US3454805A - Support for conductors of electrical apparatus - Google Patents

Description

July 8, 1969 FRQMM ETAL 3,454,805

SUPPORT FOR CONDUCTORS OF ELECTRICAL APPARATUS Filed Sept. 30, 1966 INVENTORS. MQRV/N M. FROM/1 /m 3 3 1 7'7'OR/VEY United States Patent Ofice U.S. Cl. 310-260 6 Claims ABSTRACT OF THE DISCLOSURE A support member positioned between and supporting the conductors of rotating electrical machinery extending beyond their magnetic cores. The support member comprises a pad of compressible absorbent material sandwiched between two relatively solid insulating members .Which provide sufficient rigidity to the entire support member to allow its ready insertion between the conductor bars without interfering with the conformability of the support member to the surfaces of the conductor bars.

This invention relates to supporting means for the conductors of electrical apparatus.

The conductor bars of electrical machines extending beyond their magnetic cores are frequently subjected to destructive mechanical forces during operation of the machines. These forces occur, for example, on starting and during periods of overload. Such forces tend to cause vibration and deformation of the end windings leading to eventual failure of the windings and their insulation. To prevent such forces from moving and damaging the conductor bars, it is the practice to space and support them by inserting blocking in the spaces between the bars.

One prior art method of blocking is the fitting and tying of wood blocks between the bars. A major problem in using wooden blocking is that the space between the conductor bars varies from one pair of bars to another. This variation requires that each block must be individually shaped and hand-fitted to the space between its particular pair of bars. This is a time consuming operation and contributes significantly to the cost of the machine.

Another method of spacing and supporting conductor bars which has been developed more recently is the tight fitting of a soft resin impregnated material into the spaces between the bars and the hardening of the impregnated material. The close contact and tight fit between the conductor bars of the impregnated material provides good support and spacing for the bars. This tight fit plus the molding or extending of excess impregnated material over the ends of the conductor bars is relied upon to hold the impregnated blocking material in place upon its hardening. This has not been found to be wholly satisfactory, however, because such spacers have a tendency to loosen due to the vibrating and deforming mechanical forces.

A further shortcoming of resin impregnated blocking material is the difficulty of tightly inserting it between the conductor bars when it is in a soft state. The methods of tightly inserting the resin impregnated material between bars are, for example, forcing a piece of the material between the bars which has a large width than the width between the bars or inserting a piece of the material of smaller width than the bar spacing width and squeezing the material into tight contact with the bars. The drawback of the first method is the difficulty of forcing the impregnated material into the bar spaces due to its softness and pliability. The disadvantage of the second method is that a further operation, often difficult to carry out, is added to the steps necessary to tightly fit the impregnated material in the bar spaces.

3,454,805 Patented July 8, 1969 An object of this invention is to provide conductor bar support and bracing means which is easily installed and which fits tightly between and in close contact with the conductor bars.

Another object of this invention is to provide a conductor bar support and spacer which will not loosen from its supporting position between the conductor bars.

A further object of this invention is to provide a new and improved conductor bar support for electrical apparatus.

The features of the invention which are believed to be patentable are set forth with particularity in the claims appended hereto. The invention will, however, be better understood and further objects and advantages thereof be better appreciated from a consideration of the following description and the drawing, in which FIG. 1 repre' sents a top view of the conductor bars extending beyond themagnetic core of an electrical machine with supports positioned between the conductor bars, FIG. 2 represents an isometric view of a support secured in place between two conductor bars, and FIG. 3 shows another crosssection view of a support before insertion between adjacent conductor bars and after insertion between the conductor bars.

With reference to the drawing, the support members 1 arev shown positioned between adjacent conductor bars 2 of an electrical machine. The conductor bars shown in FIGS. 2 and 3 are the end portions of the windings of the electrical machine extending beyond its magnetic core. Each conductor bar is wrapped with an insulating material 3. As illustrated, each support is tied in position by cord 4.

Each support 1 preferably comprises a layered structure having a body of absorbent compressible material 5 and sides 6 of a solid insulating material. The compressible material 5 may be a felt or woven body of absorbent fiburous material such as glass, polyethylene terephalate, polypropylene, polycarbonate, polyacrylate, polyamide, and similar type insulation materials available in felt or woven form. The compressible body of material 5 may also consist of Woven layers or alternating felted and woven layers of these synthetic insulating materials. The insulating material may be obtained in sheet form and cut by ay suitable means to the size desired. The size of the pieces should, however, be kept reasonably small to avoid blocking the ventilating passages between the conductor bars. The thickness of each body of material 5 may be varied to match the width of the space between the conductor bars by adding layers of absorbent material. The sides 6 of the supports 1 may consist of a thin, solid insulating plastic film or a hardened resin fabric laminate, or any other solid insulating sheet material that Will support the absorbent compressible body 5 without substantially interfering with its ability to conform to the shape of the sides of the conductor bars 2.

Any of a number of well-known solventless thermosetting resins or thermoplastic resins can be used in the practice of the invention. However, thermoplastic resinous compositions are not usually desirable because they will soften at higher operating temperatures. Thermosettable resinous compositions are thus preferable, particularly those thermosettable resins that will harden at room temperature. The thermosetting materials that may be used include but are not limited to polyester resins and epoxy resins. The polyester resins are those that are the reaction product of polyhydric alcohols and polybasic acids. Typical epoxy resins are the epoxidized polyols, epoxidized polyolefins and epoxidized cyclohexene type materials.

The body of compressible absorbent material 5 may be impregnated with liquid resin while it is still in sheet 3 form or after it is cut into a separate piece. The impregnating method may be by dipping the material 5 into a reservoir of the liquid resin, by pouring the resin over the material 5 or by any other suitable method. The impregnating may be done either before or after the material Sis placed between the sides 6.

As shown by broken lines in FIG. 3, the material 5 is placed between sides 6 prior to insertion of the entire support 1 between the conductors 2. Prior to insertion the width of the support 1 is slightly larger than the width of the space between the conductor bars 2 so that a tight fit will result and the sides 6 of the support 1 will be in tight contact with the sides of the conductor bars 2. A tight fit will also insure that the support 1 conforms at all points with the shape of the space between the conductor bars 2 to firmly space and support the bars.

The support 1 is inserted into the space between the conductor bars 2, as shown in FIG. 3, by applying force to the top of sides 6 by use of suitable means, such as a wooden mallet, wherein the support 1 is driven into its position shown by full lines in FIG. 3. While the support 1 is thus being inserted, sides 6 function to support the compressible body material 5 of the support 1. This allows easy, quick insertion of the support 1 which, after being impregnated with a liquid resin, is soft and pliable and is not easily forced into the conductor bar spaces unless provided with some rigidity by means such as sides 6.

The support 1 may now be firmly secured in positio between the conductor bars 2 by glass fiber cord 4. It should be noted that the securing means is not limited to glass fiber cord, but may be of any other suitable cord or tape material. Securing the support 1 in place will eliminate any possibility of the support working loose due to continuous vibration and repeated deformation of the conductor bars 2. After all of the supports have been secured the resin may be allowed to cure. If a room temperature hardening resin is used, the electrical machine is left in a room for a length of time necessary for hardening of the particular resin used to take place. If a high temperature hardening resin is used, the machine is placed in an oven for the suitable curing time.

From the foregoing it is apparent that this invention provides means for spacing and supporting conductor bars which is easily installed and which fit into tight contact with the bars. It is further apparent that the invention provides a support which will stay firmly in place between the conductor bars.

It will be evident that the principles disclosed herein are equally'applicable to windings of all types of electrical apparatus in which the conductor bars are subjected to mechanical forces causing deformation or movement of any type.

Since certain modifications which embody the invention may be made without departing from its scope, it is intended that all matters contained in the above description or shown in the drawing shall be interpreted as illustrative and not in a limiting sense.

We claim as our invention:

1. A support for spaced conductor bars comprising two members of solid insulating material and a member of compressible absorbent material impregnated with a hardenable resin disposed between said solid insulating members, said support being compressively fitted between adjacent spaced conductor bars to tightly contact said conductor bars and conform to the shape of the space therebetween.

2. A support as set forth in claim -1 which includes means for securing said solid members and said compressible absorbent member between adjacent spaced conductor bars.

3. A support for spaced conductor bars comprising a block of compressible absorbent material impregnated with a thermosettable material having two spaced sides, a solid insulating member engaging each of said sides, said support being constructed and arranged to fit tightly between adjacent spaced conductor bars whereby said block tightly contacts said bars and conforms to the shape of the space between said bars, and means for securing said support in the space between said bars.

4. A support block positioned between and engaging two spaced conductor bars for supporting the conductor bars comprising a body of compressible absorbent material impregnated with a hardenable material and having two sides and an insulating member engaging each of said sides and comprising a material of sufiicient solidity to support the absorbent material during positioning between said conductor bars.

5. A support block as set forth in claim 4 wherein the support block has a shape between the two conductor bars which conforms to the shape of the space therebetween.

6. A support block inserted between two spaced conductor bars and engaging and conforming to a surface of each of the conductor bars to thereby support the conductor bars comprising a body of compressible absorbent material impregnated with a hardenable resin material and having two sides and an insulating member engaging each of said sides and said surfaces and comprising a material of suflicient rigidity to support the absorbent material during insertion between said conductor bars without preventing conformation of the support block to said surfaces of the conductor bars.

References Cited UNITED STATES PATENTS 3,330,978 7/1967 Pettit -i 310-271 FOREIGN PATENTS 894,481 4/ 1962 Great Britain.

WARREN E. RAY, Primary Examiner.

R. SKUDY, Assistant Examiner.

US. Cl. X.R. 310-270

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