US3024328A - Electric grounding switch - Google Patents

Description

March 6, 1962 T. A. BURDESHAW ELECTRICGROUNDING SWITCH 2 Sheets-Sheet 1 Filed' Jan. 27, 1960 IOA INVENTOR. THOMAS A. BURDE S HAW FIG. 2

FIG. 3 WW/? 771 W ATTORNEY March 6, 1962 T. A. BURDESHAW 3,024,328 ELECTRIC GROUNDING SWITCH Filed Jan. 27, 1960 2 Sheets-Sheet 2 7' Hg 3x INVENTOR.

THOMAS A. BURDESHA W ATTORNEY United States Patent 3,024,328 ELECTRIC G OUNDING SWITCH Thomas A. Burdeshaw, Hampton, Ga., assignor to Southern States Inc., a corporation of Georgia Filed Jan. 27, 1960, Ser. No. 4,939 2 Claims. (Cl. 20087) This invention relates to electric grounding switches and more particularly to grounding switches which are particularly adapted for quick and easy operation.

A prime requirement for electric grounding switches is that they operate at extremely high speed to ground an associated circuit in order that maximum protection may be afforded to the circuit and to apparatus connected therewith. In order to achieve high speed operation it has been the practice to impart high speed movement to the movable switch element and to construct the fixed switch element in such a way that the fixed element is capable of arresting high speed closing movement of the movable contact and of absorbing its kinetic energy without damage. When the fixed contact is so constructed it is difiicult to open the switch. Furthermore, it is not practical to construct a grounding switch wherein the blade is swung into the space between the jaws of a jaw contact and thereafter rotated about its axis so as to establish high pressure contact. Such operation is not feasible in grounding switches because the time available is not sufiicient to accommodate such complicated operation.

A principal object of this invention is the provision of a grounding switch which is capable of high speed closing and which is also easy to open.

Another object of this invention is to provide a high speed grounding switch which is protected against damage due to arcing by the use of magnetic means for maintaining high contact pressure after the switch is closed.

The invention in one form as applied to a high speed grounding switch comprises a fixed contact, a movable contact constructed of two parts, one of such parts being a contact bearing part and the other being a motivating part arranged in articulated relation with the contact bearing part, motivating means interrelated operably with the contact motivating part, the contact bearing part and the motivating part being arranged to impart swinging movement to the contact bearing part during switch closing and the articulated relation between the parts being such that opening movement is achieved by substantially axial movement of the contact bearing part during switch opening. Thus the fixed contact structure can be constructed using magnetic means and other means, if desired, to arrest high speed closing movement of the movable contact and so as to afiord a minimum of resistance to opening movement of the movable contact relative to the fixed contact structure.

For a better understanding of the invention reference may be had to the following detailed description taken in conjunction with the drawings in which FIG. 1 is a side view of an electric grounding switch embodying the invention and showing the switch in the closed position; FIG. 2 is a View similar to FIG. 1 and showing the parts in the position they occupy during opening of the switch but before the switch contacts are separated; FIG. 3 is a view similar to FIGS. 1 and 2 and showing the switch in the fully open position; FIG. 4 is an enlarged side View partially in section of the upper end of the switch depicted in FIGS. l-3; and in which FIG. 5 is an enlarged side view partially in section of the lower end of the switch depicted in FIGS. 1-3.

With reference to FIG. 1, the numeral 1 designatm supporting structure on which an insulator stack 2 is securely afiixed. Mounted atop insulator stack 2 is a fixed contact structure generally designated by the numeral 3.

3,024,328 Patented Mar. 6, 1962 Arranged in cooperative relation to the contact structure 3 is the movable contact blade generally designated by the numeral 4. The contact blade 4 is operated by motivating means generally designated by the numeral 5 and which is shown schematically. Motivating means 5 is provided with a drive shaft 6 on which a driving gear 7 is secured. Gear 7 meshes with pinion 8 which is secured to and rotatable with a pin 9 on which the movable contact blade 4 is pivotally mounted. As will be more fully explained hereinafter, the blade 4 is formed in two parts. One such part designated by the numeral 10 is a contact bearing part and the other such part designated by the numeral 11 is a motivating part. The parts 10 and 11 are pivotally connected by a pin 12. Contact bearing part 10 is provided with a contact element 13 which is engageable with and disengageable from a fixed contact 14 secured to fixed structure 15 which in turn is mounted on the support element 1. As will be understood, the element 1 is provided with suitable grounding connections not shown. Furthermore, it will be understood that the fixed contact structure 3 is interconnected by suitable means, not shown, with a circuit which is desired to be grounded upon the occurrence of fault or other conditions.

From the description thus far it will be understood that upon the occurrence of a fault in the circuit protected by the grounding switch motivating means 5 operates upon sensing the fault condition to drive gear 7 and pinion 8 in such a direction as to swing the blade 4 from the position depicted in FIG. 3 to that depicted in FIG. 1 at high speed. In this manner a ground circuit is established from the fixed contact 3 through blade 4, contact 13, contact 14, element 15 and structure 1 which, as already explained, is grounded.

In order to open the grounding switch after the establishment of a ground, motivating means 5 is reversed and rotates the gear 7 in a direction opposite from that in which the gear is rotated during closing. Such operation imparts clockwise motion to motivating part 11 of blade 4 and causes the articulating pin 12 to swing in a clockwise direction about the pivot 8. Such move ment causes the parts to assume the positions depicted in FIG. 2. Thereafter continued rotation of pin 9 in a clockwise direction swings the pin 12 downwardly and toward the right and separates the movable contact 10A mounted atop the contact bearing part 10 from the fixed contact structure 3 and as the motion continues the parts eventually occupy the positions depicted in FIG. 3.

The details of construction of the fixed contact structure are best shown in FIG. 4. With reference to that figure, it will be understood that the contact bearing element 10 is provided with a part 16 which is engageable by a latch 17 pivotally mounted on the pin 18 and biased by the spring 19 toward rotation in a clockwise direction about the pivot 18 to a position of engagement with a stop 20. Thus it will be understood that closing of the contact bearing element 10 causes the pin 16 to engage the surface 19A of the latch 19 and to swing the latch momentarily in a counterclockwise direction until the pin 16 moves under the latch tip 19B. Thereafter, with the contact bearing part 10 in the position shown in FIG. 4 the latch 17 moves in a clockwise direction about the pin 18 due to the bias of the spring 19. Thus it will be understood that once the contact bearing element 11 is swung into the position depicted in FIG. 4 the latch 17 latches and prevents swinging movement of contact bearing part 10 in a direction opposite to that in which the part 10 is moved during closing of the switch.

In order to insure positive contact between the movable contact 10A and the fixed contact structure 3, magnetic means are provided. Such means may comprise a loop element 21 afiixed at one end by the bolts 22 and the clamping bar 23 to the fixed structure 24. In addition, the loop 21 is anchored by a screw 25 to fixed support structure 26. The free end of the loop 21 designated by the numeral 27 is biased downwardly by means of a plunger 28 which abuts pad 27A and a compressional spring 29, the upper end of which is in engagement with the combination corona shield and sleet hood 30 and the lower end of which is in engagement with a disc 31 which is secured to the plunger 28. Thus bias of spring 29 exerts a downward force on the disc 31 and the plunger 28 and in turn on the free end 27 of the loop element 21 via pad 27A. The free end 27 of loop 21 is arranged to engage contact 10A which is mounted on the upper tip of the contact bearing part 10. Thus with the parts in the position depicted in FIG. 4, current flowing through loop 21 urges the free end 27 of the loop 21 in a generally downward direction due to the expanding action of the magnetic loop. This force, together with the force of biasing spring 29, combine to provide a downward force greater than the force tending to separate the free end 27 of loop 21 from the movable contact 10A due to the effect of the current flowing from contact bearing part 10 angularly outward along the free end 27 of the loop. Thus the contact 10A and the free end 27 of loop 21 are maintained in a secure contact making relation.

Of course if no current is flowing the contacts will be held closed by the bias of spring 29.

The lower portion of the switch is best shown in FIG. 5. As can best be seen in FIG. 5, the pivot 12 interrelates the contact bearing part 10 and the motivating part 11 of blade 4 and in addition, the motivating part 11 is provided with an abutment surface 33 which engages a stop 34 forming an integral part of contact bearing part 10. Thus when counterclockwise moment is imparted to motivating part 11 by pivot 6 the stop 34 engages the abutment surface 33 and the entire blade 4 comprising contact bearing part 10 and motivating part 11 swings rigidly as a unit and the upper end of blade 4 chops in to occupy the position depicted in FIG. 4. Furthermore, it will be understood that the contact 13 mounted on contact bearing part 11 engages the contact 14A which is biased downwardly by a spring 14B toward engagement with the contact 13.

When it is desired to open the switch clockwise moment is imparted to pin 6 by the motivating means and the motivating part 11 swings in a clockwise direction about the pin 6. This causes the pin 12 to swing in an arc clockwise about pivot 6 so that the stop 35 engages the abutment surface 36 and allows the contact bearing part to move generally axially downward to open the circuit. During opening the pin 16 disengages latch 17 and contact 10A separates from the free end 27 of loop 21.

While I have shown and described a particular embodiment of the invention, I do not wish to be limited thereto and intend in the appended claims to cover all such changes and modifications as fall within the true spirit and scope of the invention.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. An electric switch comprising fixed contact structure, a tubular movable contact, and means defining a loop circuit having a fixed end secured to said contact structure and having a free end biased toward engagement with an end of said movable contact, the direction of the bias being in substantial coincidence with the longitudinal axis of said tubular contact and the magnetic force of said loop circuit and the force of the bias of the free end thereof being generally opposite to and greater than the force imparted to said free end due to the configuration of the circuit comprising said tubular contact and said free end of said loop circuit so as to maintain said free end of said loop circuit in secure engagement with said end of said movable contact.

2. An electric switch comprising fixed contact structure, a tubular movable contact, arranged to move in one general direction during closing of the switch and in a direction generally transverse thereto during opening of the switch, means defining a loop circuit having a fixed end secured to said contact structure and having a free end biased toward engagement with an end of said movable contact, the magnetic force of said loop circuit and the force of the bias of the free end thereof being generally opposite to and greater than the force imparted to said free end due to the configuration of the circuit comprising said tubular contact and said free end of said loop circuit so as to maintain said free end of said loop circuit in secure engagement with said end of said movable contact, and a latch mounted on said fixed contact structure and biased toward a position of engagement with a part of said movable contact, stop means for limiting the travel of said latch due to its bias, said latch being eiiective to engage said part of said movable contact during a switch closing operation and to prevent movement thereof in a direction opposite to the direction of closing movement but being ineffective to prevent opening movement in a direction generally transverse to the direction of closing movement.

References Cited in the file of this patent UNITED STATES PATENTS 1,843,415 Johnson Jan. 3, 1933 1,949,018 Koppitz Feb. 27, 1934 1,958,159 Bresson May 8, 1934 2,626,332 Earle et al. Jan. 20, 1953 2,695,350 Schultz Nov. 23, 1954 2,759,076 Curtis Aug. 14, 1956 2,840,671 Giefiers June 24, 1958

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