US1200041A - Method of insulating conductors. - Google Patents

Description

I. B. SPEED.

METHOD 0E INSULATING CONDUCTORS.

Patented Dot. 3,1916.

I flu/enrol.- James 5. Speed b APPLICATION FILED MAR-11,1915.

W/Tn eases 3. 71 Ma UNITED STATES PATENT OFFICE.

JAMES BUCKNER SPEED, OF WESTNEW BRIGHTON, NEW YORK, ASSIGNOR, Z BY ASSIGNMENTS, TO WESTERN ELECTRIC COMPANY, INCORIEORATED, A. CORPORA- TION OF NEW YORK.

duction of an insulating covering for conductors which shall possess a higher dielectric strength than coverings heret'ofore employed and which when applied to the conductor will permit of the winding or coiling of such conductor about small diameters without impairing the dielectric strength of the covering.

In accordance with this invention, an insulating covering comprising alternate layers of some of the commercial forms of insulating compound and mica or some similar form of insulating material of similar characteristics is applied to the conductor.- Preferably the insulating compound is applied to the conductor in a tacky or sticky condition and the mica is applied thereto in the form of finely divided particles or dust. The mica may be floated upon the conductor by passing the conductor through a chamber in which said mica particles are floating. I

While it has been possible to successfully insulate conductors with a relatively thin coating of known commercial forms of compound, such for example as described in the Holmes and Harris Patent No. 1,101,281, and similar compounds, and obtain an insulated conductor which could be wound about small diameters without affecting the high dielectric strength of the insulating passes.

coating, still when increasing the thickness of the coatings of such insulating 'com- .pounds to greatly increase the dielectric strength, such heavily insulated conductors could not be wound about small diameters without having a deleterious effect upon the dielectric strength of such insulating coating. An insulated conductor embodying the present invention overcomes the defects of telile insulated conductors heretofore produc Specification of Letters Patent.

Patented Oct. 3, 1916.

This invention will be more fully under stood by reference to the accompanying drawing which illustrates one embodiment of the invention.

In the drawing, there is shown one form of apparatus by means of which a conductor may be insulated according to the present invention.

5 represents a furnace through which a conductor '6 passes. This furnace may be and preferably is similar to that shown in the Holmes and Harris Patent No. 1,101,281. The ,wire 6 passes from a supporting spool 7, under a guide 8, over and 'under one of a series of pulleys 9 which are mounted on a shaft supported in a trough 10 containing an insulating compound. From a pulley 9, the conductor passes up through the furnace 5 and over one of a series of pulleys 11 and then down under another pulley 9 and up through the furnace 5, this cycle being repeated until the insulation is of the desired thickness. When the insulation is of suflicient thickness, the insulated conductor is passed'from the furnace 5 over one of a series of guides 12 and is wound on a spool 13.

20 represents a chamber connected with the furnace 5 by means of pipes 21 and 22. The fans 23 and 24 cause a circulation of air in the direction indicated by the arrows. In the bottom of the chamber 20 there is placed a quantity of mica dust which is agitated in any suitable manner, such for example as a hammer 25 intermittently tapping the bottom of the chamber 20. By a constant agitation of the mica dust and with a circulation of air in the chamber 20 and the furnace 5, the air in the furnace 5 between points opposite the pipes 21 and 22 will be laden with mica dust. There are openings 30, 30in the top and bottom of the. furnace 5, through which the conductor In order to prevent the mica dust from getting into the room through these openings 30, 30 and unavoidable cracks elsewhere in the furnace 5 and the chamber 20,

the pressure of the entire system is kept just particles or This conductor 6' passes through the insulating compound (preferably that der scribed in the Holmes and Harris Patent No. 1,101,281) in the trough 10, and then 6 up through the furnace 5. As the coated conductor enters the furnace 5, the coatingon the conductor is in a plastic, sticky or tacky condition, so that when the coated conductor encounters the mica laden 10 air, in the furnace 5, particles of mica will attach themselves to the coating on the conductor. form of flat particles or flakes, and it is preferable that the long diameter of these flakes be less than one fourth of the diameter of the conductor'which is being insulated, in order that the insulated conductor shall not be rough. It is a well known fact that any flat particle propelled through the air without gyrostatic action tends to travel through the air flatwise rather than edgewis'e. It will be seen then that the particles of mica, 'in attaching themselves to the sticky coating on the conductor, will attach themselves flatwise, thus forming a fish-scale covering over the coating of insulating compound. As the conductor having a coating of insulating compound and a covering of mica particles passes through the furnace, the coating of "insulating compound is hardened and the particles of mica become firmly attached to I the coating of insulating compound. An-

other coating of insulating compound and then another covering of particles of mica may now be applied to the previously cov ered conductor and again subjected to the The mica dust is in the hardening process. The number of layers,- of insulating compound and mica needed on a conductor depends upon the dielectric 40 strength desired. In order that the finished .insulated conductor may be smooth it is desirable that thecl'ast layer of insulation applied be a layer of the insulating compound. I I

"When a conductor which has been insulated according to the present invention is wound about small diameters, the insulating compound-may crack, but the particles of mica prevent the forming of a continuous 5 crack' or opening from the outside of the entire covering to the conductor. It will be seen therefore that whereas the cracking of the insulation on conductors heretofore produced materially lowers the dielectric strength, cracking of the insulating 'compound ma take place on insulated conductors er'nbo ying the present invention, without havingany deleterious efiect upon the dielectric strength.

What is claimed is:

The method of insulating a conductor which consists in coating a conductor with w an insulating compound, covering the coated conductor with particles of mica while the insulating compound thereon is in a tacky condition,and baking the covered conduc tor while applying the mica.

In witness whereof, I hereunto subscribe my name this 10th day of March, A. D. 1915.

. JAMES BUCKNER SPEED. Witnesses:

E. Emma, K. L. Sum;

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