Abstract:
An improved filter assembly module comprising an open-ended cylindrical housing containing a spindle chassis with a base radially centering the chassis in the housing. Three spindle, rods extending from the base and three sets of three cylindrical spool-wound capacitors are spindle-mounted one set on each rod. A position stabilizer mounted on the upper ends of spindle rods makes stabilizing contact with the housing inner wall. An inductance coil and core is held beneath the base by a plurality of short rods protruding from the base and by a retainer snap-fastened on the rod ends. A housing bottom cover encloses the inductance coil, short rods and retainer, and a cap closes the housing top end. Electrical circuit connectors electrically couple the capacitors, inductance coil and ground and provide output signal leads for coupling to an associated meter or the like. The housing interior space, cover, cap, capacitors, inductance coil, position stabilizer and coil retainer are all totally immersed and engulfed in a solidified thermosetting dielectric insulation material cast in-situ in the housing, cover and cap.

Description:
This is a regular United States utility patent application filed pursuant to 35 USC § 111 (a) and claiming the benefit under 35 U.S.C. § 119 (e) (1) of the priority of provisional patent application Ser. No. 60/293,850 filed on May 25, 2001. 
    
    
     FIELD OF THE INVENTION 
     This invention relates to high voltage power transmission line metering systems, and more particularly to a filtering system and module for enhancing data communication about and on power transmission lines. 
     BACKGROUND OF THE INVENTION 
     One of the problems encountered by electric public utilities in the transmission and distribution of electrical power through their high voltage power transmission system and network is the loss of power by theft from various locations along their sub-branch distribution lines of the network where power is connected to the ultimate consumer. For example, it has been reported that an electric public utility serving various remote areas of British Columbia in Canada has experienced loss by theft of a considerable quantity of electrical power to illegal marijuana growing installations. Such illegal growers have been known to buy or just move as squatters into an abandoned building. They then reconnect the existing disconnected power service line to their building power service lines in order to illegally provide electrical power service to their greenhouse operations for growing marijuana. Short of actually patrolling and inspecting all customer metering installations along the branch distribution lines, including such disconnected installations at abandoned sites, it has not been economically feasible to remotely pinpoint the geographic location where such power theft losses are occurring. Although the amount of power being distributed over a given sub-branch transmission line is metered by transmission line watt meters, due to excessive “noise” in the line, i.e., 60 cycle “hum”, it has not been possible to remotely telemeter an individual meter on the power transmission line to determine or pinpoint the location along sections of sub-branch lines that are showing excessive power loss to unauthorized power hook-ups. 
     In one approach to solving the forgoing power line theft telemetering problem, it has been proposed that the power transmission line be directly filtered to eliminate the interfering noise in the transmission line signal. It is then believed it would be possible to be able remotely identify, by comparative meter data transmitted, the particular geographic location where utility personnel could be directed to look for power theft along the sub-branch line in order to apprehend the thieves and stop the power loss in a timely and efficient manner. 
     In order to accomplish the electrical noise filtering process proposed hereinabove, it has been further proposed to provide a straight forward filter network between the typical 15 kilovolt electrical power distribution line and an associated watt meter operably connected for sensing the rate of power consumption along such line. Such filter/meter installations would be located at strategic predetermined locations along the power distribution network in order to limit the geographical extent of indicated theft searching to a reasonable geographic area and distance along the line. Such installations would be pole mounted and thus must necessarily be able to withstand the adverse environmental conditions of outdoor powerline equipment and operate in a reliable manner without service for an extensive service life of say up to 100 years. 
     A proposal for a filter in such a system having the required electrical capacitance and inductance contemplates the provision of a series of cylindrically wound capacitors (or “condensers”) that are of limited maximum size in order to be economically producible. Therefore a plurality of such capacitors are to be connected in series to provide the required total capacitance of the capacitive element in the filter circuit. 
     The inductance contemplated comprises a coil subassembly composed of an annular ferrite core with a primary winding wound on one portion of the core and having an input terminal connected to the output terminal of the array of capacitors and an output terminal connected to ground. The ferrite core would also serve as the flux link to a secondary winding also wound on the ferrite core and having its opposite terminals connected either to an appropriate watt meter or the like provided in close proximity to the filter or to some other digital communication device adapted for remote telemetering. However, the foregoing proposals did not provide a solution to the problem of how to economically construct a high voltage filter module embodying the capacitive and inductive components in a rugged, compact, durable, weather proof and reliable module. Accordingly, it is this latter problem and its solution to which the present invention is directed. 
     OBJECTS OF THE INVENTION 
     Accordingly, among the objects of the present invention are to provide an improved electrical filter network or circuit component module that is rugged, durable, difficult if not impossible to disassemble and that is reliably operable for use as a frequency filtering unit to filter out interference signal “noise” from electrical power transmission lines, and particularly, from outdoor electrical utility sub-branch distribution lines so that such filtered signals can be fed to an associated watt meter, volt meter or other digital transmitting units for remote monitoring of customer-metered power consumption versus power loss along the power transmission line. 
     Another object is to provide an improved module of the foregoing character that provides a holder and protective container for the operative electrical components of the filter network and that allows them to be initially assembled and held for making soldering or other electrical connections between the individual components, that will hold the components in a predetermined array suitably spaced a predetermined distance from one another as well as the container walls in order to enable an electrically insulative and adhesive potting compound to be infilled in a liquid state and then solidify (cure) to thereby provide not only necessary extra electrical insulating properties but also bonding of the components as a solid unit and to protect the components from harsh application environments while at the same time adherently bonding all of the assembly frame parts and related housing cover and cap parts including solder joints. 
     A further object is to provide an improved module of the foregoing character and improved method of constructing the same that supports and accurately establishes the relative positions of all internal electrical components both during subassembly shipment, circuit component testing and for the duration of the useful life of the module regardless of serious abuses to the module both from outdoor environmental conditions and rough handling during shipment, storage and installation. 
     Another object is to provide an improved filtering module of the above character and associated telemetering instrumentation in combination with appropriate power line transmission equipment and telemetering instruments in an electrical power distribution system that is operable to adequately electrically filter the electrical power transmission line noise so as to be able to communicate with individual meters and telemeter their condition remotely. 
     A still further object is to provide a filter module system of the foregoing character that enables the power transmission line to be electrically filtered so as to remove sufficient unwanted and interfering noise in the transmission line to thereby enable digital data to be transmitted over the transmission line so that digital hardwire communication may be enabled to many remote geographic areas that do not have telephone lines or fiber optic lines. 
     SUMMARY 
     In general, and by way of summary description and not by way of limitation, the invention achieves one or more of the foregoing objects by providing an improved filter assembly module comprising a cylindrical housing initially open at its opposite ends as made. A chassis component is disposed within the housing and has a planar base with a profile configuration adapted to contact the inner wall of the housing for centering the chassis radially in the housing. The chassis has at least one spindle rod extending within the housing parallel to the longitudinal axis of the housing and perpendicular to the major plane of the base of the chassis. One or more cylindrical spool-wound capacitors are mounted on the spindle rod by having the spindle rod extend axially through a spool-formed central through-passage of the or each capacitor. A position stabilizer is mounted on the spindle rod on the side of the capacitor remote from the chassis base, and also has a profile configuration adapted to contact the housing inner wall. An inductance coil component is disposed beneath the chassis base and held initially in assembly therewith by a plurality of short rods protruding from the base. A bottom cover is secured to and closes the bottom end of the housing so as to enclose therein the inductance coil component, the short rods and a retainer held by the rods. A top is cap secured to the top end of the housing and closes the same. Electrical circuit connector means extend through the cap and are operably and electrically coupled to the capacitors and inductance coil component, and also provide a ground connection as well as an inductively coupled output signal for coupling to an associated meter or the like. The interior space defined between the interior walls of the housing, cover and cap and the exterior surfaces of the capacitor and inductance coil component as well as the exterior surfaces of the chassis, position stabilizer and retainer are totally immersed and engulfed in a solidified thermosetting dielectric insulation material cast in-situ in the housing, cover and cap. 
     Preferably the chassis has three of such spindle rods extending parallel to one another and spaced apart with their longitudinal axes oriented in a equilateral triangle array. Preferably the capacitive component comprises three sets of a plurality of spool-wound capacitors electrically coupled in series and spindle supported one set on each the spindle rods. Preferably the inductance coil component comprises an inductor in the form of an annular core having a primary winding thereon with its opposite leads coupled one to the output lead of the series coupled capacitors and the other connected to ground. A secondary winding on the core has its opposite ends forming output leads adapted for coupling to the input terminals of the associated metering device or other digital communication device. 
     Preferably the foregoing filter module is constructed by a novel method wherein the capacitor and inductance components are first assembled to the chassis and then the unoccupied space enclosed by the bottom cover alone is filled with potting compound in a liquid state. Then the lower end of the housing is seated on the cover and is immersed at its lower edge in the potting compound filling the cover. Then the housing is filled with potting compound to engulf the capacitor components therein while being held on spindle rods. The housing potting material likewise engulfs the chassis structure disposed within the housing as the housing is so filled to its upper end brim with the potting compound. Then the electrical leads are trained through the cap and the cap is mounted on the upper end of the housing. Then the space within the cap is infilled with additional potting compound to thereby finish filling with potting compound the entire space enclosed within the said housing, cover and cap. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The foregoing as well as additional objects, features and advantages of the present invention will become apparent from the following detailed description of the best mode presently known to the inventor of making and using an exemplary but presently preferred embodiment of the invention, from the appended claims and from the accompanying drawings (wherein components are shown to engineering scale unless otherwise indicated), and wherein: 
     FIG. 1 as a diagrammatic and semi-schematic simplified perspective view of the basic components of a filter circuit for coupling between the utility power distribution line, ground and for operably electrically coupling the filter network to a suitable wattmeter or other digital communication device in accordance with the foregoing background description. 
     FIG. 2 is a perspective view of a preferred but exemplary embodiment of a filter assembly module of the invention with the housing, bottom cover and top cap shown in phantom to thereby show interior detail. 
     FIG. 3 is another perspective view of the module of FIG. 2 on a reduced scale and viewed from an angle looking from above and from the side of the module. 
     FIGS. 4 and 5 are side elevation views of the module of FIGS. 2 and 3 with the view of FIG. 5 rotated 90° about the longitudinal axis of the module from its orientation in FIG.  4 . 
     FIG. 6 is a top view of the module of FIGS. 2-5. 
     FIG. 7 is a perspective view illustrating the orientation of nine “condensers” (i.e., capacitors) making up the capacitance portion of the filter network of the module as the same are to be held and secured in operative relationship in the filter module of the invention. 
     FIG. 8 is a side elevational view of the array of FIG. 7 but on a reduced scale relative thereto. 
     FIG. 9 is a perspective view of a chassis component of the module viewed from above and to the side of the same. 
     FIG. 10 is a side elevational view of the chassis of FIG.  9 . 
     FIG. 11 is a perspective view of the chassis of FIGS. 9 and 10 as viewed from the side and slightly below the same. 
     FIGS. 12 and 13 are perspective views of the under side and upper side respectively of a position stabilizer component of the module assembly of the invention. 
     FIG. 14 is a side elevational view of the stabilizer of FIGS. 12 and 13. 
     FIGS. 15,  16  and  17  are simplified semi-diagrammatic views of an inductance coil component of the module of FIGS. 2-6, FIGS. 15 and 16 being perspective views of the upper and under sides respectively, and FIG. 17 being a side elevational view thereof. 
     FIGS. 18,  19  and  20  are differing views of a coil retainer component of the module of FIGS. 2-6, FIGS. 18 and 20 being perspective views of the top and bottom sides of the retainer and FIG. 19 being a side elevational view of the retainer. 
     FIGS. 21,  22  and  23  are differing views of a coil cover component of the module of FIGS. 2-6, FIGS. 21 and 23 being perspective views of the upper and lower ends of the coil cover respectively, and FIG. 22 being a side elevational view thereof. 
     FIGS. 24 and 25 are respectively perspective and side elevational views of the housing component of the filter module of the invention. 
     FIGS. 26,  27  and  28  are differing views of the cap component of the module of the invention, FIGS. 26 and 28 being perspective views of the upper and lower ends of the cap respectively, and FIG. 27 being a side elevational view thereof 
     FIG. 29 is a side elevational view of the sub-assembly of the foregoing chassis, condensers mounted thereon (shown in phantom) and held in place temporarily by the position retainer, and the coil mounted beneath the platform base of the chassis and retained thereon by the coil retainer. 
     FIG. 30 is a center sectional view of the module of FIGS. 2-6, and illustrating the assembly of the components of FIG. 29 within the housing, coil cap and cover of the module. 
     FIG. 31 is a perspective view of a modified chassis component for use in the module of the invention. 
     FIGS. 32,  33 ,  34  and  35  are perspective views of an array of nine capacitors (condensers) separated by shipping spacers and temporarily held together by tape to illustrate the appearance of actual capacitors utilized in a prototype of the module of the invention, and with electrical lead connections made by foil strips as shown, FIG. 32 being a perspective elevational view, FIG. 33 being a perspective end view and FIGS. 34 and 35 being perspective views respectively from opposite ends of the unit with one of the condensers pulled to the side to better illustrate the structure and connection by a foil strip lead therebetween. 
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     Referring more particularly to the drawings, FIG. 1 illustrates in simplified, semi-diagrammatic perspective view the electrical filter circuit and basic operative components of a filter module or unit of the invention. The filter circuit includes a suitable heavy-duty high-voltage-rated and insulated power line connector in the form of a multiple strand cable  50  having one end  52  bared of insulation. The other end (not shown) of cable  50  is suitably adapted for mechanical electrical coupling to a 15 KV utility power electrical power transmission line (not shown). 
     The capacitive component of the filter network in the illustrated preferred embodiment comprises a plurality of capacitors (also known as “condensers”) herein as shown as nine capacitors  54 ,  56 ,  58 ,  60 ,  62 ,  64 ,  66 ,  68  and  70  stacked coaxially in three sets of three each and all electrically connected in one series circuit. The upper end face  72  of capacitor  66  has one end  74  of an aluminum foil conductive strip lead  76  soldered thereto, the other end of lead  76  being soldered to the strands at the bared end  52  of cable  50 . The nine linked capacitors  54 - 70  are each wound cylindrically of two foil plates with a dielectric film therebetween, and are constructed so that the opposite end cap layers of each capacitor are electrically connected individually to the opposed plates (i.e. foil layers) within each capacitor. Preferably the total capacitance value of the nine capacitors is 0.1 Microfarad at 15 KV RMS at 60 HZ. Preferably the unit is operable even with a potential of about 10 KV RMS in most of the interfaces where conductors are present. The diameter of each capacitor winding in one exemplary working embodiment is about 1.07 inches. Preferably the windings are sprayed with zinc before the leads are soldered to these parts. 
     As indicated in FIG. 1, capacitor  66  is electrically coupled to capacitor  68  in series by an aluminum foil strip  78  collapsed in assembly between these two capacitors. Likewise capacitor  68  is electrically connected to capacitor  70  by a connector foil strip  80 . Foil strip  82  connects capacitor  70  electrically with capacitor  64 . Likewise the remaining capacitors are electrically connected in series by foil strips  84 ,  86 ,  88 ,  90  and  92 . The construction of the capacitors  54 - 70  and the operable electrical intercoupling therebetween via foil strips  76 - 94  also can be seen in the perspective views of FIGS. 32-35, it being understood that in these views the capacitors  54 - 70  are being held in a simulated array by friction tape for illustrative purposes only. Likewise, corrugated polypropylene separators appear in these views of FIGS. 32-35 that are used as optional shipment spacers and protectors that need not be employed in the method or assembly process and construction of the invention. 
     The output of capacitor  58  is connected by foil strip  94  to the input lead  96  of an inductor  97  of the filter circuit. This inductance component, i.e., inductor  97 , comprises a multi-tum primary coil  98  wound about a quarter of the circumference of an annular ferrite core or ferroid  100 . 
     Again, a secondary coil  102  is inductively coupled to coil  98  by winding coil  102  on the side of core  100  opposite that on which winding  98  is wound. Secondary coil  102  has its two opposite end leads  104  and  106  adapted to be connected to the input terminals of a suitable conventional meter for measuring whatever electrical parameter is desired to be employed as a function of power being transmitted in the associated 15 KV utility transmission line. 
     The aforementioned meter is not shown but could be a standard AC voltmeter for measuring the potential at the point in the distribution line to which the filter assembly module is connected. Typically it is contemplated that a filter assembly module  110  and such associated meter would be pole mounted at specified predetermined locations along the 15 KV transmissions lines. Meter data readings could be either sent by a suitable meter radio transmitter built into the meter or by on-board computer-generated digital communication back along the transmission line. In this manner, over a given time period power consumption data between given metering points can be accumulated and compared to like accumulated power consumption by authorized consumers from their meter reading data and the difference analyzed to reveal normal or abnormal power loss along that section of the line. 
     The filter assembly comprising the capacitance component, i.e., capacitor array  54 - 70 , in series with inductor component  97  provides a straight-forward LC filter circuit of the band reject type that is designed to present a very high impedance to a narrow frequency band width centered around the standard AC frequency (e.g., 60 cycle) employed by the utility on its transmission lines as the power transmission frequency standard. The filter therefore eliminates this  60  cycle “hum” and thereby enables the meter coupled to lead  104  and  106  to function without such noise or interference adversely affecting its performance. 
     Filter Assembly Module 
     In accordance with one principal feature of the present invention, the forgoing circuitry components  50 - 106  are securely supported in an operable array by cooperative support members and encasing housing parts as a complete filter assembly module  110  shown in FIGS.  26 . Filter assembly module  110  is made up of six basic support and encasing components comprising a chassis  112  shown by itself in FIGS. 9,  10  and  11 ; a position stabilizer  114  shown by itself in FIGS. 12,  13  and  14 ; a coil retainer  116  shown by itself in FIGS. 18,  19  and  20 ; a coil cover  118  shown by itself in FIGS. 21,  22  and  23 ; a housing  120  shown by itself in FIGS. 24 and 25; and a cap  122  shown by itself in FIGS. 26,  27  and  28 . 
     In the exemplary but preferred embodiment of module  110  illustrated in FIGS. 2-6, it is preferred to orient the nine individual capacitors  54 - 70  in three axially co-extensive stacks with three capacitors in each stack as shown in FIGS. 7 and 8, and with a predetermined lateral (radial) spacing between each stack. Preferably the manufacture of capacitors  54 - 70  is specified so that they are wound on a spooling core of a specified predetermined diameter so that each capacitor has an axially extending central through bore, indicated at  129  in the case of the capacitor  54  in FIGS. 1 and 7. It will thus be seen that the array of capacitors  54 - 70  in the preferred orientation illustrated in FIGS. 7 and 8 also appears as the orientation of these capacitors in the finished filter assembly module  110  as seen in FIGS. 2-6. 
     Chassis  112   
     As best seen in FIGS. 9,  10  and  11 , chassis  112  is preferably a one piece injection molded plastic part, preferably molded of a suitable conventional ultraviolet stabilized, glass-filled polycarbonate or a PC/ABS blend. Chassis  112  comprises a planar base  130  which in the embodiment of FIGS. 9-11 is in the form of a circular disk designed for a close clearance fit into a collar  132  of coil cover  118  (FIG. 21) and to rest on a shoulder flange  134  that joins collar  132  with the main cylindrical wall  136  of cover  118 . Chassis  112  also includes three cylindrical spindle rods  140 ,  142  and  144  integrally joined at their lower ends to base  130  and extending upwardly from base  130  with their axes perpendicular to the plane of base  130  (“integral” as used herein means joined by being molded as one-piece). Pairs of arrowhead-like snap catches  146  and  148 ,  150  and  152 , and  154  and  156  are integrally molded respectively on the upper ends of rods  140 ,  142  and  144 . Catches  146 - 156  form tongs that protrude laterally radially outwardly beyond the O.D. of each respective rod shank and are each provided with an outwardly facing cammming side surface tapering to a narrow leading edge at its upper end. 
     Chassis  112  is also provided with three integral stand-off ribs  158 ,  160  and  162  extending radially outwardly from the base of rods  140 ,  142  and  144  respectively and axially upwardly from the upper surface of base  130 , as seen in FIGS. 9 and 10. As shown in FIGS. 10 and 11, base  130  also has three short rods  164 ,  166  and  168  protruding from its undersurface with their axes perpendicular to the plane of the base and for a predetermined relatively short distance Rods  164 ,  166  and  168  are oriented in an equilateral triangle or array complimentary to the like array of spindle rods  140 ,  142  and  144  but are radially inwardly offset therefrom equidistantly. Rods  140 ,  142  and  144  are axially coextensive with one another, and likewise as to short rods  164 ,  166  and  168 . The short rods also each have the same arrowhead-like split snap catch head configuration as rods  140 ,  142  and  144  and that are thus constructed in like form to heads  146 - 156  of rods  140 - 144 . 
     Position Stabilizer  114   
     Referring to FIGS. 12,  13  and  14 , position stabilizer  114  comprises a planar part in the form of equilateral triangle and provided with three through-holes  170 ,  172  and  174  spaced inwardly from each of the respectively individually adjacent rounded corners  176 , 178  and  180  of the peripheral side surface of stabilizer  114 . The centers of holes  170 ,  172  and  174  are located by design to be respectively coincident with the axis of rods  140 ,  142  and  144  when in their nominal free-state design orientation in parallelism to one another. The central opening  182  of stabilizer  114  is likewise of equilateral triangular configuration complimental to the exterior periphery of stabilizer  114 . The apex of each of the outside three corners  176 ,  178  and  180  of stabilizer  114  is tangent to a circle having a diameter dimensioned for a close clearance fit of these corners within the inner wall of housing  120  when stabilizer  114  is in final assembly therewith and the major plane of stabilizer  114  is oriented perpendicular to the longitudinal center axes of housing  120 . Preferably each of the rod openings  170 ,  172  and  174  is chamfered from each opposite side of stabilizer  114  to facilitate passage therethrough of the cam catch split tangs  146 - 156  of rods  140 ,  142  and  144  in the module assembly procedure. Again, the fit of the shank of each of spindle rods  140 - 144  in the associated stabilizer openings  170 - 174  is a relatively close clearance fit to enable stabilizer  114  to help maintain and thus stabilize the design location of the upper ends of rods  140 - 144  transversely of housing  120 . 
     Inductor  97   
     Referring to FIGS. 15,  16  and  17 , inductor  97  is made up of the split ferrite core or ferroid  100  and the primary and secondary windings  98  and  102  that are shown semi-schematically and in a simplified form in FIGS. 15-17 and wherein core  100  is shown as a complete unsplit annulus. Note that the central annular opening  182  of core  100  has a given diametrical dimension correlated with the diameter of an-imaginary design circle tangent to outside of the shanks of the three short rods or posts  164 ,  166  and  168  of chassis  112 . In assembly the shanks of these short rods  114 - 160  are adapted to bear against the inner periphery of core  100  after their split snap catch heads have passed axially therethrough during assembly to thereby radially position inductor  97  coaxially with base  130  of chassis  122 . 
     Although core  100  appears as an unsplit annulus in FIGS. 15-17, it preferably is a split annulus as it appears in FIG.  1 . 
     Coil Retainer  116   
     Referring to FIGS. 18,  19  and  20 , coil retainer  116  comprises a base portion  200  of planar form and circular in outline. The outer periphery of base  200  has a diameter generally equal to the median diameter of coil core  100  so as to radially overlap abut the same as shown in assembly in FIGS. 2-5. Retainer  200  has three equally angularly spaced apart through-holes  202 ,  204  and  206  designed to individually respectively receive short rods  164 ,  166  and  168  therethrough in assembly. The dimensions and design of the spring catch split arrow heads of rods  164 - 168  is such that, after being cam squeezed when passing through holes  202 - 306 , they snap open and catch-hold coil retainer  200  in proper assembly relationship with inductor  97  against the underside of base  130  of stabilizer  112 , as best seen in FIGS. 29 and 30. The underside of retainer  116  has a circular flange  208  coaxial with the circular center hole  210  of base  200  and designed to encircle throughholes  202 - 206  and to be spaced inwardly from the outer periphery of base  200  as readily seen in FIGS. 19 and 20. Flange  208  stiffens base  200  and adds axial compressive strength to the part. It is also noted that only the upper side of through holes  202 ,  204  and  206  need be chamfered to provide a caming bevel thereon for passage therethrough of the snap-split catch heads of short rods  164 ,  166  and  168 . 
     Coil Cover  118   
     Coil cover  118 , in addition to the structure previously described, has imperforate bottom wall  214  that is axially reinforced by a circular dependant rib  216  (FIGS.  22  and  23 ). Three small diameter electrical lead holes (not shown) are preferably provided in wall  214 . 
     Housing  120   
     As shown in FIGS. 24 and 25, housing  120  comprises an open ended cylindrical part of uniform constant external and internal diameters and having an axial length slightly greater than the overall axial length of three stacked capacitors  54 ,  56  and  58  when arrayed in assembly. The wall thickness of housing  120  relative to the remaining parts of the assembly can be scaled from the engineering scaled drawing of FIG. 30, which is incorporated into description by reference for, inter alia, this purpose. Likewise, the axial length of housing  120  relative to the remaining parts can be determined by scaling from FIG.  30 . 
     Cap  122   
     Referring to FIGS. 26,  27 ,  28  and  30 , cap  122  comprises a base portion made of a cylindrical collar portion  220  integrally joined by a radially extending shoulder flange portion  222  to a side wall  224  of cap  122  that extends with a convergent taper upwardly to its junction with a radially extending annular top wall  226 . Cap  122  also has a funnel-like dome  230  made up of a cylindrical bottom wall  232  integral with and disposed concentrically to wall  224  and inset radially therefrom. The inside diameter of wall  232  is spaced slightly radially outwardly of snap-catch heads  146 - 156  of rods  140 - 144  in assembly, as best seen in FIG.  6 . Dome  230  also comprises an upwardly convergent frustoconical wall  234  rising from wall  232  and terminating integrally in a cylindrical collar portion  236 . Collar  236  has a cylindrical through-bore  238  defining an access opening through cap  122  to the interior of housing  120  in assembly therewith. Cap wall  226  has a pair of diametrically opposed through-openings in the form of a hole  240  (FIG. 28) and another through-hole (not shown) registering with the through-bore of a fill pipe  242  that rises from wall  226  to an open upper end generally even with the upper end of collar  226 . (FIG. 27) 
     Sequence of Assembly of Components of Filter Module  110   
     Assume that the three stacks of capacitors  54 - 70  are arrayed as in FIG.  7  and electrically connected in series by the foil lead strips as shown and described in conjunction with FIG. 1 hereinabove. The triple stack array is spindled by centering and then sliding one stack down on each of the rods  140 ,  142  and  144  of chassis  112 . The lower most capacitors  58 ,  64  and  70  of this triple stack respectively rest on the stand-off ribs  158 ,  160  and  162 , leaving the snap catch tang heads  146 - 156  at the upper ends of the rods protruding a slight distance above the upper ends of the upper-most capacitors  54 ,  60  and  66 . Position stabilizer  114  is then installed on the chassis by axially aligning holes  170 ,  172  and  174  individually with catch heads  146 - 148 ;  150 - 152 ; and  154 - 156 . Stabilizer  114  is then pushed downwardly to force the spring catch heads through these holes. As the stabilizer abuts the upper ends of capacitors  54 ,  60  and  66 , the spring catch tangs snap out over the upper surface of the stabilizer to thereby catch-hold the same and secure the capacitors axially on chassis  112 . 
     Inductor  97  is then assembled to the underside of chassis base  130  by inserting short rods  164 ,  166  and  168  through the center opening of core  100  until the windings  98  and  102  abut the undersurface of base  130 . Then coil retainer  116  is installed by aligning holes  202 ,  204  and  206  individually with short rods  164 ,  166  and  168  and then pushing the retainer upwardly to force their snap heads through these retainer holes until they catch on the underside of coil retainer base  200  to thereby hold the inductor  97  in assembly with chassis  112 . 
     The output lead  94  from the capacitor array is then soldered to the input lead  96  of inductor  97 . Note that base  130  (FIG. 9) has a notch  131  to facilitate passage of these leads from above and below base  130  for this soldered connection. Notch  131  also provides flow space for potting compound, as described hereinafter. 
     It is also to be noted that coil cover  118  is provided with three small through holes (not shown) in its bottom wall  214 . The ground lead  99  (FIG. 1) from primary coil  98  is fed snuggly through one of these holes to the exterior of the coil cover. Likewise, the secondary coil leads  104  and  106  are fed snuggly individually through the other two holes in bottom wall  214  of cover  118  to leave short lengths exposed exteriorly of the cover for appropriate connection to the associated meter terminals. 
     Coil cover  118  is then assembled to the underside of chassis  112 , as shown in FIGS. 2-5 and  30 , until chassis base  130  rests on shoulder flange  134 . Then the potting compound (e.g., dielectric thermosetting resin) in liquid state is injected into the space below base  130  and above wall  214  via notch  131  so as to fill all of this space, and thereby completely engulf and encapsulate inductor  97 , coil retainer  116  and short rods  164 - 168  in this cover space. Preferably the filling action is done to almost overflowing so that there is potting compound on the upper surface of base  130  but at a level below the upper edge of collar  132 . With these parts in their upright orientation (FIG.  29 ), housing  120  is then telescoped downwardly over the assembled array of capacitors on the spindle rods  140 - 144  and lowered until the lower end edge of the housing enters collar  132  and rests on the upper surface of base  130  and fitting with a close clearance within the inner surface of collar  132 . This submerges the lower edge of housing  120  in the liquid potting compound residing on the upper surface of base  130 . The thermoset resin typically cures to solid state in about ten minutes. Thus housing  120  is then thereby adhesively secured to cover  118  with the capacitor array supported accurately both axially and radially in the housing interior with the capacitors spaced by a predetermined clearance dimension from the interior wall surface of the housing and from one stack to the next by their support on chassis  112 . The bottom of the housing also is now both bonded and sealed to the coil cover by the cured resin-potting compound. 
     In the next step, with the partially completed assembly still oriented upright as in FIG. 29, additional liquid potting compound is poured into the interior of housing  120  to fill the same up to the upper edge of the housing, taking care to leave the input lead strip  76  supported so as to emerge upwardly clear from the potting compound. Then lead  76  is fed upwardly into the open bottom end of cap  122  while the same is yet detached from housing  120 , and then pulled up through collar opening  238 . The free end of lead  76  is soldered to the cabled strands end  52  and then cable end  52  is inserted into cap opening  238  as lead  76  is pulled back into the cap. As best seen in FIG. 30, the cable and cap subassembly is then placed on the upper end of housing  120  so that cap collar  220  encircles the upper edge of housing  120  and shoulder flange  222  seats on the upper edge of housing  120 . 
     With all of the components of module  110  now assembled, more potting compound is introduced into the remaining space enclosed by cap  122  as it sits on the filled housing  120 . This is done by injecting the liquid potting compound through the fill pipe  242  of cap  122 . During this final filling process the potting compound rises up into the neck collar  236  and fills the slight clearance space remaining between the strands or cable end  52  and the inner wall of collar  236 . 
     Although not shown in FIGS. 26-28, cap  230  may have another fill pipe similar to pipe  242  registered with the other cap hole  240  that may be used to connect to a source of vacuum to assist infilling flow of the potting compound. Likewise hole  240  itself without a pipe may be connected to a vacuum source by a suitable conduit (not shown) to provide vacuum-assist infilling of potting compound. 
     Once the potting compound injected into the headspace of cap  122  has cured to a solid state the potting compound will have bonded to the cap at the upper edge of housing  120  and to all other engulfed parts so that the module  110  is now a solid assembly of parts bonded together by a thermoset resin to provide a well sealed and rugged assembly with the electrical components well insulated electrically from one another. Hole  240 , with or without a riser tube like tube  242 , can also be used as a second fill hole so that dual injection can be practiced when using lower viscosity potting compounds that do not need vacuum-assist infilling action. After the assembly is completed and the resin is cured, if desired, pipe  242  (and another pipe associated with hole  240 ) may be cut off flush with wall  226  of cap  122 . However one or both fill pipes may be left in place without adversely affecting the performance of module  110 . 
     From the forgoing description and accompanying drawings, it will now be understood by those of ordinary skill in the art that the injected molded plastic parts comprising chassis  112 , position stabilizer  114 , coil retainer  116 , coil cover  118 , housing  120  and cap  122  cooperate to position and hold the cylindrical capacitors  54 - 70  and ferroid-type coil inductor  97  in proper position to allow them to be adequately surrounded by infilling with a dielectric insulation potting compound. This compound preferably is a suitable thermoset resin added as a liquid and allowed to cure to a solid state to thereby provide not only the necessary electrical insulating properties but also bonding of the various components in a rugged array and for protection of the components from harsh environments in the normal outdoor applications on the utility poles. The potting compound encasing the various parts holds fast all of the assembly frame parts and related parts including the solder joints, and maintains reliably the relative positions of all internal components during shocks and abuse from shipment, testing, installation, and for the duration of the useful life of the filter module. 
     Another feature to note is that the wound capacitors, prior to their assembly onto the chassis spindle rods  140 - 144 , can be electrically coupled in series by making the soldered connections of the leads  78 - 92  to the respectively associated capacitors. Then, after initial assembly of the capacitors onto chassis  112  by spindling the three capacitors stacks on rods  140 - 144 , chassis  112  serves as a convenient assembly fixture for holding the capacitors in place during the additional soldering operations involved in connecting lead  94  to lead  96  of inductor  97  and lead  76  to cable  50 . 
     Chassis  112  and associated position stabilizer  114  can also serve as a shipping fixture for the capacitors after they have been connected in a series by the soldering operation on leads  78 - 92  and prior to connection to inductor  97  and cable  50 . With the capacitors spindled on rods  140 - 144  and captured between base  130  of the chassis and position stabilizer  114 , this chassis  112  can serve as convenient cradle for shipping of this capacitor loaded subassembly from the capacitor manufacturer to the module final assembly manufacturing facility. Since the spooling method of wound capacitor construction is conventional and normally results in a central through bore  130 , this feature is taken advantage of by chassis  112  having its spindle rods  140 - 144  designed to fit into and slide through these center bores to thereby support and orient the capacitors individually and in a predetermined stack-up array without requiring any additional operations in the manufacturer of the capacitors. 
     The position stabilizer  114  readily snaps onto the upper ends of the spindle rods  140 - 144  and is captured against axial lift-off therefrom by the split catch locking tang heads  146 - 156 . The position stabilizer serves to lock the capacitors  54 - 70  onto chassis  112 , and also to position these capacitors at a fixed distance from each other radially of the array and from the inside wall of housing  120 . This ensures that the correct amount of electrical insulating material space is established and maintained during the pouring process of the thermosetting dielectric fluid as well as during the curing process of the same. Likewise the thin ribs  158 ,  160  and  162  projecting from base  130  and spindle rods  140 ,  142  and  144  function as standoffs to elevate the bottom-most capacitor in each stack so that it is held spaced away from base  130  to thereby allow the for potting material to flow and fill completely around and underneath the capacitors for optimal insulating and protection characteristics. 
     Preferably the insulating/potting material is made of a mixture of recycled glass and thermosetting resin(s), or a mixture of silica and thermosetting resins. This mixture electrically insulates, protects and bonds all of the components into one “impossible to disassemble” unit. Preferably all of the plastic components used in the filter assembly module (i.e. chassis  112 , stabilizer  114 , coil retainer  116 , cover  118  and cap  122  are injection molded using an ultraviolet stabilized, glass filled (for reinforcement), polycarbonate or PC/ABS blend. Housing  120  may also be made of such material or if desired of a less expensive plastic material having electrical insulation properties. 
     FIG. 31 illustrates a modified chassis component  112  which is identical to chassis  112  except for the base portion  130 . Base  130 , instead of being circular in outline like base  130  is made with a generally triangular shape with two sides  133  and  135  extending generally at right angle to one another and with the third hypotenuse side  137  having a curvature matching that of the inside of the housing  120  but made up of three straight segments angled relative to one another. Side  137  terminates at its diametrically opposite ends in a pair of centering tabs  139  and  141 , and the junction of sides  133  and  135  is formed into a third centering tab  143 . Tabs  139 ,  141  and  143  are spaced and oriented by base  130  to have a close clearance fit within housing  120  to thereby center the array of the spindle rods  140 - 144  about the longitudinal axis of housing  120  in assembly there with. 
     Another modification of the method and module construction of the invention is to invert and dip the subassembly of chassis  112 , capacitors  54 - 70 , position stabilizer  114 , cover  118 , inductor assembly  97  and coil retainer  116  (after potting of the components  97  and  116  in cover  118 ) into a bath of a highly insulative dielectric resin compound to thereby merely coat (followed by curing) the capacitor array with such material. Then the remaining air spaces existing after housing  120  is telescoped onto this coated array are infilled with sand or other inexpensive insulating material. Cover  122  is then installed, filled and secured with adhesive potting material as before. 
     From the forgoing description and accompanying drawings as referenced to the description, it also will now be apparent to one of ordinary skill in this art that the filter assembly module  110  of the invention amply fulfills one or more of the aforestated objects and provides many novel features and advantages. The injection molded plastic components of the assembly may be economically manufactured to close tolerances on a mass production basis and cooperate with the electrical inductance and capacitance components in enabling the foregoing economical method of manufacture and assembly of module  110 , also in accordance with the present invention. This finished module  110  is extremely rugged, weather resistant and constructed to withstand extremely high voltages when electrically coupled between a high voltage power transmission line and ground. Module  110  may be appropriately designed and rated to operate as a band reject filter for the power line transmission frequency, typically 60 HZ. The conventional meter or other digital communication device connected across output leads  104  and  106 , due to the filtering action of module  110 , is not adversely affected in performing its power line metering function by the strong power line transmission noise, i.e., 60 cycle “hum”. Hence a plurality of filter/meter units individually pole mounted along the power transmission sub branch distribution line feeding ultimate consumers can be installed at predetermined and known pole locations. These pole meters can then be read remotely by radio transmission capability built into the meter, or by conventional telemetering circuitry provided in the meter operable for sending digital information over the power line. This will enable the utility to pin point the pole-to-pole geographic area where excessive metered power is being consumed and not recorded on customer meters, whether by unauthorized meter-jump hook ups or by power line faults such as incipient short circuits.