US3623924A

US3623924A - Electrically insulating tape and method of applying same

Info

Publication number: US3623924A
Application number: US884905A
Authority: US
Inventors: Theo A De Winter; Edward J Lucas; William A Lanyi
Original assignee: Avco Corp
Current assignee: Avco Corp
Priority date: 1969-12-15
Filing date: 1969-12-15
Publication date: 1971-11-30
Anticipated expiration: 1988-11-30

Abstract

AN ELECTRICALLY INSULATING TAPE COMPRISING A THIN ROBBON OF FLEXIBLE ELECTRICALLY INSULATING MATERIAL WITH ADHESIVE ON ONE FLAT SURFACE AND IN CONTACT WITH A LOW RELEASE BACKING MATERIAL. OPENINGS SPACED ONE FROM ANOTHER ARE PROVIDED ALONG THE LENGTH OF THE TAPE. UPON REMOVAL OF THE BACKING MATERIAL, THE TAPE IS APPLIED TO AN ELONGATED SURFACE HAVING A DIMENSION LESS THAN THE WIDTH OF THE OPEN-

INGS AND TRIMMED TO LEAVE ON THE ELONGATED SURFACE ONLY THOSE PORTIONS OF THE TAPE INTERMEDIATE THE OPENINGS.

Description

9 1, Y T. A. DE WINTER E 3,$23924 ,ELEQIRI CALLY INSULATING TAPE AND METHOD OF APPLYING SAME 4 Sheets-Sheet 1 Filed Dec; 15, 1969 m R m E m w MNW l A WWL MJM ARM O EWl H BY ATTORNEYS 0v. 30, 1971 DE wm'r ETAL 3,623,924

ELECTRICALLY INSULATING TAPE AND METHOD OF APPLYING SAME Filed Dec. 15, 1969 4 Sheet::-Sheet 8 THEO A. DE WINTER EDWARD J. LUCAS WILLIAM A. LANYI INVENTOR.

BY I wmil ATTQRNEYS Nov. 30, 1971 T. A. DE WINTER ETAL 3,623,924

ELECTRICALLY INSULATING TAPE AND METHOD OF APPLYING SAME Filed Dec. 15, 1969 4 Sheets-Sheet 5 THEO A. DE WINTER EDWARD J. LUCAS WILLIAM A. LANYI INVENTOR.

BY Mwy ATTORNEYS NOV. 30, 1971 T, 35; w R ETAL 3,623,924

ELECTRICALLY INSULATING TAPE AND METHOD OF APPLYING SAME Filed Dec. 15, 1969 4 Sheets-Sheet &

THEO A. DE WINTER l5 EDWARD J. LUCAS WILLIAM A.LANY| INVENTOR.

ATTOR NEYS United States Patent Oifice 3,623,924 ELECTRICALLY INSULATING TAPE AND METHOD OF APPLYING SAME Theo A. de Winter, Methuen, Edward J. Lucas, Wayland, and William A. Lanyi, Boxford, Mass., assiguors to Avco Corporation, Cincinnati, Ohio Filed Dec. 15, 1969, Ser. No. 884,905 Int. Cl. H01b 7/03, 13/06 US. Cl. 156-51 4 Claims ABSTRACT OF THE DISCLOSURE An electrically insulating tape comprising a thin ribbon of flexible electrically insulating material with adhesive on one fiat surface and in contact with a low release backing material. Openings spaced one from another are provided along the length of the tape. Upon removal of the backing material, the tape is applied to an elongated surface having a dimension less than the width of the openings and trimmed to leave on the elongated surface only those portions of the tape intermediate the openings.

The use of superconducting materials in large electromagnets has pointed up the importance of stabilization. Stabilization is achieved when a low resistance normal substrate is intimately bonded to the superconductor, and this substrate is maintained below the critical temperature of the superconductor, even when carrying the entire current. Several factors determine the operating temperature of the substrate when the current carried by the conductor runs exclusively in the normal substrate. The most important of these factors are the electrical resistivity of the substrate, the cross-sectionalarea of the substrate, and the resistance to heat transfer between the surface of the conductor and the liquid helium environment. This last factor is directly related to the fraction of surface area exposed to the liquid helium. Any heat transfer through electrical insulation will encounter a high thermal resistance. It is therefore desirable in the design of a stabilized superconducting magnet to have part of the conductor surface in direct contact with a suitable coolant such as liquid helium. This cannot be achieved if the conductor is insulated over its complete outer surface. An intermittent type of insulation which provides turn to turn separation and electrical insulation and yet allows liquid helium to contact part of the insulated faces of the conductor will solve this problem.

In the foregoing, it will be clear that one of the primary objects of the invention is to provide a method of applying intermittent electric insulation.

Another object of the invention is to provide a method of applying intermittent electrical insulation to an electrical conductor at about the time it is to be used.

A further object of the invention is to provide a method of applying intermittent electrical insulation to an electrical conductor which permits simple and quick variation of the type and amount of insulation applied.

A still further object of the invention is to provide an electrically insulating tape for use in providing intermittent electrical insulation on electrical conductors.

The novel features that are considered characteristic of 3,623,924 Patented Nov. 30, 1971 the invention are set forth in the appended claims; the invention itself, however, both as to its organization and method of operation, together with additional objects and advantages thereof, will best be understood from the following description of a specific embodiment when read in conjunction With the accompanying drawings, .in which:

FIG. 1 is a fragmentary perspective view of an electrically insulating tape in accordance with the invention;

FIG. 2 is a fragmentary perspective view of a modified electrically insulating tape in accordance with the invention;

FIG. 3 is a fragmentary perspective view illustrating how the electrically insulating tape is trimmed after being applied to a conductor;

FIG. 4 shows diagrammatically the application of electrically insulating tape to a conductor in accordance with the invention;

FIG. 5 is a fragmentary perspective view of a conductor insulated with the tape of FIG. 1; and

FIG. 6 is a fragmentary perspective view of a ribbon conductor insulated with the tape of FIG. 2.

Directing attention now to FIG. 1, there is shown in greatly enlarged form for purposes of clarity an electrically insulating tape in accordance with the invention and designated generally by the numeral 11. The tape 11 comprises a flexible electrically insulating ribbon 12 of suitable material such as Mylar. Provided on one fiat surface of the insulating ribbon 12 is a suitable adhesive 13 which may be covered by a ribbon of suitable low release backing material 14 of the same width as the insulating ribbon 12. Provided along the length or longitudinal direction of the tape 11 are a plurality of openings or holes 15 passing entirely through the tape and spaced one from another in the longitudinal direction of the tape. The openings 15 have a dimension in the width or transverse direction of the electrically insulating ribbon that is less than the width of the tape as shown. Each opening is defined by

sides

16 and 17 substantially parallel to the longitudinal axis of the tape and substantially

parallel sides

18 and 19 normal to the longitudinal axis of the tape.

In FIG. 2 is shown a modified tape 11a wherein openings 21 are substantially rectangular in shape but disposed at an angle of about 45 to the longitudinal axis of the tape. The openings 21 in the tape may be conveniently provided by passing the tape through a punch adapted to punch out holes of the desired configuration, orientation and spacing.

As shown in FIGS. 3 and 4, insulation is provided on a conductor 22 by peeling off the low release backing where present and bringing the adhesive into contact with the surface 23 of the conductor to be provided with insulation and the tape 11 applied to this surface as by pressing, rolling, and the like. The openings and, hence, the tape itself are Wider than the surface of the conductor to be provided with insulation. After the adhesive has been pressed on to the surface to be insulated, the conductor with the tape is passed between two

trimmer knives

24 and 25 which cut the tape intermediate the openings, thereby leaving on the conductor most of that portion of the tape intermediate the openings.

FIG. 5 shows a rectangular superconductive conductor 22 insulated with the tape 11 of FIG. 1 and FIG. 6 shows a ribbon superconductive conductor 41 insulated with the tape 11a of FIG. 2.

'In one case as a superconductive coil was being wound, Mylar tape in accordance with FIG. 1 was applied to a face .086" wide on a rectangular superconductive conductor 22 as shown in FIG. 5. The tape comprised conventional adhesive coated Mylar tape wide and .0065" thick. This tape was put on a low release backing and using a die wide and by A" long, openings of this size were punched out of the tape and the backing. The openings were spaced /2 apart to leave portions 42 of the tape /2 long between openings (see FIG. 1). The tape was applied substantially as shown in FIG. 4 and trimmed substantially as shown in FIG. 3. The results were substantially as shown in FIG. 5.

In another case Mylar tape in accordance with FIG. 2 was applied to a /2" wide superconductive ribbon conductor 41 as shown in FIG. 6. In this case the tape comprised conventional Mylar tape l wide and .0035 thick. This tape was put on a low release backing and die punched to provide A" wide openings oriented 45 to the longitudinal axis of the tape as shown in FIG. 2. The openings spanned three-fourths of the width of the tape and were spaced apart to leave portions 43 between openings (see FIG. 2). Application of this tape in accordance with the invention provided the result as shown in FIG. 6.

Where the insulating material is punched prior to application of the adhesive, the backing material may be omitted if the adhesive permits winding of the tape into rolls in conventional manner.

It will now be apparent that the present invention permits the application of intermittent insulation of any desired coverage either prior to or preferably while the conductor is being wound into a coil or device.

The various features and advantages of the invention are thought to be clear from the foregoing description. Various other features and advantages not specifically enumerated will undoubtedly occur to those versed in the art, as likewise will many variations and modifications of the preferred embodiment illustrated, all of which may be achieved without departing from the spirit and scope of the invention as defined by the following claims.

We claim:

1. The method of applying intermittent insulation to an electrical conductor comprising:

(a) bringing a flexible electrically insulating tape into contact with said electrical conductor, said tape hav- 4 ing an adhesive surface disposed for contact with said conductor, said tape being wider than said conductor and provided with a plurality of openings spaced one from another and having a dimension greater than the width of said conductor;

(b) pressing said adhesive surface into contact with said conductor; and

(c) passing said conductor with said tape attached thereto past trimmer knives adapted to engage and cut said tape intermediate said openings and adjacent each longitudinal edge of said tape.

2. The method as defined in claim 1 wherein said conductor has an elongated fiat surface defining one side thereof, and only the middle portion of said tape intermediate said openings is pressed into contact with said conductor.

3. The method as defined in claim 2 wherein said openings have a dimension normal to the longitudinal axis of said tape that is greater than the width of said flat surface.

4. The method as defined in claim 3 wherein two trimmer knives are each disposed adjacent a different longitudinal edge of said flat surface whereby as said tape and conductor are passed between said trimmer knives said tape is cut only intermediate said openings and substantially parallel to the longitudinal axis of said tape adjacent the edges of said tape whereby only portions of said tape intermediate said openings remain adhered to said surface spaced apart a distance substantially equal to the longitudinal spacing of said openings in said tape.

References Cited UNITED STATES PATENTS 3,514,730 5/1970 Kassner 335-216 BENJAMIN A. BOROHELT, Primary Examiner H. TUDOR, Assistant Examiner