US1693365A - Method of forming high-tension cable joints or splices for underground systems - Google Patents

Description

Nov. 27, 1928. 1,693,365

- A W. E. BOYLE ET AL- METHOD or' FomuNe HIGH TENSION CABLE JoINTs on sPLIcEs FOR UNDERGROUND SYSTEM vFllecLDecz. 6.. 1924 Shoots-Sheet 1 INVENToRs c1607 PLw//fv f fig/ @W/cr l A oRNEY I Nov. 27, 1928. 1,693,365

w. E. BoYLE ET AL HETHOD'OF FORHING HIGH TENSION CABLE JoIN'x's on sPLIcBs FOR UNDERGRQUND SYSTEIIS Filed Dec. (i.y 1924 Simms-'Sheet 2 INVENTOR;

@diam/l? Sea/wy Agi/f5 We H A ORNEY Nw. 2v, 1923-. 3,693,365'

W. E.. BOYLE ET AL METHOD OF FORMING HIGH TENSION CABLE JOINTS OR SPLICES FOR UNDERGROUND SYSTEMS Filed Dec. 6, 1924 5 ShBBtS-Shee 3 A ORNEY Patented Nov. 27, 192s.

UNITED STATES PATENT OFFICE.

WILLIAM E. BOYLE AND HUDSON R. SEARING, 0F NEW YORK, N. Y., ASSIGNORS, BY DIRECT AND HESNE ASSIGNMENTS, TO ENGINEERING PRODUCTS CORPORATION, INC.,y 0F NEW YORK, N. Y., A CORPORATION OF NEW YORK.

METHOD 0F FORHING HIGH-TENSION CABLE JOINTS OR SPLICES FOR UNDERGROUND SYSTEMS.

Application tiled December 6, 1924. Serial No. 754,273..

This invention relates to high tension cable joints or the like, especially for underground systems.

The object of the invention generally is a novel and improved method for making a cable joint or splice for high tension underground systems and analogous applications which possesses marked resistance to electrical breakdown, is water proof, airtight and permanently stable, and is capable of being practically installed Within the confined and reduced spaces of underground systems.

With the increase in voltage of underground transmission systems the forming of satisfactory cable joints or splices becomes increasingly diflicult because of the small and circumscribed spaces within which the conductors are laid and o-f other special problems to be met which are peculiar to underground systems. The tendenc has been generally to follow the practice in ow tension systems of forming joiiits or splices of a tape or paper foundation immersed in a bath of an insulating compound, in some instances reinforced by fibrous insulating tubes immediately surrounding the tape 0r paper insulation. Joints of this character become unduly bulky for the higher voltages, and moreover experiments show that the dielectric strength and breakdown resistance of such joints are quite irregular and often fail to accord with expected results. This is believed due to the diiliculty of excluding the presence of air and moisture and this diliiculty is enhanced by the tendency of the filling compound to migrate or otherwise become depleted after installation. The latter ditliculties mayl be partially avoided by the use of the usual socalled. hard compound fillers which lare poured around the insulated joint while hot and permitted to cool, but all suoli compounds with which We are familiar either fail to .penetrate and fill the interstices of the joint or upon cooling leave numerous cracks and4 voids throughout the body thereof, or both, with resultant entrapment and penetration of air and moisture. Such hard 'compounds appear particularly incapable upon hardening of forming an air and Water tight seal with the' filling-in and cable insulation. VIn accordance with our novel method herein claimed' we have devised a joint or splice which is of the small dimensions demanded in practice and which is not only free of entrapp'ed air and moisture but is permanently stable and resistant to air and Water penetra.- tion indefinitely. We effect suc-l1 a joint by forming around the bare conductor splice and the adjacent cable insulation a hard, solid, impenetrable body of insulating material of a character and in a manner to form a permanently close air and Water tight seal with both lthe bare conductor and the cable insulation. The insulating body must be of such character' and formed in such manner as to Vavoid injury tothe bare conductor and the cable insulation during the process of formation and after formation it must withstand the severe temperature changes and moisture conditions experienced in' underground systems without internal ruptures and disintegration. The

insulatin material which We have found suitable elongs generally to the synthetic resin class, though other materials such as specially treated natural resins may be later found to be suitable for our purpose. The preferred insulating material is a synthetic resin of the phenol-formaldehyde condensation type because we have found such an artificial resin, if properly selected, to possess properties peculiarly fittm it to the formation of,such an impenetra le air and Water tight joint including a close seal or union with both the bare splice andthe cable insulation.

Moreover, an insulating body of this character possesses temperature and heat. con ducting characteristics which render it especiallyv suitable for use with the bare cop per conductor splice with which it functions and enable it to resist rupture and fracture during severe s ervice conditions.

More particularly our invention relates to the insulation of cable conductors in situ, and in one aspect involves incorporating-the raw material about the bare spllce and the interrupted cable 'insulation in the quantity dsired, either before-or' after melting, and while subjecting it to heat and/or pressure in the usual manner of transforming similar materials into a hard infusible mass, localizing the pressure about the cable joint and thereby preventing the migration of the molten or plastic material during the treating Y and forming stage. In another aspect, our

novel method involves the introduction of an insulating oil bath about thejoint or splice in a manner to thoroughly saturate the cable insulation prior to the formation of the solid mass of insulation about the joint.

For a better understanding of the invention, reference may be had-to the accompanying drawings forming a part of this application, wherein:

Fig. 1 is a side View of a cable joint embodying our invention,

Fig. 2 is a longitudinal section therethrough with enclosing casing,

Fig. 3 is a view indicating the method of forming the joint,

Fig. 4 is a longitudinal view partly in section illustrating a step in the formation of the joint,

Fig. 5 is a view illustrating apparatus which may be employed in carrying out our invention,

Figs. 6 and 7 are views of an electrical heating apparatus which may be. employed.

Figs. 8-11 and 12-13 are views illustrating a modified form of apparatus and a slightly modified method of procedure respectively.

Referring to Fig. 1 We have indicated the cable ends 1 and 2 which are to be joinedtogether and insulated in accordance with our invention. The joint resulting from our invention includes a body of hard infusible and permanently stable insulating resin-like material 3 which is formed around the splice and is of .a character to form an air and watertight seal and joint with both the bared conductor ends and the cable insulation coverings, and to permanently exclude both air and moisture from the joint. We have found that a material of the phenolformaldehyde condensation type, if properly selected and treated, is especially suited for insulating cable joints, particularly in lthat such a material may be treated and operated upon so as to form a permanently solid air and Water proof insulating mass about both the bared metallic conductor, and the cable insulation. Its insulation and dielectric strength are such that joints of this character may be employed for the highest voltages in use in underground systems Without unduly increasing the dimensions of the cable at the` joint, and its temperature, heat conducting and other physical properties are such that its structure remains firm and intact indefinitely, notwithstanding the severe service conditions to which it is subjected in underground systems.

In Fig. 2 we have shown a casing 4 surrounding the body of insulation 3,- the casing 4 forming a wipe joint with the lead sheath 5 of the cable. The lead sheath 5 is illustrated as'cut off to the point 6 and the exposed insulation 7 of the cable may, if desired, be beveled olf along the surface 8. The bared ends of the conductors of the cable ends 1 and 2 are joined together by a metallic sleeve 9 inthe usual manner. The body of insulating material 3 is observed to adhere to both the cable insulation 7 and the bared conductor ends and copper sleeve 9, and to fill all the crevices and interstices within the casing 4 and about the splice.

One embodiment of our method of formation and insulation of the joint in situ is indicated in Figs. 3 andv 4. Fig. 3 indicates the conventional manhole having the cables 1 and 2 leading thereinto which cables are to be joined and insulated according to our .invention. The casing 4 is passed over one of the cable ends 1 or 2 before the bared conductor ends are joined by the copper sleeve 9 and after the anchoring of the sleeve 9 in position about the abutting ends of the bared conductors` the casing 4, which is indicated as of cylindrical form With an opening on its upper side` is then, slipped into position to surround the copper splice 9. The ends of the casing 4 are then sealed to the lead sheath 5 of the cables in any suitable manner, as for example by the usual Wipe oint. The casing 4 is then filled or almost filled With the insulating material which is ultimately treated to form the resin-like body 3 about the cable splice. IVe prefer to use for our purpose a phenol-formaldehyde condensation product which, before it is melted and treated, is in a granular, flaky, lump-like or plastic form. This material isv introduced through the opening in the upper side of the casing 4 and preferably in the melted form. It can be easily melted by the application of moderate heat in a suitable vessel "(omitted from the drawings for convenience in illustration) and after melting or bringing it to a liquid or plastic state it is then poured into the casing.' A cover 10 is indicated more or less diagrammatically for closing the opening in the casing 4 and between the cover 10 and the melted raw material 3 there is a chamber 11 to provide, for the application of suitable fiuid pressure during the process of treatment. In the preferred embodiment a layer of oil 12 of suitable depth completely covers the material 3 which serves to shield the material from direct contact With the pressure fluid applied to the top thereof. The oil used docs not mix with or penetrate into the body of phenol resin product 3. Pressure and heat are then simultaneously applied to the melted material 3. for a suitable length of time to convert and transform the same into the hard infusible resin-like body 3 of Figs. 1 and 2.

Fluid pressure such as CO2 or the like may be applied through a pipe line 13 controlled by a valve 14, the pipe 13 having a connection 15 leading down through the cover 10 to the chamber 11 above the raw-material or substance 3. Heat may be applied in any suitable manner, but I have ndiated diagram- Lacasse matically an electrical heating coil 16 surrounding the casing 4 for externally applying heat to the substance 3. Before the pressure and heat are applied, binding means such as clamps 17 are ap lied to the cables 1 and 2, these clamps 17 eing indicated as binding very tightly about the cables 1 and 2 and functioning to localize the pressure within the immediate neighborhood of the joint. Migration of. the resinous material along the bare conductors and throu h the cable insulation beyond the joint is t ereby avoided. Sufficient heat is then applied to the substance 3 to convertit to ahard resin like body 3 and at the same time pressure is .applied and maintained thereon during the heating step. A pressure of from 100-125 pounds upon the material 3 and a temperaturel of 125-135,J C. are suitable for most phenol condensation products with which We have worked, although satisfactory results may be obtained with consider-able variations in pressures and temperatures. The pressure and heat are preferably applied continu(- ously for four or five hours which is ordinarily suilicient to convert the raw material 3 into the hard infusible resistant resin-like body 3 which under this treatment closely lsurrounds and binds tightly both the bared conductor splice and the insulation. The process also results in the impregnation of the insulation 7 b the raw material 3 before it hardens an it penetrates all the interstices and crevices about the joint and within the casing 4 to form an airtight insulated joint with no voids and interstices therein. The binding means 17 `function to prevent the bursting of the cable sheath 5 during the application of pressure and to relieve the joint of bending strains, and enables the maintenance of suitable pressure and p revents the penetration of the fluid material (before it hardens) therebeyond.

' lVe have found it advantageous to thoroughly saturate the joint with oil before the introduction of the raw' material 3 and this may be readily effected by temporarily filling the casing 4 Withoil and then applying pressure, say of 100 pounds thereon for a brief period to inipregnate the insulation and cause the oil 'to thoroughly enetrate the interstices and crevices thereo The oil is then removed from the casing and the raw material 3, introduced as above indicated for forming about the joint. Preferably the oil bath is removed entirely before the introduction of the'rawmateria-l 3, including the wiping of the bare conductor to remove the yoil film, but it would of course be possible lto introduce thematerial 3 directly into Ithe oill bath since the resin would supplant the oil and cause it to rise tothe top. a It is possible to form a vfairly satisfactoryjoint by treating a groperly selected resin at approximately ,60o and at atmospheric ltion and remains in its intact, homogeneous,l

voidless form indefinitely. 1pts heat conducting characteristics render it particularly free of internal stresses due to changes in temper- 'ature with the consequent reduction of tendency torupture and form cracks and crevices therein.

Referring to Fig. 5 of the drawings we have illustrated an apparatus f or practicing our invention. The casing 4 is positioned around the splice and is sealed to the lead sheath of the cables 1 and 2 in the manner above indicated, and on opposite sides of the casing 4 in which the insulating body is to be formed are disposed the elongated clamps 17 the latter having securing and binding means 20 for engaging the adjacent edges 21 of the cl-.mps 17 By this means the clamps 17 may be caused to bind the cables 1 and 2 very firmly and tightly to enable the maintenance of the pressure within the casing 4 and to prevent the migration of the phenol condensation products during the'treatment. The casing 4 is provided with a cover 10 which rests upon the peripheral edge 22 of the opening in the casing 4 and is secured firmly thereto by bolts 23. The cover l0 is provided with openings for the reception of the pressure intake pipes 24 and 25, these being attached thereto in any suitable manner, as for example by the screwthreaded connections illustrated. A pair of HNI expansion and pressure equalizing tanks 26 and 27 are carried by theseintakcs 24 and 25 and the tank 26 has an intake 28v With a control valve 29 therein for admittingr fluid pressure such as air, COgand such like for vapplying pressure to the phenol products 3 under treatment. Theintake pipe 24 which is centrally disposed-With reference to the cover 10 carries on its upper end a double T connection 30, the horizontal connect-ions of this T leading to the tanks 26 and 27 nection 33 between the-vertical pipes 24 and 25 and similarly there is a connection 34 leading from the vertical pipe 24 to the bottom of the tank 27 near the left-hand end thereof. The connection 24 is observed to lead into the tank 27 substantially centrally thereof in line with its longitudinal axis and into the tank 26 at a point above the center thereof, while the pipe leads into the bottom of tank 26. The upper connection of the member 30 is provided for the purpose of inserting a thermometer casing into thecasing 4, the casing 35 being in the form of an elongated tube having its lower end closed. It is carried by the telescopically arranged screw-threaded sleeves 36, the lower one of these sleeves being carried directly by the T connection 30. This casing 35, therefore,l

extends centrally through the intake pipe 24 and to casing 4 and a thermometer as indicated, may be inserted thereinto for the purpose of determining the degree of heat to be applied.

In Figs. 6 and 7 we have indicated views of an electrical heating unit which is in the form of two similar mating parts 37 and 38 which may be clamped externally about the casing 4 in close proximity thereto for api plying the heat to the casing 4. One of these halves 38 is shown as broken off and only partially illustrated. Both are provided with electrical heating coils 39 (only one group shown) which may be supplied with electrical energy after the assembly thereof about the casing 4. They are hinged at their lower edges as indicated at 40 and have suitable latches 41 on their upper portions for fastening them together after assembly about the joint. At 42 is indicated a pressure gauge for indicating thepressure applied to thev system.

In the particular embodiment illustrated not only the chamber 11 above the condensation product 3 is filled with a neutral fluid likeV oil, but this oil is iilled in in quantities suiiicient to raise the level thereof to substantially the top of the intake pipe 24 and to a point slightly above the central axis of the tank 26 and slightly below the central axis of the tank 27. With the melted or plastic material 3 contained in the casing 4 and the parts assembled as indicated with the body of oil for shielding the material 3 against the direct influence of the fluid pressure, the pressure and temperature are raised to the desired degrees and continued for the desired period necessary to convert and transform the product 3 into a solid, infusible permanently stable insulating body. After the continuation of this treatment for the desired period, the pressure and the heat energy supply are removed from the system and the insulating body 3 thus obtained forms a permanent solid insulator about the cable splice of marked electrical resistance and dielectric strength. AIf desired, the cover l0 may be =removed from the casing 4 with the other parts, or 'it may be permitted to remain there indefinitely. Similarly the binding devices 17 may be permitted to remain or they may be removed and used in the formation of other cable spliccs and joints. In Figs; 8 and 9 we have shown a simplified and preferred apparatus for carrying out our invention. The casing or sleeve 4 which surrounds the joint and is sealed to the lead sheath 5 of the cable by the usual wipe joint is similaito the casing 4 described above. Instead of a flat casing plate 10, 10. however, we employ an elongated chambered cap 45 whiclrmay be tightly fastened over the openingof the'casing 4 as by means of the series of fastening bolts indicated. This casing is provided on its top with an intake opening 46 with a suitable closing cap thereon whereby, upon removing the cap, insulating oil may be introduced therein to saturate the joint before the introduction of the material 3 or to form a'body of oil which is interposed between the point of application of the luid pressure and the body of raw mateserve as a guide for maintaining the proper treating temperature within the casing 4. rihe method of treatment is similar to the method described above in connection with Figs. 1 5 inclusive. After the required treatment which results in the transformation of the raw material 3 into a hard infusible mass tightly gripping both the bared conductor and adjacent insulation and penetrating into the crevices and interstices to form a solid mass thereabout, the application of pressure and heat may be removed and the cap 45 exchanged for the permanent plate 51, illustrated in Fig. 9. This plate 5l is in the form of a Hat plate which may be secured to the casing 4 by the same attaching bolts` illustrated in Fig. 8. This plate 51 forms a permanentclosure for the casing 4 during the life of the joint.

The means for applyingy heat energy to maintain the proper temperature Within the casingfl during the treatmentot the raw material 3 may be effected by au electric heating apparatusillustrated in Figs. l() and 1l, which is of the general character indicated diagrammatically in Figs. 6 and 7. This heating unit comprises the two casing halves 52 which are hinged at 53 and each h'alf y52 carries therewithin near the bottom thereof a heating elementl 54, these elements 54 being adapted to closely surround the bottom and sides of the casing 4. In the particular structure illustrated each of these heaters 54 comprises a series of siav coils 5.5 which are carried by the spacing insulating members 56, suitably secured to the casing parts 52 and these coils may be connected up in the usual manner ,to supply electrical energy thereto through any suitable connections passing out through the casings 52,-`-these connections not being shown for convenience in illustration. The two hinged halves 52 may be retained inmating relation in any suitable manner as for example by means of the latches 57 Vsecured to the adjacent ends thereof. These casings 52 are also provided with semi-circular mating grooves 58, 59 and 60 on their upper meeting edges 4to form openings for accommodation of the pipe connection 48, the thermometer socket 50 and the closing cap 46, f

Referring to Fig. 8 -it is observed that the cable insulation 6l is not tapered or beveled Off as is' done in Figs. 1-4,inclusive, but instead a cylindrical section of. insulation' is removed from each end of the cable so as to provide end surfaces 62 at right angles to the Icable. In Fig. 12 We have indicated a slight modification wherein the insulation is'removed in series of steps 63 adjacent the cable ends, the creepage surface being slightly larger than the surface in Fig. A8. In Fig. 13

4we have indicated the cable insulation-adjain Fig. 8,-it having been found that'this is entirely satisfactory for practicalpurposes. We have shown our invention as applied to the insulation of cable splices to' which it ifs yparticularlyy adapted, but .certain features thereof are of advantage in the formation of pot head joints and similar applications.

i x Having thus described our invention, what K cluding the application of pressure, binding the cable on oppositesides of the casing chamber and then subjecting the material to a we claim and desire to protect by Letters Patent is;

1. The method of insulating af cable conductor splice in situ which consists in forms ing a casing around the splice, introducing a. quantity of raw materia into the casing,

vsaid material bein capable of being trans-- formed into a soli impermeable insulating mass binding the cable on opposite sides of the casing Aand then subjecting the material to combined pressure and heat to transform it into a solid impermeable insulating mass surrounding the splice.

2. The method 0f insulating a cable conductor splice in situ which consists in form# ing an enclosing casing around the splice, introducing an' insulating oil in the casing and applying pressure to thoroughly saturate the cable insulation adjacent the splice, and then forming around the splice and within the casing a solid body of insulating material.

3. The method of insulating acable conductor splice in situ which consists in forming an enclosing 'casing around the splice, introducing an insulating oil bathvvithin the casing and applying pressure thereto to satu' rate the cable insulation therewithin, then removing the oil bath and introducing a quantity of raw material into the casing which is capable of transformation by treatment into a Iquantity of raw material into the casing which is capable of transformation by treatment into a sol-id impermeable insulating mass, and then subjecting the material to treatment to transform it into a solid imfpliermeable mass surrounding the splice and lling the crevices and interstices vWithin the casing and about the joint.

5. Thel method of insulating a cable conductor splice in situ Awhich consists informing a casing around the splice, .introducing a vquantity, of material into the casing which is capable of being formed into a solid imermeable insulating mass by a 'treatment intreatment including the application of pressure to transform it into a solid impermeable insulating mass surroundingthe splice.

In testlmony whereof, We havesi'gned our names to this specification.

v WILLIAM E. -BOYLE.

HUDSON R. SEARING.

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