US2504775A - Ground testing device - Google Patents

Description

April 18, 1950 J. D. wool:

GROUND TESTING DEVICE 4 Sheets-Sheet 1 Filed Feb. 26, 1947 INVENTOR 5oseph D.Wood BY ATTORNEYS April 18, 1950 J. D. WOOD 2,504,775

GROUND TESTING DEVICE Filed Feb. 26, 1947 4 Sheets-Sheet 2 INVENTOR. 5056p? D.Wood

ATTORNEYS April 18, 1950 J. D. WOOD GROUND TESTING DEVICE 4 Sheets-Sheet 5 Filed Feb. 26, 1947 INVENTOR. 5059p!) D.Wood

mwv f/xow' ATTORNEYS A ril 18, 1950 J. D. WOOD 2,50

GROUND TESTING DEVICE Filed Feb. 26, 1947 4 Sheets-Sheet 4 INVENTOR. sose b D.Wood BY ATTORNEYS Patented Apr. 18, 1950 UNITED STATES PATENT OFFICE GROUND TESTING DEVICE Application February 26, 1947, Serial No. 731,165

1 Claims. I

This invention relates to a grounding or earthing device which may be connected to power generating or power consuming apparatus in order to protect the same when the electrical circuits are intended to be deenergized and in order, especially, to protect men who are working on these apparatus.

In most modern switchboards, a stationary structure is provided into which electrical connections from power generating apparatus and to power consuming apparatus are led. The structure contains the bus and cable terminals which are attached to stationary elements of separable contact members through which current is led into switching apparatus which is usually readily removable.

In many types of switchboards, circuit breakers or switches are mounted in trucks or on other means which permit easy insertion or withdrawal of the switch so that its complementary contacts may be engaged with or disengaged from the stationary circuit connections.

In such installations it is often necessary for men to work on certain of the incoming or outgoing lines. For the protection of these men, it is essential that these lines be deenergized and preferably be connected to the earth in order to prevent personal injury.

The principal object of the present invention is the provision of a grounding device which may be inserted in the switchboard after the removal of a circuit breaker from its compartment.

Another object of the present invention is to engage switch elements of the grounding device with a selected set of stationary contacts within the switchboard and to provide means for thereafter connecting these elements to the earth without any danger to the attendant.

One type of switchboard construction in connection with which the grounding device of the present invention may best be used is one in which all of the stationary contacts comprising the legs of one circuit (i. e. the line) are arranged in a straight line and all of the stationary contacts comprising the legs of the circuit (the load) to which the circuit breaker will connect the first circuit are also arranged in a straight line parallel to the first group of contacts.

The grounding device of the present invention is provided with a group of contacts which may be moved selectively so that, when the device is entered into the switchboard, they may engage either the first group of contacts or the second group of contacts.

Another object of this invention, therefore, is

the provision of means in a single grounding de-' vice which may be engaged and disengaged with a selected set of circuit connecting elements in a stationary switchboard.

A further object of the present invention is the provision in a grounding device of selectively moveable connecting elements the position of which in the grounding device may be altered to engage a selected set of stationary circuit connecting elements.

A further object of my invention is the provision in my novel grounding device of a barrier so arranged that the contact elements to which connections are to be made cannot be reached until the grounding device has been racked into the compartment.

A further object of my invention is the arrangement of the grounding device so that the completion of the racking-in and grounding operation will result in movement of the aforesaid barrier to a position wherein the contacts to be engaged and grounded are exposed.

Another and modified object of my invention is the arrangement of the grounding device so that the barrier can be moved into position to expose the contacts only after the racking-in operation is completed.

Another object of my invention is the arrangement of my novel grounding device in such a manner that the barrier is moved to a position rendering the contacts inaccessible before the racking-out of the grounding device can begin.

The foregoing and many other objects of my invention will become apparent in the following description and drawings, in which:

Figure 1 is a side view of my novel grounding device showing the elements thereof in the test position before the grounding device has been racked in.

Figure 2 is a corresponding side view showing my novel grounding device fully racked in with the contacts exposed so that they may be grounded.

Figure 3 is a side view corresponding to that of Figure 1 showing a slightly modified form of my novel grounding device.

Figure 4 is a view in perspective of the grounding device of Figures 1 and 2 showing a ground clamp with ground clamp cable and a ground clamp stick connected to one of the contact members.

Referring now to the Figures 1, 2 and 3, the compartment into which my novel grounding device is to be racked and in which it is to operate is indicated generally by the back wall Ill thereof. The circuit breaker originally in the compartment and in engagement with the disconnect 3 contacts H recessed in insulating housings l2 in the back wall has been removed and the grounding device has been racked in in its stead.

The fronts of the individual housings i2 are closed by the isolation shutters !3, Id which, when the compartment is empty, are so arranged that their respective openings I and it are not in registry with each other, the shutter portion Hi being then lowered.

In order to admit the connecting elements of either the circuit breaker or the grounding device, the shutter element l4 must be raised to bring the openings [5 and I5 into registry with each other.

The grounding device is shown in Figure l with its connection stud 2!] having th contact element 2! entered through the registered openings i5 and it into the recessed housing 12 but not yet engaged with the stationary disconnect contact ll leading to a box behind the compartment.

In Figure 2, my novel grounding device is shown racked in all the way so that the contact element 2! on the end of the conductive stud 26 is in engagement with the stationary disconnect contact H. The conductive stud 2G is provided with a sheath 2% of insulating material preferably phenolic insulation molded around the stud in order to isolate the group of studs and their contacts 2| from each other.

As shown more particularly in Figure 4, the individual studs are connected together by the insulating cross bars 25, 25 which are clamped on opposite sides of the aligned studs to yoke them together to operate as a single unit mechanically, although of course they are isolated from each other electrically.

My novel grounding device comp-rises a main supporting platform or tray 3! with side vertical supports 32, 32 secured to the upstanding flanges 33, 33 of the tray 3|. A suitable cover plate 35 isprovided across the tops of the side vertical plates 32. The cross bars or yoke members 25 are provided with flanges 38, 39 on each side, which are respectively connected to the links so and ll on each side.

The opposite ends of each or'the links 4 3,4! on each side are pivotally mounted on pivots 42, 43 respectively, the said pivots being secured in any suitable manner to the front ends of the vertical side panels 32, 32. The arrangement is such that the cross bar or yoke 25 carrying the three or more contact studs 26 and their associated contacts 2! may be moved from the upper portion shown in the figures wherein they engage the line terminals in the compartmentto the lower position indicated at 20a of Figure 1 wherein they are in a position to engage the load terminals in the compartment.

The upper covering panel 35 is a tray-like memberprovided with a downwardly dependent flange 35 in the rear. Similarly the main platform or tray 3! is provided with an upwardly ascending flange 46 in the rear.

Latch members 63 and 49 respectively are secured to the lower member 46 and'the upper member at the rear where these latches may respectively engage the pins 533 and 5E which connect the links as and 4| to the transverse bar or yoke 25.

Only one latch need'be used for either the up or down position although a pair of latches may be used on each side for the up and down position if desired. Each latch member is a simple latching bar 53 pivotally mounted on pin 54 carried by lug 55 securedeithertothe flange do or the flange 45. The latch member 53 of the lower latch 48 is spring biased in any suitable manner as by a coil. spring around the pin 5 into clockwise rotation; while the corresponding latch member 53 of the latch element 49 at the upper end is similarly biased into counterclockwise rotation with respect to Figure 2.

The latch 18 will engage pin 56 when the contacts 2| are in the lowered position and hold them in that position; the latch 43 will engage the pin 5| when the contacts are in the upper position and will hold them in that position.

In order to prepare my novel grounding device for use in connection with either the line or the load contacts, it is necessary merely to release the particularlatch 43 or 49 which holds the contacts by .manually pressing the end of lever 53 opposite its hooked portion and then by grasping either the cross bar 25 or one of the studs 28 to move the aligned studs 29 and the cross bar 25 to the proper position where they will then be latched for an engagement with the desired set of contacts.

This of course must be done before the grounding device is moved into the compartment.

The platform 3! has secured thereto at the lower end, the downwardly extending lateral cross piece 60 having the side flanges 6! on each side, which side flanges carry the rollers 63 and 64 to ride on the track of the compartment. Adjacent the front end of theplatform is a downwardly extending cross bar 66 carrying rollers 61 on eachside to ride on the rail of the compartment.

The cross bar (it? and the front end of the platform 3! combine in supporting the front lower side panels l'il, it on each side by which the rotatable racking shaft 12 is rotatably supported.

Racking shaft '52 has keyed thereto a racking disk 13 provided with radial notches 14 into which a racking bar may be inserted to rotate the shaft 12.

The outer ends of the racking shaft ?2 beyond the side panel it areprovided with levers l5, 15 on each side which engage suitable projections or carnming surfaces on the side wall of the compartment of the type shown in application Ser. No. 434,544 filed March 13, i942, now abandoned, to cooperate with them to force the grounding device 36 into the compartment on rotation of shaft 12 in a counterclockwise direction with respect to the figures and to move the grounding device out of the compartment on rotation of the shaft 12 in a clockwise direction.

The particular form of racking means used does not comprise a specific part of the present invention as long as a shaft similar to the shaft 12 is provided, which must be rotated during racking-in and racking-out of the grounding devioefii}.

Inany event, in the specific racking device shown, the racking disk is provided with a latch surface 16. engaged by the latch ii spring biased upwardly by spring 78 and locking the racking disk;'!3 against accidental rotation in a clockwise direction and therefore against accidental operation to remove the grounding device from the compartment.

The main horizontal platform 3! of the grounding device 36 is also provided with the lower housing 80 including the side panels 8! and 82. Panels BI and 82 carry between them at the lower end thereof, the shaft 83 on which are pivotally secured the lower ends of the bars 84, 84. Bars 84., 8 3 carry between them the barrier 8.5;. Barrier 85: is provided with openings 86, 86 through which the contact members 8! at the front end of the connecting studs 29 may pass.

In the test position of the grounding device, the barrier 85 is in the position shown in Figure 1 where the front contact elements 8'! of the studs 29 are inaccessible. In the fully racked-in position of the grounding device 39 shown in Figures 2 and 4, the barrier has been moved to a position where the front contacting elements 8'! of the connecting studs 29 have passed through the openings 89 and are accessible for grounding purposes.

The bars 84 carry above their pivot point cross shaft 99 to which is connected the rear end of the operating link 9!. The front end of the operating link 9! is slotted at 92 so that it may engage the shaft 12 without interfering with the operation of shaft 12. The slot 92 is sufficiently long so that the operating link 9! may be pushed back and forth without interference from the shaft I2.

Cam 94 is mounted on the shaft 12 and is arranged to cooperate with and bear against the cross pins of 95 and 99 carried between the parallel arms of the operating link 9 I.

With the grounding device in the test position before it has been racked in, all of the elements are in the position shown in Figure 1 with the operating link 9! in the retracted position and the barrier 95 in a position where the contact elements 8'! are not accessible.

On rotating the shaft 12 in a counterclockwise position to rack the grounding device in, the cam 94 is also rotated in a clockwise direction. Owing to the fact that the surface 94a of cam 99 is however part of a true circle concentric with the center of shaft I2, the operating link 9! is not pushed to the left during this initial portion of the racking operation. As the racking operation nears completion, however, the surface 941) of cam 94 engages the pin 95 and pushes pin 95 to the left, thus pushing the operating link 9! to the left and rotating the vertical bars 84 in a counterclockwise direction to move the barrier 85 from the position of Figure 1 to that of Figures 2 and 4.

As the racking operation is fully completed, the section 940 of the cam 94 moves against the pin 95 resulting in no further movement of operating link 9! or barrier 85.

During the racking-out operation, it will be noted that cam surface 94a is now against the pin 99 and again during the initial stages of the racking-out operation while the contact 2! is being pulled away from contact II, the pin 99 is not moved by the cam at all. When, however, the racking operation nears completion, then the surface 94a of the cam moves against the pin 99 to move the pin 96 outwardly towards the front of the grounding device thereby pulling out the link 9! and rotating the barrier 85 from the position of Figure 2 to the position of Figure 1.

By this means, therefore, the barrier 85 is so integrated with the racking mechanism that it cannot be moved into the position where the contact elements 8'! are accessible for grounding until the grounding device 39 is racked in; and the barrier 85 is moved back to a position where the contacts 81 are inaccessible for grounding as soon as the racking out of the grounding device commences.

When the grounding device 39 has been racked in and the barrier 85 has moved to a position where the contact elements 8'! are accessible, a grounding clamp I99 may be mounted over each of the contact elements 81, the said contact elements 8'! being channel-shaped or having a flange to facilitate the placement of the U- shaped clamp I99 thereon.

The ground clamping element I99 has an ex-' tension I9! which preferably is a bolt threaded thereinto, the outer end of the extension or boltcarrying the square plate I92. An insulating ground clamp stick I93 having prongs I94 may readily engage the plate I92 so that an operator may thereby lift up the clamp I99 and place the same over the contact elements 8'! without danger to himself. The stick I93 and prongs I94 may then be removed by a straight pull since the prongs I94 are of spring metal. Or the stick I93 may be rotated so that the prongs I94 rotate the plate I92 and the bolt I9! to remove the bolt I9! and plate I92 from the clamp I99.

Clamp I99 has secured thereto in any suitable manner as by the connecting element H9 the grounding cable I I I which is connected to a suitable ground so that any current which may reach the terminals II will be safely grounded without danger of injury to the workmen.

In Figure 3 I have shown a slight modification of my invention in which the barrier is not automatically moved to the position where the contact elements 8'! are accessible on the racking end of the circuit breaker, but wherein the barrier 85 may thereafter be manually moved by a stick or otherwise to the position where contacts 8'! are accessible.

The shaft F2 in this case is provided with a disk I94 having the peripheral notch I into which the end of link I9! may enter. In the racked out position of the circuit breaker, the notch I 95 is in the outer position away from the end of link I9!. When the circuit breakeris fully racked in, the notch I95 is rotated 180 to the position where it is in the dotted-line position opposite the end of link I9!. Link I9! is biased towards the left by the compression spring I 89 which bears between the roller I9! keyed to the link I9! and the stationary plate I 82 having an opening I93 through which the end of link I 9! passes.

Link I9! is connected by pin I92 to lever E93 pivoted on the stationary pin I89. The opposite end of lever I93 is connected by pin I85 to link I86. Link I89 is pivotally connected to pin 99 on the vertical bars 84.

The upper end of the barrier 85 is provided with a central notch 29! which bears against the latch bar 292; the said latch bar 292 is pivotally mounted on stationary pin 293 and is zp iing biased downwardly by the tension spring When the grounding device is fully racked in and the notch I95 has moved to the dotted line position where the front end of link I9! may enter into the said notch, then the elements are arranged so that the barrier 85 may now be pushed by a prod or otherwise to the left into the dotted line position where the contact elements 8'! are accessible. When the barrier 95 is pushed towards the left, the link I86 is pulled to the left rotating the lever I93 in a clockwise direction around the pin I 84 and pushing the link I9! against the compression of spring I89 so that the front end of the link I9! enters into the notch I95.

At the same time the upper end or notch 29! in the barrier 85 moves into the latch detent 296.

of the latching member 202 so. that the barrier 851s held. inthe position where the contactele ments 8'! are accessible against.the pressureofo wise and pulling the link 585 to the right. This resultsin pulling the vertical bars 34 to theright around their pivot 83 and pulls the barrier. 85 out.

This then permits the grounding device. to

be racked out after the contact elements have been rendered inaccessible by movement of the barrier 85 to the solid line position of Figure 3. The barrier 85 is thus so arranged in the construction of Figure 3 that it is always spring biased to the outward position. It cannot be moved and latched into the position of accessibility of the contacts 8'! until the racking in operation has been completed so that contact 2! has engaged the disconnect contact or terminal i i.

It may then be moved in by a prod or stick as above pointed out. Likewise the racking out operation cannot even be commenced untiltne barrier is unlatched and returned to the position where contact elements 81 are inaccessible.

Thus in both forms of my novel device, the provision is made of a barrier so arranged that the contact elements of the grounding device are unavailable for grounding of the circuit until the grounding device is fully racked in. The barrier is moved into a position where the contacts are available for grounding either on completion of the racking in operation and connection of.-

the grounding device to'the terminals 01' immediately following the completion of the racking in and the aforesaid connection. The barrier is then moved to a position where the contacts which are to be grounded are inaccessible for connection either during the initial portion of the racking out operation before the elements 2| and ii separate or the device may be so arranged that the barrier mustbe mcvedto the position where the contact elements are "iaccessible before the racking out operation is even commenced.

I claim:

1. In a device for engaging a contact, a

connection stud, a support for said stud,.a racking mechanism connected to said support for racking said stud into engagement with-the said contact, a pivotally mounted barrier connected.

to said racking mechanism, said barrier being in front of said stud when said racking mecha-,

nism is in one position for renderingflsaidstud. inaccessible and being operated simultaneously with said support by said rack whensaid, rack. is operated to operate said stud into engagement. with said contact for rendering said stud accessible for connection thereto.

2. In a device for engaging a c ntact, a connection stud, a support for said stud, a racking In order to accomplish.

mechanism connected to said support for racking said stud into engagement with the said contact, a movable barrier connected to said racking mechanism and having an opening, said barrier being in .front of said stud when said racking mechanism is in one position for rendering said stud inaccessible and being operable by said racking mechanism, when said rack isoperated to operate said studinto engagement with the selected contact, to a position where one end of said stud protrudes through said opening for connection thereto.

3. In a device for selectively making contact with a first and a second contact, a connection stud, a support for said stud, a pivoted link connected at one end to said stud and pivotally mounted at its opposite end to said support, said link being operable on its pivot to move said stud selectively to a position to engage one of said contacts, a racking mechanism connected to said support for racking said stud into engagement with the selected contact, a barrier carried by said racking mechanism, said barrier being in front of said stud when said racking mechanism is in one position for rendering said stud inaccessible and being operable, when said rack is operated to operate said stud into engagement with the selected contact, to a position for rendering said stud accessibl for connection thereto.

4. In a device for selectively making contact with a first and a second contact, a connection stud, a support for said stud comprising a main platform, a side vertical support and a cover plate, a pivoted link connected at one end to said stud and pivotally mounted at its opposite end'to said support, said link being operable on itspivot to move said stud selectively to a position to engage one ofsaid contacts, latch members for latching said stud in operated position, a racking mechanism connected to said support for racking said stud into engagement with the selected contact, a barrier carried by said racking mechanism, said barrier having an opening, said barrier being in front of said stud when said racking; mechanism is in one position for rendering said stud inaccessible and being operable, when said-rack is operated to operate said stud into engagement with the selected contact, to a position where one end of said stud protrudes through said opening making said stud accessible for connection thereto.

JOSEPH D. WOOD.

REFERENQES CITED The following references are of record in the file of this patent:

UNITED PATENTS Number Nam c Date 1,584,623 McCoy May 11, 1926 1,699,753 Rawlings Jan. 22, 1929 1,904=,565 Swanson Apr. 18, 1933 1,955,287 Graves Apr. 17, 1934 2,353,518 Specht July 11, 1944 FOREIGN PATENTS Number Country Date 296,113 Great Britain Aug. 24, 1928 337,384 Great-Britain Feb. 6. 1933

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