517 which was filed on Dec. 21, 2012.
BACKGROUND
• The present disclosure relates to a multiple parameter sensor-transmitter/receiver unit which may be installed on or removed from an energized electric power line, such as an overhead power line. With the advent of Smart-Grid applications for electric power systems, there is an ever increasing need for a device that measures electric, mechanical, and environmental parameters of the power line.
• In order to address the increasing need for monitoring power lines, devices have been developed that attach directly to the power line. These devices generally require a power source, such as batteries or solar panels. When utilizing batteries, regular maintenance must be performed to replace the batteries, which can become costly. When solar panels are used, the device may only be powered during sunny weather conditions and during daylight hours. Therefore, there is a need for a device which is low maintenance and can be constantly powered independent of weather conditions.
• When it comes to measuring or sensing rainfall, both infrared and capacitive sensors can be used. For example, in the automotive industry, infrared optical rain sensors measure a rate of rainfall to control windshield wipers.
SUMMARY
• A device for attaching to an electric power line conductor and an electrically conductive housing with an opening for accepting the power line conductor. The housing is configured to be grounded to the power line conductor. At least one magnetic core is configured to surround the power line conductor and power a power supply electronics module. An infrared optical rain sensor measuring device is located within the housing.
• A method of measuring rainfall on a power line conductor including signal conditioning measured values of a rate of rainfall. The signal conditioned measured values are sent to a remote location with a transmitter-receiver unit located within a housing. A sensor electronics module and the transmitter-receiver unit are powered from current flowing in the power line conductor. The measured values are processed to determine a current carrying capacity of the power line conductor.
• These and other features of the disclosed examples can be understood from the following description and the accompanying drawings, which can be briefly described as follows.
BRIEF DESCRIPTION OF THE DRAWINGS
• FIG. 1 illustrates a right side view of an example sensor transmitter receiver unit (“STR unit”).
• FIG. 2 illustrates a front view of the STR unit ofFIG. 1.
• FIG. 3 illustrates a cross-sectional view taken along line A-A ofFIG. 2.
• FIG. 4 illustrates a cross-sectional view taken along line A-A ofFIG. 2 with an example hotstick.
• FIG. 5 illustrates another cross-sectional view taken along line A-A ofFIG. 2 with the example hotstick.
• FIG. 5aillustrates an enlarged view of a keyhole slot.
• FIG. 6 illustrates another cross-sectional view taken along line A-A ofFIG. 2 engaging a conductor.
• FIG. 7 illustrates an example upper magnetic core subassembly.
• FIG. 8 illustrates an expanded view of an example upper magnetic core and an example lower magnetic core surrounding the conductor and an example power supply transformer.
• FIG. 9 illustrates a schematic view of the line mounted power supply, electronics and transmitter-receiver of the STR unit.
• FIG. 10 illustrates an expanded view of the lower magnetic core, example lead screw assembly, and an example hotstick guide tube.
• FIG. 11 illustrates the collapsed view of the lower magnetic core, the lead screw assembly, and the hotstick guide tube.
• FIG. 12 illustrates a cross-sectional view taken along line B-B ofFIG. 2.
• FIG. 13 illustrates a cross-sectional view taken along line C-C ofFIG. 1.
• FIG. 14 illustrates an exploded view of example support blocks mounting the upper magnetic core subassembly and example upper and lower jaws.
• FIG. 15 illustrates an exploded view of an upper magnetic core mount and the upper and lower jaws.
• FIG. 16 illustrates an infrared optical rain sensor.
• FIG. 17 illustrates the optical rain sensor ofFIG. 16 with rain and electronics shielding.
• FIG. 17aillustrates an enlarged portion of an electrostatic shielding mechanism.
• FIG. 18 illustrates a right side view of the optical rain sensor ofFIG. 16 mounted in a lower housing.
• FIG. 19 illustrates a right side view of a bezel and a rain sensor shield.
• FIG. 20 illustrates a cross-sectional view taken along line P-P ofFIG. 19 including electrostatic and electromagnetic shielding.
DETAILED DESCRIPTION
• FIGS. 1 and 2 illustrate an example sensor transmitter receiver unit (“STR unit”)1 installed on a power line conductor C for measuring and monitoring various parameters of the power line conductor C and its environment. TheSTR unit1 is formed from a one pieceupper housing2 and a one piecelower housing3. Thelower housing3 is accepted into abead4 formed on a distal end of theupper housing2. In this example, thebead4 which is an integral part of theupper housing2 is formed by machining a portion of theupper housing2 to form a groove on the inside of thebead4. Thelower housing3 is secured to thebead4 and theupper housing2 by acollar5. Thecollar5 attaches to a hotstick guide tube13 (FIG. 3) that is secured to theupper housing2 and extends through thelower housing3.
• In one example, theupper housing2 and thelower housing3 are made of aluminum or other suitable electrically conductive material. The material chosen should accommodate subassembly installation without the use of external surface fasteners which could generate corona discharges due to high voltage being applied to theupper housing2 and thelower housing3. Theupper housing2 has the advantage of reducing the number of mating surfaces and eliminating mismatches between multiple cast parts which can generate corona discharges and audible noise due to slightly offset sharp edges of the mating surfaces of the adjacent castings.
• Referring toFIGS. 3 and 4, before theSTR unit1 is clamped onto the conductor C, alower jaw7 is moved to its fully lowered position spaced fromupper jaws6. This allows the conductor C to pass from position “A” ofFIG. 3 through a throat T on the left side of theupper housing2 and onto theupper jaws6 in position “B” as shown inFIG. 5.
• With thelower jaw7 of theSTR unit1 in its fully lowered position, a specially designedhotstick10 is inserted into the bottom of theSTR unit1 and inside thehotstick guide tube13. In this example, thehotstick10 is made of an electrically insulated material such as fiberglass. Thehotstick10 includes a hotstick driver assembly9 (FIG. 4) attached to thehotstick10 with apin36. Thehotstick10 provides the required electrical insulation between the hands of the linemen and the energized conductor C. A flexible stirrup assembly11 (FIG. 4) contains a flexiblebraided conductor12 which bends out of the way to allow thehotstick driver assembly9 to enter a hole in thecollar5. As mentioned earlier, thecollar5 secures thelower housing3 to thebead4 on theupper housing2. Thecollar5 is fastened to thehotstick guide tube13 using theset screw5awhich is screwed into thecollar5 and into a hole in thehotstick guide tube13.
• With thehotstick10 and thehotstick driver assembly9 fully engaged inside thehotstick guide tube13, theSTR unit1 can be lifted by the lineman with thehotstick10 onto the conductor C while maintaining theSTR unit1 securely attached to thehotstick10.
• Theupper housing2 includes twojaw inserts8, shown inFIGS. 5 and 14, located adjacent the throat T and theupper jaws6. The twojaw inserts8 includeinclined surfaces8aand theupper jaws6 includeinclined surfaces6a.The angle of incline of theinclined surfaces8amatches the angle of the incline of aninclined surface2aon theupper housing2.
• The angle of theinclined surfaces6ais steeper than the angle of theinclined surfaces8aand theinclined surface2ato aid in installing theSTR Unit1 on the conductor C. As the conductor C slides across theinclined surfaces2aand8aand reaches the steeper incline of theinclined surface6a,theSTR unit1 will bounce slightly upward and land in acircular notch6bof the upper jaws6 (SeeFIG. 4). This allows a conductor temperature sensor to be mounted vertically and in the middle inside theupper jaws6 and initially extends slightly below thecircular notch6bfor the upper portion of the conductor C. The two differentinclined surfaces6aand8aof the jaw inserts8 andupper jaws6 prevent the conductor temperature sensor S, shown inFIGS. 3 and 4, from becoming damaged since the conductor C firmly lands vertically in thecircular notch6bof theupper jaws6 and pushes the conductor temperature sensor S up to the inside surface of thecircular notch6b.
• InFIG. 3, thelower jaw7 is located in a pocket P between two legs of a lowermagnetic core14. Thelower jaw7 is held in place with twospring pins132 and133 (FIG. 15) located in thelower jaw7 that snap into twoholes15 in a lower jaw holder16 (FIGS. 10 and 11) which is attached to abottom block19 using two screws20 (FIG. 3). Thebottom block19 is located adjacent the base of theupper housing2.
• Two identical electrically conductive lower core covers17 partially surround the two legs of the lowermagnetic core14. The lower core covers17 are attached to thebottom block19 on each side of thelower jaw holder16 usingscrews18 ofFIG. 3 on the front right side and one set of thescrews18 on the back left side (not shown). The front and backlower jaw holders16 are both held in place by the fourscrews20, two in the front and two in the back. The two legs of the lowermagnetic core14 are totally encased by the two lower core covers17 and the front and backlower jaw holders16. Therefore, the lowermagnetic core14 is not exposed to any moisture, such as from rain, snow, and ice that could enter through the throat T of the upper housing2 (FIG. 3).
• Thebottom block19 contains a conical hole21 in the center which provides a very low friction bearing surface for the semi-circular top of a lead screw22 (FIG. 3). Thelead screw22 is held in the conical hole21 with aretainer plate23 which has a hole in the middle the size of thelead screw22 diameter and is fastened to thebottom block19. Thelead screw22 is threaded into the center of a threadedbushing25. The threadedbushing25 has a reduced diameter cylindrical lower portion which fits inside thehotstick guide tube13 and a larger diameter cylindrical top portion of the threadedbushing25 is supported on the upper end of thehotstick guide tube13. Both the threadedbushing25 and thehotstick guide tube13 are attached to ahotstick guide support26 using two large throughbolts27 and nuts which are placed through the holes in abottom support28.
• Referring toFIG. 2, theupper jaws6 include two spaced apart jaws and thelower jaw7 includes a single jaw aligned between the two spaced apartupper jaws6. Whenlower jaw7 is clamped onto the conductor C, the conductor C is bent slightly upward as thelower jaw7 extends upward between theupper jaws6 creating a bending moment in the conductor C. The bending moment in the conductor C prevents theSTR unit1 from sliding down the conductor C, especially when theSTR unit1 is mounted at the point of attachment adjacent a utility pole or tower where the slope of the conductor C is at its maximum value. Preventing theupper jaws6 and thelower jaw7 from sliding down the conductor C at the point of attachment is necessary when the STR unit is being used to measure sag of the power line conductor.
• Referring toFIGS. 5 and 5a, thebottom support28 includes an upside down “U” shaped cross member and is fastened at each end to the upper housing with two large threadedscrews29 on each side. The threadedbushing25 has two smallvertical holes25adrilled through the threadedbushing25 on each side of the threaded hole in the middle for thelead screw22. Thevertical holes25aare countersunk on the top and provide drainage paths for fluid, such as rain water, that can accumulate underneath thebottom block19 and on top of the bottom support28 (FIG. 5a). The water then drains through the twovertical holes25ain the threadedbushing25 and drops on the inside of thehotstick guide tube13 and out the bottom of theSTR unit1. Therefore, water will not leak into thelower housing3.
• Referring toFIG. 6, thelead screw22 has a small diameter hotstick guide30 which is threaded on the inside and is screwed on the bottom of thelead screw22. Apin31 keeps thehotstick guide30 from turning on thelead screw22. Thehotstick guide30 prevents the inside of a hotsticklead screw driver33 from coming into contact with the threads on thelead screw22 and damaging the internal bore of thelead screw driver33. It also guides thelead screw driver33 onto thelead screw22. When thepin31 engages thelead screw driver33 theSTR unit1 is ready for installation on the conductor C.
• Thehotstick driver assembly9 includes thelead screw driver33, ahotstick driver coupling32, arivet34, ahotstick sleeve35, thepin36, and thehotstick10. Thehotstick10 ofFIG. 4 rests on the rounded portion of thehotstick driver coupling32 and the rounded inside bottom of thehotstick guide tube13. This prevents thelead screw driver33 from applying pressure to the threadedbushing25 upon installation of theSTR unit1 on the conductor C. Thelead screw driver33 and thehotstick driver coupling32 are each fastened to thehotstick sleeve35 by therivet34 and thehotstick sleeve35 is attached to thehotstick10 with thepin36. A long narrow vertical slot in thelead screw driver33 allows thepin31 of thelead screw22 to be engaged with thelead screw driver33 and is free to slide up or down in thevertical slot37 as the lead screw is turned to tighten thelower jaw7 on the conductor C or to loosen thelower jaw7 from the conductor C to remove theSTR unit1.
• When thehotstick driver assembly9 is engaged with thelead screw22 as shown inFIG. 4, theSTR unit1 is raised to position “A” relative to the height of the conductor C. TheSTR unit1 is then moved toward the conductor C so that the conductor C passes through the throat T of theupper housing2 and into position “B” as shown inFIG. 5. Once theSTR unit1 is fully supported by the conductor C in position “B”, thehotstick driver assembly9 is turned clockwise by the installer with thehotstick10 and allowed to drop down from its position inFIG. 4 to a lower position as inFIG. 5. Ahorizontal keyhole slot38 of thelead screw driver33 is now engaged with thepin31 of thelead screw22. With thepin31 in thehorizontal keyhole slot38, thehotstick driver assembly9 and thehotstick10 are secured to theSTR unit1.
• In this example, an opening andclosing mechanism39 ofFIG. 6 extends thelower jaw7 upward to secure theSTR unit1 on the conductor C. Additionally, the opening andclosing mechanism39 can also retract thelower jaw7 to remove theSTR unit1 from the conductor C. The opening andclosing mechanism39 includes the lowermagnetic core14, the lower core covers17, thelower jaw holders16, thelower jaw7, spring pins132 and133, thebottom block19, theretainer plate23, twofasteners24, thelead screw22, thehotstick guide30, and thepin31.
• FIG. 6 illustrates thekeyhole slot38 on thelead screw driver33 engaged with thepin31 on thelead screw22. As thelead screw22 is turned clockwise, the opening andclosing mechanism39 moves the lowermagnetic core14 toward an uppermagnetic core40. The uppermagnetic core40 has two large compression springs41 to bias the uppermagnetic core40 downward. The compression springs44 provide pressure to hold both the uppermagnetic core40 and the lowermagnetic core14 together to reduce the magnetic reluctance caused by air gaps54 (FIG. 8) between the uppermagnetic core40 and the lowermagnetic core14.
• Thehotstick driver assembly9 can continue to be turned clockwise even after the lowermagnetic core14 begins to mate with the uppermagnetic core40 because the compression springs41 compress at the top of the uppermagnetic core40. The clockwise motion of thehotstick driver assembly9 can be achieved either manually or with a battery powered drill or another rotating device, until thelower jaw7 is tightened onto the conductor C. After theSTR unit1 is mounted on the conductor C, thehotstick10 is turned slightly to the left, or counterclockwise, and thepin31 will become disengaged from the horizontal portion of thekeyhole slot38. Thehotstick10 is then free to be removed when thepin31 aligns with thevertical slot37.
• FIGS. 7 and 8 illustrate the bottom of the compression springs41 are held in alignment in twocylindrical pockets42 of two identical horizontal upper core blocks43 which are each used to clamp the uppermagnetic core40 to two identical magnetic horizontal lower core blocks44. The top of the compression springs41 are held in place with twoprojections49 extending downward on the inside of theupper housing2. The compression springs41 are totally enclosed by theupper housing2 and are protected from the adverse weather which can cause corrosion. Theair gaps54 between the upper and lowermagnetic cores40 and14 are totally enclosed by theupper housing2 which prevents theair gaps54 from becoming corroded due to moisture from the environment. The horizontal upper core blocks43 and the horizontal lower core blocks44 are clamped around the uppermagnetic core40 on each side using two throughbolts45 and twonuts46 in the front and two throughbolts45 and twonuts46 located in the back of the upper horizontal core blocks43 and horizontal lower core blocks44.
• When the two large compression springs41 push the upper core blocks43 down, the uppermagnetic core40 is prevented from falling out of aleft core shoe50 and aright core shoe51, by astep52 located at the bottom of theright core shoe51 and astep53 located at the bottom of theleft core shoe50.
• When the lowermagnetic core14 mates with the uppermagnetic core40, thelead screw22 can be turned further clockwise to move the two upper core blocks43 away from thesteps52 and53 and further compress the compression springs41. Thelead screw22 can continue to be turned clockwise and compress the compression springs41 until thelower jaw7 and theupper jaws6 are tight on the conductor C.
• Electrical insulating spools47 are inserted over each of the throughbolts45 and electrical insulatingwashers48 are inserted under the head of each throughbolt45 and under eachnut46. The insulating spools47 and the insulatingwashers48 on each of the throughbolts45 prevent shorted electrically conductive paths around the uppermagnetic core40 which is comprised of the four throughbolts45, fournuts46, the two electrically conductive upper core blocks43 and the two lower core blocks44.
• When theupper jaws6 and thelower jaw7 are firmly tightened on the conductor C, the compression springs41 are compressed to their maximum distance, and thus the maximum compressive force is also applied to the lowermagnetic core14 and the uppermagnetic core40. This decreases the size of theair gaps54 between the lowermagnetic core14 and the uppermagnetic core40 and the magnetic reluctance between the lowermagnetic core14 and the uppermagnetic core40. Depending on the size of the conductor C, varying amounts torque can be applied to thehotstick driver assembly9 to tighten the opening andclosing mechanism39 on the conductor C.
• The physical size and shape of theupper jaws6 and thelower jaw7 are designed such that approximately the same compressive force is applied to the uppermagnetic core40 and the lowermagnetic core14. In one example, there are five different sets of upper andlower jaws6 and7 that can fit different conductor sizes and types ranging from 0.162 inches in diameter and up to 1.17 inches in diameter. The opening andclosing mechanism39 allows theSTR unit1 to be installed on a wide range of conductor diameters without changing theupper jaws6 and thelower jaws7 while maintaining sufficient contact between the uppermagnetic core40 and the lowermagnetic core14 to complete the magnetic circuit of thepower supply transformer55 of theSTR unit1 which derives its power from the current flowing through the conductor C to power apower supply module60 ofFIG. 9. Because theSTR unit1 derives power from the conductor C, batteries or solar cells are not required to power theSTR unit1. TheSTR unit1 is powered at all times when current is flowing in the conductor C, even at current levels as low as 6.8 amperes and still process data and transmit data at 1 watt power levels because of the low threshold of thepower supply module60.
• Maintaining a minimum magnetic reluctance insures that a power supply transformer55 (FIGS. 8 and 9) will provide the needed secondary voltage V₂and secondary current I₂to operate thepower supply transformer55,sensor electronics module63, and transmitter/receiver64. Thepower supply transformer55 includes the uppermagnetic core40, the lowermagnetic core14, and a coil winding56. The upper magnetic core and the lower magnetic core form a window W for accepting the conductor C.
• The number of secondary turns N₂of wire on the coil winding56 are optimized to produce the required secondary voltage V₂and secondary current I₂with a minimum of current I₁in the conductor C. The coil winding56 is held in place by twocoil bobbins57 which are supported laterally by the two upper core blocks43 and the two lower core blocks44. Secondary leads58aand59aofcoil windings58 and59, respectively, are connected to thepower supply module60 which maintains the same level of secondary voltage across leads61 and62 for thesensor electronics module63 and the transmitter/receiver64 even though the primary current may range from 34 amperes up to 1000 amperes. Lower primary currents of6.8 amperes are achievable with the low threshold currentpower supply module60. Thepower supply module60 contains an energy storage device256 (FIG. 13) which can power the transmitter/receiver64 when the conductor C current ceases to flow. A transmitting and receivingantenna81 for the on-board transmitter/receiver64 is mounted on the upper housing2 (FIG. 12).
• Locating the coil winding56,58, and59 on the uppermagnetic core40 allows the heat from the coil winding56,58, and59 to escape through a vent65 (FIG. 1) in theupper housing2. When the conductor sensor S located within theSTR unit1 measures the temperature of the conductor C, it is important that the heat from thecoil windings56,58, and59 does not affect the temperature of the conductor C or the conductor temperature sensor S, which is in electrical communication with thesensor electronics module63. As shown inFIG. 6, a thermally insulatingbarrier66 located below thecoil windings56,58, and59, allows for a more accurate temperature reading of the conductor temperature by blocking heat from thecoil windings56,58, and59.
• FIGS. 10-12 and13 illustrate the lowermagnetic core14 with the lower core covers17, thelead screw22, thehotstick guide tube13, and other related parts in both exploded and collapsed views. Thehotstick guide tube13 is anchored at the top with the throughbolts27 that extend through thebottom support28 and thehotstick guide support26. A round cylindrical milledslot67 is located along opposing sides of the top of thehotstick guide tube13 to accept the throughbolts27 that support thehotstick guide tube13.
• Acentral hole70 extends through abase plate support68 and abase plate69 for accepting a bottom portion of thehotstick guide tube13. Thebase plate support68 and thebase plate69 are connected to each other with four identical threaded screws71. Thehotstick guide tube13 is attached to thebase plate support68 and thebase plate69 withset screws72 and73. Left andright side panels76 ofFIG. 12 are attached to thebase plate support68 and thebottom support28 for thelower core14 with the use of two identical screws74 extending through thebottom support28 and theside panel76 and at the bottom with twoidentical screws75 extending through theside panel76 and thebase plate support68.
• The threadedbushing25 rests on top of thehotstick guide tube13 and is prevented from turning relative to thehotstick guide tube13 using aset screw77. The left andright side panels76 not only provide added strength, but also provide the physical space to mount thepower supply module60, the transmitter/receiver64, thesensor electronics63, and support left and right lower core guides78 and79.
• The leftlower core guide78 and a rightlower core guide79 are “U” shaped and guide the opening andclosing mechanism39 such that the lowermagnetic core14 is aligned with the uppermagnetic core40. Each of the left and right lower core guides78 and79 are attached to the left andright side panels76 with four threadedscrews80. Thelower housing3 is placed over thehotstick guide tube13 at the bottom and fitted up to thebase plate69 and held in place with thecollar5. This means that once thecollar5 is removed, thelower housing3 can be removed thus allowing access to thepower supply module60,sensor electronics module63, and the transmitter/receiver64 ofFIG. 9 mounted inside and on the left andright side panels76 for easy maintenance and repair.
• FIGS.7 and12-15 illustrate an uppermagnetic core subassembly40amounted to theupper housing2. The left and right core shoes50 and51 support the uppermagnetic core40 such that the uppermagnetic core40 can move freely up and down inside the left andright shoes50 and51. The left and right core shoes50 and51 are attached to theupper housing2 using four support blocks86 and87 ofFIG. 14, right and left upper core guides90 and93, and four vertical throughbolts94,95,96, and97.
• The uppermagnetic core subassembly40acan be inserted through the throat T and fastened to the inside of theupper housing2. A top portion of theupper housing2 is “C” shaped which provides a surface on the inside for mounting acurrent sensing device156 for measuring the power line frequency current (60Hz or50Hz) and aloop coil157 for measuring lightning stroke current (FIGS. 13 and 16).
• Theright core shoe51 has two identical threadedholes82 and83 on the front and back for a total of four, and leftcore shoe50 has two identical threadedholes84 and85 on the front and back for a total of four as shown inFIGS. 7 and 14. As shown inFIG. 14, two identical support blocks86 on the right side are placed on the front and back of theright core shoe51 and two identical support blocks87 are placed on the front and back of theleft core shoe50.
• To align the two right side support blocks86 with the two sets of threadedholes82 and83 on the right side of theright core shoe51, threaded screws88 and89 are first inserted into the upper and lower holes in the right sideupper core guide90 and then through the two holes in theright support block86 and screwed into the accommodating threadedholes82 and83 of theright core shoe51. The two left side support blocks87 are held in alignment with theleft core shoe50 by first inserting two threadedscrews91 and92 through the other end of the right sideupper core guide90 and then through the holes in the leftside support block87 and screwed into the threadedholes84 and85 of theleft core shoe50. The same process is repeated on the back side by connecting support blocks86 and87 to the left upper core guide93 with the backside of theright core shoe51 and the back side of theleft core shoe50.
• The purpose of the upper core guides90 and93 is to insure the two long vertical throughbolts94 and95 placed through the vertical holes in the two right side support blocks86 and two long vertical throughbolts96 and97 placed through the vertical holes in the two left side support blocks87 line up with the four threaded holes in four threadedinserts98,99,100, and101, which are embedded in the casting of theupper housing2. The two right side support blocks86 are prevented from falling down by inserting the back of a right sideupper jaw holder102 and the back of the left sideupper jaw holder103 over the vertical throughbolts94 and95 and threadingnuts104 and105 onto the two vertical throughbolts94 and95 and tightening them down, respectively. The two left side support blocks87 are held in place by inserting the vertical throughbolts96 and97 through the front hole in the right sideupper jaw holder102 and the front hole in the left sideupper jaw holder103 and threading twonuts106 and107 on the vertical throughbolts96 and97 and tightening them down, respectively.
• Four threaded throughstandoffs108,109,110, and111 are screwed onto the four vertical throughbolts94,95,96, and97, respectively. Thethermal barrier66 is placed over the four bottom holes of thestandoffs108,109,110, and111 and screwed to thestandoffs110 and111 on the front left side with two flat head screws112 as shown inFIG. 15.
• FIGS. 2 and 15 illustrate castingfillers113 and114 located on the back left and back right sides of theSTR unit1 and secured with round head screws115 which are first inserted through holes in the castingfillers113 and114 and then through the two back holes on the right and left side of thethermal barrier66 and into thestandoffs108 and109, respectively.
• After the uppermagnetic core subassembly40ais mounted, the left and right lower core guides78 and79 including the opening andclosing mechanism subassembly39 and the left andright side panels76 are inserted through the bottom of the upper housing2 (SeeFIG. 12). Fourscrews29 are inserted through the two holes on the left and the two holes on the right of thebottom support28 and screwed into the threaded holes of theupper housing2. It should be noted that during the insertion process, the rightlower core guide79, shown inFIG. 12, slides around the outside surface of theright core shoe51 and underneath atab116 at the top as a weldment on the right upper side of theright core shoe51.
• As shown inFIG. 12, thetab116 insures that the rightlower core guide79 fits precisely around the outside of theright core shoe51 to provide a near perfect alignment of the lowermagnetic core14 with the uppermagnetic core40. The precise alignment between the uppermagnetic core40 and the lowermagnetic core14 reduces magnetic reluctance by decreasing theair gaps54. This results in a decrease in the threshold current for the operation of thepower supply module60.
• Referring toFIGS. 14 and 15, the right sideupper jaw holder102 and the left sideupper jaw holder103 support the twoupper jaws6 and the jaw inserts8. The long vertical throughbolts96 and97 which are screwed into the threadedinserts100 and101 at the top and on the inside of theupper housing2 fit throughtop holes117 and118 on the back and front of the right sideupper jaw holder102 on the right side. Also, flush mount screws119 and120 are inserted on the back and through corresponding holes in the right sideupper jaw holder102 and are screwed into the upper housing. The flush mount screws119 and120 are installed before theupper jaws6 and inserts8 are mounted to the right sideupper jaw holder102. The same arrangement for mounting the left sideupper jaw holder103 is followed usingscrews121 and122.
• Right and leftupper jaw keepers123 and124 prevent theupper jaws6 from dropping down on the inside, because spring pins126 and127 are located on the outside and when depressed snap into theholes128 and129 of the right sideupper jaw holder102. The same procedure is followed with the leftupper jaw keeper124.
• The jaw inserts8 on the right and left sides of theSTR unit1 and in front of theupper jaws6 are held in place by inserting threadedbolts130 and131 into eachinsert8 and through the right and leftkeepers123 and124 and screwing into theupper jaw holders102 and103. The spring pins132 and133 are included in thelower jaw7 which when depressed snap into the twoholes15 in thelower jaw holder16.
• The transmitting and receivingantenna81 for the on-board transmitter andreceiver64 shown inFIG. 9 is mounted on thehousing2. Theantenna81 is displayed inFIGS. 1 and 2 and is installed on the top left side inFIG. 1. Thesolar sensor assembly134 is located at the top of this housing and on its vertical centerline (FIG. 1). Thesmall hole140 located directly to the right of theconductor1 allows access and adjustment of the electric power line sag sensor140 (FIG. 1).
• Referring toFIGS. 16 and 17, an opticalrain sensor assembly138 emitsbeams328 of infrared light from anemitter diode329, which is powered by thepower supply module60 ofFIG. 9, throughglass330 at an angle of45 degrees. Thebeams328 are totally reflected by the outside surface of theglass330 without water or ice on the outside surface of theglass330 and return to areceiver diode331 as shown inFIG. 16. A signal from thereceiver diode331 is amplified by anamplifier332 and sent to thesensor electronics module63 ofFIG. 9.
• When rain drops333 or ice, as shown inFIG. 17, appear on the outside surface of theglass330 some of thebeams328 emitted from theemitter diode329 becomescattered beams334 thus reducing the intensity of thebeams328 reflected by theglass330. Thereceiver diode331 measures a reduction in intensity of beams when rain drops andice333 appear on the surface of theglass330 and causescattered beams334.
• Since the intensity of the ambient sun light can be as high as100 watts per square foot and theemitter diode329 only produces a few thousandths of a watt, thereceiver diode331 must distinguish between the light from theemitter diode329 and the light from the sun. The energy from the sun is broad band and includes infrared, therefore two alternative solutions to this problem may be either to pulse thebeams328 from theemitter diode329 or to use two channels ofemitter diodes329 andreceiver diodes331 to suppress the effect of external light.
• An amount of rain drops333 on the surface of theglass330 is measured in milliliters and thereceiver diode331 is able to detect as little as 0.005 milliliters of water. In one example, theemitter diode329 is an OSRAM SFH 4281 infrared 880 nm and thereceiver diode331 is anOSRAM BP 104 FAS.
• The infraredoptical rain sensor337 ofFIG. 17 installed in theSTR unit1 measures the rate of rainfall in milliliters per unit time. Measuring the rate rather than volume is more meaningful for determining the real time current carrying capacity of the conductor C and the formation of ice on the conductor C, because the convected heat from the conductor C due to the current flowing therein can increase more than20 to30 percent during average rainfall conditions. Also, rate of rainfall, ambient air temperature, wind velocity and conductor temperature are very important parameters to determine when ice will form on line conductors, and the rate of ice buildup.
• Referring toFIGS. 17 and 17a, an electrostatic shield is provided by coating the inside of theglass330 with a transparent electricallyconductive substrate297 such as indium-tin oxide. The transparent electrically conductive substrate is bonded atpoint335 to an electricallyconductive ground strap336 which in turn is connected to acase ground162 and the combination of thelower housing3 andupper housing2. The combination of thesubstrate297 and the electricallyconductive ground strap336 connected to the upper andlower housings2 and3, which completely surround the infraredoptical rain sensor337, are at the same voltage as the conductor C. Therefore, the arrangement provides the electrostatic shield which prevents any of the components of the infraredoptical rain sensor337 from creating corona discharges when theSTR unit1 is installed on the conductor C.
• The electromagnetic shielding is provided by enclosing the infraredoptical rain sensor337 within a ferrouselectromagnetic shielding box338. The ferrouselectromagnetic shielding box338 includessmall aperture holes339 which allowbeams328 from theemitter diode329 to pass uninterrupted to theglass330 and be reflected back to thereceiver diode331.
• FIGS. 1 and 18 illustrate the opticalrain sensor assembly138 mounted in an opening in thelower housing3 on the right side of theSTR unit1.
• The infraredoptical rain sensor337 is electrostatically shielded by the upper andlower housings2 and3, an electricallyconductive bezel340, and theglass330, which includes the transparent electrically conductingsubstrate297 coated on the back side (inside) of theglass330. The transparent electrically conductingsubstrate297 includes the electricallyconductive ground strap336 shown inFIGS. 17 and 19 which is bonded to the transparent electrically conductingsubstrate297 with an electricallyconductive cement335 shown inFIG. 17a. The electricallyconductive ground strap336 is connected to thecase ground162.
• The electrostatic shielding completely surrounds the infraredoptical rain sensor337 and the electrical components contained therein thus preventing corona discharges from forming when theSTR unit1 is mounted on the conductor C.
• The electricallyconductive bezel340 is used to mount both theglass330 and the infraredoptical rain sensor337. Thebezel340 is located within alarge hole346 provided in thelower housing3 ofFIG. 18. As shown in the cross section along line P-P ofFIG. 20, two radii comprise the cross-sectional shape of thebezel340. The large inside diameter of thebezel340 prevents the edges of thesubstrate297 from producing corona discharges. For high voltage applications, alarge radius341 should be approximately equal to or larger than a radius of the largest size conductor C upon which theSTR unit1 is to be mounted upon. Asmall radius342 must be designed to intersect the surface of theglass330 at 90 degrees on the inside diameter of thebezel340 and become flush with the surface of thelarge radius341.
• The ferrouselectromagnetic shielding box338 encloses the back side of the infraredoptical rain sensor337 and contains a cover with two identifiedapertures339. Theapertures339 allow the emittedbeams328 and the receivedsignal beams328 to pass through and be reflected back to thereceiver diode331. The signal leads344 and345 return to thesensor electronics module63 and the power supply leads347 and348 emanate from thepower supply module60.
• TheSTR unit1 measures rainfall on the conductor C by signal conditioning values of a rate of rainfall measured by the infraredoptical rain sensor337 with thesensor electronics module63. The signal conditioned measured voltage values from therain sensor337 are directly proportional to the rate of rain fall. The signal conditioned measured values are sent to a remote location with the transmitter-receiver unit64 via theantenna81 on a real time basis. The measured values of the rate of rainfall are used to determine a current carrying capacity of the conductor C. An amount of current traveling through the conductor C is determined to prevent ice from forming on the power line conductor. Additionally, theSTR unit1 determines if ice will form on the power line conductor C based on conductor temperature, wind velocity, and an ambient temperature.
• The preceding description is exemplary rather than limiting in nature. Variations and modifications to the disclosed examples may become apparent to those skilled in the art that do not necessarily depart from the essence of this disclosure. The scope of legal protection given to this disclosure can only be determined by studying the following claims.

Claims (13)

What is claimed is:

1. A device for attaching to an electric power line conductor comprising:

an electrically conductive housing including an opening for accepting the power line conductor and configured to be grounded to the power line conductor;

at least one magnetic core configured to surround the power line conductor and power a power supply electronics module; and

an infrared optical rain sensor measuring device located within the housing.

2. The device ofclaim 1 wherein the infrared optical rain sensor measuring device is mounted on a vertical wall of the housing.

3. The device ofclaim 1 wherein the infrared optical rain sensor measuring device includes an infrared optical rain sensor located behind a transparent lens.

4. The device ofclaim 3 wherein the transparent lens is undercoated with a transparent electrically conductive substrate.

5. The device ofclaim 4 wherein the lens is mounted to an electrically conductive bezel, the electrically conductive bezel is attached to the housing and forms a Faraday cage completely surrounding the infrared optical rain sensor for preventing corona discharges when the device is exposed to the electric power line conductor.

6. The device ofclaim 4 wherein the transparent electrically conductive substrate is indium-tin oxide.

7. The device ofclaim 3 wherein the transparent lens includes an electrically conductive transparent undercoat that is electrically grounded to an electrically conductive corona free bezel mounted to the housing to completely surround the infrared optical rain sensor.

8. The device ofclaim 3 wherein the infrared optical rain sensor is enclosed inside a ferrous electromagnetic shielding enclosure, the enclosure includes two apertures configured to allow infrared beams to travel from a sensor emitter through a first aperture and to the outside of the transparent lens and then the infrared beams or a portion thereof are reflected back and pass through a second aperture to a receiver diode.

9. The device ofclaim 3 wherein the infrared optical rain sensor is configured to produce a voltage output proportional to a rate of rainfall falling upon an exterior portion of the transparent lens.

10. A method of measuring rainfall on a power line conductor comprising:

signal conditioning measured values of a rate of rainfall;

sending the signal conditioned measured values to a remote location with a transmitter-receiver unit located within a housing;

powering a sensor electronics module and the transmitter-receiver unit from current flowing in the power line conductor; and

processing the measured values to determine a current carrying capacity of the power line conductor.

11. The method ofclaim 10 wherein the signal conditioned measured values are transmitted by the transmitter-receiver unit to a remote location receiver.

12. The method ofclaim 11 wherein the measured values are transmitted by the said transmitter-receiver unit to the remote location receiver on a real time basis.

13. The method ofclaim 10 including:

determining if ice will form on the power line conductor based on conductor temperature, wind velocity, and ambient temperature.

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