US2714646A

US2714646A - Inching device for switch jaw

Info

Publication number: US2714646A
Application number: US380046A
Authority: US
Inventors: Jamison Donald Ray
Original assignee: ITE Circuit Breaker Co
Current assignee: ITE Circuit Breaker Co
Priority date: 1953-09-14
Filing date: 1953-09-14
Publication date: 1955-08-02
Anticipated expiration: 1972-08-02

Description

Aug. 2, 1955 D, R, JAMISQN 2,714,646

INCHING DEVICE FOR SWITCH JAW Filed Sept. 14, 1953 2 Sheets-Sheet l y INVENTOR.

Aug. 2, 1955 D. R. JAMISON 2,714,646

INCHING DEVICE FOR SWITCH JAW Fil-ed Sept. 14, 1953 2 Sheets-Sheet 2 INVENTOR.

. A v hm/Jaw o dk K T United States Patent fiice Patented Aug. 2, 1:95.:

2,714,646 IN CHIN G DEVICE FOR SWITCH JAW Donald Ray Jamison, Greensburg, Pa., assignor to I-T-E Circuit Breaker Company, Philadelphia, Pa., a corporation of Pennsylvania Application September 14, 1953, Serial No. 380,046 4 Claims. (Cl. 200-462) My present invention relates to a safety device for hookstick operated switches and is more particularly directed to a device which permits the opening of a disconnect switch by a hook stick only a small amount during the initial opening operation and thereafter permits the disconnect switch blade to be fully opened by the operator if he observes no arc during the initial opening operation.

My invention is particularly directed to disconnect switches of a high voltage hook-stick operated type. In switches of this type, one or more blades, usually rectangular in cross section and having one end attached to a hinged terminal, are rotated about the hinged terminal into and out of engagement with a break jaw to close and open the switch. This operation is usually accomplished from a remote point by means of an insulated hook stick which engages pull ring at the break end of the blade.

When this type of switch is opened by means of an insulated switch stick or hook stick, it is impossible to open it a short distance and close it again, since considerable effort is required to pull the blade out of the jaw. However, as is well known in the art, disconnect switches serve primarily to sectionalize electrical circuits and are not designed to open or interrupt the circuit when there is a current flowing therein.

Thus, it is essential, in order to protect the switch and circuit, that the disconnect switch be opened only under no load conditions.

However, due to the frictional engagement between the switch blade and the jaw end as a result of the dimensions and mass of the switch blade, it is relatively impossible to open the blade only a short distance. That is, since the magnitude .of effort or force required to initially separate thecooperating contacts is so great, it is impossible for the operator to only open the blade a short distance.

Hence, it is possible that due to an operators mistake or for some other reason, a disconnect switch may be completely opened under load conditions. Such faulty operation can result in total destruction of the disconnect switch and in considerable harm or even death to the, operator. That is, a relatively heavy pull is required on the hook stick ring or pull ring to disengage the blade on the jaw contact. Whereas, thereafter, a relatively light pull will move the switch to the full open position, the natural resuit, is that when the necessaryheavy pull is applied to disengage the Switchblade, the switch will immediately move rapidly to the full open position whether or not there is current flowing inits circuit.

. In disconnect switches other than hook sticks which do not require the initial heavy pull of a hook stick to separate the cooperating contacts, faulty operation of the device can be eliminated by instructing the switch operator to first open the disconnect switch by a very small amount and if an arc is drawn, to, immediately reclose the switch.

However, the main shortcoming of this scheme is that, as above noted, it is impossible, in most hook stick operated disconnect switches to separate the contacts a short distance due to the relatively large pull that is required to initially separate the cooperating contacts.

i: ll

stationary part and a spring.

Many units of the prior art have been developed to provide a safety device for opening disconnect switches that renders it impossible for the operator to fully open the switch without first observing whether or not current is flowing in a circuit.

With these prior art devices, added to the switch blade, it is automatically stopped when it is opened far enough to cause an are but not far enough to initiate an are over to ground or between phases. The operator will be able to observe the small arc and be able to reclose the switch thereby preventing an interruption of service or destruction to the switch.

Thus, with this arrangement, the possibility of drawing an are an appreciable length is eliminated and hence there will be no subsequent fault or short circuit to destroy the switch. That is, an arc with this attachment is of such short length that it is usually not sufiicient to cause a flashover to ground or cross phase.

However, the safety or inching devices of the prior art prevent the opening of the disconnect switch unload and are usually applied to the hinge end of the disconnect switch and not to the blade end as set forth in my invention.

A representative example of the type of prior art inching device applied to the hinge end is disclosed in U. S. Patent 1,933,285, issued October 31, 1933.

However, this type of arrangement has many disadvantages, for example, when the inching device is on the hinge end of the blade, it must be close to the hinge so that it the device is much shorter than the distance from the hinge to the, pull ring which is located at the blade end of the aw.

Thus, with this arrangement, the operator would be able to bend or damage the blade. By providing the inching device at the hinge end, it must be mounted so close to the pivot point that the mechanical advantage is very unfavorable.

Hence, a pull of 100 lbs. at the pull ring might result in a pull of 1,000 or 2,000 lbs. at the inching device. On the other hand, in my novel arrangement, wherein the inching device is mounted at the jaw end of the switch, a mechanical advantage of l to 1.5 is obtained so that it is much less likely to fail.

Furthermore, with the inching device positioned at the hinge end of the blade, additional manufacturing diificuities are encountered.

In order to provide proper protection for the circuit it is essential that the are drawn during the initial opening operation be a very short length. Thus the blade must stop just clear of the jaw, approximately of an inch. The blade moves only a short distance.

Since the distance from the jaw to the hinge is much greater than the distance from the inching device to the hinge, it is extremely difficult to design the device and manufacture one which will be accurate enough to stop the blade in the proper position.

My novel device is comprised of a movable part, a

This device is permanently secured to the break or jaw end of a hook stick operated disconnected switch in such a manner that the disconnect switch can be completely opened only after it has been opened by a small amount, thus permitting the operator to notice whether an arc has been drawn and if an arc is drawn to move the disconnect switch blade back to the closed position or if no arc is drawn to cornpletely open the disconnect switch.

The safety or inching device of my invention consists essentially of a base (stationary part), resilient spring and latch (movable part), which are mounted at the jaw end of the disconnect switch. The pivot pin of the pull ring or any other latch p'in extending from the switch blade engages the latch portion of the inching device when the switch is initially opened. The resilient member is rigidly secured at one end to the base and the latch member is slidably mounted on the base. When the latch is in a first position, the resilient member applies a force to the latch on one side of its pivot point to prevent its counterclockwise rotation. However, when the latch is moved to its second position, thereby changing its pivot point, the resilient member applies a force on the other side of the pivot thereby causing counterclockwise rotation thereof.

In the switch closed position, the inching device latch is engaged by the latch pin which is attached to the rotating blade of the disconnect switch. In this position, the resilient member applies a force above the pivot of the latch thereby preventing counterclockwise rotation thereof. As the switch is initially moved toward the open position, the switch blade latch pin comes into contact with the inching device latch thereby causing it to move upward due to its slidable mounting on the base of the inching device to thereby change its pivot point.

in this second step, the blade latch pin is hooked by the inching device latch and hence even though the force of the resilient member is now exerted below the pivot point of the latch, the hook engagement will prevent counterclockwise rotation thereof. While the components are held in this position, the blade is slightly separated from the jaw and hence, the operator can readily ascertain whether or not an attempt is being made to open a switch on an energized circuit. That is, if the line being interrupted is not dead, a spark or arc will exist between the blade and the jaw to indicate to the operator that the switch should not be opened. However, if no sparking or arcing exists between the blade and the jaw while the unit is held in this second position, the operator can relax the force on the hook stick which will remove the hook engagement between the inching device and the blade latch pin.

Since the latch has been moved to its second position, the resilient member will bias same in a counterclockwise direction and thus the release of the hook engagement will result in counterclockwise rotation of the inching device latch. This movement automatically removes the obstacle in the opening path movement in the switch blade and hence the operator can now pull the blade to its full open position. That is, when the operator has ascertained the correctness of the operation, it is only necessary for him to move the blade slightly in the opposite direction to permit disengagement of the inching device latch from the blade latch pin so that the operator can now move the blade to its full open position.

During the closing operation, the blade latch pin engages a second extension of the inching device latch thereby slidably moving same from its second pivot to its first pivot point. Thus, the inching device is automatically moved to its reset position on the manual reclosing of the disconnect switch to thereby render it effective as a safety device on a subsequent opening operation.

Accordingly, a primary object of my invention is to provide a novel safety device or inching device which may be secured to the break or jaw end of a hook stick operated disconnect switch to protect the circuit, the disconnect switch and the spring from faulty operation of the disconnect switch and provides a mechanical advantage so that the spring will not bend or damage the blade when it is initially stopped during the opening operation.

Still another object of my invention is to provide an inching device which will be engaged by the switch blade near the jaw end so that the construction and dies do not have to be accurate and, in addition, needs no means for adjustment in order to maintain and hold the proper spacing between the jaw and the blade.

Still another object of my invention is to provide an inching device which can be operated on the break or jaw end of a hook stick operated disconnect switch without blade dismantling or making any alterations of the disconnect switch.

A still further object of my invention is to provide a safety or inching device which will not prevent the closing of the switch blade in the event the device is moved while the switch blade is in the fully opened position.

Another object of my invention is to provide a novel inching device permanently mounted at the jaw end of a hook stick operated disconnect switch which will permit operation of the switch to appraise the operator of the line being interrupted prior to the complete opening of the switch.

A still further object of my invention is to provide a novel safety device which will prevent the manual operation of the disconnect switch from the fully closed to the fully opened position by a single operation, thereby compelling the operator to take cognizance of the condition of the line prior to moving the blade to the full open position.

A still further object of my invention is the provision of inching means at the jaw end of the blade whereby the disconnect switch can be fully opened only after a previous trial opening to ascertain whether the disconnect switch is being opened under load or not.

Still another object of my invention is the provision of means whereby a disconnect switch, during its opening operation, must first be opened by a small amount and if the operation is found to be correct can subsequently be moved to its fully opened position.

Still another object of my invention is to provide an inching device at the jaw end of a hook stick operated disconnect switch that is easily applied to standard type switches for all voltage ratings.

Another object of my invention is to provide an inching device which has only three basic components, is relatively inexpensive and due to its simplicity cannot be rendered inoperative.

These and other objects of my present invention will be apparent from the following description when taken in connection with the drawings in which:

Figure 1 is a side view of a typical hook stick operated disconnect switch to which my invention can be applied. This figure illustrates the manner in which my inching device is secured at the jaw end and shows the various components when the switch is in the completely closed position.

Figure 2 is a side view similar to Figure 1 and illustrates the position of the various parts when the switch is in the partially open position. This figure illustrates the manner in which the novel inching device permits only a small initial movement of the disconnect switch blade.

Figure 3 is a side view similar to Figures 1 and 2 and illustrates the position of the various parts following the initial opening operation. This figure illustrates the position of the novel inching device to permit the blade to be moved to its fully opened position.

Figure 4 is a perspective view of my novel inching device.

Referring now to Figure 1, the disconnect switch shown may be of any type well-known in the art. The switch illustrated is similar to that set forth in copending application Serial No. 315,619, filed October 20, 1952.

Although the disconnect switch per se forms no part of my present invention, a brief description thereof is included to facilitate the understanding and operation of my novel inching device incorporated therewith.

The insulator units 10 and 11 are mounted on the base 12 in any desirable manner. The upper end of the insulator units 10 and 11 support the

terminals

14 and 15 which are attached thereto by means of bolts 17 and 18. The

terminals members

14 and 15 are each provided with a horizontal extension 16 and 16', respectively, which have appropriate means to permit connection to the electrical line in which the disconnect switch is connected. The vertical extension 19 of the terminal connector 14 has the hinged end of the contact blades 30, 31 rotatably mounted thereon by means of pin 32. The terminal connector 15 located at the jaw. end of the disconnect switch is provided with a vertical extension 40 which forms the break tongue of the disconnect switch.

It will be noted that the disconnect switch has contact blades and 31 which straddle the tongue when the switch is in closed position as seen in Figure 1. At the jaw end of the blades an opening is provided to receive a screw-nut arrangement which serves the triple purposes of;

1. Providing a mounting and pivot for the pull ring 80;

2. Providesa force on the spring washers 110 to thereby urge the blades 30-31 against the jaw 40 when the switch is in the closed position and 3. Serves as a latch pin for cooperation with the latch 103 of the inching device, as will hereinafter be more fully described.

The inching device of my invention comprises the base unit 101, resilient member 102 and latch member 103. The base member 101 is rigidly secured by any appro priate means such as

bolts

104, 105 at the jaw end of the disconnect switch. The vertical extending member 106 of the base 100 has a vertical slot 107, as best seen in the cut away view of Figure 4. The latch member 103 is comprised of two parallel spaced sections 110 and 111 which straddle the vertical extension 106 of the base. A pin 108 rigidly secured to the parallel section 110, 111 is seated in the vertical slot 107 to thereby provide a slidable mounting of latch member 103 on base member 101. The lower portion of the parallel spaced sections 110, 111 have a protruding section 113 which may be joined together by welding, rivet or pin 114. The upper portion of the parallel member 110, 111 have an insulating hook or latch 116 secured therebetween by means of the rivets or pin 117.

When the disconnect switch is in the closed position of Figure 1 so that the blades 30-31 straddle between the break tongue 40, the blade latch pin 100 will be resting on the protruding portion 113 of the latch member 103, as seen in Figure l. The resilient member 102 is rigidly mounted at its lower end to the base 101 by means of screw 120. The upper free end of the resilient spring 102 has a V-shaped section 121 which is resiliently urged against the latch member 103. When the switch is in the closed position, the blade latch pin 100 will urge the latch member 103 to its lowermost position so that the pin 108 isat the bottom of the vertical slot 103. In

this position, the force exerted by the V-section 121 of the resilient member 102 on the latch member 103 will be above the pivot 108 thereof. Hence, the bias on the latch member 103 will be in a counterclockwise direction, but due to the protruding joined sections 113 of the spaced parallel sections 110, 111, the latch member 103 will be prevented from having counterclockwise rotation.

When the operator desires to open the switch, the end of a hook stick is inserted in the ring 80 and the switch blade 30 is moved upwardly. During this initial movement, the blade latch pin 100 will be brought into engagement with the insulating latch or hook 116 of the latch member 113. The insulation material extends a short distance beyond the metal side pieces 110-111 so as to make contact with latch pin 100 when the switch is partially open, (Figure 3). Hence, there will not be a conducting path through the inching device when the switch is partially open. Since the force exerted through the pull ring 80 will rotate the blades 30-31 around its hinge end 32, upward force will be exerted on the latch member 103. Hence, this unit will moved from its lowermost position of Figure 1 to its uppermost position of Figure 2. That is, the pin 108 will be moved from the lower end of the slot 107 to the upper end thereof. In this first disengaged position of blade 30, the movable pivot 108 of the latch member 103 will be above the V-section 121 of the resilient member 102 and hence the bias exerted on the latch member 103 will be in a counterclockwise direction. However, the latch member 103 will be prevented from moving in this clockwise direction due to the hook engagement between the latch 116 and the blade latch pin 100. Therefore, even though the operator is exerting a continuous opening force on the switch blades 30-31, the latch member 103 will present an obstacle through its continued movement and the blade 30-31 cannot be moved to its full open position. However, in the partial open position indicated in Figure 2, there is a slight separation of approximately /8 of an inch between the switch blades 39-31 and its cooperating stationary contacts comprising the break tongue 40.

If operator has attempted to open the disconnect switch on a live line, the spark or gap existing in the area will immediately appraise him of the condition of the line and hence he can now move the switch blade 30 back to the closed position of Figure 1. That is, when the blade 30 is moved to its engaged position, the blade latch pin 100 will reengage the protrusion 113 and thereby move the latch member 103 back to its initial position so that the biasing force thereon is now changed to a counterclockwise direction. However, if no spark or are exists between the blade 30 and members 40, 41 at the area 130, the operator will be insured of the fact that the switch is being opened on a dead line and hence, full opening operation of the switch will not result in a dangerous condition to either the equipment or the operator.

To remove the barrier created by the latch member 103, the operator need only move the switch blade 30 for a short distance in the opposite direction to the second disengaged position. This will remove the hook engagement between the latch 116 and the blade latch pin 100.

Since the latch member 103 is pivoted about the upper portion of the slot 107, the V-section 121 of the resilient member 102 will rotate the latch member 103 in a clockwise direction.

It will be noted that the vertical extension 106 of the base 100 is provided with a cut away portion 131 to receive the V-section 121 of the resilient: member 102 when the latch member 103 is rotated in a clockwise direction.

The upper portion 132 comprising one leg of the V 121 of the resilient member 102 is at an angle and'will limit the extreme clockwise rotation of the latch member 103 when its back surface is parallel to and in engagement with the portion 132, as seen in Figure 3. Thus, after the latch member 103 has been rotated to its extreme clockwise position, the operator may then again exert an opening force on the switch blade 30 through the pull ring 80 to thereby move it to the full opened or 3rd disengaged indicated in Figure 3.

Thus, it will be noted that this disconnect switch can be opened completely only after it has been opened by a small amount to thereby enable the operator to notice whether or not an arc has been drawn. If an arc has been drawn, the operator may then move the operating switch blade back to its engaged position. In the event no arc has been drawn, the operator may then subsequently completely open the switch to its full opened position.

When the switch blade 30 is moved from the full opened position of Figure 3 to the completely closed position of Figure 1, the sequence of operation is indicated respectively in Figures 3, 2 and 1. The components follow the reverse operation heretofore described in connection with the opening operation. That is, the switch blades 30-31 are moved towards its closed position and the engagement of the blade latch pin 100 with the protrusion 113 will initially rotate the latch member 103 against the biasing force of the resilient member 102 and also move this member from its extreme upward position of Figure 2 to its extreme lower position of Figure 1. Thus, all of the components will be reset in their initial position and the inching device wil. be efiective as a safety means for a subsequent opening operation.

It will be noted that in the event the latch member 103 is moved from the position of Figure 3 to the position of Figure l or 2 when the disconnect switch blade 30-31 are in the fully opened position that the operator can nevertheless move the blades 30--31 from the fully open position of Figure 3 to the fully closed position of Figure 1.

During the closing operation, the latch pin 100 will engage the upper portion of the insulating surface 116 and the closing force on the switch blade will cause the latch member 103 to rotate clockwise, thereby removing itself as an obstacle to the movement of the blades from the fully opened to the fully closed position. Thus, in some rate, it will be noted that I have provided a novel inching device which can be operated at the blade and at a hook stick operated disconnect switch which due to its novel construction and positioning, provides safety operation of of bending or damage to the blade when the operator exerts a large force by means of a hook stick through the pull ring to initially separate the cooperating contacts.

In the foregoing, I have described my invention only in connection with preferred embodiments thereof. Many variations and modifications of the principles of my invention within the scope of the description herein are obvious. Accordingly, I prefer to be bound not by the specific disclosure herein but only by the appending claims.

I claim:

1. In a switch having a blade, a hinge end and a jaw end; said blade rotatably mounted on said hinge end of said switch; said blade having an engaged and a first, second and third disengaged position with respect to said jaw end; a safety device comprising a base member, a resilient member and a latch member; said safety device mounted at said jaw end of said switch; said latch member slidably mounted on said base member; said resilient member secured to said base member; said resilient member biasing said latch member in a first direction when said blade is in said engaged position; said resilient member biasing said latch member in a second direction when said blade is in said first, second and third disengaged position.

2. In a switch end; said blade rotatably mounted on said hinge end of said switch; said blade having an engaged and a first, second and third disengaged position with respect to said jaw end; a safety device comprising a base member, a

the switch and still prevents the possibility having a blade, a hinge end and a jaw 7 resilient member and a latch member; said safety device mounted at said jaw end of said switch; said latch member slidably mounted on said base member; said resilient member secured to said base member; said resilient member biasing said latch member in a first direction when said blade is in said engaged position; said resilient member biasing said latch member in a second direction when said blade is in said first, second and third disengaged position; said latch member having a first pivot point when said blade is in said engaged position; said latch member having a second pivot position when said blade is in said first, second and third disengaged point.

3. In a switch having a blade, a hinge end and a jaw end; said blade rotatably mounted on said hinge end of said switch; said blade having an engaged and a first, second and third disengaged position with respect to said jaw end; a safety device comprising a base member, a resilient member and a latch member; said safety device mounted at said jaw end of said switch; said latch member slidably mounted on said base member; said resilient member secured to said base member; said latch member having a first and second position with respect to said base member; said switch blade eflective to maintain said latch member in said first position when said switch blade is in said engaged position; said switch blade effective to move said latch member to said second position when said blade is moved to said first disengaged position; said resilient member eifective to bias said latch member in a first and second direction; said resilient member rendered effective when said latch member is in said first position to bias said latch in said first direction; said resilient member ineffective to move said latch member in said second direction when said'blade is in said first disengaged position; said resilent member effective to move said latch member in said second direction when said blade is in said second and third disengaged position.

4. In a switch having a blade, a hinge end and a jaw end; said blade rotatably mounted on said hinge end of,

said switch; said blade having an engaged and a first, second and third disengaged position with respect to said jaw end; a safety device having a base member, a latch member and a resilient member; said base member rigidly secured at said jaw end of said switch; said latch member slidably mounted on said base member; said blade effective to maintain said latch member in a first position when said blade is in said engaged position; said resilient member efiective to rotate said latch member in a first direction when said blade is in said engaged position; said blade efiective to maintain said latch member in a second position when said blade is in said first disengaged position; said resilient member eflective to rotate said latch member in a first direction when said blade is in said second and third disengaged position.

References Cited in the file of this patent UNITED STATES PATENTS 1,669,125 Hartmann May 8, 1928 1,933,285 Strai Oct. 31, 1933 2,420,166 Corey et a1 May 6, 1947