US2029546A - Insulated conductor - Google Patents

Description

Feb. 4, 1936. R, AL SCHATZEL 2,029,546

INSULATED CONDUCTOR Filed Aug. 22, 1929 PQUef INVENTOR ATTORNEY Patented Feb. 4, 1936 UNITED STATES PATENT OFFICE 2,029,546 v INSULATED CONDUCTOR Rudolph A. Schatzel, Rome, N. Y.,

Corporation,

General Cable assigner to New York, N. Y., a

My invention relates to improvements in insulated electrical conductors which are particularly adapted for use in exposed positions.

The principal object of myfinvention is the provision of insulation for conductors which, among other things, has a high dielectric strength; which continues to be effective even after prolonged periods of exposure to atmospheric conditions, such as moisture, heat and cold; and which also withstands abrasion and time, the invention pro- Other objects of the invention will be apparent from the following specification, wherein a preferred and illustrative form of the invention has been selected for description. In the accompanying drawing- The single ligure of the drawing shows an enlarged section of insulated conductor, wherein the several sheaths of insulating material are progressively removed to illustrate the entire construction and assembly thereof.

In the distribution of electrical energy wherein Wires are carried by poles, a type of wire is used which is known as weatherproof wire. Ordinarily, the wire is finished with insulation comprising two or three braids of cotton saturated with appropriate compounds. This covering has certain insulating values suiicient, when the wire is dry and newly installed, to insulate the circuit at ordinary voltages. However, the type of covering is not wholly satisfactory in view of the higher voltages which are now frequently used in local distribution systems with step down transformers, and, moreover, this type of insulation is subject to deterioration, so that after a relatively short period of service it often affords uncertain protection and creates a dangerous situation for linemen working in proximity to operating circuits. In view of the large quantities of this type of wire which are used and the relatively infrequent occasions when the insulation is required to function as such, it is not economically expedient to substitute the superior and more expensive known forms of insulation such as rubber. Nevertheless, an economical insulation of relatively high dielectric strength and long life is highly desirable.

My invention contemplates, among other things, the provision of a relatively inexpensive weatherproof wire, wherein the insulation has a high dielectric strength even in the presence of moisture; and wherein the insulation is substantially unaected by extreme climatic cycles, continuing to aiod maximum protection over a. relatively long period of time.

To this end, I provide an insulated conductor of the character shown in the drawing, wherein the complete structure is built up on a metallic conductor l which is covered with an inner wrapping 2 of protective material. Such wrapping may take the form of a strip or tape of an insulating brous material, such as paper. The particular form of tape shown comprises a strip of relatively thin kraft paper. Preferably, such tape is spirally wound around the conductor I, with the side edges thereof overlapping.

The fibrous wrapping 2 may be impregnated with a moisture-proofing compound, wherein the principal ingredients are preferably gilsonite, rosin, montan, corn oil and paraiiln. Satisfactory results have also been obtained with a saturant of vulcanized oil. Such saturants constitute relatively hard, non-migrating fillers which are not readily displaced by water as compared with oil.

A viscous seal may now be formed on the paper wrapping 2 by applying thereto a relatively thin layer 3 of a Compound which preferably includes rubber, palm oil and rosin. Should a more inexpensive compound be desired, then the viscous seal may be formed by a mixture, the principal distinguishing ingredients of which are heavy boiled linseed oil and gilsonite. Still another inexpensive satisfactory compound includes heavy boiled linseed oil, gilsonite and rosin.

In accordance with my invention, a second or intermediate covering 4 is provided. Such covering is preferably formed by a paper tape wound spirally in the same direction as the paperxtape forming the covering 2, with the side edges thereof overlapping. The covering 4 may be saturated with a lubricating compound so as to ensure flexibility, as well as to provide inner and outer flexible oiled surfaces, for reasons as will presently appear. Such compound may conveniently include say, petrolatum and rosin.

Preferably, a coating 5, which may be similar to the coating 3, is next applied to the intermediate paper covering 4 so as to form an intermediate viscous seal, and this preferably is followed by a third or outer paper covering 6. The covering S may be formed of thin, overlapping paper strips, as in the case of the coverings 2 and 4, and it is preferably oppositely wound in order to break joints with the preceding windings.

If convenient, a relatively thick coating 'l of heat and waterproof putty or compound is now applied. The compound is preferably composed of a base of a fatty acid pitch, such as stearin pitch, and a ller of asbestine (magnesium silicate) as set forthfin the patent of Frank M. Potter for Cable, No. 1,904,527, Apri1 18, 1933. The asbestine, which is in a nely divided state, is added to the pitch in the amount required to give the desired consistency, which preferably, at normal atmospheric temperatures, is about like glazing putty and at 300 F. about like cold molasses. The amount of asbestine added varies with the consistency of the pitch but is between 10% and 30% of the whole. If a putty of a higher viscosity is desired, fibre asbestos may also be added with the asbestine as a ller. Other fillers, such as alumina, ground quartz, mica or magnesium oxide may be substituted for the magnesium silicate if desired.

The resulting compound is extremely resistant to heat and oxidation, inasmuch as each individual substance is almost completely oxidized before being combined. Moreover, the putty does not become brittle in cold weather nor unduly soft in hot weather. It is further noted that since the putty maintains its fluidity, it follows that it tends to flow toward and heal any bruise or rupture which may later be made to the braided conductor.

Conveniently, a braid 8 is next applied over the putty coating 1. This braid may be saturated with a suitable waterproofing compound which may be composed of gilsonite, rosin, montan and corn oil. A second cotton braid 9 may be fabricated over the inner braid 8 and similarly saturated with a relatively soft wax compound. If desired, the saturant just described for the inner and outer braids 8 and 9 may be replaced by a waterproofing compound having an asphalt base. Preferably,A the outer braid 9 is now covered with a. tough, skin-like wrapper Il, which may take the .form of a thin coating of paint. One such paint, which is disclosed in the aforesaid application, is formed of a metallic oxide, such, for example, as red iron oxide, litharge, alumina, magnesium oxide, etc. This metallic oxide is mixed with a specially prepared oil which may include boiled linseed oil, boiled partially polymerized China-Wood oil, stearic acid and zinc resinate.

This paint, when dry, provides a tough, weatherproof skin, which is effective to prevent migra.

the saturant for also protects the tion of the soft wax constituting the braids 8 and 9. The paint insulation, particularly the cotton braids 8 and 9, from the deteriorating eifect of the ultra violet rays; and the germicide which is contained in the paint resists bacterial growth, especially in the braids 8 and 9. Weather conditions over a long period of time have substantially no effect on the paint and it is especially resistant to acid and alkalis such as are frequently found in the atmosphere. The paint further affords the insulation protection against 'attacks by insects and the like. If desired, the completed conductor may be provided with a coating I 2 of paraffin which ensures a smooth outer surface of bright appearance.

The embodiment of my invention just described provides a homogeneous flexible insulating covering for the metallic conductor l of high dielectric strength and maximum weather resisting properties. It is noted that the exibility of the covering is, in a measure, due to the saturation of the intermediate paper covering 4 with a substance such as petrolatum and rosin, which acts as a. lubricant, so that the oiled surfaces of the covering li readily slip over the relatively hard combination,

inner and outer paper coverings 2 and 6, respectively.v

Although only one embodiment of the invention has been shown and described herein, it will be understood that the invention may be variously modified and embodied within the scope of the subjoined claims.

What I claim is:

1. An article of manufacture comprising, in combination, a conductor, an impregnated protective covering in strip form, a non-migrating viscous compound applied over said covering in a continuous thin layer and constituting a permanent seal, a second protective covering in strip form surrounding said compound and saturated with a lubricating material, a continuous thin layer of non-migrating viscous compound applied over said second covering forming a permanent seal, a third protective covering in strip form, and a braid surrounding the whole.

2. An article of manufacture comprising, in

a conductor, a plurality of independent paper coverings applied successively about the conductor, adjacent paper coverings being separated by thin'layers of viscous sealing material, a continuous coating of an oxidized moisture-resisting, plastic compound over one of the paper coverings, a. braid over said plastic compound and a tough, non-metallic skin-like protective coating for said braid.

3. An article of manufacture comprising, in combination, a conductor, a protective covering in strip form directly applied to said conductor, a v

coating of oil and rosin applied to said covering so as to form a viscous seal, a second protective covering in strip form saturated with a lubricating material, a compound applied to said second protective covering forming a viscous seal, a third protective covering in strip form, a layer of asbestos putty, a braid over said putty having a wax saturant, a metallic oxide paint over said braid, and a paraffin coating for said paint.

4. An article of manufacture comprising, in combination, a conductor, a multi-layer paper jacket for said conductor wherein the several layers are lubricated for relative movement and rendered non-hygroscopic by overlying layers of Viscous sealing material, and a surrounding protective double braid covering impregnated with a waterproofing compound and coated with a waterproofing paint. l

5. An article of manufacture comprising, in combination, a conductor, a paper jacket comprising a plurality of independent paper coverings providing electrical insulation for said conductor, adjacent paper coverings being separated by thin layers of viscous sealing material, a heat and water resistant protective coating of a non-hardening oxidized plastic compound over said paper jacket forming a self-healing seal, a braid surrounding said protective coating, and a tough skin-like covering over said braid.

6. An article of manufacture comprising, in combination, a conductor, a protective covering in strip form directly applied to said conductor, a layer of non-migrating viscous compound applied over said covering so as to form a seal, a second protective covering in strip form saturated with a lubricating material, a non-migrating viscous compound applied over said second protective covering forming a seal, a third protective covering in strip form, a layer of plastic bituminous compound, a braid over said last-- braid and the outermost one of said protective strip coverings.

8. An article of manufacture comprising, in combination, a conductor, a plurality of overlying layers of helically wrapped paper tape, adjacent paper layers being separated by thin layers of viscous sealing material, a continuous relatively thick layer of non-hardening, oxidized, moistureresistant, plastic compound forming an enclosing protective covering for the paper layers, and an 10 outer braid.

RUDOLPH A. SCHATZEL.

Images