US1482318A - Protective device - Google Patents

Description

Jan. 29, 1924. 1,482,318

' F. W. PEEK, JR

PROTECTIVE DEVICE Original Filed May 20. 1918 Invent or F'r-ank W.PeeK Jr,

His fitter-neg.

Patented Jan. 29, 1924.

FRANK W. PEEK, JR., OF PITTSFIELD, MASSACHUSETTS, ASSIGNOR TO GENERAL ELEC- TRIO COMPANY, A CORPORATION OF NEW YORK.

PROTECTIVE DEVICE. 1

Application filed May 20, 1918, Serial Ito 235,450. Renewed July 19, 1922. Serial No. 576,150.

To all whom it may concern:

Be it known that I, F RANK W. PEEK, Jr., a citizen of the United States, residing at Pittsfield, county of Berkshire, State of 6 Massachusetts, have invented certain new and useful Improvements in Protective Devices, of whichthe following is a specification.

My invention relates to protective devices 1 and more particularly to devices for the rotection of electrical conductors from conditions of lightning disturbances, transients and other over-voltage phenomena' The object of my invention is to provide a 16 device which is operative to relieve a conductor from excessive voltage conditions caused by transients, sur es and similar phenomena and more speci cally to provide a spark gap device for use in outdoor serv- 2 ice, which will discharge at very nearly its dry arc-over voltage setting independent of the weather conditions with substantially no time delay between the application of arc-- over Voltage and the discharge across the device and which is, in general, an improvement on similar devices heretofore known in the art.

It is well known, as described in U. S. Letters Patent No. 1,232,467, granted to me, that a protective or spark gap device which comprises two cooperating electrodes having their proximal surfaces in the form of surfaces of revolution, such as two spheres, and separated by a certain distance relative to 85 the radius of the spheres, forms a spark having a substantially uniform dielectric field. When arc-over voltage occurs across such a gap, ther is substantially no time delay between the occurrence of arc-over voltage and the rupture of the dielectric or the discharge across the gap, is no formation or brush discharge of corona prior-to the discharge of-the gap to introduce a time delay. A sphere gap so 46 proportioned is therefore very fast and serves to quickly relieve from theconductor to be protected, gall excessive voltage conditions and particularly surges of steep wave front. An arrester comprising a gap is, 50 however, not always at maximum efficiency when used for butdoor service due to the fact that, the spacing must be varied because of weather conditions, for example, rain, snow, and ice collecting upon the electrodes that is, there serve to lower the voltage at which an arcover will occur as the wet arc-over voltag of the gap is lower than the dry arc-over voltage.

According to my invention, I provide a protective or sphere gap device of the type described, which is operative in a substantially uniform dielectric field and hence with substantially no time delay, provided with means for protecting the spark gap from conditions of the weather whereby the device is operative out of doors at its dry arc-over voltage setting practically inde pendent of the weather conditions, and whereby'the dielectric field is maintained uniform so that the time delay is unaffected.

, I maintain the arc-over voltage of the spark gap device constantand substantially independent of the weather, by protecting each electrode with a metallic hood or shielding means and for preventing such protecting means from distorting the dielectric field and hence increasing the time delay, I prefer to rovide the shielding member for each electrode of a configuration or of a contour to follow a substantially equipotential sur face for the electrodes, that is, all points on the shielding means is at substantially equal potential. The field of the main gap thus remains practically unchanged when the shields are introduced.

The novel features which I believe to be characteristic of my invention will be definitely indicated in the claims appended hereto while the features of construction and method of operation will be understood by reference to the accompanying drawings in which:

Figure 1 is a view, partly 1n section, of an arrester or spark gap device embodying the features of my invention; Fig. 2 shows a modified form of my invention; Fig. 3 1s a sectional view of a further modified form of my invention, and Fig. 4 is a top elevation of the device shown in Fig. 3.

In Fig. 1 my arrester or spark gap device comprises cooperating electrodes 1 and2 having their proximal surfaces in the form of surfaces of revolution. In the preferred form, the proximal surfaces are spherical and separated by a dlstance having such a relation to the radius of the spheres, as to provide a spark gap havin a substantially uniform dielectric field. spark gap of' 7 this construction has practically no time lag,

that is, there is practically no time delay between the occurrence of arc-over voltage and the discharge of the gap. Furthermore, a gap of this construction has an impulse ratio of substantially unity. By the form of shielding means which certain advantages over other types used for for maintaining the voltage of the gap at which an arc-over occurs always controlled by the dry arc-over voltage setting. For accomplishing this function I provide a shielding means for protecting the spark ap'device from the weather, and accordmg to the drawings I provide a specific possesses this pur ose.

In or er to keep the impulse ratio of the sphere gap substantially unity and also to prevent an increase ,in the time lag of the gap, a shielding means for the gap which does not distort the dielectric field possesses material advantages. I obtain these advantages, by providinga shielding means which desi has a contour, or is shaped to follow the 1 points of equal potential in the dielectric eld. In Fig. 1, I have shown a shield 3 of thin metal inclosing sphere electrode 1 of a contour following an equipotential surface surrounding the electrode and which I ate as an equipotential shield. This shie dis insulated from the electrode 1 by an insulating member 4 which also serves to support the equipotential shield 3 in posi-- tion. Similarly an equipotential shield 5 I incloses the cooperating electrode 2 and is member 6 and supported by the insulating1 t e electrode. I

is thus insulated from have thus provided a shielding means which enables the spark gap device comprising the electrodes 1 and '2 to be protected from .wea-Liier conditions; and which is controlled from its dry arc-over voltage setting. At

' the same time. the shielding means does not distort the dielectric field andfl-hence does not impair the time delay of the device. .As

shown in Fig. 2, I may'utilize a-horn gap .to quickly extinguish the arc, and for this purpose horn members 7 and 8 are provided suitably opposed to the shield members 3 and 5. For purpose of illustration I have shown an electrolytic cell 9 in series with the spark gap, such a device serving to extinguishthe are which follows the discharge across the gap as is well known in the art.

In Figs. 3 and 4 I have shown a modified spark gap device embodying my in? vention in which the cooperating electrodes comprise a conducting ring or annular mem ber 10 and a rod or c lindrical member 11. In protecting these e ectrodes I provide a shielding means consisting of an annular or ring-shaped shield member 12 inclosing electrode 10 and a cooperating shield member 13 inclosing electrode 11, said shields having a contour to follow an equipotential surrounding the respective electrodes. In the illustration shown electrode 10 is connected to the conductor to be protected and electrode 11 is connected to ground through, for instance, an electrolytic cell 9 for the pur ose above set forth.

hat I claim as new and desire to secure by Letters Patent of the United States, is,-

1. In a protective device, the combination with cooperating electrodes spaced apart to form a spark gap, of shielding means for said electrodes'having a contour corresponding substantially to an equipotential surface. 2. In-a protective device, the combination with cooperating electrodes spaced apart to form a spark gap, of a shield partially enclosing each electrode but insulated therefrom, said shields having a contour such that.

all points thereof are at substantially the same otential.

3. n a protective device, the combination with cooperating electrodes spaced apart to form a spark gap, of means for shielding said electrodes comprising a conducting shell having a contour corresponding substantially to an equi-potential surface.

4. ha protective device, the combination with cooperating electrodes spaced apart to .form a spark gap, of shielding means for protectin each of said electrodes from the weather aving'a form corresponding sub stantially to an equipotential surface whereby the characteristics of said gap are unchan ed.

5. n a protective device, the combination with two cooperating electrodes having their proximal surfaces spherical and spaced apart to form a spark gap, of shields surrounding each of said electrodes, but insulated from the same, said shields havinga contour corresponding substantially to an equipotential surface.

6. The combination with an electrode member, of a shield partially inclosing said electrode member insulated therefrom and of a contour conforming substantially to an equipotential surface, and a second-electrode member cooperating with said' firstmentioned electrode member to form a spark gap.

' 7. In a protective device, the combination formed with an electrode and a metallic shieldin member therefor comprising a 10 sheet lying substantially along an equipotential surface.

In witness whereof I have hereunto set my hand this 14th day of May, 1918.

FRANK W. PEEK, JR.

Images