US1191186A - Insulator. - Google Patents

Description

' ma July is; 1.916.

ATTU'HNEY UNITED sTA'rEs PATENT oEEIoE.

RAY P: JACKSON, OF EDGEWOOD PARK, PENNSYLVANIA, ASSIGNOR TQ WESTINGHOUSE ELEo'rnIo AND MANUFACTURING COMPANY, A CORPORATION or PENNSYLVANIA. Y

INSULA'IOR.

To all w/tom'z't may concern Be it knovvn that I RAY P. JACKSON', a citizen of the United States, and a resident of Edgewood Park, in the county of Alleghenyl and State of Pennsylvania, have invented a new and useful Improvement in Insulators, of Which the following a speciication.

My invention relates to insulators, and it has special reference to devices of this character that severally comprise a plurality of vertically arranged sections fitted one Within another.

The object of my invention is to provide a device of the above-indicated character Which shall be simple and durable in construction, and shall embody adequate means for preventing heavy leakage currents and consequent excess static fringing over the surface of the insulator.

Another object of my invention is to provide an insulating device'vvhich shall be constructed of a plurality ,of identical sections so formed as to he readily assembled.

Thev .advantage of such a structure, of course', resides in the economy which may be effected by reason of the fact that each section is of standard size and pattern. Furthermore, the number of separate sections determines the electrical strength of the insulator, and it is, therefore, a simple matter to design and construct any insulator for any desired voltage, within reasonable limits.

In the prior art,.it has been common practice to build multi-section insulators, the component sections of 'which have been ce mented together foi' the purpose of providing a rugged and integral structure. However, when such insulators have been construct-ed, the individual sections have been of such form and have been assembled in such a manner that the usual flaring petticoat portion of each section has been located below the layers of cement which secured. that section to the adjacent lower section. It is Well known that cement is a good con- Vductor, as compared with porcelain, and

' hence it is obvious that in a multi-section porcelain insulator of the type indicated, the various layers of cement and interposed porcelain constitute a series of condensers. For mechanical reasons, in certain types of insulators, the layers of cement have not been disposed opposite'fone another, but have been slightly overlapped or entirely offset, so that Specification of Letters Patent.

. finally assembled.

Patented July 18, 1916.

Application led December 21, 1910. Serial No. 598,515.

there existed abnormal and excessive leakage current and static fringing over the surface of the insulator from one layer of cement to another. This concentrated fringing7 rcsultedin a particularly severe and unstable electro-static condition over the insulator surface in proximity to the layers of cement and the air immediately surroundin the insulator become ionized and its dielectric strength so weakened and broken down that a discharge was effected. It is evident that if'these layers of cement were opposite each other, as in the usual type of condenser, no such unstable conditions of leakage current and static fringing7 would have existed, as the charges of opposite sign would have neutralized each other. However, for mechanical strength the clfset disposition of the cement layers is desirable, and it is to establish quiet and sta ble static conditions and to eliminate this leakage current and its disastrous effects, Without changing the mechanical design of the insulator,that my present invention is intended.

According to iny invention, I design the insulator sections so that the flaring petticoat portion of each section shall be located above the cement layer which is interposed between the section and the adjacent lower section, when the insulator, as a Whole, is Thus, a relatively long path is provided for the leakage current in traversing from one cement layer to the next, which tends to materially reduce the leakage current and to cut olf the localization of excessive static fi-inging. Hence, the dielectric properties of the enveloping air are not subjected to abnormal stress and a prematureV breakdown over the insulator is avoided.

Those skilled in the art Will readily understand that the principle of my ,invention may be embodied in various structural devices and, whileI shall show and describe, Vin detail, only a single embodiment of my invention, it is evident that, broadly considered,

it is not restricted to the specific structure section insulator shown comprises a plurality o interchangeable porcelain insulator sections l and .2 which are vertically arranged and nested the one within the other, and which are provided with a suitable metallic cable unit 3 and supporting pin 4. The insulator sections 1 and 2 are identical in size and forni and each4 comprises a tapered plug or cap portion 5 having a corrugated eX- terior surface, a flaring petticoat section 6, and a body portion 7 or' the same general taper as the plug portion 5. lThe top 5a of each plug portion 5 forms a top-closure diaphragm, separating the air spaces of the vertically adjacent sections.

The body portion 7 and the plug portion .5 :e provided 'with a centrally located rethe lower portion 9 of which is corrued in the usual nia-mier and is adapted receive the plug por uion 5 of the insulator section next below it. The upper portion 10 el" the central recess is adapted to receive a or plug 11 oit wood or other suitable insulating material which comprises a body member l2 and an integrally associated head member i3, The head member 13 ts reasonably tight within the recess and is adaptcd to rest upon 'the upper end of the plug or cap portion 5 of the adjacent lower insul tor sections in order to properly space the several sections apart, maintain the same in their relative positions under all Conditions, prevent the entr of cement into the space between the hea s of juxtaposed units., which might otherwise occur if ce ment is supplied between the heads of the adjacent units while they aresupported in inverted position by the pins 12. The insulator sections 1 and l2 are thus assembled, one above another, and are intimately secured together by means of a'layer or band of' cement 14 which is interposed between the cooperating plug portion 5 of section 2 and the body portion 7 of section 1.

The upper insulator section 1 is pr'pvided with the metallic cap 3 which is held in place by a layer of cement 15 for the purpose of receiving a line conductor (not shown), whilethe lower section 2 is mounte upon the supporting pin 4 and is secured thereto by layer or band of cement 16 in a manner similar to that hereinbefore described. Since cement is a comparatively good conductor, it is evident that the layers of cement 14, l5 and 16 and the interposed porcelain portions constitute a series of condenscrs, the plates of which are not opposite ach other` as in the usual condenser construction, but are entirely offset.

Assuming, for the moment, that the insulator sections 1 and 2 are not provided with i'ietticcat portions 6, it will be understood ithat the electric lield will be concentrated ietweci the edges of the offset condenser p aies l5 and 16 and a leakage tending to neutralize each other.

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current will How which produces an eX- cessive static fringing between the plates,

This excessive leakage current is caused by reason of the abnormal positions of the condenser plates 14, 15 and 16, and the resulting static fringing intensities the usual electrostatic field, and acts upon the surrounding air to break down its dielectric strength to suchl an extent that a discharge is effected over the surface of the insulator. It is the purpose oi my invention to eliminate this abnormal lealrage current and static fringing so that the dielectric properties of the surrounding air may be utilized to their full extent. This I accomplish by locating'the petticoat portions 6 above the lower portion 9 of the cent-rally located recess which re' ceives the plug portion 5 and the interposed layer ci cement 14 'or 16. It is manifest, therefore, that a considerable increase in the length of the path of the leakage current is provided which reduces the amount of current andl also tends to cut off the excessive static iringing hereinbefore described.

The specific structural details ofthe device heretofore shown and described may, of course, be varied and the materials of construction changed, without exceeding the spirit and scope of my invention.

'I claim as my invention:

1. The combination with a plurality of identical insulator sections arranged vertically, one within another and secured together by longitudinally spaced layers of ccmcnting material, each section comprising a` cap portion and a body portion having centrally disposed communicating recesses therein and an outwardly flaring Petticoat portion located above the upper end of its inclosed layer of cementing material, of a spacing pin of insulating material disposed in the recess in said cap portion and adapted to rest against the upper end of -the projccting cap portion of' the adjacent lower section.

2. A built-up insulator comprising interchangeable, nested units, top-closure diaphragme for each of said units, said diaphragme being spaced apart and serving to form incloscd air chambers together with a cap unit formed to receive an electric cable, the `bottom unit receiving the supporting 3. A built-up insulator, havingV nested units, in combination with means for spacing said units apart and preventing the entry of cement into the space between the heads of juxtaposed units.

4. A built-up insulatorI having nested units, the heads of which are air-spaced apart, in combination with means for preventingr the entry of rement into said air space during the assembly of thc parts.

5. n. built-up insulator having nested units, the heads of which are air spaced the entry of cement into the space between 10 apart, 1n combination with means supportadjacent dmphragms.

ing a nested unit during; assembly vin in- In testimony whereof, I have hereunto verted position and excluding cement from subscribed my nume this 9th day of Dec. Suid air Space. 1910. v I

6. A built-up insulator comprising nested RAY P. JACKSON. units, top-Closure diaphragms for the said Vvvitnesses: units, said diuphrngms being' spaced apart H. M. Sonmn,

from o'ne another, and means for preventing B. RA j-INEs.

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