US2849578A - High voltage switch - Google Patents

Description

Aug. 26, 1958 1.. c. HART HIGH VOLTAGE SWITCH Filed 00th 10. 1955 HHGH VQLTAGE SWITCH Lester C. Hart, Cicveland, Qhio, assignor to Joslyn Mfg. & Supply (30., Chicago, iii, a corporation of Illinois Application October 10, 1955, Serial No. 539,367

Claims. (Cl. 200-146) The present invention relates to high voltage switches, and, more particularly, to high voltage switches of the type employed in power distribution circuits, which, in addition to operating as disconnecting or isolating switches for certain sections of the power distribution circuits, are also capable of interrupting substantial currents in the form of line charging currents, transformer magnetizing currents and even energy loads.

It Wiil be understood by those skilled in the art that high voltage switches are extensively employed, particularly in outdoor switching stations for isolating sections of transmission lines and the like under certain conditions. Such high voltage switches are generally air break switches which are crank operated through a manual crank mechanism or the like to isolate desired sections of the distribution circuits and to insert other sections. it has been common practice to provide such high voltage switches with arcing horns to interrupt transformer magnetizing currents and the like. However, as the distribution circuits have become larger and more complicated, the line charging currents have become so large that such conventional air break switches have been incapable of satisfactorily interrupting the currents flowing. It would be desirable to provide a high voltage air break switch capable of switching capacitive currents such as those encountered in deenergizing transmission lines, underground cables and capacitor banks. It would also be desirable for such a high voltage switch to interrupt the energizing current of large transformers. At the same time, such high voltage or air break switch should conform in general to the configuration of the well-known high voltage air break switches so extensively employed for this purpose.

Various means have been suggested in connection with hi h voltage air break switches to provide some sort of current interrupting contacts in parallel with the current carrying contacts of the high voltage switch. Most of these arrangements have been very expensive, requiring a complicated mechanism and many of them did not separate the arcing contacts with sufficient velocity and did not provide sufiicient spacing to insure interruption.

Accordingly, it is an object of the present invention to provide a new and improved high voltage air break switch.

It is another object of the present invention to provide a new and improved high voltage air break switch capable of interrupting capacitive currents such as those encountered in deenergizing transmission lines, underground cables and capacitor banks, and also capable of interrupting the energizing current of large transformers.

Still another object of the present invention is to provide a new and improved high voltage air break switch comprising an attachment which will remain in contact while the main current carrying contacts of the switch separate and then open with very high speed without oscillation or swinging back to at least partially reclose the *atent O It is another object of the present invention to provide high velocity interruption contacts in the form of an attachment for a high voltage air break switch readily applicable to existing high voltage switches.

Further objects and advantages of the present invention will become apparent as the following description proceeds and the features of novelty which characterize the invention will be pointed out with particularity in the claims annexed to and forming a part of this specification.

For a better understanding of the present invention, reference may be had to the accompanying drawing, in which:

Fig. 1 is an elevational view of a high voltage air break switch embodying the present invention showing several different positions of the switch during operation thereof;

Fig. 2 is a somewhat enlarged sectional view taken along line 22 of Fig. 1;

Fig. 3 is a somewhat enlarged sectional View taken along line 33 of Fig. 1;

Fig. 4 is an enlarged sectional view taken along line 4-4 of Fig. 1;

Fig. 5 is a fragmentary elevational view illustrating a modification of the present invention; and

ig. 6 is a sectional view taken along line 66 of Fig. 5. it will be understood that high voltage air break switches are generally employed for multipole operation,

although they might equally well be employed for singlepole operation. To simplify the drawing, only a single pole of a high voltage switch has been illustrated. However, it should be appreciated that in a multipole switch additional units identical to that shown in Fig. 1 of the drawing would be provided with links interconnecting the operating mechanisms to insure simultaneous operation of the switch blades.

In order to illustrate the present invention, there is disclosed in Fig. 1 of the drawing a high voltage switch of the type shown in United States Letters Patent No. 2,514,263, Hart et al., granted July 4, 1950. This switch generally indicated at 10 may obviously comprise any form of high voltage air break switch. As illustrated, the switch 10 comprises a base member 11 formed of channel iron or other suitable material which will provide a rigid member for supporting the switching contacts and op erating means for air break switch 10. As illustrated, the base 11 is disposed in a horizontal position. It should be understood, however, that it might equally well be disposed in a vertical or some other position, and the illustrated position is merely by way of example. Secured to the base 11 are a pair of fixed insulators 12 and 13 mounted in spaced relationship on the base 11. There is also provided a movable insulator 14 positioned between the fixed insulators 12 and 13. The insulators 12 and 13 are provided with suitable means for securing them in a fixed position to the base 11. The insulator 14, on the other hand, includes a downwardly extending shaft 15 which is adapted for rotation in a suitable bearing 16 mounted on the base 11. As illustrated, the end of the shaft 15 disposed on the opposite side of the base 11 from the insulator 14 is provided with a hexagonal end designated as 1511 which may be engaged by a suitable manual operating lever or the like to cause rotation of the insulator 14. Preferably the bearing 16 and a substantial portion of the shaft 15 are provided with a suitable sleet hood 17.

For the purpose of operating the switch 10 as a multi pole switch, one or more crank arms 18 may beprovided to rotate with the insulator and shaft 15. As illustrated, the crank arm 18 is provided with an operating eye 19 which may be connected to suitable rods interrelating the plurality of poles of the multipole switch to insure simultaneous operation of all poles thereof. It will be understood that in the event a single-pole switch is desired, the crank arm 18 will be disposed with. Also, instead of employing a crank for engaging the hexagonal end of the shaft 15, it will be understood that power from a suitable source may be applied to the crank arm 18 to operate the switch 10.

In order to support electrical conductors which together with the switch 10 comprise the circuit to be controlled, there is mounted on the insulator 12 a hinged base and terminal support 21. On the other hand, there is mounted on the insulator 13 a contact support 22. It will be understood that the supports 21 and 22 are suitably fastened to their associated insulators 12 and 13 in a conventional manner. Mounted on the support 22 is a stationary contact means or assembly generally designated at 23 and described in greater detail hereinafter. The stationary contact itself is not visible in the drawing, since it is covered by a sleet hood 24, preferably formed of bronze or the like. It will be understood that the stationary contact member may comprise any suitable contact capable of carrying the currents at the high voltages involved, and in general preferably comprises spring biased contact jaws for engaging and receiving therebetween the bladelike contact portion 25 of a switch blade 26. The support 22 also includes an extension 27 to which a suitable terminal (not shown) may be bolted or otherwise secured, which terminal is electrically connected to one side of the circuit controlled by the switch 10. The support 22 further includes a contact base guide 28 for supporting and guiding the movable bladelike contact portion 25 fastened to the end of the switch blade 26 in its initial movement during a circuit opening operation and its final movement during a circuit closing operation, when the switch blade moves endwise along its longitudinal axis.

Preferably and as indicated above, the switch 10 is of the type in which the switch blade 26 moves along its longitudinal axis both during the initial opening movement and the final closing movement thereof, and during the rest of its cycle of operation pivots or swings in an are about the effective pivot point described hereinafter. To accomplish this, the support 21, which is in the form of a casting suitably bolted or otherwise secured to the stationary insulator 12 has associated therewith a plurality of links 30, 31 and 32. The lower ends of the links 30 and 31 are pivoted to spaced points on the support 21, and the upper ends thereof are pivoted to spaced points on the link 32. The link 32 is provided with an extension 32a connected to the switch blade 26. A suitable crank 33 fastened to the rotatable insulator 14 is connected by means of a connecting rod, not visible in the drawing, with the link 32 so that upon rotation of the insulator 14 the particular arrangement of the links 30, 31 and 32 causes the switch blade 26 to move substantially along its longitudinal axis when in a position closely associated with stationary contact 23, and to pivot about an effective pivot point remote from the end thereof supporting blade portion 25 for the remaining and major portion of the switch blade movement. Also associated with the support 21 is a terminal extension 36 to which may be bolted or otherwise secured to a suitable terminal (not shown) connected to the other side of the circuit to be controlled by the switch 10. It will be apparent that the switch 10 provides a control path between suitable conductors connected to the terminal extensions 27 and 36, respectively. As was pointed out above, the details of the structure supported by the terminal supports 21 and 22 form no part of the present invention, but are fully disclosed and claimed in Hart et al. Patent No. 2,514,263 mentioned above.

By rotation of the insulator 14, assuming that the switch blade 26 is in the closed position indicated in Fig. l of the drawing, it first moves along its longitudinal axis in a direction toward the support 21 until it is free of the stationary contact 23, and then it pivots about the effective pivot point associated with support 21 to the successive positions shown in dot-dashed and in dashed lines in Fig. l of the drawing. When in the maximum open position, there is presented a very large air gap which is suificient completely to isolate the two sides of the high voltage circuit connected to terminals 27 and 36, respectively.

Before discussing the features of the present invention associated with the high voltage switch described above, a brief discussion of the problem of interrupting capacitive currents is believed to be desirable. When opening a capacitive circuit, there is always a moment of time when conditions are perfect for circuit interruption. Perfect conditions would, of course, comprise current zero and with no voltage across the contacts at the instant of current zero. Actually, this occurs at the first current zero after the contacts of the switch have separated. At this moment when there is no current flowing, the voltage across the contacts is also zero. This is because the voltage lags the current about ninety degrees and reaches its peak at current zero, but it should be remembered that at this instant the condensers comprising the capacitive circuit have been charged to a voltage equal to the peak voltage, so that there is no diiference in the voltage across the switch contacts to be opened. If, therefore, the interrupting contacts are separated at a sufficiently high velocity at the instant of current zero when no voltage drop occurs across the contacts so as to provide during the next half-cycle after the first current zero a sufficiently wide gap which will not break down, the circuit will remain interrupted. For interrupting the energizing currents of large transformers, initially high speed separation of the contacts is also essential and this high speed separation must continue through a distance almost equal to the normal open gap of the switch. The present invention satisfactorily interrupts capacitive currents and transformer energizing currents.

Referring now to Figs. 1 to 4 of the drawing, the high velocity interrupting contacts of the present invention, connected in parallel with the switch blade 26 and stationary contact 23, essentially comprise a resilient rod or whiplike member 40 preferably formed of stainless steel and ground to a taper so as to gradually taper from one end to the other. Moreover, the stainless steel rod or whip 40 is preferably heat treated so as to be very resilient. In accordance with the present invention, the large end of the tapered rod 40 is suitably secured or clamped to the pivotal end of the blade 26 in a manner so as normally to be disposed in spaced parallel relationship with the blade 26, as is clearly shown in the solid lines and in the dashed lines of Fig. 1 of the drawing. As best shown in Fig. 4, a suitable rod support 41 is provided of somewhat L-shaped configuration. The rod 40 is suitably secured, preferably as being inserted within a sleevelike portion 41a of the support 41. This support is clamped as by clamp means 42 to the blade 26 closely adjacent the end thereof, which rotates about the effective pivot described above. In this manner the resilient tapered rod 40 is supported in cantilever fashion with respect to the blade 26, the free end of the rod 40 extending beyond the blade portion 25, as is clearly apparent from Fig. l of the drawing. The whiplike rod 40 is effectively the movable interrupting contact of the high velocity circuit interrupting contacts paralleling the current carrying contacts 26 and 23.

T 0 provide a cooperating interrupting contact, there is supported on the support 22 and electrically connected therewith a catch 44, best shown in Fig. 2 of the drawing. This catch 44 comprises the stationary interrupting contact and is illustrated as having a sort of arrowheadshaped projection 44a, which defines on either side thereof shoulders 45 and 46 which are adapted to engage the free end of the flexible rod 40. In Fig. 2 of the drawing the rod 40 is indicated as cooperating with the shoulder 46, but it might equally well cooperate with the shoulder 45. The arrowhead shape of the portion 44a will guide the rod 40 during the closing movement of the air break switch to move into engagement with either shoulder 45 or 46. The combined stationary contact and switch latch or catch 44 further includes projections 44b and 44c disposed beneath the shoulders 45 and 46, respectively, which function to guide the resilient tapered rod 40 and insure ultimate engagement thereof with one of the shoulders 45 or 46. Moreover, the arrangement is such that whenever the switch blade 26 is moved to the closed or solid line position of Fig. l of the drawing, the free end of the rod 40 moves into engagement with one or the other of the shoulders 45 or 46 of the catch 44. During the opening movement of the switch blade 26 it will be apparent that as it pivots from the solid line position to the dot-dashed line position of Fig. 1, the free end of the rod 40 will remain in engagement with the catch 44, and due to its resilience, it will assume the bowed position shown in dot-dashed lines in Fig. l. The length of the rod 4% is sufficient so that it remains in engagement with the catch 44 until the blade contact portion 25 of the switch blade 26 has separated from the associated stationary current carrying contact 23 to such an extent that a gap which will not restrike is provided when the whiplike member 49 is suddenly released from the catch 44. Continued movement of the switch blade 26 toward the dashed line position will cause the free end of the whiplike member 4h to be released from the catch 44 and whip at high speed in a manner to interrupt the circuit at the arcing contacts and eventually come to rest relative to the blade 26 in the position shown in dashed lines in Fig. 1 of the drawing. Actually, the fully open position of switch It? is not shown in the drawing.

The arrangement described above, without more, would result in oscillation of the whiplike member 41 during the switch opening operation with the possibility of restriking of the are when the member 4d moves to ward the catch or stationary arcing contact 44 during oscillation thereof. To insure dependable interrupting operation, there is provided a dampering mechanism generally designated by the reference numeral 48 and best shown in Fig. 3 of the drawing. This dampering mechanism is disposed so as to be engaged by the whiplike member 40 during the circuit opening operation so as to quickly bring it to rest without oscillation which would cause restriking of the arc to be interrupted thereby. As illustrated, the dampering mechanism 48 comprises a support member 49 clamped as by clamping screws St} to the end of the blade 26 adjacent the blade contact portion 25. The support 49 includes a projection 4% to which is secured a resilient member 53 preferably in the form of a fiat stainless steel leaf spring. The spring 51 is illustrated as being mounted so as to be disposed generally parallel with the blade 26 and the whiplilze rod 48 when the latter is in its at rest position. Secured to the free end of the leaf spring 51 is a flat spring 52 disposed in the form of a loop and preferably also formed of a strip of stainless steel bent into the form of a resilient loop and secured in any suitable manner to the leaf spring 51. The loop is of sufficient width, as is clearly shown in Fig. 3 of the drawing, so that the whiplike rod member Ml will strike it, whereupon the kinetic energy in the whiplike member 4% may quickly be absorbed thereby preventing any undesirable oscillations of the rod -40.

Preferably the support 49 also includes a guide portion 4912 which defines with the portion 49a a sort of V-shaped guide to receive therein the whiplike rod member 40. The dampering mechanism 48 has been found to work very satisfactorily and insures high velocity interruption of the are so that satisfactory interruption of capacitive currents and transformer energizing currents can be accomplished. It will, moreover, be appreciated that the high velocity contacts can be applied as an attachment to existing switches in a very simple manner by merely supplying the dampering mechanism 48, the catch 44 and the rod member 40 with its mounting means. The mechanism for interrupting high voltage currents is very sturdy and many years of satisfactory operation are insured.

if it should be desired to afford still higher relative separation between the interrupting contacts, a modification of the present invention as illustrated in Figs. 5 and 6 of the drawing may be employed. This modification consists solely in a modification of the catch 44. The corresponding parts of Figs. 5 and 6 are designated by the same reference numerals as in the preceding embodiment. As illustrated in Figs. 5 and 6 of the drawing, there is provided a spring catch 54 formed of resilient spring wire material. As illustrated, the catch 54 comprises a wirelike member which is formed to provide a sort of arrowhead-shaped portion 54a defining the shoulders 55 and 56 corresponding with the shoulders 45 and 46 described above. The intermediate portion of the catch 44- comprises a turn or two designated as 541) acting some what like a coil spring. It will be appreciated that the catch 54 has a portion which will tend to follow to some extent during the switch opening operation the whiplike contact 40 as shown in other than solid lines in Fig. 5

. of the drawing. Consequently, upon separation of the whiplike rod member 40 from the resilient spring catch 54, both the spring catch 54 and the rodlike member 40 will tend to move in opposite directions, thus insuring even higher speed contact separation than in the arrangement disclosed in Fig. 1 wherein the catch 44 is stationary. Additionally, a longer gap is also produced in a shorter space of time, thus insuring operation within the halfcycle period most satisfactory for interrupting high voltage capacitive currents and transformer energizing currents. The catch 54, although somewhat movable, may still be characterized as the stationary interrupting contact, cooperating with the movable interrupting Whiplike rod contact 40.

it will be appreciated that although the present invention is particularly adaptable for high voltage air break switches whether mounted for horizontal or vertical operation, the invention is also applicable to other types of switches such as hook operated disconnecting switches and the like.

In view of the detailed description included above, the operation of the high voltage switch of the present invention will readily be understood by those skilled in the art and no further discussion thereof is included herein. It will be apparent that there has been provided a simple arrangement for converting high voltage air break switches to such switches capable of interrupting high line charging currents, transformer magnetizing currents and the like. The means for converting such conventional air break switches to switches capable of interrupting capacitive circuits and the like is very simple and inexpensive, and results in a switch which will give long years of satisfactory service.

While there have been shown and described particular embodiments of the present invention, it is not desired that the invention be limited to the constructions shown and described, for it will, of course, be obvious to those skilled in the art that numerous changes and modifications can be made without departing from the invention in its broader aspects. It is, therefore, intended in the appended claims to cover all such changes and modifications as fall within the true spirit and scope of the present invention.

What is claimed as new and desired to be secured by Letters Patent of the United States is:

1. A high voltage switch comprising a pair of relatively movable current carrying contacts, one of said current carrying contacts being supported on a movable elongated switch blade, a pair of relatively movable arc interrupting contacts connected in parallel with said current carrying contacts, one of said are interrupting contacts including an elongated resilient whiplike rod contact normally disposed in spaced parallel relationship with said elongated switch blade and supported for movement therewith, said rod contact being at least coextensive With said switch blade, the other of said are interrupting contacts comprising a latch, said latch holding said whiplike rod contact in electrical engagement during a substantial portion of the switch opening operation, means for absorbing the kinetic energy of motion of said rod contact when released by said latch comprising a loop of resilient material, and means for supporting said loop from the said blade in a position to be struck by said rod contact when released by said latch.

2. The switch of claim 1 wherein the last mentioned means comprises a resilient member disposed parallel with said switch blade.

3. The switch of claim 1 wherein said loop comprises ill a fiat strip of stainless steel supported from one of said current carrying contacts.

4. The switch of claim 1 wherein said rod contact is tapered.

5. The switch of claim 1 wherein said rod contact is formed of stainless steel.

References Cited in the file of this patent UNITED STATES PATENTS 1,702,075 Chireix et al Feb. 12, 1929 1,825,002 Kratzer Sept. 29, 1931 1,861,641 Nicholson et a1 June 7, 1932 1,919,065 Jacobs July 18, 1933 2,317,118 Schultz et a1. Apr. 20, 1943 2,572,625 Johnson Oct. 23, 1951 2,727,105

Turner Dec. 13, 1955

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