US2391758A - Protective device - Google Patents

Description

Dec. 25, 1945. WADE HAL 2,3917% PROTECTIVE DEVICE Filed May 9, 1942 2 Sheets-Sheet l F'I J.

ITIVET'YCOYS'. Elmer J.\/\/ade, Joseph Horvatl'hJr; by W 6. JMM} Their Attorney.

2 Sheets-Sheet 2 Fig.4.

n m w m fiw n rJ er A veH Tmw 5w J Dec. 25, 1945. E. .1. WADE ET AL PROTECTIVE DEVICE Filed May 9, 1942 Patented Deals 1945 rnorrzc'rrva navrcn Elmer J. Wade and Joseph Horvath, In, Pittsfield, Masa, assignora to General Electric Company, a corporation of New York Application May 9, 1942, Serial No. 442,338

13 Claims.

Our invention relates to protective and circuit interrupting devices, and has application to overvoltage protective devices such as lightning arresters, and to fuse devices and electric circult interrupters.

An object of our invention is to provide an improved protective device which is efllcient and reliable in operation and which has a relatively long life.

Another object of our invention is to provide an improved protective device which is efflcient in operation over a relatively wide range circuit conditions.

A further object of our invention is to provide an improved overvoltage protective arrangement which has a relatively rapid insulation recovery characteristic.

A still further 1 object of our invention is to provide an improved circuit interrupting device which is efiicient and reliable in operation, and which has a relatively long life in service.

Further objects and advantages of our invenorder to provide an arc path the concentric cylinders have openings adjacent the electrodes. These openings may be staggered in any suitable direction, such' as an axial direction so as to provide a circuitous or zig zag arc path between each axially disposed electrode and the adjacent end of the tubular member. The pair of gaps may be serially connected across an apparatus in any suitable manner such as by connecting, one of the axial electrodes to a suitable apparatus to be protected and the other tion will become apparent from the following description referring to the accompanying drawings, and the features of novelty which characterize our invention will be pointed out with particularity in the claims annexed to and forming a part of this specification.

Fig. 1 is a sectional side elevation of an overvoltage protective device which is provided with an embodiment of our invention; Fig. 2 is an exploded perspective view of a portion of the protective device illustrated in Fig. 1; Fig. 3 is a sectional side elevation of a modification of the device illustrated in Fig. 1, and Fig. 4 is a sectional side elevation of a modification of the over-voltage protective devices illustrated in Figs. 1, 2, and 3.

In the arrangements illustrated in the drawings, we have shown our invention as applied to an overvoltage protective device which will pass high current impulses such as those caused by. switching impulses or lightning discharges, but it is to be understood that our invention has application to any other suitable protective device .or circuit interrupting device which may provide a path for surges of short duration, or such devices as may be called upon to interrupt a power follow current, or interrupt an electric circuit. One of the illustrated embodiments of our invention includes a pair of axially disposed electrodes and a tubular arrangement radially spaced from the axial electrodes and having electrode portions at either ends thereof providing radial arc gaps with the adjacent ends of the axially disposed electrodes. A plurality of spaced barriers or radially spaced concentric cylinders are provided between each of the axially disposed electrodes and the adjacent electrode portion of the cylindrical member. In

portions 55 and I6 providing the electrodes.

one to ground. One of the ends of the concentric ,cylinders may be closed by a cap member, the opposite end being open so that gases formed by an arc passing between the adjacent electrodes may flow axially through the spaces between the concentric conductors and acros the are, thus extinguishing it.

Referring more particularly to Fig. 1 of the drawings, we have illustrated an overvoltage protective device iii which may be placed in any suitable housing ll of insulating material. The protective device includes a pair of axially disposed electrodes l2 and 93 which may have any suitable shape such as a rod shape. To cooperate with the electrodes l2 and 63 we provide a suitable electrode arrangement, and in the structure illustrated in Fig. i this includes a tubular arrangement M having an electrode portion H5 at one end and an electrode portion l5 at the opposite end. Since these portions l5 and i8 are adjacent to but spaced from the electrodes l2 and i3, respectively, it will be seen that the electrodes l2 and i5 form one gap and the electrodes l3 and i6 form. a second gap. These gaps may be connected in series in any suitable manner such as by forming the tubular arrangement H of a conducting material with A discontinuity, however, is provided in the tubular arrangement l4 for reasons which will be brought out below. A tubular member ll of suitable insulating material surrounds the tubular member I4, and the end members or caps l8 and I9 relatively rigidly support the tubular member H intermediate the ends of the insulating member I! by spacers 20. The electrode assembly including the pair of gaps may be connected across any suitable circuit or apparatus, and in the arrangement illustrated in the drawing the electrode I2 is adapted to be connected to a transmission line throu a conducting member 2| which is electrically connected to the opposite end of the rod which forms the electrode I 2 by means of a nut 22; An insulator 23 is supported on top of the conducting member 2|, and the upper end of the insulator 23 supports a conducting member 24 which may be attached to the transmission line through a conductor 25. A conventional gap 23 is provided between the adjacent portions of ground through a conductor 21. The cap member 13 has an integral central portion 23 which supports the electrode l3, and another integral portion 28 of the cap I3 is electrically connected to the conductor 21 through a connector 30. When a high voltage surge occurs on the transmission line to which the electrode l2 is connected .the gap 26 will spark over and an arc will be formed between the electrodes l2 and 3. the electrode l3 and form another are between it and the cooperating electrode l3. The surge may then pass through the electrode l3 and the conductor 21 to ground.

Between the gaps provided by the electrodes I 2 and I and the electrodes I 3 and it we have provided a plurality of radially spaced concentric cylinders 3| which, in the arrangement illustrated in Fig. 1.v are coaxial with the axiallyspaced electrodes l2 and I3. Any suitable number of cylinders 3| may be provided, and in Fig. 1 three are shown. These cylinders are supported through an insulating member 32 which spans the space between the electrodes i2 and I 3. Plus 33 of suitable insulating material passthrough the member 32 and cooperating apertures in the cylinders 3| so as to support them in proper spaced relationship. As will be seen in Figs. 1 and 2 these insulating cylinders 3| are of difl'erent lengths and the opposite ends thereof cooperate with concentric insulating cylinders 34 and 35, these latter cylinders being supported in proper spaced relationship by means of a plurality of pins 33 which are supported by the electrodes l2 and I3 and which pass through cooperating apertures in the cylinders. Openings or slots 31 are formed between the ends of the cylinders 3i .and the adjacent ends of the cylinders 34 and 33 which are not in contact. These slots define arc paths through which an arc may pass between the cooperating electrodes 12 and I5, and I3 and It. By properly dimensioning the cylinders ll, 34, and 35, the openings 31, as will be seen in Fig. 1, are staggered so as to provide a zig zag or circuitous arc path between the electrodes l2 and i5, and I3 and I8. Instead of axially staggering the openings 31, it is to be understood that the openings may take any other Furthersuitable relationship to each other. more, instead of forming the passages 31 by 00- operating ends of separate cylinders a single integral cylinder may be employed which merely has openings or slots therein, as is iliustratedin Fig. 3.

When a sufliciently high voltage is impressed across the electrodes i2 and i3, it will be seen that a pair of arcs will be formed between the cooperating electrodes 62 and i5, and i3 and it. In order to enhance the rate at which gaseswill be formed when an arc takes place, the cylinders 3|, 3%. and 35 may be made of insulating material such as hard fiber which has the property 01- giving off deionizing or un-ionized gases.

when heated. Let us assume that a high voltage surge of short duration causes the gaps formed by the electrodes to arc over. The power follow current will then continue to cause an arc to be formed in the gaps and during increasing values of the power follow current cycle, gases of a the deionizing type will be formed at an increas-- ing rate. These cases will flow in both directions and in flowing upwardly towards the end cap it The electrical impulse will then pass to a pressure will be developedflin the spaces, be tween the radially spaced concentric cylinders.-

Then as the power follow current cycle apders will be open to the atmosphere. The pressure thus developed at the end of the tube adjacent the enclosing cap l8 will cause the gases to be blown downwardly toward the vent openings 38. Since the arc paths between the cooperating electrodes l2-and l5, and I3 and it are relatively far apart the gases will become cooled and deionized as they pass between the concentric tubes towards the vent openings 38. Furthermore, the gases formed by the upper arc will contribute to the production of the pressure to extinguish or blowout the are formed between the electrodes l3 and id as the power follow current passes through zero and the recoveryvoltage is immediately impressed acrossthe protective device. By blowing the gases over the cylindrical or peripheral surfaces of the concentric tubes and by pacing the parallel disposed gaps a relatively great distance apart and further by providing a zig zag arc path between the electrodes,

we have found that the resulting protective device has a relatively high insulation recovery strength. v

In order to further improve the operating characteristics of the device, a coil 40 may be provided with opposite ends electrically con-v nected to the electrode portions l5 and I6, re-

. spectively. The conducting tubular arrangement I4 is provided with a radial discontinuity II, or the portions of tubular arrangement l4 having electrode portions l5 and ii ar spaced apart so as to provide a gap in parallel with the coil 40 whereby the power follow current will traverse the coil and cause the arcs between the cooperating electrodes to rotate. This gap shunting the coil also helps to prevent impulse currents from flowingthrough the 'coil. Movement or rotation of the arc helps to prevent localized burning and to cool the are at low currents and it will cause the are to pass over a relatively large portion 01' the gas evolving material thus contributing to a relatively rapid rate of evolution of deionizing gas. Furthermore the staggering of the gaps or slots in the concentric cylinders contributes to the relatively high insulation recovery characteristics which we have found-our device possesses. The idea of coupling a coil with one electrode to rotate the power arc is described in further detail and claimed in application S. N.- 442,337,- Wade, filed concurrently with the present application and assigned to the same assignee as this present invention.

Referring to Fig. 3 of the drawings, we have illustrated a modification of our improved protectivedevice which includes an electrode, 50 which i supported by a pair of insulating columns 5i and 52. We have provided a plurality of concentric cylinders 53 which are coaxial with the longitudinal axis of the center electrode Ell. An electrode arrangement is provided on the outside of the cylinders 53 including electrodes 56 and 55. These electrodes are placed on opnumber of openings 88 which may be staggered so as to provide an arc path between the electrode Ill and an electrode portion 51 oi the electrode 50. Similar openings 58 are provided between the electrode 55 and the electrode portion 59-01 the electrode member 50. The electrode 54 may be supported and electrically connected to an end cap 80 while the electrode 56 may be in turn supported by an opposite end cap H.

The end cap Si is rovided with vent openings iii which communicate with the spaces between the concentric cylinders, while the end cap 60 provides an enclosing member so as to provide a space 63 between the ends of the concentric cylinders lit and the end cap 60. The end caps 60 and bi may, therefore, be connected across the apparatus which is to be protected, and when a suflicient voltage is impressed across the protective device an arc will be formed between th electrodes d and 51 through the openings 56 and between the electrodes 59 and 55 through the openings 58. The concentric cylinders may be composed of any suitable materiel such as one having the property of giving oh the deionizing or un-ionized gases when heated, and during increasing values of power follow current a pressure will be developed in the reservoir 83, which during decreasing values of power i'ollow current, will cause the gases to move outwardly through the vent passages 52. The gases flow across the arc path and introduc gas of a relatively high dielectric strength into the arc stream by turbulent iiow which contributes to the rapid recovery insulation strength at the current zero.

In Fig. 4 we have illustrated a further modification oi our protective device including an up per electrode lill which may be connected to a line or apparatus to be protected, and a lower electrode ii which may be connected to ground through the conductor l2. A pair of gaps are provided between the electrode Ill and an adiaccnt electrode is which is radially spaced therefrom. Anothergap is provided between an electrode it and the center electrode ill. The electrodes it and it may be of any suitable construction and in the arrangement illustrated in Fig.

' 4 they include opposit ends oi a spaced wound coil l5. An arc path is provided between the electrodes it and i3 by insulating disks l6 and ii. The coil it is carried by an insulating housing 18 and is spaced therein between a shoulder l9 and a cylinder til. enclosed at one end by a metal cap 8i and the other end is enclosed by a metal cap 82 having vent openings 83. The insulating disk 16 is spaced from the inner walls of the insulating cylinder at providing a passage 84 which leads to a reservoir 85. The are path between the electrodes II and 14 is provided by an insulating circular plate 86 and a plurality of concentric cylinders 8! which are supported at their lower ends by an insulating member 88. Teeth 89- are provided at the opposite endof the cylinders 81, which teeth extend into cooperating slots in the plate 88. Vent openings 98 are provided in the disk 88, which openings communicate with th spaces between the concentric cylinders 81. The outer edge of the insulating plates 11 and 85 are spaced fromth'e inner surface of the coil 15 so as to provide a passage M which communicates with the arc spaces between the electrodes l0 and It, and 'H and 14.

When a voltag of suihcient magnitude i 'impressed across the electrodes and Ii, arcs will be formed in the gaps provided between the The housing is tightly electrodes I8 and I8, and II and II. In order to enhance the quantity 01' gas which is given out due to the heat of the arc the insulating plates I8, Ti, and 88, and th concentric cylinpower follow current cycle, gases will be formed by the upper gap. mrt of which will flow into the reservoir 85. As the power follow current decreases and approaches zero the pressure in the chamber 85 will be greater than at the open end thereof so that the gases will flow across the upper gap, down the peripheral or cylindrical passage 9! and across the are between the electrodes 'iiand i4, thus providing for a relatively rapid insulation recovery characteristic of the protective device.

Since the electrode id is in the form of a spaced wound coil, the power follow current will flow through the turns or the coil and cause the arcs to rotate. Since the coil has gaps impulse currents will jump th gaps between each turn instead of flowing around the coil. A plug d2 of suitable magneticmaterial such as iron may be provided between the insulating plates ii and 86 for enhancing the electromagnetic force avail able tor rotating the arc.

Although we have shown and described par ticular embodiments of our invention, we do not desire to be limited to the part cular embodiments described, and we intend in the appended claims to cover all modifications which do not depart from the spirit and scope of our invention. 1 What we claim as new and desire to secure by Letters Patent in the United States is:

l. A protective device including a substantially rod-shaped metal electrode, a second metal electrode having a tubular shape spaced from and surrounding said first electrode to form a gap, and a plurality of substantially concentric insulating radially spaced cylinders between said electrodes, said cylinders formed of an insulating material which gives 0E an arc-extinguishing gas when subjected to the heat of an electric arc, said cylinders having staggered openings dem a circuitous arc path through which an arc may strike between said electrodes.

2. A protective device including a tubular shaped electrode, a rod shaped electrode concentric with said tubular electrode and having a portion within said tubular electrode, and a plurality of radially spaced substantially concentric insulating cylinders between said electrodes formed oi a material which gives off a gas when subjected to the heat of an electric are, said cylinders having openings axially staggered defining a circuitous arc path through which an arc may strike between said electrodes.

3. A protective device including a plurality of radially spaced substantially concentric insulating cylinders, first electrode means inside said cylinders and second electrod means outside said cylinders defining two spaced arc gaps, said cylinders having at least two groups of openings defining at least two radially extending arc paths between said first and said second electrode means, and mcansfor enclosing the adjacent ends of one end of said cylinders the opposite end of said cylinders being substantially unobstructed so that gases formed due to arcs may flow from the enclosed end of said cylinders between said cylinders and across the arcs between said gaps.

one endof said cylinders th other end thereof flow from said enclosed end through the spec 7 aeerfr se mentioned electrodes and said tubular means electrode portions, said insulating cylinders having openings adjacent said electrodes providing between said cylinders across th arc and out the open end of said cylinders.

5. A protective device including a plurality of radially spaced substantially concentric insulating cylinders of a type which give oil a gas when subjected to the heat of an electric arc, a solid electrode having .a, portion within said cylinders, a tubular electrode surrounding said cylinders, said cylinders having substantially radially extending openings defining an arc path between said electrodes, and means for enclosing one end of said cylinders the other end thereof being open so that gases evolved from said cylinders during arcing between said electrodes may flow from said enclosedend through the spaces between said cylinders across the arc and out the open end of said cylinders.

6. A protective device including a pair of axially spaced electrodes, tubular means radially.

spaced from said first-mentioned electrodes and having electrode portions at each end providing arc gaps with the adjacent of said first-mentionedelectrodes, and a plurality of substantially concentric insulating cylinders between said firstmentioned electrodes and said tubular means electrode portions, said insulating cylinders having openings adjacent said electrodes providinga pair of arc paths for the arc gaps.

'Z. A protective device including a pair of axially spaced electrodes, tubular means radially I spaced from said first-mentioned electrodes and having electrode portions at each end providing arc gap with the adjacent of said first-mentioned electrodes, a plurality of substantially concentric insulating cylinders between said firstmentioned electrodes and said tubular means electrode portions, said insulating cylinders having openings adjacent said electrodes providing a pair of arc paths for the arc gaps, and means for enclosing one end of said cylinders so that gas formed by the arc of one gap will flow between said cylinders and across the arc of the other gap.

8. A protective device including a pair of aid-- ally spaced electrodes, tubular means radially spaced from saidfirst-mentioned electrodes and having electrode portions at each end providing arc gaps with the adjacent of said first-mentioned electrodes, and a plurality of substantially concentric insulating cylinders between said first-mentioned electrodes and said tubular means electrode portions, said insulating cylinders having openings adjacent said electrodes providing a pair of arc paths for the arc gaps,

and coil means for providing a field to rotatethe arcs in said are paths.

9. A protective device including a pair of axially spaced electrodes, tubular means radially spaced from said first-mentioned electrodes and having electrode portions at each end, providing arcgaps with the adjacent of said first-mentioned electrode, a plurality of substantially concentric insulating cylinders between said firstelectrode portions so that the power follow cur-- rent will fiow through said coil and rotate the arcs in said are paths.

10. A protective device including a p ir of am-' ally spaced electrodes, tubular means radially spaced from said first-mentioned electrodes and having electrode portions at each end providing arc gaps with the adjacent of said first-mentioned electrodes, a plurality of substantially concentric insulating cylinders between said firstmentioned electrodes and said tubular means electrode portions, said insulating cylinders hav= ing openings adjacentsaid electrodes providing a pair of arc paths for the arc gaps, means for connecting one of said axially spaced electrodes to an electrical apparatus to be protected and the other of said axially spaced electrodes to ground, an electrical coil surrounding said tubular means and having ends connected to said electrode portions so that the power follow current will flow through said coil and rotate the arcs in said are paths, said tubular means having a. discontinuity to provide a gap in shunt with said coil.

.11. A protective device including a solid electrode, substantially concentricinsulating cylinders radially spaced and coaxial with an axis of said electrode, said cylinders being formed of a material which evolves an arc-extinguishing gas when subjected to th heat of an electric of radially spaced substantially concentric'cyl- 1 inders formed of gas evolving insulating material, electrode means forming a plurality of arc gaps, said cylinders having at least one group of openings defining at least one radially ex--' tending arc path for one or said are gaps, and means for enclosing the adjacent ends of one end of said cylinders the opposite end of said cylinders being substantially unobstructed so that gases evolved from said cylinders when arcs are formed across said gaps may flow from the enclosed end of said cylinders between said cylinders and across the arc in said are path formed by said cylinder openings.

13. A protective device-including a pair of axially spaced electrodes, electrod means radially spaced from said first-mentioned electrodes and having electrode portions providing arc gaps with the adjacent of said first-mentioned electrodes, plate means defining an arc path for one of said arc gaps, a plurality of substantially concentric insulating cylinders having openings providing an arc path for another of said are gaps,

' means providing a passage communicating with said are paths, means providing a reservoir communicating with said one of said are gaps and said passage, and a vent means communicating with said other of said arc gaps.

ELMER J. WADE. JOSEPH HORVATH, JR.

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