ARC extinguishing device with a high speed whip

Information

  • Patent Grant
  • 6392181
  • Patent Number
    6,392,181
  • Date Filed
    Thursday, November 2, 2000
    24 years ago
  • Date Issued
    Tuesday, May 21, 2002
    22 years ago
Abstract
Rapid arc extinguishing devices for air switches are provided with a whip element of strong nonmetallic material, such as of a fiber reinforced plastic or polymer material, with a conductive path, e.g., by metalizing. The whip element can replace the formerly used metal whip in quick break devices for faster separation with less chance of arc restriking and facilitates achieving higher current and voltage ratings.
Description




BACKGROUND OF THE INVENTION




1. Technical Field




This invention relates generally to electrical switchgear, such as air break (or disconnect) switches used in transmission lines, and, more particularly to quick break whips for rapid arc extinguishers in such switches.




2. Background Art




Air break switches, sometimes called disconnect switches, are used in electrical transmission, or distribution systems to assist in isolating sections of line or faults. Under some conditions opening a line can be performed, reliably and without appreciable arcing of consequence, by normal opening of the switch main contacts. Under some other conditions, it is important to minimize and rapidly extinguish the arc that occurs on opening the main contacts.




A situation that raises a need for rapid arc extinction is upon a switch opening a line, typically extending for miles, where the line is connected at one end to a live source, i.e., a generator of AC power, but no load is connected to the other end of the line. The line becomes highly charged and its opening normally causes a high voltage arc. Typical system voltages are in a range of from about 69 KV. To about 230 KV. Under the described conditions, the current is of a magnitude that depends on the length of the line being disconnected from the source and is typically in a range of from about 6 to about 20 amperes; a larger current results from a greater length of disconnected line due to the capacitance between the line and ground.




The industry has recognized the desirability of rapid opening of the switch to minimize the size of the arc and to minimize restriking of the arc. Restriking of the arc occurs when the sinusoidal voltage typically at 60 Hz, rises after the current has interrupted and the contacts are still close enough for an arc that was extinguished at the zero current crossing to strike again as the voltage rises.




Ideally, the gap between switch contacts should become large enough sufficiently fast that no restrike can occur. There is, in a 60 Hz system, only about 8.3 milliseconds (ms.) between zero current crossings, or between peaks, which is a half-cycle of the AC sine wave. It is therefore preferred to get a safe separation of the contacts in less than about 8 ms. Restriking of an arc not only prolongs the time needed for switch opening, it can sometimes make it even harder to finally extinguish the arc on successive zero crossings because a restrike can cause the current and voltage to increase.




Prior known equipment has sought to have rapid contact separation to achieve arc extinction. Some air break or disconnect switches with the otherwise usual main contact and switch opening features have been provided with an arc extinction device sometimes referred to as a quick break whip or a high velocity arc interrupter. These devices are characterized by having a flexible resilient rod (or “whip”) of a metal, such as beryllium-copper alloy, stainless steel or aluminum, that is conductively joined with one of the main switch contacts, and a latch or hook, of a more rigid conductor, that is conductively joined with a second main switch contact.




In operation, when the switch is initially opened, the whip slides against the latch and maintains a temporary by-pass of the main switch contacts. During that initial opening, the whip is flexed into an arcuate configuration by the latch, thus storing spring energy. After further opening, the whip is freed from the latch and its stored energy is released. The whip end then moves with high velocity away from the latch, due to the spring properties of the whip, to interrupt the circuit.




To further contribute to the speed of the whip or rod, some designs have had an arrangement with an additional spring (sometimes referred to as an accelerator spring) for storing additional contact opening energy. Some designs also have shock absorbing elements intended to keep the released whip from springing back to a location near the latch where the arc can again ignite.




The prior art equipment is commonly used but is not consistently able to avoid arc restriking and is limited in how long a line it can interrupt at a given voltage.




Other known apparatus for switching at high current and voltage includes vacuum interrupters. They can be made to perform reliable switch opening but incur a considerable disadvantage in cost compared to air switches with a quick break whip.




The present invention is directed to overcoming one or more of the problems or disadvantages associated with the prior art.




BRIEF SUMMARY OF THE INVENTION




The invention is directed to such apparatus as generally described above but with a whip element of a strong and flexible nonmetallic material, such as a fiber reinforced plastic or polymer material on, or in, which there is a conductive path. Such a whip element is found to enable opening at a sufficiently fast rate to minimize any chance of arc restriking and to allow higher current, and longer lines, to be interrupted at higher voltages.




The invention is directed to such whip elements as well as to quick break arc extinguishing devices that include such a whip element and air switches that include such an arc extinguishing device.




The whip of the invention can be conveniently made from readily available fiber reinforced plastic members like, or similar to, those formerly used in fishing rods and golf club shafts. Known techniques for filament winding and resin application and curing are satisfactory for making the basic member of the whip. The required conductive path of the whip can be provided, for example, by metalizing the surface of the plastic member. It is also suitable to have sufficient conductivity within the plastic member, either by conductive, e.g., carbon, filaments or some other conductive additive. In addition, a combination of conductive filaments and a metalized surface is a further example.




By way of further example, a whip is made of a commercially available fiber reinforced plastic rod, for example of epoxy resin, on which a conductor, e.g. silver, has been plated. In addition, a conductive paint can be applied to the plastic rod to serve as the conduction path or the rod may be first painted with a conductive paint and then coated with a metal such as by plating or vacuum deposition.




The improved whip element can be used in a quick break device of otherwise known structure by replacement of the formerly present all metal rod. Improved performance is represented, for example, by one set of experiments showing whip speed under comparable conditions. An air switch with a quick break whip device having a conventional metal whip produced open gap dimensions of only about 6 to 8 inches in 8 ms. With a whip in accordance with the invention, of substantially the same size, in the same device, an open gap of between about 14 to 26 inches was attained in the same time, 8 ms. Further tests with voltage applied have shown that the increase in speed of the improved whip substantially reduces arc restrikes and can normally avoid any restriking thus reducing the size of the arc. That makes it less likely for a phase to phase fault or a phase to ground fault to occur.




The improved whip of such an example was of a carbon filament reinforced epoxy resin in a tapered, tubular configuration, substantially like a fishing rod. It has about four times the strength to weight ratio (referred to as the “specific strength”) of beryllium copper alloy, which is the strongest material commonly used in the prior art for such whips. The new whip also stands out in flexibility, i.e., the ability to bend a large amount without breaking or permanent deformation, and resilience, i.e., the ability to return to its original configuration. The very low weight of the fiber reinforced plastic, even with a metalized surface, (for example about 1.5 oz., compared to about 10 oz. for a metal whip) contributes to the high specific strength of the improved whip. Furthermore, the plastic member can be tapered and tubular for lowest weight and highest strength as is readily available from commercial sources because similar articles, with no metalizing, have been manufactured for totally unrelated purposes.




The inventive whip element can be used along with, but does not require, the prior art structures that have extra accelerator springs for additional energy storage, but which incur some extra cost and complexity. It is advantageous that the whip itself can, at least in many, if not all cases, provide all the spring energy necessary; also, shock absorbers to prevent a rebound arc are not considered necessary.




The benefits of the invention are believed attainable with no significant cost increase and obviate the need for a vacuum interrupting device in many applications.




While it is convenient to modify prior whip devices by introducing the whip element of the invention, it also can be practical and advantageous to use a whip as described in a device of a modified design which will achieve more separation of the whip tip in 8 m.s. because of the higher specific strength of the nonmetallic materials used in the whip. A further advantage is the lower force needed to bend the whip into its energy storing position thereby making it easier to operate the switch manually.




Other aspects and features of the present invention will be obtained from the entirety of the description, drawings and claims.











BRIEF DESCRIPTION OF THE DRAWINGS





FIG. 1

is a top plan view of apparatus, called a vertical break switch, improved by the invention;





FIG. 2

is a front elevation view party broken away, of the apparatus of

FIG. 1

with a phantom showing of the motion of certain parts;





FIG. 3

is a top plan view of another apparatus, called a center break switch, improved by the invention with a phantom showing of the motion of certain parts;





FIG. 4

is an elevation view of the apparatus of

FIG. 3

;





FIG. 5

is an elevation view of an example of a whip in accordance with the invention for use in apparatus such as those of

FIGS. 1-4

;





FIG. 6

is an enlarged cross-sectional view taken along the line VI—VI of

FIG. 5

;





FIG. 7

is an enlarged cross-sectional view taken along the line VII—VII of

FIG. 5

;





FIG. 8

is an enlarged cross sectional view taken along the line VIII—VIII of

FIG. 5

;





FIG. 9

is an elevation view of a further example of a whip in accordance with the invention; and,





FIG. 10

is an enlarged cross-sectional view taken along the line X—X of FIG.


9


.











DETAILED DESCRIPTION OF THE INVENTION




Referring to

FIGS. 1 and 2

, an air switch


10


is illustrated. The switch


10


includes a movable conductive blade or arm


12


assembled at the left end with a hinge


14


and elements of a switch opening mechanism


16


. The hinge


14


includes a conductive contact that maintains conductive engagement with the end of the blade


12


. The contacts of hinge


14


also maintain a conductive path to a terminal pad


18


.




The blade or arm


12


is shown in FIG.


1


and in the solid line view of

FIG. 2

with its right end engaged, or in a closed switch position, with contacts of a jaw


20


that is joined in a conductive path to another terminal pad


22


. Insulators


24


and


26


support the left terminal pad


18


and hinge


14


and insulator


28


supports the jaw


20


and terminal pad


22


. Switch


10


can be installed, for example, in a transmission line (not shown) with line segments connected to the respective terminal pads


18


and


22


.




The switch opening mechanism


16


, not detailed here, is one that is, for example, manually operated by use of a swing handle or wormgear mechanism or electrically operated by use of a motor operator. Mechanism


16


also serves to reclose a switch


10


after it has been opened.




In

FIG. 2

it can be seen that when the arm


12


is pivoted on the hinge


14


, the right end of the arm


12


separates from the jaw


20


and the arm rises from its original horizontal orientation to successive arm positions including the position indicat with the arm referenced by


12




a


and the position with the arm referenced by


12




b


. Upon completion of the operation of the mechanism


16


, the arm


12


is in a substantially vertical orientation (not shown).




Because the apparatus of

FIG. 2

has the arm


12


moving in a vertical plane it is referred to as a vertical break switch. It may, however, be mounted for arm motion in other orientations.




The apparatus of

FIGS. 1 and 2

, as described so far, is substantially in accordance with the prior art, such as described in Cleaveland/Price Inc. Bulletin DB-106BH97, published 1997, which is herein incorporated by reference for additional description of such switches and their operation and applications.




In addition to the previously mentioned elements,

FIGS. 1 and 2

also show, as part of the switch


10


, a rapid arc extinguishing device


30


, sometimes referred to as a “quick break whip” although the arc extinguishing device


30


includes elements in addition to a whip


32


. In this example, the device


30


includes a clamp


34


fastening the left end of the whip


32


to the arm


12


. The device


30


also includes a latch or hook


36


conductively joined with the right terminal pad


22


. The elements (such as


34


and


36


) of the arc extinguishing device


30


can be like those previously used in arc extinguishing devices for vertical break switches, except for the whip


32


itself.




In arc extinguishing devices that use some kind of whip, and are applied to an air switch, when the switch is initially opened, the whip is flexed into an arcuate configuration by the motion of the contact arm, to which one end of the whip is joined, and the fixed location of the latch, which catches the other end of the whip. The view of the whip referenced as


32




a


in

FIG. 2

indicates such an arcuate configuration during which spring energy is stored. After the contact arm


12


moves to a position beyond that shown at


12




a


, the free end of the whip


32


separates from the latch the stored energy causes a whip like motion for the whip


32


that separates it a larger distance from the latch. The position shown with the arm referenced as


12




b


and the whip referenced as


32




b


is illustrative of the whip like motion away from the latch


36


that the whip


32


makes to increase the distance between the arc carrying parts.




In accordance with the present invention, in contrast to prior rapid arc extinguishing devices, the whip


32


of the device


30


is one that principally includes a nonmetal material that also has sufficient conductivity for initially capturing any arc occurring when the whip


32


and the latch


36


separate. It has been found that rapid arc extinction is enhanced by high velocity motion of the end of the whip and that a nonmetal, such as a polymer, or plastic, material having fiber reinforcement, provides a high strength and high flexibility whip that results in faster motion upon release of the whip


32


from the latch


36


.




Further description of examples of the whip


32


will be found in the following discussion but first reference is made to

FIGS. 3 and 4

for a different sort of air switch


110


incorporating the invention.




The air switch


110


is one referred to as a center break switch. It has a pair of insulative supports


126


and


128


. Support


126


has a conductive contact arm


112


and a line terminal


118


secured at one end to the support. A contact


115


is secured to the other end of the arm


112


. The right support


128


has a conductive contact arm


113


and a line terminal


122


secured to it. The other end of the arm


113


has a contact


120


secured to it. In most instances, the elements of

FIG. 3

have reference numerals whose last two digits are the same as reference numerals for corresponding elements of

FIGS. 1 and 2

.




Corona shields (not shown) may be arranged on opposite sides of the contact


115


and opposing sides of contact


120


. The switch


110


operates by a mechanism (not shown) at the lower end of the supports


126


and


128


between a closed position and an open position by equal angular movement of the two supports


126


and


128


. The basic elements of a center break switch, such as switch


110


and the parts described so far, can be consistent with prior art designs which are well known and will not be described further here.





FIGS. 3 and 4

also show a rapid arc extinguishing device or “quick break whip”,


130


. The device


130


includes a whip element


132


secured at one end by a clamp


134


to the contact arm


112


. The device


130


also includes a hook or latch


136


that is supported at one end by a clamp


135


to the contact arm


113


.




In the closed position of the switch


110


shown in

FIG. 3

the contact


115


on the arm


112


is confined in contact


120


. As the switch


110


opens successive positions with the arms at positions with reference numbers


112




a


and


113




a


and, later, at


112




b


and


113




b


are reached. With the arms at


112




a


and


113




a


, the main contacts


115


and


120


have just separated and the electrical conduction transfer to the whip


132




a


and latch


136




a


has just begun. When the contact arms are in the positions referenced as


112




b


and


113




b


, the whip element


132




b


is flexed into a curvature with its free end engaging the latch


136




b


. Upon subsequent motion (not shown), the whip springs out from the latch and moves away from the latch similar to the effect described in connection with FIG.


2


. (The motion illustrated in

FIG. 3

reflects the fact that the motion of the arms


112


and


113


is not all in one vertical plane.) While other elements of the arc extinguishing device


130


may be substantially as used in prior arc extinguishing devices, the whip element


132


is not. The whip element


132


is as described previously for the whip


32


of

FIGS. 1 and 2

and further described below. It principally comprises a member of a nonmetallic material of high strength that achieves higher acceleration when released than prior metal whips but which also has a light weight conductive pathway that achieves the necessary conduction for carrying the current on separation of the main contacts


115


and


120


.





FIGS. 5 through 8

illustrate an example of a whip


32


for use in switch


10


of

FIG. 1 and 2

, and which also may be used as the whip element


132


of

FIGS. 3 and 4

.

FIG. 5

shows an overall exterior view of whip


32


with its tapered configuration from a wider, blunt, end


40


to a pointed or tip, end


42


. The blunt end


40


is the end secured to a switch arm, such as arm


12


in FIG.


1


. The end


40


may include a greater mass for a few inches of length for sturdier support when clamped to a contact arm, as further described in connection with FIG.


6


. The tip end


42


may have a small conductor


44


extending from it, as further described in connection with FIG.


8


. The drawings are not to scale. Dimensions can be selected from a wide range. Typical outer dimensions include those in which the length of the whip


32


is between about three feet and about seven feet, the outside diameter at the stub end


40


is typically between about 0.2 inch and about 0.6 inch, and the outside diameter at the tip end


42


is typically between about 0.1 inch and about 0.2 inch.





FIG. 7

shows a cross-section of the whip


32


along line VII—VII between the ends


40


and


42


. The innermost part of the whip


32


is a nonmetal member


46


of a polymer, a composite, or a plastic material that is tubular with an open center


47


. Merely by way of example, the wall thickness of member


46


may typically be between about 0.03 inch to about 0.1 inch. The wall thickness may be consistent over the length of member


46


and whip


32


or it, too, may taper from a greater thickness at the blunt end


40


to the tip end


42


.




The form of member


46


and its composition can be conveniently selected from among commercially available members, such as for fishing rods, where a high degree of strength and flexibility are desired. Such members include those of fiber reinforced plastics, such as with glass or carbon fibers in epoxy or polyester resins where the fibers may be either present as particles or are filament wound. Suitable materials include, without limitation, those sold by various commercial suppliers such as Lamiglas, Shakespeare, and Skypole.




Fiber reinforced plastics suitable for use as the member


46


of the whip


32


may be made in accordance with known practices such as open contact molding and tube rolling, including tapered tube rolling, as generally described, for example, in “FRP Materials, Manufacturing Methods and Markets” in Composites Technology, Yellow Pages 2000, pages 6-20, published by Ray Publishing Inc., Wheat Ridge, Colo., which is herein incorporated by reference for its general description of materials and processes used in making fiber reinforced plastic articles.




In its broader aspects, a whip


32


need not necessarily be tapered or tubular and need not necessarily be circular. The illustrated embodiments are examples of whips that are conveniently available and are effective.




A whip composite member


46


may have conductive elements (e.g., carbon filaments or metal particles) within its polymeric or plastic mass but the principal examples to be described do not rely on constituents of the member for their total electrical conduction.




In the illustrated examples, a layer of metallization


48


is on the exterior of the composite member


46


. Typically the metallization


48


is applied by electroplating of a good conductor, such as silver or copper, although other techniques may be employed, including vapor deposition and dipping into, or otherwise applying, a conductive paint. In the particular example illustrated the composite member


46


first has a layer


49


of a conductive paint applied to its surface on which a thicker metallization


48


is applied. It has been found effective, for example, to plate silver, such as in a thickness of from about 0.002 in. to about 0.006 in. onto a member


46


that has a thin conductive paint layer


49


. Good adherence and good conduction are achieved. Even with such layers as


48


and


49


on it, the member


46


is found to retain its high strength and acceleration because the added mass of the thin layers is relatively low.





FIG. 6

shows a section of the blunt end


40


along line VI—VI. Here the center


47


of the composite member


46


is filled, such as with a plastic material


50


, e.g. epoxy resin. The center material


50


, in this example, is substantially limited to just the whip portion clamped to a contact arm and helps achieve secure fastening without collapsing the tubular member


46


. Other examples need not have resin filled centers if the tube has sufficient strength. Also, added strength can be provided by inserting a short section of another, smaller, tube of material like that of the tube


46


into the blunt end for the portion engaged by the clamp


34


.





FIG. 8

shows a section of the tip end


42


of the whip


32


taken along line VIII—VIII. Here, the tip conductor


44


is shown confined by the tubular member


46


but it may also be secured by a bonding material (not shown), such as epoxy resin. The tip conductor


44


may be conductively joined to the metal layer


48


during the metalizing process and extends a short distance beyond the tip end


42


of the member


46


. Conductor


44


serves as an arcing point, like a lightning rod, to catch an arc between the whip


32


and the latch


36


, when they initially separate, so as to minimize any melting damage as might occur from the heat of the arc. Other examples may not have a tip conductor


44


if the thickness of the metal


48


is sufficient to resist arc burning. The tip


42


may have some other form of extra conductor at its end instead of the tip conductor


44


.




In some versions, a composite member


46


may have a highly flexible conductive strand extending within its whole length to provide some or all of the necessary conduction. In general, the composite member


46


has a conductive path on it or within it, or both, including the case in which a conductive path is within the tubular member


46


, as by a continuous strand of wire, and the case in which a wire is embedded in the material of the composite member


46


itself. By such embodiments, adequate conduction is provided but the desired spring like characteristics are achieved by the composite member rather than merely a metal conductor as in prior apparatus.




For illustration of one such alternative embodiment,

FIGS. 9 and 10

show a composite member


46


, with metallization


48


and conductive paint


49


as in

FIGS. 5-8

, having a flexible conductive strand, or wire,


52


extending within it.




It has been demonstrated that a whip


32


as shown and described can achieve a substantially greater acceleration and velocity on separation from a hook


36


than does a metal whip. The greater velocity of separation achieves the ability to avoid arc restrikes. Tests at 70 KV. on a center break switch as in

FIG. 3

have shown that a metal whip will have frequent arc restrikes but a whip


32


, with higher separation velocity, can avoid restriking altogether. The improvement of the invention is one that, at least, substantially minimizes arc restriking compared to metal whips under the same conditions. Furthermore, such improvement shows that the extra springs and shock absorbers of the prior art, which have not been highly effective, are not necessary to achieve a quick break whip operating with minimal arc restriking. Furthermore, the invention facilitates interruption of longer lines and lines energized to higher voltages than has been achieved with metal whips.




Switch designs do not have to be changed. A rapid arc extinguishing device, or quick break whip device, with the improved whip may be applied as an accessory to existing air break switches. The switch design and the rapid arc extinguishing device design may, also, be varied in other ways from those formerly used. For example, a configuration can be made so even greater flexing of the whip occurs so even greater spring energy is stored and then released for higher velocity.




Longer life of the whip


32


is aided if the configuration of a hook or latch


36


or


136


is such as to insure continuous contact with the whip throughout operation until final separation. If the configuration is one that allows the whip


32


to skip, or briefly separate, from the hook and then recontact, there can be arcing during the interval of the brief separation that is desirably avoided to minimize arc damage.




A further optional feature is for the surface of the whip


32


and the latch


36


, either one or both, to be made with engaging surfaces that have a lower coefficient of friction to aid in high velocity separation. Polishing or buffing the mating surfaces, with sufficient conduction, are among the various techniques, although a smooth metalized metal surface


48


and a hook or latch


36


of metal such as has been used in prior apparatus are suitable without extra treatment. The hook or latch


36


can still be of an economical metal such as one of galvanized or stainless steel. Alternative conductors may also be used.




Other modifications and variations are believed apparent to those skilled in the art from the foregoing description of examples and are intended to be embraced by the appended claims.



Claims
  • 1. A rapid arc extinguishing devices for use in combination with an air break switch, comprising:a whip element and a latch element each having a respective attachment device for securement to a conductive contact element of a switch; the whip element comprising a nonmetal composite member, of a flexible fiber reinforced plastic polymer material, and a conductive pathway supported by the nonmetal composite member from one end secured by its attachment device to a second end that is last to disengage from the latch element during operation of the device.
  • 2. The device of claim 1 where:the nonmetal composite member of the whip element comprises a hollow tubular, tapered, member with a blunt end and a tip end, and its blunt end is secured by the attachment device, and the conductive pathway supported by the composite member comprises a layer of metallization on the surface of the composite member.
  • 3. The device of claim 1 where:the blunt end of the composite member that is secured by the attachment device is reinforced with an additional material.
  • 4. The device of claim 1 where:the tip end of the composite member has a metal conductor member which is electrically connected to form part of the conductive pathway.
  • 5. The device of claim 2 where:the layer of metallization comprises a layer of plated silver.
  • 6. The device of claim 5 where:the layer of plated silver is disposed over a layer of conductive paint that is on the surface of the composite member.
  • 7. An air break switch comprising:a pair of main switch contacts each with a line terminal for connection with segments of an electrical line; a switch opening mechanism for opening the main switch contacts; a rapid arc extinguishing device, for extinguishing arcs occurring on opening of the main switch contacts, including a whip element attached in electrical contact with one of the main switch contacts and a latch element attached in electrical contact with the other of the main switch contacts; the whip element comprises a flexible fiber reinforced plastic polymer member with a flexible conductive path extending from end to end of the polymer member; the latch element comprising a substantially rigid conductive metal member.
  • 8. The switch of claim 7 where:the conductive path of the whip element comprises a layer of metal on the surface of the polymer member.
  • 9. The switch of claim 7 where:the conductive path of the whip element comprises a conductor extending within the polymer member.
  • 10. The switch of claim 7 where: the reinforced plastic polymer member comprises carbon fiber reinforced epoxy resin.
  • 11. The device of claim 2 where:the tip end of the composite member has a metal conductor member which is electrically connected to form part of the conductive pathway, and a strand of wire extends within the composite member.
  • 12. The switch of claim 8 where:the polymer member also has a strand of wire extending within it.
  • 13. The device of claim 1 where:the conductive pathway supported by the nonmetal composite member includes a conductor on the exterior of the composite member arranged to make sliding conductive engagement with the latch element during switch opening.
  • 14. The device of claim 2 where:the tip end of the composite member has a metal conductor member that is electrically connected with the layer of metallization on the surface of the composite member.
  • 15. The device of claim 14 where:the metal conductor member comprises a tip conductor secured within and extending beyond the tip end of the composite member.
  • 16. The device of claim 13 where:The conductor on the exterior of the composite member includes a metal conductor at the tip end of the composite member that makes final electrical contact with the latch member prior to separation.
  • 17. The device of claim 13 where:the conductor of the whip element and the latch element are formed with smooth engaging surfaces.
  • 18. An air break switch comprising the rapid arc extinguishing device of claim 13 and further including:a pair of main switch contacts; a switch opening mechanism for opening the main switch contacts; conductive attachment of the conductive pathway of the whip element and of the latch element with respective ones of the main switch contacts, the whip element conductor making sliding conductive engagement with the latch element upon operation of the switch opening mechanism, during which flexing of the whip element occurs, until a point at which separation between the whip element and the latch element occurs and the whip element springs away from the latch element.
  • 19. The device of claim 13 where:the whip element has characteristics to achieve a speed of the second end thereof upon disengagement from the latch element of about 14 to 26 inches in 8 ms.
  • 20. The switch of claim 7 where:The whip element has characteristics to achieve a speed of the second end thereof upon disengagement from the latch element of about 14 to 26 inches in 8 ms.
US Referenced Citations (8)
Number Name Date Kind
3217115 Kaplan Nov 1965 A
4170014 Sully Oct 1979 A
4243854 Pahl Jan 1981 A
4860481 Christenson Aug 1989 A
4945333 Stroud et al. Jul 1990 A
5186315 Koppe et al. Feb 1993 A
5359167 Demissy et al. Oct 1994 A
5369234 Demissy Nov 1994 A
Non-Patent Literature Citations (4)
Entry
Josyln, D.B. 730-201, Mar. 1989, “Hi-Velocity Interrupters”.
Cleaveland/Price Inc., Bulletin DB-106BH97, 1997, (No month).
BBC Brown Boveri, Inc., Bulletin 2.3.1-1C, 12/84, “I-T-E Outdoor Air Switches”, p. 9. (No date).
Composites Technology, Yellow Pages 2000, pp. 6-20, “FRP Materials . . .” (No date).