The invention relates to high voltage insulators, particularly those of the one-piece pin type, and has for its principal object the provision of a novel Insulator characterized by possessing greater leakage distance and higher flash-over value than those of ordinary design, and capable of better operation under dirt, dust and fog conditions.

Another object of the invention is to provide an Insulator of this character in which the exterior is of such design as to provide a long leakage distance, and in which the interior design is of such character that certain of the walls will remain dry, there being moreover an annular pocket which will catch warm air rising from the earth in the daytime and retain it, thereby preventing the condensation of moisture on the surface which results In sparking from drop to drop of moisture and consequent radio interference.

Another object is to provide an insulator having a preliminary cavity therein which will catch the full force of swirling air currents laden with moisture or dust and direct them away from the Internal pocket containing the warm dry air.

An additional object is to provide an insulator having these advantageous characteristics and which will at the same time be simple and inexpensive to make by any of the ordinary methods which, being of one piece, does not involve any assembling and which will moreover be not only efficient but durable in service.

To the attainment of the foregoing and other objects and advantages, the invention preferably consists in the details of construction and the arrangement and combination of parts to be hereinafter more fully described and claimed, and illustrated in the accompanying drawing in which:

The figure is a view partly in elevation and partly in section illustrating the Invention.

Referring more particularly to the drawing, I have shown the Insulator as of one-piece construction and formed of appropriate dielectric material, preferably porcelain.  The device is represented as consisting of a generally cylindrical body 10 provided at Its top with an upstanding reduced extension 11 transversely grooved at 12 for the reception of a line conductor and peripherally grooved at 13 for the accommodation of the usual tie wire for holding down a conductor In the well known manner. The top of the body slopes from the groove 13 downwardly and outwardly as indicated at 14.

Formed centrally of the underside of the body is a cavity 15 and also a socket 16 in the latter of which is preferred to provide a metallic thimble  17 cemented in place and of threaded form so as to be screwed upon the usual supporting pin. It is of course conceivable that the thimble might be of some other shape or might even be omitted without departing from the essence of the invention. A very important feature is the formation of an annular groove 18 leading into the cavity 15 and defining a depending portion 19 concentric with the socket 16. The cavity 15 has a substantially vertical wall 20 which is a continuation of the outer wall of the groove 18. Outwardly of the cavity 15 the lower edge of the body is formed with an annular groove 21 defining a main or outer skirt 22 and a petticoat 23 spaced inwardly thereof.

In order to provide a long external leakage path the periphery of the body is formed with a series of corrugations or alternating ribs and grooves 24 and 25, respectively.

The insulator is mounted and used in the same manner as others of the same general type but in service it will perform far more efficiently than those of the conventional designs, this being so for numerous reasons. In the first place, the series of corrugations on the exterior will provide a long leakage path as mentioned above. Moreover these corrugations are freely exposed to wind and rain and will therefore be what might be called self-cleaning or in other words there

will be no opportunity for the accumulation thereon either of water, dust or other substances which may be in the air and which are frequently found particularly in the neighborhood of cement mills and chemical plants. Water falling upon the insulator or fog condensing upon it will pass off at the lower edge of the skirt 22. The groove 21 defines what might be termed a preliminary cavity, the surfaces of which will be dry because of the substantially vertical walls which will discourage the creeping of surface moisture along the inner surface of the skirt 22 and the outer surface of the petticoat 23. Moreover this groove 21 will have a tendency to catch the full force of swirling air currents laden with moisture or dust that pass under the bottom of the insulator and will direct them away from the large or inner cavity 15. The cavity 15 is large, spacious and deep and it and the groove 18 in particular will retain a large volume of warm, dry air that will be caught during the day from warm air rising from the earth. This will keep the practically vertical wall 20 and also the wall of the depending portion 19 dry and prevent the condensation of moisture on these surfaces which would result in causing sparking of leakage currents from drop to drop of moisture. These wet and dripping conditions on the interior of insulators of conventional designs are a productive source of radio interference.

For the foregoing reasons the insulator has proved to be highly satisfactory in every respect and to be quite superior to those of ordinary design. From the above it is believed that the construction and benefits will be readily apparent to one skilled in the art without further explanation.

While I have shown and described the preferred embodiment of the invention and a certain definite location and relation between the grooves and other similar features it will be understood that the disclosure is merely illustrative of the principles involved and that the right is reserved to make whatever changes constitute no departure from the spirit of the invention or the scope of the claims hereunto appended.

Having thus described the invention, I claim:

1. An insulator comprising a dielectric body formed in its underside with a pin receiving socket and having its bottom provided with a cavity communicating with said socket, said cavity leading into an annular groove located outwardly in spaced relation to the socket and defining a depending portion within which the socket is located, the bottom edge being further formed with an annular groove extending upwardly and located between the wall of said cavity and the external periphery, thereby defining an outer skirt and an inner petticoat in spaced relation thereto in combination with a series of alternating ribs and grooves formed on the exterior.

2. A high voltage insulator comprising a dielectric body having its underside formed with an upwardly extending cavity, the top of the insulator having its underside formed with a depending projecting portion extending into the cavity and defining with the wall thereof an annular groove, said downwardly projecting portion being formed with a pin receiving socket, said groove providing a space for the entrapment of air, said cavity having its outer wall substantially vertical, and the lower edge of the body being formed with an upwardly extending annular groove located between the wall of the cavity and the outer periphery and defining an outer skirt and an inner petticoat spaced therefrom, said last named groove providing a space within which swirling air currents may be caught, in combination with a series of alternating ribs and grooves formed on the periphery of the body and extending at right angles to the longitudinal axis thereof.

  BENTLEY A. PLIMPTON.