US2426009A - Electric switch - Google Patents

Description

. 1947- E. J. FRANK ETAL ELECTRIC SWITCH Filed Oct. 17, 1944 2 Sheets-Sheet 1 Fig.3.

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E; J. FRANK-ETAL 2,426,009

ELECTRIC sw'ITcH Filed Oct. 17,1944 2 Sheets-Sheet 2 In vecos: Edward JFYank, Hugh F? Fitzpatrick,

f Patente Aug, l, 1947 UNITED STATE TENT OFFICE ELECTRIC SWITCH Application October 17, 1944, Serial No. 559,054

Claims.

Our invention relates to improvements in electric switches and more particularly to improvements in disconnecting switches and especially disconnecting switche for high-voltage circuits and fast opening and closing operations.

In high-voltage circuits, a large separation or break distance is required. when disconnecting switches are in the circuit open position. The use of a single moving contact in the form of a blade or arm becomes impracticable, particularly when fast separation and closing of the contacts are required. In general practice, when used in conjunction with air blast circuit breakers, the disconnecting switch closes the circuit. At 138,- 000 volts, for example, the gap between the closing contacts is bridged by an are well in ad- Vance of their engagement. Obviously, fast closing is necessary in order to minimize contact deterioration caused by such arcing. Under these high voltage conditions, the use of a single blade structure requires such pcnderous, moving, forcetransmitting masses as to be impracticable because in such a design the high operating and reactive forces are unduly concentrated at localized points of the structure. Moreover, under iced conditions of the switch, particularly at the contacts, both opening and closing become more difficult. Also, parts of the switch structure, such as ceramic insulators for example, are frequently subjected to stresses which they are not well adapted to withstand. Furthermore, such iced conditions of the switch require increased operating forces and impose additional stresses which necessitate increased structural strength and therefore cost. As far as we know, switch structures heretofore proposed to overcome these difficulties fail in one or more respects in that they lack the necessary speed in opening and closing, require excessive space to provide voltage clearance to ground or between adjacent switch poles, can be operated only with difficulty or not at all under iced conditions, and require more or less impractical and uneconomical structure.

An object of our invention is to provide an electric switch of the disconnecting type which is, in general, an improvement over switches heretofore known to the art. Another object of our invention is to provide an improved switch structure wherein fast closing and opening of the contacts is obtained by relatively small operating forces and without ponderous structure. Still another object of our invention is to provide an improved switch wherein the necessary voltage clearances to ground and between adjacent switch poles, especially in the circuit open position, are

available at minimum cost, space, and simplicity of structure. A further object of our invention is to provide an improved switch structure wherein opening and closing of the switch under iced conditions of the contacts is rendered more eifective by subjecting the ice around the contacts to stresses which the ice is least constituted to withstand. These and other objects of our invention will hereinafter appear in more detail.

In accordance with our invention, weprovide a switch structure embodying two cooperating electric current conducting members which are mounted for simultaneous turning in the same direction in the circuit opening and circuit closing operations. Also, in accordance with our invention, one of the members is relatively long to provide fast opening and closing operations, and the other member is relatively short and rigid so as to provide effective mechanical advantage for the actuating force. Again in accordance with our invention, the members are rotatable in a vertical plane, the long one upwardly and the short one downwardly upon opening the switch so as to provide economical minimum spacing with adequate voltage clearances between adjacent switch poles and to ground. Further in accordance with our invention, for effective ice breaking action, the long member preferably i transversely resilient throughout its length and the short member is substantially rigid and so arranged relatively to the resilient member as to subject ice formations in and about the engaging parts of the members to bending stresses in order more readily to disrupt the ice.

Our invention will be better understood from the following description when considered in connection with the accompanying two sheets of drawings, and its scope will be pointed out in the appended claims.

In the accompanying two sheets of drawings, Fig. 1 is an elevation of a single pole of an electric switch embodying our invention with the switch shown in the circuit closed position; Fig. 2 is an elevation to a greater scale of the switch contact mechanism shown in Fig. 1 at the beginning of a circuit opening operation under iced.

conditions of the contacts; Fig. 3 is an elevation similar to Fig. 2 showing the condition of the switch contact mechanism just prior to separation; Fig. 4 is a plan view of the switch operating mechanism shown in Fig. 1; Fig. 5 is a plan view of a modified switch operating mechanism for the switch shown in Fig. 1; Fig. 6 is a plan view of another modification of an operating mechanism for the switch shown in Fig. 1; Fig. 7

is a side elevation to an enlarged scale of a contact mechanism which is adapted for use in switches embodying our invention; and Fig. 8 is a partial cross-sectional elevation on the line 8-8 of Fig. 7.

In Fig. 1 we have illustrated an embodiment of our invention in a single pole disconnecting switch I which is shown in conjunction with a series related single pole element 2 of an air blast circuit interrupter on the left. A similar circuit interrupter element may also be mounted on the right. In accordance with our invention, the switch I comprises two cooperating rotatably mounted electric current conducting members such as switch arms 3 and d respectively relatively long and relatively short in order to obtain fast tip action in separation and engagement and suitable mechanical advantage for force application. For adequate voltage clearance between adjacent switch poles, we preferably arrange the arms 3 and 4 for rotation in a vertical plane into and out of conductive engagement with each other. For adequate voltage clearance to ground when the switch is open, we arrange both arms for counterclockwise rotation when opening, so that while the end of the long arm 3 swings upward, the end of the short arm :3 swings downward to a permissible ground level during the switch opening operation. The arms rotate in the reverse direction during the switch closing operation.

Thus, as illustrated, the hinged end of the long arm 3 is in the form of a yoke 5 which is rigidly secured to a horizontal shaft 6 rotatably mounted in a housing I. This housing is supported vertically by suitable means suchas an insulator 8 and is restrained laterally by tie bar conducting supports 9 which extend rigidly from the circuit breaker 2 and conductively engage the sides of the yoke 5 preferably in high pressure line contact in a manner well known to the art. For actuating the long am 3, the insulator 8 is rotatably mounted on a flxed support, comprising members 10 and H, and in the housing 1, and the insulator and the shaft 5 are respectively provided with bevel gears l2 and L3. The short arm 4 is also similarly mounted and actuated except that, in the event only one series related circuit breaker is used, suitable insulating means 14, carrying a terminal element i5, is provided for supporting and securing the tie bars 9.

For simultaneously rotating the arms 3 and d, we provide an operating means which, as illustrated in Figs. 1 and 4, is of the fluid-pressure operated link type. Thus, for example, each of the insulators 8 is provided with a crank it, and these cranks are interconnected by links H which are pivotally connected to the piston rod is of a suitably mounted cylinder i9 having a piston 28. Turning of the cranks IE to rotate the insulators 8 simultaneously is effected upon admission of the energizing fluid under pressure through one or the other of two pipes 2i and 22 to the back of the piston 20. For controlling the movement of the piston, suitable m ans such as a four-way valve. 23 is provided.

In the arrangement shown in Figs. 1 and i, the cranks l6 extend from their respective insulators 8 in almost opposite directions. Conse qu'ently, ,movement of the piston 25] in either direction causes the insulators 8 to rotate simultaneouslyin opposite directions. Therefore, in order to have, the arms 3 and i rotate in the same direction so that their tips mutually recede from or approach one another, the positions of the gears E3 on the shafts E5 of the arms 3 and 5 are reversed relatively to the respectively cooperating gears 12 on the insulators 8. A similar result can be obtained by having the cranks It substantially parallel and each pair of gears 3 arranged alike, as shown in Fig. 5. The speed of separation and engagement of the ends of the arms 3 and I. can be increased by so arranging the mechanism that the angular movement of the arm 3 is greater than the angular movement of the arm This, as will be apparent to those skilled in the art, can be accomplished by having the tooth ratio between the gears i2 and it; associated with the arm 3 smaller than the tooth ratio between the gears l2 and i3 associated with the arm ll. This also provides greater mechanical advantage for turn-- ing the arm l. Instead of having different gear ratios, it will be apparent to those skilled in the art that the disproportionate turning effect can be obtained by having the gear ratios the same and making the crank 55 associated with the insulator 3 for moving the arm t longer than the crank it associated with the insulator 8 for moving the arm 3. This also provides a greater mechanical advantage for moving t e arm In accordance with our invention, the switch arms 3 and i and their cooperating engaging portions or tips are so constructed and arranged that, when these arms are rotated the same direction, one of them is flexed during circuit closing engagement and circuit opening disengagement with the other arm. The purpose of this is to submit any ice around the tip portions 2 and 25 of the arms 3 and '1 respectively to stresses, such as bending, which ice is least able to withstand. Thus, for example, the long arm 3 is relatively resilient, preferably throughout its length, and the short arm 4 is substantially rigid. Also, as shown more clearly in Figs. 1, 2 and 3, the contact tip 25 of the short arm is provided with a guiding face 2% a contact face 2'? and a stop portion 20 and the longer arm 3 is provided with a contact face 29. The slopes of the faces 25 and 2'? on the contact tip 25 and the lengths of the arms 3 and i are such that, during the switch closing movement as the extreme corner of the contact face it on the arm 3 engages and moves downward across the guiding face 26 of the arm 6, the arm 3 i flexed or bowed downward until the extreme or lower corner of the contact face 29 jumps by the es ge 33 between the faces 26 and 27. The arm movement substantially ceases as the end of the arm 3 engages the stop portion 23 on the arm A with the contact surfaces 2? and 29 in engagement as shown in Fig. 1. To insure the desired contact pressure, the sum of effective lengths of the arms 3 and 4 is slightly greater than the distance between their pivotal axes so that the arm 3 is bowed downward slightly in the final switch closed position.

Assuming the switch closed, as shown in Fig. 1, with the contacting tips of the arms 3 and 4 incased in ice, as indicated, then to open the switch, the valve 23 is turned degrees to admit fluid under pressure through the pipe 22 into the cylinder l9 back of the piston 20. At the same time, the pipe 2! is connected to atmosphere for exhausting the fluid of the cylinder [9 in front of the piston 20. As the insulators 3 start toturn, the arms 3 and 4 because of the ice incasement are virtually one piece. Because of the relative flexibility in the long arm 3, the rigid arm 4 preponderates to move the coated contact region downward. Consequently, the initial movement a e-aces of the insulators places the arms in the condition shown in Fig. 2 with the arm 3 generally bowed upward but having a reversed curvature near its end. This distortion puts the ice under increasing bending stresses which initiate cracks radiating in general from the edge 39 of the contact tip 25 thereby fracturing the ice seal. The long arm 3 is now sufiiicently free of the ice to snap momentarily into the bowed configuration shown in Fig. 3. Upon continued movement of the in sulators 8, the arm 3 is bowed upward until the end of this arm passes by the edge 39 on the contact tip 25. The arm 3 then straightens and the ooacting tips move apart at high speed, since further movement of the arms 3 and t to the open position indicated by the dash-dot lines in Fig. 1 is unimpeded. From the foregoing, it will be apparent that the arrangement of the arms 3 and 4 and their cooperating free ends or tips is such as to cause the end of the long arm 3 during the opening operation initially to move with or translationally in the same direction as the end of the short arm 4 and to move in the opposite translational direction subsequently to the opening operation of the arms 3 and t.

Instead of rotating both arms 3 and l simultaneousl during engagement and disengagement, one alone may be rotated prior to their joint rotation. Thus, for example, in the arrangement shown in Fig. 6, the power or rigid arm i is first rotated sufiiciently, for example, to effect the ice breaking action and then both arms are simultaneously rotated to produce the desired air gap separation. For this type of rotation, as shown in Fig. 6, there are provided for the arms 3 and 4 individual fluid pressure actuating means such as cylinders 38 and 32 respectively provided with pistons 33 and 3 and piston rods 35 and 36. These are respectively connected by links 31 and 38 to the cranks E6 of the left and right insulators 8. For the opening operation, the operating fluid is admitted to the cylinder 32 in back of the piston 3 3 through valve 23 and pipe 39 and thence through a part as in the cylinder 32 and a pipe 4! to the cylinder 3i, but only after the port 40 in the cylinder 32 is opened by the movement of the piston 35 from right to left. In this alternative arrangement, flexibility in the long arm is not essential if provision is made to permit a slight initial freedom of downward rotational movement for the arm 3 by such means as, for example, allowing some clearance between the right hand face of the piston 33 and its end stop in the cylinder 3 l. Thus, during this initial travel of the piston 34, no opposing rotation of the arm 3 occurs and the long arm 3 briefly remains inert while the short power arm 4 is exerting the initial ice breaking bending movement, following which both arms are quickly rotated away from each other. Upon turning the valve 23 90 degrees, fluid under pressure will be admitted to both cylinders 3i and 3'2 simultaneously through pipes 32 and d3 quickly to swing the arms 3 and 4 toward each other to complete the final closing engagement of the contacts that provides the desired contact pressure.

Instead of the abutting type of contacts shown in Figs. 1 to 6, inclusive, a blade and jaw contact may be used. Thus, as shown in Figs. 7 and 8, the arm 3 is provided with a blade contact t4 and the arm 4 with a jaw contact comprising contact fingers 45 mounted in a bifurcated housing 46 secured to the arm 4. The fingers 45 are pivoted at 41 in the housing 45 and biased toward each other by suitable means such as springs 48. The number of fingers in each side of the housing will be varied in accordance with the current to be transmitted, but in generala plurality of fingers in each side of the housing is preferable to one single finger of greater width in order to obtain better conductivity. In this modification of our invention, if the arm 3 is made suitably resilient, sufficient ice breaking spring energy is accumulated therein due to the deformation of the arm 3 during the opening and closing operation to effect fracture of the ice at the contacts.

While we have shown and described our invention in considerable detail, we do not desire to be limited to the exact arrangements shown, but seek to cover in the appended claims all those modifications that fall within the true spirit and scope of our invention.

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

1. An electric switch comprising two insulat- "3g supports respectively mounted for rotation about spaced vertical axes, relatively long and short cooperating electric current conducting members respectively mounted on said supports for rotation in a vertical plane, the long member being transversely relatively resilient and the short member being substantially rigid, and means including said supports for rotating said members in the same direction into and out of conducting engagement with each other.

2. An electric switch comprising relatively long and short cooperating electric current conducting members respectively mounted for rotation in a vertical plane, the long member being transversely relatively resilient and the short member being substantially rigid, the eifective lengths of said members and the shapes of the ends thereof being such that when the members are rotated in the same direction, the long member is flexed during circuit closing engagement and circuit opening disengagement with the short member, and means for rotating both of said members in one direction to close the switch and in the opposite direction to open the switch.

3. An electric switch comprising relatively long and short cooperating rotatably mounted electric current conducting members, the long member being transversely relatively resilient and the short member being substantially rigid, the effective lengths of said members and the shapes of the engaging portions thereof being such that when the members are simultaneously rotated in the same direction the long member is flexed during circuit closing engagement and circuit opening disengagement with the short member, and means for simultaneously rotating both of said members in one direction to close the switch and in the opposite direction to open the switch.

4. An electric switch comprising two cooperating rotatably mounted electric current conducting members, one of said members being transversely relatively resilient substantially throughout its length and the other of said members being substantially rigid and the shapes of the engaging portions of said members being such that when the members are simultaneously rotated in the same direction the resilient member is flexed during circuit opening disengagement with the other member, and means for simultaneously rotating both of said members in one direction to open the switch.

5. An electric switch comprising two cooperating rotatably mounted electric current conducting members, one of said members being transversely relatively resilient substantially throughout its length anditheother of said members being substantially rigid and the shapes of the engaging portions of said members-being such that when the members are simultaneously rotated in the same direction the resilient memberisifiexed during circuit closing engagement with the other member, and means for simultaneously rotating both. of said members in one direction to olosezthe switch. '.1

6. An electric switch comprising two cooperating rotatably mounted electric current conduct ing members, one of said-members being transversely relatively resilient substantially throughout its length and the other of said members being substantially rigid and the shapesof the engaging portions'of said members being such that when the members are simultaneously rotated in the-same directionthe resilient member/is fiexed during circuit closing engagement .:and circuit opening disengagement with the' other member, and means for simultaneously rotating both of said members in one direction to close thetswitch and in the opposite direction to open the switch.

'7. An electric switch comprising two spaced insulating supports respectively mounted for rotation about substantially vertical axes, a relatively long, transversely relatively resilient electric current conducting member mounted on one of said supports for rotation in a vertical plane, a cooperating relatively short, substantially rigid electric currentconducting member (mounted. on the other of said supports :for rotation in avertical plane, the effective lengths of said members and the shapes of the free ends" thereof being such that when the members are simultaneously rotated in the same direction the longer member is flexed during circuit closing engagement and disengagement with the shorter member, and means including said supports for simultaneously rotating both of said members insone direction to close the switch and in the opposite direction to open the switch.

8. An electric switch comprising two respectively relatively flexible and relatively rigid cooperating conducting members, means supporting saidsmembers for rotation intoand out of conducting engagement with each' other, means for turning both of said members in one rotational direction toward conducting engagementand in the-opposite rotational direction away fromconducting engagement, and means interengaging said members inthe circuit closed. position of the switch for causing during the-opening operation of the switch the end of said relatively flexible member initially to move in the same translational direction as the. end of said relatively rigid member and to move in the opposite translational direct from the relatively rigid member subsequently to the release of the interengaging means during the opening operation of the switch.

'9. An electric switch comprising relatively long and'short electric current conducting members, the long member being relatively flexible in coinparison with the short member, means supporting said members for rotation in a substantially vertical plane into and out of conducting engagement with each other, means for turning both of said members in one rotational direction into conducting engagement and in the opposite rotational direction out of conducting engagement, and means interengaging the ends of said members in the circuit closed position of the switch for causing the end of the long member during the opening operation initially to move in the same translational direction as the end of the short member and to move in the opposite translational direction subsequently to the release of the interengaging means during the opening operation of the'switch.

, 10.- Anelectric switch comprising a relatively long and flexible electric current conducting member, a cooperating relatively short and rigid current conducting member, means supporting said members for rotation in a substantially vertical plane into and out of conducting engagement with each'other, means for turning both of said members-in one rotational direction into conducting engagement with each other and in the opposite rotational direction out of conducting engagement, the eiiective lengths of said members and the shapes of the free ends thereof being such that during the opening operation the end of the long member first moves translationally with the end of the short member and then moves in the opposite translational direction subsequently to the opening operation of the members.

EDWARD J. FRANK. HUGH P. FITZPATRICK.

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

UNITED PATENTS Number Name Date 1,731,065 Steinmayer Oct. 8, 1929 1,906,505 Alsaker May 2, 1933 1,913,106 Christensen June 6, 1933 2,006,866 Lemmon et a1 July 2, 1935 1,897,537 Prager Dec. 2'7, 1932

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