US3824359A

US3824359A - Vacuum loadbreak switch

Info

Publication number: US3824359A
Application number: US00295527A
Authority: US
Inventors: K Date
Original assignee: McGraw Edison Co
Current assignee: Cooper Industries LLC
Priority date: 1972-10-06
Filing date: 1972-10-06
Publication date: 1974-07-16
Anticipated expiration: 1991-07-16
Also published as: CA996163A

Abstract

A loadbreak switch is provided in which a pair of spaced apart main current carrying blades are pivotally mounted for movement into and out of engagement with a stationary terminal, and a vacuum interrupter assembly has a nested position between the two blades and is also pivotable into and out of engagement with the stationary terminal. The main blade assembly and the vacuum interrupter assembly are both operable in response to a main switch operating mechanism. The vacuum interrupter assembly includes a vacuum switch and an operating device which is responsive to disengaging movement of the main blade assembly from the stationary terminal to first open the contacts of the vacuum switch and then unlatch the vacuum interrupter assembly from the stationary terminal. Subsequent to unlatching of the vacuum interrupter assembly, spring means snaps the vacuum interrupter assembly away from the stationary terminal and into the nested position of the vacuum interrupter assembly between the main blades. The main blades and the vacuum interrupter assembly are also pivotable into engagement with the stationary terminal as a single unit in response to the main switch operating mechanism.

Description

Date

VACUUM LOADB REAK SWITCH [75] inventor: Kazou H. Date, Milwaukee, Wis. [73] Assignee: McGraw-Edison Company, Elgin,

Ill.

[22] Filed: Oct. 6, 1972 [21] Appl. No.: 295,527

[52] US. Cl 200/146 R, 200/144 B [51] Int. Cl. H01h 33/12, H01h 33/66 [58] Field of Search 200/144 B, 144 [56] References Cited UNITED STATES PATENTS 2,344,113 3/1944 Schultz 200/146 R 2,480,622 8/1949 Warnock 200/146 R 2,883,493 4/1959 Stoelting 200/146 R 3,042,766 7/1962 Ross 200/146 R 3,077,526 2/1963 Owens 200/146 R 3,243,538 3/1966 Rodeseike 200/146 R 3,671,696 6/1972 Brunner 200/144 B Primary ExaminerRobert S. Macon Attorney, Agent, or Firm-Jon Carl Gealow; Roger J. Falkowski 1 [11-1 3,824,359 [451 July 16, 1974 ABSTRACT ally mounted for movement into and out of engagement with a stationary terminal, and a vacuum interrupter assembly has a nested position between the two blades and is also pivotable into and out of engagement with the stationary terminal. The main blade assembly and the vacuum interrupter assembly are both operable in response to a main switch operating mechanism. The vacuum interrupter assembly includes a vacuum switch and an operating device which is responsive to disengaging movement of the main blade assembly from the stationary terminal to first open the contacts of the vacuum switch and then unlatch the vacuum interrupter assembly from the stationary terminal. Subsequent to unlatching of the vacuum interrupter assembly, spring means snaps the vacuum interrupterassembly away from the stationary terminal and into the nested position of the vacuum interrupter assembly between the main blades. The main blades and the vacuum interrupter assembly are also pivotable into engagement with the stationary terminal as a single unit in response to the main switch operating mechanism.

7 Claims, 5 Drawing Figures fi -142 2?; 1116 P -4 F140 go o) L 52 PATENTED JUL 1 61974 SHEU 1 (IF 5 l VACUUM LOADBREAK SWITCH BACKGROUND OF THE INVENTION Loadbreak switches are well known in the art and have been used in the past for purposes such as switching transformers, capacitors, opening feeders, and for sectionalizing. In these loadbreak switches, arcing and subsequent deterioration of the stationary contacts and the switch blade have been a continuous problem. More recently, vacuum switches have been utilized for interrupting the current in conjunction with a switch blade which is used to carry the continuous current but not to interrupt the current. In these type of loadbreak switches, an operating mechanism is required which provides an operating sequence of opening the switch blade while maintaining the vacuum switch closed and then opening the vacuum switch to interrupt the current. These type of switch operating mechanisms are somewhat complicated and, of course, add to the overall price of the loadbreak switch. Also, using both a continuous current carrying switch blade and a vacuum switch results in a relatively large, space consuming loadbreak switch, particularly where a three phase switch is used.

An object of the invention is to provide a vacuum loadbreak switch having a continuous current carrying switch blade means and a vacuum switch for interrupting current which provides a positive switch blade opening and vacuum switch interrupting operational sequence and which has a very compact arrangement. A further object is to provide a vacuum loadbreak switch in which the vacuum switch contacts are opened to interrupt the current and the vacuum switch is moved to a disengaged position with a stationary contact to thereby insure circuit is interrupted and to indicate open gap position.

SUMMARY OF THE INVENTION The objects-of the invention are accomplished by providing a loadbreak switch having a continuous current carrying main blade assembly and a vacuum switch assembly which opens in response to the main blade assembly subsequent to the latter. Thus, the main blade assembly does not interrupt the current and the current is interrupted by the vacuum switch assembly upon its opening. The vacuum switch opens to interrupt the current in response to opening of the main blade assembly after it reaches a predetermined disengaged position relative to the stationary contact. Continued opening movement of the main blade assembly causes the vacuum interruption to quench the arc and the switch assembly to also disengage from the stationary contact and move to its nested position between the two blades of the main assembly.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a front view of the vacuum loadbreak switch shown in a closed position;

FIG. 2 is a side view of the switch in a closed position;

FIG. 3 is a view similarto that of FIG. 2 with the switch means shown midway between its fully closed and fully open positions and the vacuum switch contacts closed;

FIG. 4 is a view similar to FIGS. 2 and 3 with the switch means having moved a further distance towards its open position and with the contacts of the vacuum switch in an open condition; and

FIG. 5 shows the switch means in a fully open position with the vacuum switch disengaged from the stationary contact.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring generally to the drawings, a vacuum loadbreak switch is shown as having switch means 2 and a switch operator 4 both supported on support means 6.

The support means 6 includes

insulators

8 and 10 on which the switch means 2 is mounted. Electrically

conductive terminals

12 and 14 are mounted on the ends of

insulators

8 and 10 and also comprise part of the support means 6. The

terminals

12 and 14 are connected to electrical cables (not shown) comprising part of an electrical power system. The switch means 2 is pivotally mounted on the terminal 14 and includes

links

16 and 18 attached to the switch operator 4 to permit pivotal movement of the switch means 2 by the switch operator 4.

With reference to FIG. 1, the switch operator 4 includes a rotatable blade shaft means 20, a rotatable operator shaft 22, a handle 24 and a spring operating mechanism 26. The rotatable blade shaft means 20 is connected to the

links

16 and 18, and when rotated in either a clockwise or counterclockwise direction about its longitudinal axis, pivots the switch means 2 between open and closed conditions as will be described hereinafter in greater detail. As shown in FIG. 2, an arm 28 is-affixed to the rotatable blade shaft means 20 and functions to transmit rotative motion from the shaft means 20 to the

links

16 and 18 and thus to the entire switch means 2. The spring operating mechanism 26 and the rotatable operator shaft 22 are both mounted on the support means 6 and the handle 24 is rigidly pinned to the rotatable'operator shaft 22. The spring operating mechanism 26 includes latch means 30 and a spring 32 which is connected between the blade shaft means 20 andthe operator shaft 22. The spring 32 is charged by rotation of the handle 24 in either a clockwise or counterclockwise direction and, at a predetermined point in the rotation of the handle 24, the latch means 30 is released to permit the spring'to provide a snap action opening or closing pivoting movement to the spring means 2.

The switch operator 4 is described in greater detail in co-pending application Pat. No. 3,790,731, issued Feb. 5, 1974, and assigned to the assignee of the instant invention.

The switch means 2 includes a main blade assembly 40 and a vacuum switch assembly 60. The main blade assembly 40 comprises two parallel, spaced apart

conductive blades

42 and 44, a pivoted end 46 and an end 48 whichis movable between engaged and disengaged positions with the terminal 12. The main blade assembly 40 also includes a pin 50 which holds the end 48 at a spaced position permitting positive contact engagement with the terminal 12 and a cross member 52 which acts as a stop to position the vacuum switch assembly in its position between the

blades

42 and 44 as shown in FIGS. 1 and 2.

As shown in FIG. 1, the vacuum switch assembly 60 includes electrically

insulative side members

52 and 64 pivotally supported on the

conductive blades

42 and 44 by pin 66. The

side members

62 and 64 are held spaced from the

conductive blades

42 and 44 by spacers 68 ing from the vacuum interrupter 82 and rigidly at-,

tached to the cross member 72, and movable contact means 92 having a stem 94 extending from the vacuum interrupter 82 and rigidly attached to the stem extension 84. The spring 86 functions to maintain the fixed and movable contact means 90 and 92 toward engagement with each other. Suitable bolts and nuts are utilized for attaching the various components of the vacuum switch means 80 together and will not be described in detail. Also, the vacuum interrupter 82 is of a type well known in the art and the extent to which it is shown is only that necessary to describe it in conjunction with the instant invention. I

The vacuum switch means 80 also includes a vacuum switch operating means 100 having an actuating mem- 4 2, the rotatable blade shaft and the arm 28 are in what may be considered their closed position in which the main blade assembly and the vacuum switch assembly are in engagement with the terminal 12. In the closed or engaged position of the switch means 2, the load current will be carried by the

conductive blades

42 and 44 and substantially no current will be carried by the vacuum switch assembly 60. In this position of the switch means 2, the fixed and movable contact means and 92 in the vacuum interrupter are closed due to the boasing force of spring 86 and the pin means 104 is in engagement with the ends 121 of lost

motion slots

116 and 118 to hold the double cam means 110 out of engagement with the cam rollers 112 and 114.In FIG. 3, the rotatable blade shaft means 20 has pivoted toward its open position and out of engageber 102 comprising a pin 104 mounted on

arms

106 and 108 respectively rigidly affixed to

conductive blades

42 and 44. The vacuum switch operating means further includes a double cam means 110 pivotally mounted on the

side members

62 and 64, cam rollers 112 and 114 rotatably mounted on stem extension 84 and

double links

116 and 118 pivotally mounted on the double cam means 110 and connected to the pin means 104 through lost motion slots'120 in the

links

116 and 118. The lost motion slots 120 include ends 121. Note that only the lost motion slot 120 of link 118 can be seen in the Figures, however, the other lost motion slot 120 in link 116 is identical to slot 120 in link 118 and connects the link 118 to the pin means .104. A pair of

torsion springs

122 and 124 are positioned coaxially with the pin 66 adjacent the

insulative side members

62 and 64 and have extending fingers 126 and 128 respectively hooked on the

side members

62 and 64 and extending fingers 130 and 132 each hooked on the pin 134 connecting the

conductive blades

42 and 44 adjacent the pivotable end of the main blade assembly 40. The torsion springs 122 and 124 function to bias the vacuum switch assembly 60 pivotally about the pin 66 and away from the terminal 12 as shown in FIGS. 3 and 4.

As shown in FIG. 2, the vacuum switch assembly 60 .also includes latch means comprising a support member 142 mounted on the terminal 12, a latch finger I44 pivotably mounted on the support member 142, a latch surface 146 comprising an edge of the cross member 72 and a latch spring 148 biasing the latch finger 144 toward engagement with the latch surface 146. As

. can be seen in FIGS. 1 and 2, when the switch means 2 is in its engaged position with the terminal 12, the latch spring 148 maintains the latch finger 144 in engagement with the latch surface 146 so that the vacuum switch assembly 60 has its nested position substantially between the

conductive blades

42 and 44 of the main blade assembly 40.

The operation of the vacuum loadbreak switch may be'best described with reference to FIGS. 2 5. In FIG.

ment with the terminal 12. In this position of the main blade assembly 40, the vacuum switch assembly 60 has started downward movement due to its attachment to main blade assembly 40 at pin 66. This movement,

however, is not yet sufficient to disengage the latch sur- I face 146 from the latch finger 144 and permit the torsion springs 122 and 124 to rotate the entire vacuum switch assembly 60 toward the main blade assembly 40. Also as shown in FIG. 3, the pin means 104 has moved along lost motion slots 120, but the pin means 104 has not yet engaged the ends 121 of the lost motion slots 120. Consequently, the double cam means 110 is in engagement with the cam rollers 112 and 114 but is not yet applying sufficient pressure to the cam rollers 112 and 114 to move the movable contact means 92 against the biasing force of spring 86 and away from the fixed contact means 90. The switch means 2 is now in a momentary condition in which all of the load current has transferred from blade assembly 40 to the vacuum switch'assembly 60. Therefore, the blade assembly 40 is not required to interrupt the current.

In FIG. 4, the rotatable blade shaft 20 and arm 28 have rotated further toward their open position so that the main blade assembly 40 is further away from the terminal 12. The vacuum switch assembly 60 also has I moved further downward relative'to the views of FIGS.

2 5 and is at a position just prior to disengagement of the latch surface 146 from the latch finger 144. Further, the pin means 104 has engaged the ends 121 of the lost motion slots 120 and moved the slots 120 downward and thereby moved the double cam means 1 110 into engagement with the cam rollers 112 and 114. The view of FIG. 4 shows that the double cam means 110 has rotated sufficiently toward the high point of its cam surface to move the movable contact means 92 away from the fixed contact means 90 so that the contact means 90 and 92 of the vacuum interrupter means 82 have interrupted the current formerly fiowing between the

terminals

12 and 14. The vacuum interrupter means 82 has thus performed its intended function in the overall load break switching operation so that the entire vacuum switch assembly 60 is ready to be moved to its open position between the

conductive blades

42 and 44 of the main blade assembly 40. In FIG. 5, the vacuum switch assembly 60 has been moved sufficiently downward and away from the latch means 140 by the continuous pivoting movement of the main blade assembly 40 to result in the disengagement of the latch surface 146 from the latch finger 144.

Upon disengagement of the latch surface 146 from the latch finger 144, the torsion springs 122 and 124 snap the vacuum switch assembly 60 downward into a position between

blades

42 and 44 identical to the position which the two assemblies had relative to each other when in the closed condition shown in FIG. 2. When the vacuum switch assembly 60 moves to this nested position, the lost

motion links

116 and 118 are moved toward the pin means 104 so that the pin means 104 is disengaged from the ends 121 of slots 120. As a result, the cam rollers 112 and 114 are freed to rotate the double cam means 110 to the low part of its can surface and permit the movable contact means 92 to return to engagement with the fixed contact means 90 under the force of the spring 86.

The return of the switch means 2 to its engaged position with the terminal 12 is accomplished by rotation of the blade shaft means and arm 28 in a clockwise direction relative to the view of FIGS. 2 5. As previously discussed, this rotation of the blade shaft means 20 and closing of the switch means 2 is provided by the switch operator 4 when the handle 24 is rotated in a clockwise direction. It may be noted that when the switch means 2 closes, the main blade assembly 40 and the vacuum switch assembly 60 move as a single unit into engagement with terminal 12/ This closing sequence is advantageous when inadvertently closed in on fault, thus, preventing interrupter assembly 60 from becoming extensively damaged.

It may thus ben seen that a vacuum load break switch has been provided which can carry a high continuous load current while still utilizing a relatively small vacuum switch for interruption purposes. Because of the physical positioning of the vacuum switch assembly between the load current carrying switch blades, a' very compact vacuum loadbreak switch has been provided. Also, the vacuum loadbreak switch provides positive sequential operation of main current carrying blade opening, temporary transfer of current to the vacuum switch, interruption of the current only by the vacuum switch, and seapration of the entire vacuum switch assembly from the stationary contact. Also, closing sequence will assure more positive closing of a switch when inadvertently closed in on a fault and preventing extensive damage to a switch or to the operating personnel.

While only a single embodiment of the invention has been shown herein, it will be realized that many modifications thereof are feasible without departing from the spirit and scope of the invention, It is accordingly intended that the scope of the invention is not to be limited to the specific embodiment disclosed.

lv claim:

1. In a load break switch including support means having first and second spaced apart insulative support members, first and second electrically conductive terminals respectively affixed to one end of said insulative support members, and a switch operator mounted on said support means, the combination comprising:

an electrically conductive switch blade including a first end having an engaged and a disengaged position with the first conductive terminal and a second end pivotally mounted on the second conductive terminal, said switch blade being pivotable in response to the switch operator about said second end between the engaged and disengaged positions of the first end with the first conductive terminal;

a vacuum switch electrically connected to said first and second conductive terminals and electrically connected in parallel with the switch blade, said vacuum switch having an open and a closed condition;

said vacuum switch having an engaged and disengaged position with the first conductive terminal;

latch means for holding the vacuum switch in said engaged position with the first conductive terminal,

a vacuum switch operator means connected to the vacuum switch and the switch blade and being responsive to movement of the switch blade to move the vacuum switch from said closed to said open condition, and resilient means for moving the vacuum switch from said engaged to the disengaged position subsequent to disengagement of the vacuum switch from the latch means responsive to further movement of the switch blade means.

2. The combination according to claim 1 wherein:

normal current flow between the first and second conductive terminals is through the switch blade means when the latter is in its engaged position with the first conductive terminal;

current flow between the first and second conductive terminals is through the vacuum switch when the switch blade means is in its disengaged position with the first conductive terminal and the vacuum switch contacts are in their closed position; and

, said switch blade means has a first intermediate position spaced from the first conductive terminal, said intermediate position occurring during movement of the switch blade means from its engaged to its disengaged position with the first conductive terminal; and

said vacuum switch operator is responsive to the switch blade means to open the vacuum switch contacts when the switch blade means is in said first intermediate position.

3. The combination according to claim 2 wherein:

said switch blade means has a second intermediate position spaced a greater distance from the first conductive terminal than the first intermediate position during movement of the switch blade means from its engaged to its disengagedposition with the first conductive-terminal;

' said vacuum switch means is pivotable between engaged and disengaged positions with the first conductive terminal; and further comprising latch means engaging the first end of the vacuum switch means for holding the vacuum switch means in its engaged position with the first conductive terminal; and

said vacuum switch operator is responsive to the switch blade means to disengage the vacuum switch means from the latch means when the switch blade means is in said second intermediate position.

. 4. The combination according to claim 1 wherein:

said switch blade means has spaced apart substantially parallel blade members; and

said switch blade means and vacuum switch means have at least one position in which the vacuum switch means is located between said spaced apart substantially parallel blade members.

7 8 5. The combination according to claim 1 wherein said lost motion link for moving the roller and movsaid vacuum switch operator means is responsive to the able contact means in said opening direction in revacuum switch during movement of the latter to its dissponse to movement of said lost motion link, reengaged position to move the vacuum switch to its sponsive to movement of said member with the closed condition. Switchblade.

6. The combination according to claim 1 wherein: 7. The combination according to claim 1 wherein: said vacuum switch has a stationary contact and movsaid switch blade has first and second sequentially ocable contact means movable in opening and closing curring movement portions while pivoting from directions relative to said stationary contact; and said engaged to said disengaged positions; and said vacuum switch operator means comprises: 10 said lost motion means is inoperative during the first a lost motion means having a roller mounted on the movement portion of the switch blade and operamovable contact means; a lost motion link contive during the second movement portion of the nected to and movable with the member mounted switch blade to move the vacuum switch to its open I on the switch blade; and condition. cam means engaging said roller and connected to

Claims

1. In a load break switch including support means having first and second spaced apart insulative support members, first and second electrically conductive terminals respectively affixed to one end of said insulative support members, and a switch operator mounted on said support means, the combination comprising: an electrically conductive switch blade including a first end having an engaged and a disengaged position with the first conductive terminal and a second end pivotally mounted on the second conductive terminal, said switch blade being pivotable in response to the switch operator about said second end between the engaged and disengaged positions of the first end with the first conductive terminal; a vacuum switch electrically connected to said first and second conductive terminals and electrically connected in parallel with the switch blade, said vacuum switch having an open and a closed condition; said vacuum switch having an engaged and disengaged position with the first conductive terminal; latch means for holding the vacuum switch in said engaged position with the first conductive terminal, a vacuum switch operator means connected to the vacuum switch and the switch blade and being responsive to movement of the switch blade to move the vacuum switch from said closed to said open condition, and resilient means for moving the vacuum switch from said engaged to the disengaged position subsequent to disengagement of the vacuum switch from the latch means responsive to further movement of the switch blade means.

2. The combination according to claim 1 wherein: normal current flow between the first and second conductive terminals is through the switch blade means when the latter is in its engaged position with the first conductive terminal; current flow between the first and second conductive terminals is through the vacuum switch when the switch blade means is in its disengaged position with the first conductive terminal and the vacuum switch contacts are in their closed position; and said switch blade means has a first intermediate position spaced from the first conductive terminal, said intermediate position occurring during movement of the swItch blade means from its engaged to its disengaged position with the first conductive terminal; and said vacuum switch operator is responsive to the switch blade means to open the vacuum switch contacts when the switch blade means is in said first intermediate position.

3. The combination according to claim 2 wherein: said switch blade means has a second intermediate position spaced a greater distance from the first conductive terminal than the first intermediate position during movement of the switch blade means from its engaged to its disengaged position with the first conductive terminal; said vacuum switch means is pivotable between engaged and disengaged positions with the first conductive terminal; and further comprising latch means engaging the first end of the vacuum switch means for holding the vacuum switch means in its engaged position with the first conductive terminal; and said vacuum switch operator is responsive to the switch blade means to disengage the vacuum switch means from the latch means when the switch blade means is in said second intermediate position.

4. The combination according to claim 1 wherein: said switch blade means has spaced apart substantially parallel blade members; and said switch blade means and vacuum switch means have at least one position in which the vacuum switch means is located between said spaced apart substantially parallel blade members.

5. The combination according to claim 1 wherein said vacuum switch operator means is responsive to the vacuum switch during movement of the latter to its disengaged position to move the vacuum switch to its closed condition.

6. The combination according to claim 1 wherein: said vacuum switch has a stationary contact and movable contact means movable in opening and closing directions relative to said stationary contact; and said vacuum switch operator means comprises: a lost motion means having a roller mounted on the movable contact means; a lost motion link connected to and movable with the member mounted on the switch blade; and cam means engaging said roller and connected to said lost motion link for moving the roller and movable contact means in said opening direction in response to movement of said lost motion link, responsive to movement of said member with the switch blade.

7. The combination according to claim 1 wherein: said switch blade has first and second sequentially occurring movement portions while pivoting from said engaged to said disengaged positions; and said lost motion means is inoperative during the first movement portion of the switch blade and operative during the second movement portion of the switch blade to move the vacuum switch to its open condition.