US803010A - Insulator. - Google Patents

Description

' PATENTED OCT. 31. 1905.

i No. 803,010.

E. EMORRIS.

INSULATOR. APPLIOATION FILED JUNE 6. 1904.

mum I. GRAHAM cu. nmw-mmmmsu mam UNITED STATES ELMER P. MORRIS, OF EA STDRANGE, NEW JERSEY.

INSULATOR.

Specification of Letters Patent.

Patented Oct. 31, 1905.

Application filed June 6,1904. Serial No. 211,440.

To all whont it may concern.-

Be it known that I, ELMER P. MORRIS, a citizen of the United States, and a resident of East Orange, county of Essex, and State of New Jersey, have made certain new and useful Improvements in Insulators, of which the following is a specification.

My present invention relates to insulators, and has for its object to provide a secondary insulation for wires carrying currents of high potential or of considerable power, providing a factor of safety in the insulation of such wires from each other and from the ground.

In modern high-potential systems it is the custom to provide large and costly porcelain insulators for each Wire, separating the wires by so much space as may be necessary to prevent any accidental are striking across from one to the other, and thus short-circuiting the system, the distance required being proportioned to the voltage or potential difference between the wires of the circuit. The custom is to mount these insulators upon wooden cross-arms supported by a wooden pole for the purpose of affording additional insulation, since dry wood is a fairly eflicient insulator. Under some circumstances iron poles are employed; but their use has been limited because of the danger of the wires striking them and becominggrounded. Where the wooden crossarm is used, when the insulator carrying the power-wire breaks the wire falls upon the cross-arm, and in damp weather or in localities exposed to dust, salt spray, or fumes of manufacturing establishments the collected dirt forms a suflicient conductor to permit the escape ofenough current to char the arm. The charcoal being a high-resistance conductor permits increased leakage, and eventually the arm burns through (even if no destructive are be formed) and allows the wire to drop upon the next cross arm below or under some circumstances to the ground, if the spans be long. Iron cross-arms under ordinary conditions have been prohibited, because when an insulator breaks the wire is immediately grounded. For these difficulties I provide by placing below the petticoat-insulator commonly employed a second insulatingsurface so designed and located that when the petticoat-insulator breaks and releases the current-carrying wire the latter will be caught by and retained upon the secondary insulator. The latter is of such size and shape as to afiord a substantial creeping surface, as it is called in the art, and thus prevent escape of current sufficient to cause any difficulty in the transmission-line. It is manifest that this creeping-surface need not be as extensive as in the case of the petticoat-insulator, since it is of course not intended that the secondary insulator shall be exclusively relied upon. As the lines in which the device is useful are generally under inspection, when the petticoat-insulator is broken it will soon be observed and a new one substituted. The difficulty is one which has interfered seriously with the maintenance of high-voltage transmission-lines, since the insulators are often used as targets by mischievous marksmen, in some cases with disastrous results. It is manifest, however, that under other conditions my device may also be useful, and I do not mean to limit its utility to the particular situation indicated.

The accompanying drawings show an embodiment of the invention.

Figure 1 is a plan of a cross-arm equipped with the device and with two petticoat-insulators. Fig. 2 is a side elevation of the parts shown in Fig. 1 or Fig. 3. Fig. 3 is an end elevation of Fig. 1, partly in section. Fig. 4: is a modified detail. shown in plan.

In Fig. 2 A is the pole, and B is the crossarm, in the case illustrated made of wood. U C are wooden pins supporting the petticoatinsulators D D. The insulator D is shown as broken away, and the conductor E, which is normally supported on the top of it in the hollow (Z,as shown in connection with the insulator D, is in this case in one of the grooves, hereinafter referred to, of the secondary insulator. The parts thus described are all old and well known.

Fig. 3 shows the insulator forming the main subject of my present invention. This is preferably composed of vitrified porcelain having very high insulation resistance, though it is manifest that under conditions Where extreme potentials are not employed less expensive materials might be used and still be within the invention. The insulator is shaped to fit a cross-arm of standard size and construction and is provided upon its upper surface with projections f, between which lie grooves f 3 of such size as conveniently to take the conductor E when the latter falls from the petticoat-insulator D. To retain the secondary insulator upon the cross-arm, lugs f f are provided, which project below the top of the arm. The top of the insulator is curved sufficiently to prevent the conductor coming in contact with sharp edges, and the edges may be slightly rounded ofi, if desired. If the device he made in a single piece, which is the approved form for new construction, the lugs'f, in conjunction with the hole in the middle surrounding the pin C, furnish a substantial attachment.

In Fig. 4L I show a modified form which is within the invention. In this the secondary insulator F is made in two parts, counterparts of one another. These are so shaped as to leave an opening G for the pin C, and dovetails f f upon the two parts secure them together.

In this way by first putting one in place and then putting the other above it the latter may be dropped into place. This is the form in which the device may be conveniently used for lines already installed; but where reasonably possible it should be in a single piece, since its insulation resistance in this form is higher.

Changes in form may be made without departing from the invention, and other ways of securing the insulator in place or different ways of dividing it are within the scope ofmy claims.

Having thus described my invention, what I claim, and desire to protect by Letters Patent of the United States, is

1. A secondary insulator for. lines of relatively high-potential difference, consisting of a flat body of hard porcelain longer than the primary insulator carrying the conductor, with a groove or grooves across its upper surface substantially parallel to the course of the conductor, and means integral with the insulator for attaching it to a support.

2. A secondary insulator, for lines of relatively l1igl1-potential difference consisting 01 a flat body of hard porcelain longer across the course of the conductor than the primary insulator carrying the latter, with a groove or grooves across its upper surface, substantially parallel to the course of the conductor, lugs extending below the body, and a perforation through it.

3. A secondary insulator for lines of relatively high-potential diflerence, consisting of a body of insulating material made in counterparts each of which is provided with means of attachment to the other and to a cross-arm and with a groove or grooves substantially parallel to the electric conductors.

In witness whereof I have hereunto set my hand and seal.

ELMER P. MORRIS.

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