US2810806A - High voltage switch - Google Patents

Description

Oct. 22, 1957 L. c. HART HIGH VOLTAGE swrrcn 7 Sheets-Sheet 1 IN V EN TOR.

Oct. "22, 1957 1. c. HART HIGH VOLTAGE SWITCH '7 Sheets-Sheet 2 Filed Oct. 26, 1953 m m m [m C H016 BY WW,WWM7V c. HART men VOLTAGE snrrcn 7 Sheets-Sheet 3 Filed Oct; 26. 1953 Z 6 jVVENTOR. m, nub,

Oct. 22, 1957 L. c. HART HIGH VOLTAGE swncn Filed Oct. 25. 1953 Y'Sheets-Sheet 4 INVENTORQ [T 1392 C 71/140, (MW, z d y Oct. 22, 1957 Filed 001;. 26, 1953 L. c. HART 2,81

HIGH VOLTAGE smcn' '7 Sheets-Sheet 5 Oct. 22, 1957 1.. c. HART 2,810,806

HIGH VOLTAGE swmcn Filed Oct. 26, 1955 V '1 Sheets-Sheet a Oct. 22, 1957 1.. c. HART 2,810,806

HIGH VOLTAGE SWITCH Filed 001;. 26. 1953 7 Sheets-Sheet 7 INVENTOR.

United States Patent HIGH VOLTAGE SWITCH Lester C. Hart, Cleveland, Ohio, assignor, by mesne assignments, to Joslyn Mfg. and Supply Co., Chicago, 111., a corporation of Illinois Application October 26, 1953, Serial No. 388,322

24 Claims. (Cl. 200-146) This invention relates to high voltage switches, and, more particularly, to high voltage switches of the type employed in power distribution circuits which, in addition to operating as disconnecting or isolating switches for certain sections of the distribution circuit, are also capable of interrupting substantial currents in the form of line charging currents, transformer magnetizing currents, energy loads and the like. Where voltages of the order of 69 kv. and above are involved, the interruption of line charging currents will be the principal application of the present invention. Where lower voltages obtain, the present invention will be used principally to interrupt power load currents. Specifically, the present invention is an improvement on Hart Patent No. 2,601,138, granted June 17, 1952, and assigned to the same assignee as the present application.

High voltage switches have been extensively employed, particularly in connection with outdoor switching stations for isolating sections of transmission lines and the like under certain conditions. Such high voltage switches are generally air break switches, which are commonly crankoperated through a manual crank mechanism or the like to isolate desired sections of the transmission line and to insert other sections. Heretofore, air break switches have been generally provided with arcing horns for interrupting transformer magnetizing currents and the like, and, in these switches, the circuit interrupting ability is dependent upon the elongation in air of the circuit interrupting arc.

The lengths of the arcs formed by opening these high tension switches in which substantial currents are to be interrupted are such as to make it difi icult, if not economically impossible, to provide sufiicient phase spacing between the units making up a polyphase switch to prevent the arcs occurring upon opening the switch from being blown together by wind, thereby short-circuiting the connected circuit. Moreover, the problem has become more acute in recent years with the increase in line charging currents, and such air break switches which have heretofore been extensively used are no longer satisfactory for interrupting such line charging currents.

It would be desirable to provide a high voltage air break switch capable of satisfactorily interrupting such line charging currents under all conditions, while still conforming in general to the configuration of the well-known high voltage air break switch so extensively employed for these purposes heretofore. In the above-mentioned Hart patent, there is disclosed an air break switch capable of interrupting line charging currents under all conditions. This switch employs an arc extinguishing unit including a contact rod which is freely propelled within an are extinguishing chamber to interrupt the circuit therein upon opening of the switch. The present invention is particularly concerned with providing improvements in the switch shown in the above-mentioned Hart patent, while incorporating some of the basic principles thereof.

Accordingly, it is an object of the present invention to provide a new and improved high voltage air break switch.

It is another object of the present invention to provide a new and improved high voltage air break switch capable of interrupting line charging currents under substantially all operating conditions.

It is another object of the present invention to provide a new and improved high voltage air break switch having improved means for transferring the current to an arc interrupting unit during the switch opening operation.

A further object of the present invention resides in the provision of a novel means for controlling the operation of the are interrupting unit in accordance with the position and movement of the high voltage switch.

Further objects and advantages of the present invention will become apparent as the following description proceeds, and the features of novelty which characterize the invention will be pointed out with particularity in the claims annexed to and forming a part of this specification.

For a better understanding of the present invention, reference may be had to the accompanying drawings in which:

Fig. 1 is a side elevational view of an air break switch incorporating the present invention with the switch shown in the closed position;

Fig. 2 is an end elevational View of the switch shown in Fig. 1;

Fig. 3 is an enlarged view of a portion of the switch of the present invention viewed from the top and looking generally in the direction of the arrows 3-3 of Fig. 1;

Fig. 4 is an enlarged fragmentary front elevational view of a portion of the switch shown in Fig. 2 looking in the direction of the arrows 44 and showing in dotted lines certain parts under certain operating conditions;

Fig. 5 is an enlarged view, partly in section, of a por tion of Fig. 2 looking in the direction of the arrows 5-5, with the switch in the closed position shown in Figs. 1 and 2;

Fig. 6 is a view similar to Fig. 5 but showing the parts in the position which they assume while the switch is in the open position;

Fig. 7 is an enlarged sectional view taken on line 7--7 of Fig. 3;

Fig. 8 is an enlarged sectional view taken on line 8-8 of Fig. 3;

Fig. 9 is a sectional view taken along line 99 of Fig. 7, assuming the entire apparatus to be shown therein;

Fig. 10 is a fragmentary sectional view taken along line 1010 of Fig. 7, assuming that Fig. 7 is a complete illustration;

Fig. 11 is a partial view of Fig. 7 illustrating the position of the parts immediately following a latch tripping operation when-the movable interrupting contact is in flight between its open circuit and closed circuit positions;

Fig. 12 is a view similar to Fig. 11 with certain parts cut away illustrating the relative position of the parts following an interruption of the arc with the interrupting rod in its latched open position; and

Fig. 13 is a view similar to Fig. 11 showing the parts in the positions which they assume during a circuit closing operation, while the movable interrupting rod is moving to the position which it assumes when the air break switch is closed.

High voltage air break switches are generally employed for multipole operation, although, obviously, they might equally well be employed for single pole operation. To simplify the drawings, only a single pole air break switch is illustrated. It will be understood that the present invention is applicable either to single pole or multipole switches, and in the case of multipole switches the mecha- 3. nism would be identical except that the operating mechanism would include interconnecting links between the separate phase units to insure simultaneous operation of all poles of the multipo'le switch.

Briefly, the present invention is concerned with an air break switch consisting ofthe conventional movable switch arm capable of isolating two adjacent ends of an electric circuit by a substantial distance to prevent arcing thereacross. Incorporated in the air break switch of the present invention is a novel circuit interrupting mechanism whichis incorporated in a manner so as in no way to interfere with the operation of the isolating switch. If desired, a resistor may be connected across the arc interrupting chamber. This resistor maybe connected continuously or may be in series with a calibrated gap so that it is rendered eifective when the voltage across the arc interrupting chamber is high enough tocause the calibrated gap to breakdown. Such a resistor will drain the charge left on theline when the circuit is interrupted before thesource of generated voltage increases at the opposite polarity during the next half cycle.

Referring now to the drawings, there" is illustrated a high voltage switch embodying the present invention. This, switch 20 is in many-respects similar to the high voltage switch disclosed in Hart Patent No. 1,829,349, granted October 27, 1931, and assigned tothe same assignee as the present application; The high voltage switch 20 embodying the present invention includes a stationary terminal or contact structure 22 which is provided with a terminal portion 24 electrically connected to anotherswitch terminal 26 by means of a movable switch arm assembly indicated generally at 28. The details of construction ofthe switch arm assembly and the mechanism for causing movement thereof form-nopa-rt of the present invention, but are disclosed in the above-mentioned Hart Patent No. 1,829,349. Generally, the assembly 28 inoludes a suitable insulating support in the form of a fixed insulator 30 mounted on a suitable frame or base member 32: The fixed insulator 30* supports a casting 34 on its upper end, which casting is connected to a movement controlling unit 36, including a pair of movable links 38 and 40. The details of the movement controlling unit 36 are similar to the arrangement of the above-mentioned Hart Patent No. 1,829,349, and provides the necessary movement for the switch arm assembly, as isdescribed in greater detail hereinafter. The casting 34 also-pivot ally supports'a switch arm 42' formed of a copper tube, one end being swaged down to a smaller diameter" indicated as portion 44. In accordance with'the disclosure of the above-mentioned Hart Patent No. 1,829,349, the I switch arm 42, during a circuit opening operation, is first moved in a direction along the longitudinal axis thereof and then pivots, so that, during the latter part of the opening operation, the portion 44 swings in an arc. During the circuit closing operation, the reverse movement occurs with movement along the longitudinal-axis of the'tubular switch arm occurring just prior to. complete closing of the circuit.

In order to actuate the movable switch arm assembly 28 and to cause the movementof the switch arm 42 referred to above, there is provided a rotatable insulator 48 which is rotatably mounted onthe-frame or base member 32. This rotatable insulator 48 isprovided with a pair of crank arms 46 adapted to be connected by suitable rods or the like with an operating mechanism such as a-hand operating lever or the like. To connect the rotatable insulator 48 with the mechanism in the movement controllingunit 36, there is provided a bearing assembly 50 through whichi'a drive with aplurality of gears contained within the unit 36 is. accomplished, and in this manner rotary movement of'the insulator 48. is converted to satisfactory-movement of the links 38 and 40, and eventually to the movement of the switch arm 42 in the'manner described above.

When the switch arm assembly 28 is in the position shown. in Figl of the drawings, movement of the link 38, as well as the link 40, displaces the assembly 28 to the left, as viewed in Fig. 1, so as to cause movement along the longitudinal axis of the switch arm 42, and thereafter continued movement of the link 38 causes pivotal movement of the switch arm 42 about a pivot point adjacent the upper end of insulator 30 in a counterclockwise direction as viewed inPig. l of the drawings, there by to move the switch arm 42 relative to the stationary or fixed contact assembly 22 with the resulting electrical disconnection of the terminals 24* and 26. When it is desired to close the switch 20, rotation of the movable insulator 48 pivots the switch arm 42 about the pivot point mentioned above in a clockwise direction, as viewed in Fig. l of the drawings, until such time as the stationary contact assembly is engaged, and thereafter produces rectilinear movement of the switch arm 42 along the longitudinal axis thereof toward the right, as viewed in Fig. 1 of the drawings.

For the purpose of supporting, the stationary contact assembly 22, there is also provided a fixed insulator 52 mounted on the frame or base member 32. The stationary contact assembly 22 includes a sleet hood 54 mounted upona housing 56, which housing contains suitable control mechanism, described in detail hereinafter and forming an important part of the present invention. The stationary contact assembly 22 further includes suitable contact means for engaging with the switch arm 42. As best shown in Fig. 5 of the drawings, there are disposed within the sleet hood 54 spaced contact elements or fingers 58 for making electrical contact with a switch blade 60, which is an extension of the switch arm 42 and comprises a part of a contact blade and arcing horn assembly 62, which assembly is secured to the particular end of the movable switch arm 42 which describes the maximum movement during a switch operation. The movable contact fingers 58 are electrically connected through the housing 56, which is formed of conducting material with the terminal element 24 whereby, when the switchblade 60 is in contact with the contact fingers 58, an electrical circuit is completed between the terminals 24 and 26,- which are each provided with suitable means for'connecting the same to an external electrical circuit.

The arrangement described thus far has been conventional in high voltage switches of the type shown in the above-mentioned Hart Patent No. 1,829,349. However, without. more, the only way line charging currents can be extinguished with the switch' described above is to depend. on drawing a sufiiciently long arc in' air to. extinguish the same. For reasons mentioned. above, this is unsatisfactory, and, in;accordance with the present invention, means are provided to interrupt high line charging and similar currents, which means comprises an arc extinguishing structure 64 mounted on the housing 56, which housing 56 contains certain operating mechanism for controlling the arc extinguishing structure which will readilybecome apparent as the following description proceeds. Essentially, the arc extinguishing structure 64 and associated mechanism includes means for freely propelling an arc contact rod 65 within an arc extinguishingtube or thelike to interrupt such line charging currents which have. been transferred to the arc extinguishing structure. Thus, there is provided an auxiliary circuit which might be termed aparallel branch circuit through thearc extinguishing structure 64 only-when it is desired to interrupt the current flowing through the high voltage switch 20. Normally, this parallel branch circuit does not conduct any current, but is rendered elfective only during the interrupting operation. The movable arc interrupting contact rod 65 is normally disposedwithin an are confining tube or structure 67 which extends between the housing 56 and a latching control unit 66 (Figs. 4 and 7 of the drawings),.which is 'mounted on the upper end of the arcconfiningtube 67. The freely propelled interrupting rod contact 65, which is normally disposed within the enclosure, or tube 67, is propelled upwardly during an arc extinguishing operation in the manner disclosed in Hart Patent No. 2,601,138, and is moved into an upper or top tube 68 which extends upwardly from the control unit 66. The upper end of this top tube 68 is closed by a suitable gradient shield or top tube plug 69. The movable rod contact or interrupting element 65 is received and held within the top tube 68 during a circuit interrupting operation of the high voltage switch 20.

The are interrupting structure 64 further includes means for actuating the latch control unit 66 when the switch arm 42 reaches a predetermined position during both the opening and closing stroke thereof. To this end the control unit 66 is provided with a pivotally mounted trip rod 70 which is disposed outside the control unit 66, best shown in Figs. 1 and 4 of the drawings, which trip rod is capable of operating suitable mechanism contained within the control unit 66. In order that certain control functions can be produced when the switch arm 42 is approaching its fully closed position, there is also included a latch rod '71, which extends between the housings 56 and 66, to perform certain control functions during operation of the high voltage switch 20. This latch rod 71 is preferably contained within an insulating tube 72.

In accordance with the present invention, the freely propelled rod contact or are interrupting element 65, disposed within the arc tube 67, requires latching or similar means for holding it in this position. Likewise, means are also required to maintain the arc interrupting element 65 within the top tube 68 to make sure that the circuit is not reclosed until the desired point during the circuit closing operation. As in the above-mentioned Hart Patent No. 2,601,138, suitable energy storage means, specifically illustrated as a compression spring 73 (Figs. 5 and 6 of the drawings), are provided in which energy is stored during the closing operation of the high voltage switch, and which energy can be appropriately released to propel the interrupting element 65 from its position within arc tube 6'7 to an upper position within top tube 68. As will become apparent from the foilowing description, the closing movement of the switch arm 42, in addition to charging the energy storage means 73, also actuates the latch rod 71 extending between the housings 56 and 66, which rod 71 actuates suitable latching means also described hereinafter, whereby the interrupting element or contact rod 65 is latched against vertical movement.

Before considering the structural details of the are interrupting mechanism, consideration will first be given to the circuit arrangement which connects the arc contact rod 65 in parallel or, in any event, renders it effective during a circuit interrupting operation. As was mentioned above, there is provided a contact blade and arcing horn assembly 62, best shown in Figs. 1 and 3 of the drawings. This contact blade and arcing horn assembly 62 includes a blade holder 82. which is suitably clamped to the tubular portion 4- of the switch arm 40 and which has secured thereto the switch blade 66, as is clearly apparent from Fig. 3 of the drawings. Extending laterally from the blade holder 82 is a horn support 74, which is preferably integrally formed with the blade holder 82. Actually, the blade holder and horn support may be a unitary casting or the like formed of good conducting material. To the free end of the horn support 74 is secured a contact horn 75 as by means of suitable bolts or similar fastening means 76. As illustrated, when the high voltage switch is in the closed position, as shown in Fig. l, the switch arm 42 is in the horizontal position, and the horn support 74 is perpendicular thereto and also in a horizontal position. The contact born '75, on the other hand, is perpendicular to the horn support 74 or, in other words, parallel with the switch arm 42 and, in the closed position of the switch, is also in the horizontal position.

For the purpose of actuating the trip rod 70, there is also secured to the horn support 74 a U-shaped trip born 78. This U -shaped trip horn is secured to the horn support 74 as by suitable fastening means 77 and is disposed so that during the opening and closing operation of the high voltage switch, the trip horn 78 will engage the trip rod 7) in a manner described hereinafter.

For making electrical contact with the contact horn 75 so as to complete the aforementioned circuit through the rod contact 65, there is provided a horn bracket 79 secured to the latch control unit 66. From the outer end of the horn bracket 79 depends an arcing horn 80 disposed in a generally vertical direction, as illustrated in the drawings, and having at the upper end thereof a diverging guide portion 80a. During opening and closing movement of the high voltage switch, it will be apparent that the contact horn 75 will be in electrical contact with the arcing horn 8d. The guide portion 80a, during the closing movement of the high voltage switch, wili guide the contact horn 75 into proper contacting engagement with the arcing horn 89.

From the above description it will be apparent that there is provided an electrical path from the switch blade 42 through the horn support 74, the contact horn 75, the arcing born 86 engaging therewith, and horn bracket 79 to the latch control unit 66. Since the rodlike interrupting contact 65 extends between the latch control unit 66 and the housing 56, it will readily be apparent that there is an electrical circuit provided through this parallel path after the switch blade 66 no longer makes contact with the associated circuit such as the contact fingers 58. It will, furthermore, be apparent that during the opening movement of the switch arm 42, when a predetermined opening operation has occurred, the trip horn 78 will engage the trip rod 74 to actuate certain trip and latching means releasing the rod contact 65 and subsequently latching this contact rod 65 in the open circuit position. Such engagement of the trip horn 78 and the trip rod 76 will occur while contact horn 75 and arcing horn 80 are still in electrical engagement thereby also to complete the circuit through trip horn 78 and trip rod 70. Subsequently, and while the trip horn 78 and the trip rod 70 are still in electrical engagement, the contact horn 75 and the arcing horn 8i) disengage so that all current flow to the top of rod contact 65 is through members 70 and 73. The members '76 and 78 disengage with a snap action at approximately the same instant as the rod contact 65 is released for movement into top tube 68. The quick snap movement of trip rod 70 very quickly introduces an air gap in the circuit and there may be momentary arcing until the extinguishment within the arc tube 67. Then there is an air gap in existence relieving all voltage stress across the interrupting mechanism. The are drawn within the arc tube 67 is rapidly extinguished.

An important part of the present invention resides in mechanism for storing energy in the energy storage means 73 and converting this stored energy to kinetic energy of movement of the interrupting element or contact rod 65 thereby freely propelling it from its position shown in Fig. 5 of the drawings to its position within top tube 68. Before describing in detail the mechanism within the housing 56, a brief description will first be included of the arc extinguishing structure 64 which includes the movable arc contact rod 65. As illustrated, the are extinguishing structure includes the tube 67, which, since it is exposed to atmosphere, must be made exteriorly of a suitable Weather resistant material. Preferably, it is formed of Bakelite or the like. For the purpose of defining a satisfactory arc extinguishing structure, however, the tube 67 is provided with an inner liner 88 formed of a suitable gas evolving material such a horn fibre. It Will be appreciated that such gas evolving insulating material is capable of evolving an 'arc extinguishing gas when subjected to the heat of an arc. Actually, the opening in the liner 8% is only slightly larger than the diameter of the arc interrupting contact rod 65, so that the arc gas evolved therein is confined within a relatively small chamber rapidly to extinguish any are drawn be- 1 moses tween the rodcontact 65 and the current conducting structure within the chamber 56 described hereinafter.

For the purpose of securing the arc tube 67 to the structure comprising the housings 56 and 66, the lower end of the tube 67 is preferably threaded and received within an internally threaded boss or collar 90, which is rigidly secured to the frame or housing 56. The upper end of the arc tube 67 is likewise threaded, as indicated at- 91 in Figs. 5 and 6 of the drawings, for reception in a similar collar associated with the latch control unit 66 described hereinafter.

To normally support the movable arc interrupting contact rod 65 and to propel the same in response to release of the energy stored in the energy storage means 73, there is provided within the housing 56 a throw lever 92 having a sort of pocket portion 91 at the free end thereof upon which the lower end of. the interrupting contact rod 65 rests. The throw lever 92 is pivotally mounted. within the housing 56 by means of a suitable pivot pin 94. In Fig. 5 of the drawings, the throw lever 92 is shown in the closed position of the switch, while in Fig. 6 of the drawings the throw lever 92 is shown in the open position of the switch. In this latter position the cup-shaped portion 91 of the throw lever 92-engages a suitable bushing 93 extending. within the housing 56 and defining a stop or upper limit of movement of the throw lever 92. This bushing 93 is provided with a suitable opening for re mounted roller 110 which is disposed for engagement with the end of the switch blade 60. With this arrangement, movement of the reset crank 101 in response to movement of the switch arm 42 can be obtained.

ceiving the movable contact rod 65, and, in effect, this opening is a continuation of the bore within the lower arc tube 67.

For the purpose of connecting the energy storage means 73 with the throw lever 92 in a manner to permit the energy stored in energy storage means 73 to be transferred to kinetic energy of the throw lever 92 when the latter is free to move, the throw lever 92 is provided with a sort of extension 96 defining a sort of bellcrank, which extension 96 is connected by means of an ejector spring rod 100 with a sort of pistonlike member 98 disposed in a cylindrical housing 102 confining the energy storage means 73. As illustrated, the energy storage means 73 is a compression spring compressible between one end wall of the cylinder 102 and the pistonlike member 98 connected to the ejector spring rod 100. The cylindrical housing or cylinder 102 is rigidly secured to the housing 56, and one end of the cylindrical housing 102 is closed by suitable plug 104. As illustrated in Figs. 5 and 6 of the drawings, it is readily apparent that the energy stored in the compression spring 73 tends, when released, to move the piston like member 98 tothe right, as viewed in Figs. 5 and 6 of the drawings, thereby to pivot the throw lever 92 about pivot point 94 in a counterclockwise direction from the position shown in Fig. 5 to the position shown in Fig. 6 of the drawings. Compression spring 73 will be chosen so that suflicient energy may be stored therein to move the arc contact rod 65 with the desired speed to interrupt the circuit Within arc tube 67'.

It would be desirable to charge the energy storage means 73 during. the final closing operation of the switch blade 42, and to this end there is provided a reset crank 101 pivotally mounted at 103 within housing 56; A suitable spring 105 normally biases the reset crank 101 to the position shown in Fig. 6 of the drawings. This spring 105 is secured at one end to the frame 56, while the other end of the spring is secured to a lug 106 defined on the reset crank 101. To limit the maximum counterclockwise movement of the reset crank 101, as illustrated in. Fig. 6 of the drawings, the spring 105 biases the reset crank 101 against a suitable stop- 107 adjustably disposed within the housing 56 whereby any desired setting of the stop 107 may be accomplished. The stop 107 is engageable with a suitable cam follower roller 108 rotatably mounted between the bifurcated ends 109' of the reset. crank 101.. The end. of the reset crank 101 remote.

from the roller 108 is provided with another rotatably To fully understand how the reset crank 101 is operated in response to movement of the switch arm 42, brief considerationwill now be given to closing movement of the switch arm 42-. As was mentioned above, during. the initial closing operation of the high voltage switch 20, the switch arm 42 pivots about a point adjacent the upper end of the fixed insulator 30. At the end of this pivotal movement of the switch arm 44, the blade portion 60 engages what is. commonly termed the anvil or a portion disposed above the housing 56. The position of the free end of the blade 60, when the pivotal movement stops, is represented by the dashed line A in Fig. 5 of the drawings. The dashed line B in Figs. 5 and 6- of the drawings represents the position when the blade 60 engages the roller 110, or (in other words, the limiting.

will cause rectilinear movement of the blade portion 60- in a direction from the dashed line A toward the dashed line B, and continued closing of the switch arm 42 will cause the blade 60 to move from position A to position B, where it will engage the roller 110. For guiding the blade, suitable tapered guide portions 111, shown in Fig. 3 of the drawings, are provided. These are engaged by the blade 60 while moving from position A to position B- It will be apparent that movement of the switch blade 60 to the right after reaching position B will result in pivotal movement of the reset crank 101 in a clockwise direction, as viewed in Fig. 6 of the drawings, with the stressing of return spring 105. The reset crank 101 is so designed that the roller 108 engages the throw lever 92, whereby continued clockwise movement of the reset crank 101 will cause clockwise rotation of the throw lever 92 about pivot 94 from the position shown in Fig. 6 to the position shown in Fig. 5 of the drawings. Such move ment of the throw lever 92, by virtue of its connection with the energy storage means 73 described above, will also cause storing of energy in the compression spring 73'. By dashed lines in Fig. 5 of the drawings, there is indicated the position C, which is the end of movement of the blade 60 and which,

hence, determines the maximum clockwise rotation of the reset crank 101 and the throw lever 92, as viewed in Fig. 5 of the drawings. There is also illustrated in Fig. 5 a position D, which is reached before the end of the closing movement of the switch blade 60 and which indicates the position of the parts when the interrupting rod contact has moved sufiiciently to permit latching of the trip means within the latch control mechanism 66 described in greater detail hereinafter. Let us assume for the moment that the interrupting contact rod 65 is latched in the position shown in Fig. 5 of the drawings so that, if the switch arm 42 were moved to the open position, throw lever 92 would be held in the position shown in Fig. 5 of the drawings. Under these conditions, as the switch blade 60 moves from position C toward position A, the reset crank 101 would follow it by virtue of the spring 105, so that, when the contact blade 60 reached position B, the reset arm 101 would be in the position shown in Fig. 6 of the drawings against the stop 107 ready to be engaged by the blade 60 during the subsequent closing operation.

To reset suitable latching means described in detail hereinafter disposed within latch control unit 66 to latch the interrupting rod 65 in a position within interrupting tube 67, there is included within the housing 56 suitable mechanism for operating latch rod 71 described above disposed within insulating tube 72. The latch rod 71 is preferably formed of Bakelite or other suitable insulating material so as not to provide any electrical path between housing 56 and latch control unit 66 except through interrupting contact rod 65. For the purpose of securing the tube 72 in position, the lower end thereof is preferably received within an internally threaded boss 112 which is rigidly secured to the frame 56 in a manner so that the bore within the tube 72 is in alignment with an aperture "ll i defined in the upper part of the housing A. flange 116 secured to latch rod 71 engageable with the bottom of the upper wall of housing 56 defines with the housing 66 a suitable stop for the mechanism for controlling the latch rod 71. The lower end of the latch rod 72 is provided with a shouldered collar 118 on which one end of a suitable compression spring 120 rests, which compression spring is concentrically arranged with respect to the latch rod 71. The other end of the compression spring 129 is received within a shouldered opening 322 defined in a pull lever 124 pivotally mounted in the housing 56 by means of a pivot pin 125. The pull lever 124 is provided at its free end with a lateral projection 124a which is engageable by the roller 168 of the reset crank 1'81 following a predetermined closing movement of the switch arm 42 to pivot pull lever 124 about pivot point 125, thereby to perform a suitable control operation described below.

it will be understood from the ensuing description of the latch control unit 66 that during a circuit closing operation one of the last things that should occur is the operation of certain trip means to latch the movable contact rod 65 in its lowermost position. Such latching operation should not occur until one of the final steps in the circuit closing operation. In order that this may be accomplished by the pull lever 124 subsequent to complete closing of the switch 20, there is provided a time delay mechanism associated with the latch rod 71, indicated generally by the reference numeral 126. This time delay mechanism effectively is a dashpot device which prevents latch rod 71 from being moved immediately to its most downward position, even though pull lever 124- is actuated to the position shown in Fig. 5 of the drawings. Actually, the collar 118 and the spring 12% already described form a part of the time delay device 126 which further includes a dashpot mechanism in the form of a cylinder 134 having a piston 132 mounted therein with a suitable connecting rod 130 extending outside of the cylinder 134 and having secured thereto a cup-shaped collar member 128. The piston 134 is suitably supported within housing 56. A compression spring 133 is interposed between the cup-shaped collar 128 and a flange 136 secured to the cylinder 134. It will be apparent that the springs 120 and 138 have energy stored therein when the pull lever 124 is pivoted in a counterclockwise direction about pivot 125, as viewed in Fig. 5 of the drawing, or, in other words, when moving from the position of Fig. 6 to the position of Fig. 5 of the drawings. The dashpot mechanism prevents the connecting rod 136 from moving except with a time delay in a downward direction, and, hence, rod 71, which rests on the upper end of the collar 128, likewise cannot move downwardly, so that, during such downward movement of the pull lever 124, energy is stored in compression springs 120 and 133. This energy is converted to movement of the piston 132 and to downward movement of the latch rod 71 after a predetermined delay. It will be understood by those skilled in the art that with the simple dashpot mechanism described, the latch rod 71 will be moved downwardly with a time delay after the pull lever 124 is moved to the position shown in Fig. 5 in response to closing movement of the switch blade 66.

From the above description it will be apparent that there has been provided an arc interrupting unit 64 with energy storage means for propelling an arc contact within an arc extinguishing structure to draw an arc, and to interrupt such are within such are extinguishing struc ture. A mechanism is also provided whereby the energy storage means is recharged and the mechanism is reset in response to closing moving of the switch. When the switch blade 64? is moved to the open position, both the reset crank 161 and the pull lever 124 are permitted to move from the position of Fig. 5 to the position of Fig. 6. The compression spring means and 133 will move the latch rod 71 upwardly, but it will be understood from the following discussion that such upward movement of the latch rod 71 performs no control function, but merely conditions apparatus in tne latch control unit 66 for operation in response to the next closure of the high voltage switch 26. Moreover, it will be apparent that, as the switch blade 60 is moved to the open position, both reset crank 161 and pull lever 124 move to the position shown in Pig. 6 of the drawings in response to the bias produced by the springs 105, 126 and 138, respectively, whereby energy storage means 73 when the energy stored therein is released only need move the pull lever 92 to move interrupting contact rod 65 whereby all the energy stored in compression spring 73 is available to move rod contact 65 thereby insuring high speed operation thereof.

Thus far, no consideration has been given to the latch control unit 66 except to describe the trip rod 70 extending therefrom in the path of movement of the trip horn 73. This trip rod 76 is normaliy in the intermediate position shown in solid lines in Fig. 4 of the drawings. Upon opening movement of the switch 20, the trip horn 7%, upon a predetermined opening movement, will engage the trip rod 76 and move it to the position 70a, indicated in dotted lines in Fig. 4, against a rodlike stop 14% extending from the latch control unit 66, as best shown in Fig. 8 of the drawings. During the closing movement or" the high voltage switch 26, the trip horn 78 will engage the trip rod 70, which is normally in the solid line position of Fig. 4, and move it downwardly to the dotted line position 7% against a limiting stop 141 also projecting from the latch control unit 66. The trip rod 7b is preferably secured to a trip rod shaft 142 pivotally supported from a trip rod shaft bracket 143 forming a part of the latch control unit 66. A suitable bolt or et screw 14-4 secures the trip rod 70 to the portion of the trip rod shaft M2 which extends out of the housing of the latch control unit 66.

The latch control unit 66, shown in detail in Figs. 7 to 13, inclusive, is jointly controlled by movement of the switch blade 60 relative to the stationary contact structure 22 through the intermediary of the latch rod '71 and by actuation of the trip rod 70 through engagement therewith by the trip horn 78 during both the opening and closing movements of the high voltage switch 20. Essentially, the latch control unit 66 includes two latching means. The first of these is for latching the arc rod contact 65 in the lowermost position shown in Figs. 5 and 7 of the drawings to prevent vertical upward movement thereof until a predetermined point during the opening movement of the high voltage switch 20, at which point the switch blade 66 is no longer in electrical engagement with the contact fingers 58 and the electrical circuit has been transferred to the interrupting path including rod contact 65. The second of these latching means is to latch the rod contact 65 in a position within top tube 68 for subsequent release during a switch closing operation when trip horn 78 again actuates trip rod 76.

Considering now the latch control unit 66 and the first of these latching means, reference should be had to Figs. '7 to 13, inclusive, of the drawings. The unit 66 includes the base plate or frame 148 which is provided with an internally threaded collar or boss 149 for receiving the upper threaded end of the arc tube 67. This plate or frame 148 also includes a recess to receive the upper end of the tube 72 including the insulated latch rod 71. Eifectively, therefore, latch control unit 66 is supported on tubes 67 and 72, but primarily on tube 67. The main atlases 11 frame 148 for the latch control unit 66 is, of course, provided with openings in alignment with. the openings in tubes 67 and 72.

For the purpose of guiding the freely movable rod contact 65' in its movement from lower tube 67 to top tube 68 through latch control unit 66, there is included in the latch control unit 66 vertically extending guide means 150 having defined therein a passageway 151 in alignment with the bores in tubes 67 and 68 and the interrupting contact 65. The upper extremity of the guide member 150 is provided with an internally threaded bore 152. within which is received a bushing 153 extending outside of a cover member 154 for the latch control unit 66. The bushing 153 is internally threaded to receive the top tube 68 into which the interrupting contact 65 is propelled during an interrupting operation. it will be understood that the frame member 148, the trip shaft bracket 143, and the cover 154 define the housing for the latch control unit 66.

Considering the latch control unit 66 first with respect to holding the rod contact 65 within the arc tube 67 during the initial stages of a circuit interrupting operation, the most important element for this purpose comprises a trip lever 158 pivotally mounted within the housing of latch control unit 66 to bosses 156a on the guide member 1511 by means of a pair of oppositely positioned shoulder studs 159. Actually, trip lever 158 might be termed a latch, since this trip lever 158 has numerous extensions and projections to perform its tripping and latching functions and also to be actuated toward its latched position during the closing operation of the high voltage switch 20. As illustrated, the trip lever 158 comprises a main portion of somewhat U-shaped configuration comprising the two legs 158a and 1581) of the U, each of which contains an opening for the shoulder studs 159.

The bight portion 158a of the trip lever 158 is capable of being disposed over the movable interrupting rod 65 to latch the latter in the position 'shown in Fig. 7 of the drawings.

In order that trip lever 158 may be actuated to move latching portion 1580 thereof out of its latching position with respect to interrupting contact rod 65 during a circuit opening operation of high voltage switch 20, the trip lever is provided with an extension 158d having an integral projecting arm 160 disposed in the path of means actuated by trip rod 78 when moved from the solid line position to the position 70a as shown in Fig. 4 of the drawings. To accomplish this, trip shaft 142 has connected thereto within the housing of latch control unit 66 a trip shaft lug 161 having a trip arm 162 engageable with arm 160. With this arrangement, movement of the trip arm 70, from the solid line position shown in Fig. 4 to the position 70a during an opening operation of the high voltage switch 20, will cause similar movement of trip arm 162 with the resultant engagement of the projecting arm 160 of the latch 158, to move the latch 158 from the position shown in Fig. 7 of the drawings to the position shown in Figs. 11, 12 and 13 of the drawings. As viewed in Fig. 7 of the drawings, it may be noted that there is a space between the latching portion 1580 of the trip lever 158 and the upper end of rod contact 65. This is because the switch blade 60 during the final closing movement has moved from the position D (Fig. of the drawings), where the rod contact 65 is in the position which is assumes when in latching engagement with the latching portion 1580 of the trip lever 153 and a position C where the contact rod 65 is moved somewhat below this latching position. Normally, then, during the closed position of high voltage switch there is a gap, as is evident in Fig. 7, between the upper end of the contact rod 65 and the latching portion 1580 of the trip lever 153, and efiectively, therefore, there is a gap in this circuit through rod contact 65. It will be appreciated, however,

that. as. soon as an. opening operation of the. switch blade.

60 is initiated and the blade 66 moves from the position C (Fig. 5 of the drawings) to position D and beyond, the throw lever 92' will move upwardly so that the energy stored in compression spring 73 will move the rod contact 65 against the latching portion 1580 of the trip lever 158, thereby insuring a good electrical circuit in parallel with the switch blade portion 66 through the contact horn 75 and the arcing horn described above. Whenever the latching portion 158c of the trip lever 158 is moved out of the position shown in Fig. 7 to the position of Figs. 11, 1'2 and i3, and the switch blade 66 is moved out of the way during a circuit opening operation so that the energy stored in spring 73 is free to be converted to kinetic energy of the movable rod contact 65, this rod contact 65- will be freely propelled into the upper tube 63.

Trip lever 158 further includes a resetting lug 153a operable by the latch rod 71, as described hereinafter, to reset the trip lever 158 during a circuit closing operation. Trip lever 158 also includes a spring lug 158 a stop projection 158g, and another spring lug 15811.

For the purpose of maintaining the trip lever 158 in either its latched position relative to rod contact 65 shown in Fig. 7 of the drawings, or its unlatched position shown in Figs. 11, 12 and 13 of the drawings, a suitable overcenter spring assembly is provided. This overcenter springassembly includes a coiled compression spring 166 having one end secured by a pin 167 to a lug 168 secured to the frame 148, while the other end is secured by a pin 169 to the spring lug 158 on trip lever 153. A suitable spring guide 170 encloses and guides the overcenter spring 166. Thisovercenter spring assembly 165 tends to bias the trip lever 158 into either one of two positions, i. e., the latching position shown in Fig. 7 of the drawings, or the nonlatching position shown in Figs 11, 12 and 13 of the drawings.

If the contact rod 65 were projected into top tube 68 during an arc. interrupting operation, it is obvious that gravity would cause it to fall back almost immediately so as again to rest on the pocket portion 91 of throw arm 92. It would be desirable to maintain rod contact 65 within. top tube 68 and release it during a circuit closing operation to close the circuit within arc tube 67 before the main contacts of the. high voltage switch 26 are closed. In accordance with the present invention, means are provided to maintain the rod contact 65 in its upper position in top tube 68 once it has been propelled into this position until a predetermined point in the closing movement of the switch arm 42 occurs. To this end there is provided a very light latch member which can be moved out of the way by the rod 65 when it moves to its upper position, or, in other words, which will not interfere with movement of the rod 65 to its uppermost position. This light latch, designated as 172 in the drawings, is pivotally mounted to a latch crank 174, which latter in turn is pivotally mounted on trip lever 158 by means of suitable shoulder studs 175. The latch 172 is a sort of L-shaped member including a pair of integral lugs 172a which are pivotally supported by the shouldered studs 175, which likewise support the latch crank 174 on the trip lever 158, as is clearly shown in Fig. 10 of the drawings.

The latch crank 174 is a somewhat U-shaped member comprising two legs of the U, 174a and 174b, intercon nected by a crosspiece 1740, The shouldered studs 175 extend through these legs 174a and 17 1b. in order that the latch 172 may be released during a circuit closing operation when trip horn 78 engages trip rod 78 to release movable rod contact 65 held in top tube 68, as viewed in Fig. 12 of the drawings, latch crank 174 is provided with a projecting reset arm 178 connected to leg 174a, which arm 178 projects into the path of trip arm 162 during a circuit closing operation when latch crank 174 is in the position of Fig. 12 of the drawings. Latch crank 174 also includes an extension 174d from leg 17412 which is engageable with stop projection 158g of trip lever 158 to limit the maximum counterclockwise rotation, as viewed in Figs. 7, 11 and 12 of the drawings, of latch crank 17 trelative to trip lever 158. This extension 174d is engageable with a stop integral with the guide 150 to limit the maximum clockwise rotation of latch crank 174, as viewed in Figs. 7, 11 and 13 of the drawings. The stop 15% also limits maximum counterclockwise rotation of trip lever 158.

For the purpose of biasing the latch 172 into latching position, there is provided a suitable compression spring 186 interposed between the latch 172 and the crosspie-cc 1740 of the latch crank 174. This compression spring 186 effectively biases the latch 172 in a counterclockwise direction, as viewed in Figs. 7, 11, 12 and 13 of the drawings. To prevent any possibility of annealing spring 188,

the latch 172, preferably made of a hard material such as stainless steel, is insulated at its pivot points and at the support for spring 180 so that there is no conducting circuit from the latch to any other part of the mechanism. It will be apparent from Fig. 11 of the drawings that the latch 172 is very light and can be moved out of the way by the movable interrupting rod contact as it moves during a circuit interrupting operation in an upward direction. However, the spring 180 will bias the latch 172 to a latching position beneath the rod contact 65, as shown in Fig. 12 of the drawings, as soon as the rod 65 moves sutficiently far into top tube 68. The guide memher is provided with a suitable recess 181 (Fig. 13 of the drawings) to permit the latch 1.72 to move into latching position within this recess.

It will be apparent that the latch 172 cannot be effective to latch rod contact 65 in an open position unless the latch crank 174 is moved to a proper position relative to the trip lever 158. Latch crank 174 is capable of being in either one of two stable positions by virtue of an overcenter spring means 183 connected between the trip lever 158 and latch crank 174. As illustrated, the overcenter spring means 183 is very similar to the spring means described above, and comprises a compression spring 185 having one end connected by means of pin 186 to the spring lug 158k on trip lever 158, while the other end is connected by pin 187 to an extension of leg 174a of latch crank 174. A spring guide 188 completes the connection of the overcenter spring means 183. Actually, the spring guides 1'70 and 188 are slotted at the ends to receive the pins described above, and the compression springs 166 and 185, respectively, are held in position by the associated spring guides and pins. Thus, latch crank 174 will be maintained in one of two positions relative to trip lever 158; one position being shown in Figs. 7 and 11 of the drawings, where the overcenter spring means 183 tends to rotate the latch crank 174 in a counterclockwise direction, as viewed in Figs. 7 and 11, against stop lug 158g on trip lever 158, and the other position being shown in Fig. 13 of the drawings, where the overcenter spring t means 183 tends to move the latch crank 174 in a clockwise direction, as viewed in Fig. 13, relative to trip lever 158 against stop 15012.

From the above description it is apparent that through actuation of the trip rod 70 by the trip horn 78 during a circuit opening operation, the trip arm 162, in pivoting in a clockwise direction, as viewed in Fig. 7 of the drawings, engages projection 160 of the trip lever 158 effectively to release the latch holding movable interrupting contact 65 within the arc extinguishing chamber 67. On the other hand, during a circuit closing operation this same trip arm 162, in pivoting in a counterclockwise direction, as viewed in Figs. 11 and 12 of the drawings, engages the projection 178 of latch crank 174, thereby effectively releasing latch 172 holding interrupting contact 172 in the top tube 68. Obviously, some means must be provided to position or center trip arm 162 in readiness to perform either of the above two functions and restore it to such center position immediately after it has performed either of its functions without any un- 14 desirable oscillations thereof or the like. To this end there is provided trip arm centering means in the form of a trip shaft spring assembly, generally indicated at 190. This trip shaft spring assembly 190 includes an upper support member 191 having a trip shaft receiving recess whereby the support member 191 is secured to trip shaft 142 by a set screw 192 extending into a recess 142a defined in the trip shaft. The upper support member includes a weight engaging extension 191a Whose function is described hereinafter. The support member 191 also includes a downwardly extending cylindrical recess 1911b within which is received the upper end of a tightly wound coiled spring 195. The lower end of the spring 195 is received within an upwardly directed recess 196a of a lower spring support 196 having an elongated slot 19612 for receiving a shaft 197 mounted on the trip shaft bracket 143 whereby pivotal movement of the lower spring support 196 is permitted. In Fig. 4 of the drawings the positions of spring supports 191 and 196 and the coil spring 195 are shown during the instant the trip rod 70 is deflected to the position 70b. It will be apparent that deflection of these elements in the opposite direction will occur when trip rod 70 is moved to the position 70a.

In order to give the trip arm 162 and the trip shaft spring assembly 190 an aperiodic or nonoscillatory operation, there is provided a cylindrical weight 198 supported between the adjacent ends of a pair of spaced weight arms 199, which arms have their other ends pivotally mounted as by a weight arm pin 200 to the trip shaft bracket 143. The weight 198 rests on the weight engaging extension 191a of the upper spring support member 191 and moves with this extension 191a during a counterclockwise movement of extension 191a, as viewed in Fig. 7 of the drawings. A suitable stop in the form of a machine screw 201 threadedly received within an extension of trip shaft bracket 143 limits the maximum clockwise rotation of the weight arms 199 and, hence, the weight 198, as viewed in Fig. 7 of the drawings.

Accordingly, during opening of the high voltage switch 20, the trip rod 70 is deflected in a clockwise direction to the position 70a shown in Fig. 4 of the drawings to displace the latching portion 1580 of the trip lever 158 from a position capable of engagement with the upper end of the movable interrupting element 65, and, in response to such movement of the trip lever 158, the element 65 is displaced vertically upward at high speed under the control of the throw lever 92. The movement of the trip lever 158 also moves the resiliently urged latch 172 into latching position. Due to the lightness of this latch 172, the interrupting rod contact 65 will move it out of the way, as shown in Fig. 11, during its upward movement, so that when the rod contact 65 is entirely disposed within top tube 68, latch 172 is biased by spring 180 into latching position in recess 181 in alignment with the passageway 151 and beneath the element 65, as shown in Fig. 12 of the drawings, thereby to prevent downward movement of the element 65. The displaced trip rod 70 and the trip shaft 142 are immediately returned to their normal position under the control of the trip shaft spring assembly 190. The latch control unit 66 then remains in this condition shown in Fig. 12 of the drawings during the open position of switch 20 or until the high voltage switch 20 is reclosed at a subsequent time.

When it is desired to close the switch 20, the switch arm 42 is rotated in a clockwise direction, as viewed in Fig. 1 of the drawings, until such time as the trip horn 78 engages the trip rod 70 to produce counterclockwise deflection thereof from the solid line position of Fig. 4 to the dotted line position 70b thereof. In response to such counterclockwise deflection of the trip rod 70, the trip shaft 142 is also rotated in a counterclockwise direction, so that the trip arm 162 thereof engages the projection 178 on latch crank 174 and displaces the latch crank 174 in a clockwise direction around the axis provided by the shoulder studs 175, without, however, producing an accompanying deflection of the trip lever 158. This movement of latch crank 174 is that occurring to accomplish the changed positions indicated between Figs. 11 and 13 of the drawings, whereby the interrupting contact rod is free to move back into arc tube 67. The instant of this occurrence is shown in Fig; 13 of the drawings. During this movement of latch crank 174, the overcenter spring assembly 183 aids in moving it to the position shown in Fig. 13 of the drawings, with the extension 174d against stop 1501?. During the closing operation of switch 20, accompanied by the counterclockwise rotation of the trip shaft 142 and trip arm 162, the weight engaging extension 191a of the member 191 lifts the cylindrical weight 198 from the stop member 201, so that the weight 198 and the weight arms 199 are displaced to the position indicated in dotted outline in Fig. 4 of the drawings, thus limiting the overswing of trip shaft 142. The counterclockwise rotation of the trip shaft 142 bows the coil, spring 195,, so that the tension of the bowed coil spring 1955 returns the trip rod 70 and trip shaft 142 to the normal position in which the weight 198 is resting upon the stop member 201. The coil spring 195 tends to limit the overswing of the trip shaft 142 and trip arm 162, inasmuch as. deflection of these elements beyond their normal position tends to extend the coil spring 195, which extension is opposed by the resilience thereof It is desirable for the trip arm 162 to be returned to its normal position without engaging the Projection 178 on the latch crank 174. As. described hereinabove, inasmuch as the spring assembly 190 tends to rotate this latch crank in a clockwise direction beyond the point at which trip arm 162' can engage the same (Fig. 13 of the drawings), no adverse elfect will result upon return of trip rod 70 to its normal position.

From the above description it will be apparentthat latch control unit 66 includes means for effectively unlatching or releasing arc interrupting rod contact 65 during a circuitopening operation to permit it to be propelled out of arc chamber 64 to extinguish any arc drawn therein. Likewise, during a circuit closing operation the latch control unit includes means for releasing the latch 172 to permit the interrupting rod contact 65 to move into arc tube 67 for a subsequent circuit interrupting operation. It is necessary for latch control unit 66 to perform an additional function, namely, to restore trip. lever 158 to its latching position with respect to rod contact 65. at the end of a circuit closing operation. accomplish this, the downward movement of latch rod 71 is employed, which movement was described above as responsive to movement of the switch blade 60 to the closed circuit position. To this end the upper portion of the latch rod 71 is threaded to receive a pair of nuts 203, so that latch rod 71 may engage a latching rod lever 204 to actuate the same during a circuit closing operation. As illustrated, latching rod lever 204 is pivotally mounted by a pivot pin 205, one end of which pivot pin is supported by a bracket 206 supported from the base portion 148 of the latch control unit 66, while the one end of the pin 205 is supported by the trip shaft bracket 143. A projecting portion or stop member 204a formed integral with the lever 204 engages oppositely positioned shoulders 210 and 211 on the bracket 206 to limit the maximum pivotal movement thereof about ivot point 2:)5. Actually, latching rod lever 204 is provided with an opening 204!) therein through which the latch rod 71 extends. With this arrangement the downward movement of latch rod 71 causes nuts 203 to engage latching rod lever 204 to pivot the same in a counterclockwise direction, as viewed in Fig. 11 of the drawings, with the result that the free end thereof engages the reset lug 158a of the trip lever 158. From the above description it will, moreover, be apparent that by virtue of the time delay means 126. such resetting does not occur until the interrupting Contact rod 65 is surely disposed'within the are tube 67. Upon upward move- 16 ment of latch rod 71, the nuts 203 no longer restrain the latching rod lever 204, so that it is free to move during the unlatching operation against the stop 211. Thus, during the closing movement of the high voltage switch 20, the final thing that occurs is for latching rod lever 2mto move trip lever 158 from the position shown in Fig. 11 of the drawings to the position shown in Fig. 7- of the drawings.

It will be appreciated that suchclockwise rotation of the trip lever 158 in response to movementof latching rod lever 204 also returns the latch crank 174 and the latch 172 supported thereon to the normal position illustrated in Fig. 7 of the drawings. This occurs because with the latch crank in the position shown in Fig. 13 of the drawings the extension 174d is in engagement with the stop 15%, thereby limiting further clockwise rotation of latch crank 1 74. Thus, as trip lever 158 is rotated in clockwise rotation from the position shown in Fig. 13 of the drawings, latch crank 174 remains stationary with the extension 174d against stop b, so that the'parts are restored to the position shown in Fig. 7 of the drawings. The rotation of trip lever 158 continues until the lug 158g engages the extension 174d of latch crank 174, as shown in Fig. 7 of the drawings. Thus, downward movement of the latch rod 71 not only restores trip lever 158 to its normal position, but makes sure that latch crank 174 is in its normal position for another cycle of operation.

The downward movement of the latch rod 71 islimited only by engagement of the nuts 203 with the lever 204 and by-ithe sp ring means in housing 56 associated therewith. it; will be appreciated that the latch rod 71 and the latching rod lever204' remain in the downwardly deflected position once having been so moved by the pull lever 124 until such time as the reset crank 101 is ro tated in a counterclockwise direction, as viewed in Fig. 5 of; the drawings, in response to the opening of the high voltage switch 20.

Itwill be understood that suitable venting means will be provided in latch control unit 66 and housing 56 to permit arc gases to escape during a circuit interrupting operation. At. the current zero when the arc is interrupted, the voltage of the line charging currents to be interrupted is likely to be a maximum, and in order to drain' off this voltage a suitable resistor in series with a calibrated gap or without such gap is preferably connected' across arc extinguishing structure 64.

Such aresistor 220 and associated calibrated gap 221 is illustrated in Figs. 1' and 20f the drawings. The resistor 220 has its lower end supported from a conducting support 222 extending from housing 56 while the upper end is connected to one elect-rode 221a of the gap 221. The other electrode 221b of the gap 221 is supported beneath housing 66 and electrically connected to trip lever 158. The electrodes 221a and 221b are preferably such as to permit adjustment of the gap length from zero to some desired maximum value.

If the resistor 220 is connected directly across the arc interrupting chamber without a series gap, it provides a circuit to reduce the voltage of the charge left on the line as the impressed generator'voltage wave, which occuts at each alternation, falls from crest toward zero. This is not a problem when interrupting energy loads, but it is a problem when interrupting line charging current which is a capacitive current. If the resistor 220 is connected across the arc interrupting chamber by a gap such as 221,it does not act to reduce the cumulative voltage on the line until the gap has arced over, which may be during the second alternation of voltage after the contacts in the are interrupting mechanism have separated.

Whenthe resistor construction is used, an arc may continue between thehorns of'switch 20 after the arc chamber has interrupted its are, because the resistor providesa cireuit-to'the line; Afterthe arc is-inter-rupted in tube 64,- the resistance limits the current to the line.

17 This limited current is immediately broken by the gap between the horns of switch 20.

It will be understood that the use of such a resistor circuit across the arc extinguishing structure 64 eliminates large cumulative voltages when the switch 20 interrupts capacitive loads or line charging current. An unloaded transmission line will for a time hold a charge at the peak voltage at which it was energized. The load break mechanism will interrupt the circuit at a zero point of the line charging current. This leaves the line charged at close to peak transmission system voltage, which we may assume is a positive voltage. The next alternation of system voltage will be negative. At this time the voltage across the contacts of the arc interrupting mechanism will be the system voltage plus the voltage to which the line was charged, the total being about twice system voltage. If in the time between the interruption of the circuit and the next alternation of voltage the contacts have not separated far enough, an arc will restrike across them. With this establishment of the circuit, an equalizing current results which charges the line at a voltage which may be close to the voltage that caused the restrike. This may repeat for several alternations, charging the line to a higher voltage at each restrike until the contacts have separated far enough to effect a final interruption of the circuit.

For voltages above 69 kv. such a resistor circuit, therefore, becomes a necessity. However, for lower voltages it is preferable to permit such cumulative voltages to build up and use a longer are extinguishing chamber to interrupt them.

In view of the detailed description of the high voltage switch 20 included above, the operation during both circuit opening and circuit closing will be readily understood by those skilled in the art. Let us assume that the high voltage switch 29 is in the closed position indicated in Figs. 1, and 7 of the drawings and that it is desired to open the high voltage switch. It should be observed, first of all, that during the closed position of the switch, as viewed in Fig. 7 of the drawings, there is a space between the upper end of the rod contact 65 and the latch portion 158s of the trip lever 158. This means that, efiectively, there is an open circuit as far as the parallel path through the rod contact 65 is concerned, and, of course, the current carried by the high voltage switch passes directly through the switch arm 42, the switch blade 60, the contact fingers 58, to the terminal element 24.

When it is desired to open the switch 20, the crank arms 46 are actuated to produce rotation of the movable insulator 48, which results in rectilinear movement along the longitudinal axis of the switch arm 42, with the result that switch blade 60 is moved to the left, as viewed in Fig. 5 of the drawings, from the position C toward the position A. When the switch blade reaches the position A, the switch arm 46 then proceeds to describe an arcuate movement in a counterclockwise direction, as viewed in Fig. 1 of the drawings. However, during the rectilinear movement of the switch blade 60 described above, the reset crank 101 under the bias of spring 105 rotates in a counterclockwise direction, as viewed in Fig. 5 of the drawings, until engagement with the stop 107 occurs, when the switch blade 60 reaches the position B during its movement to the left, as viewed in Fig. 5 of the drawings. This counterclockwise movement of the reset crank 101 permits the pull lever 124 to be rotated in a clockwise direction, as also viewed in Fig. 5 of the drawings, under the energy stored in compression springs 120 and 138. Such upward movement of the pull lever 124 results in upward movement of the latching rod 71, with the result that nuts 203 no longer restrain latching rod lever 204, which lever is then free to move in response to movement of the trip lever 158, whereby the trip lever 158 is conditioned to be moved out of its latching position with respect to rod contact 65.

The counterclockwise rotation of the reset crank 101 also permits the throw lever 92 to move slightly in a counterclockwise direction, as viewed in Fig. 5 of the drawings,

under the force of the energy stored in compression spring 73. This movement is very slight, however, and is limited by the upper end of rod contact 65 moving into latching engagement with the latching portion 1580 of the trip lever 158. At this time, while the circuit through the main switch contacts of the high voltage switch is still completed, there is also completed the parallel or auxiliary circuit through the rod contact 65 now in good electrical contact with trip lever 158. This circuit in parallel with the movable contacts comprising switch blade 60 and fingers 53 includes, beginning with terminal 24, the mechanism in housing 56 connected to the lower end of rod contact 65, trip leve: 158, frame 143, horn bracket 79, arcing horn 80, contact horn 75, and horn support 74 connected to switch blade 42.

When the switch blade 60 moves out of engagement with the contact fingers 53, no arc is drawn, since the current is transferred to the auxiliary arc extinguishing circuit including the rod contact 65, which completes the circuit path between the switch arm 42 and the terminal 24. As the high voltage switch continues to open, switch arm 42 begins to move in the arcuate manner described above, with the contact horn 75 making sliding contact with the arcing horn 80, thereby maintaining the electrical circuit through rod contact 65. After a predetermined opening movement of the high voltage switch 20 has occurred, the trip horn 78 engages the trip rod 70 and moves the same in a clockwise direction, as viewed in Fig. 4 of the drawings, from the solid line position to the position 7 0a. Such movement of the trip rod 70 causes like rotation of trip shaft 142 and movement of trip arm 162 into engagement with the projecting arm of the trip lever 158, with the resultant movement of the trip lever 15% from the position shown in Fig. 7 of the drawings to the position shown in Fig. 11 of the drawings. Such movement, of course, moves the latching portion 1580 of the trip lever 153 out of restraining engagement with the rod contact 65, whereby the latter is free to be propelled vertically upward into the top tube 68. As the lower end of rod contact 65 moves out of engagement with throw lever 92, an arc is drawn within the arc tube 67 so as to evolve gas from the liner 8% of the arc tube 67. The evolution of arc extinguishing gas from the liner $8 rapidly extinguishes the are drawn. Shortly thereafter, the continued arcuate movement of the switch arm 42 causes contact horn 75 to move out of engagement with arcing horn $0, with the resultant complete opening of the circuit.

It will be appreciated that when the trip lever 15% is moved from the position shown in Fig. 7 of the drawings to the position shown in Fig. 11 of the drawings, the latch crank 174 and the latch 172 are also moved to the position shown in Fig. 11 of the drawings, so that when the rod contact 65 moves to its uppermost position, the latch 172 will engage the lower end thereof upon subsequent downward movement to latch the same in the top tube The latch 172 is sufiiciently light, however, so that it will not interfere with upward movement of the rod contact 65, as is clear from Fig. 11 of the drawings, Where the upward movement of rod contact 65 moves the latch 1'72 out of latching position. The subsequent latched condition of the rod contact 65 in the open circuit position is shown in Fig. 12 of the drawings.

With continued opening movement of the switch arm 42, the trip rod 70 becomes disengaged from the trip horn 78, and the trip rod 70, together with the associated trip shaft 142, are returned to their normal position under the control of trip shaft spring assembly 190, which trip shaft spring assembly had previously been displaced in response to rotation of the trip shaft 142. The apparatus is now in an open circuit position in condition for a subsequent reclosing operation of the high voltage switch.

When it is desired to close the high voltage switch 20, the crank arms 46 are actuated to produce rotation of the movable insulator 48 in a direction opposite that described above during an opening operation of the is switch. Such rotation of movable insulator 48 results in an arcuate movement of the switch arm "42 in-a clockwise direction, as viewed in Fig. 1 of the drawings. It will be appreciated that under these conditions the rod contact 65 is latched in the open position, asshown in Fig. 12 of the drawings. When a predetermined closing movement of the switch arm 42 has occurred,'the trip horn 78 moves into engagement with'the trip rod 70'to move the trip rod 70 from the solid line position shown in Fig. 4 of the drawings to the position 701), whichis counterclockwise rotation, as viewed'in Fig. 4 of the drawings. Such counterclockwise rotation of the trip rod 70 producesa like rotation of the trip shaft 142 and'the trip arm 162. Trip arm 162engages the projection'178 on latch crank 174 and rotates the latch crankl74ifrom the position shown-in Fig. l2'of the drawings t'othe position shown in Fig. 13 of the "drawings. Such movement of the latch crank 174 'moves'thelatchl'72i from beneath the-rodcontact 65 thereby permitting rod contact 65 to fall under the force of gravity into arc extinguishing tube67 and into'the pocket portion"91 of thefthrow lever 92, as clearlyshown inFig. 6 of "the drawings. This downward movement of rod con'tact'65 is indicated in Fig. 13 of the drawings. It willbe apparent that the overcenter spring assembly crank to'the position shown in Fig. whereextension 174d engages stop member 15012, after such movement of the latch crank has been initiated by trip arml62. The momentarily displaced position of the trip shaft spring assembly I90 under these conditions is shown in dotted lines in Fig. '4 of the drawings. .As soon as trip horn "78 disengages trip rod 70 upon continued closing movement of the switch arm '40, the trip shaft 142 is returned to its normal position under the control ofthe trip shaft spring ass'embly'190.

Continued closing movement of the switch arm 42 will cause the switch blade to-strike the. anvil and then move in a rectilinear direction along the longitudinal axis of the switch arm 42 toward the right, as viewed in Fig 6 of the drawings, so that the end of the switch blade :60 engages the roller 110 on the reset crank -101. This movement of the switch blade 60 is continued until such time as the blade 60 is moved to the position indicated at C (Fig. 5 of the drawings). During the initial rotation of the reset crank 101, in a clockwise direction against the force of the spring 73 to permit the movable conductive element 65-to move downwardly to the position disclosed in'Fig. 5 -of .the drawings in which the upper end thereof is positioned approximatelyflush with the uppersurface of the frame 143. Also during this movement, the :pull lever 124 is rotated in a counterclockwise direction to actuate the time delay .assemblyi126, so that following a predetermined time delay the rod 71 is moved downwardly.

This downward movement moves the latching rod lever 204 into engagement with the lug 158a on the trip lever 158, so that this lever is rotated. in a clockwise direction to move the'latching bar 1580 into a position .in alignment with and. spaced from the upper end of the rod contact member 65. Also during this movement,.the latch crank 174 is rotated in. a counterclockwise direction to return the latch element 172 to its normal -position (Fig. 7 of the drawings). This completes the closing operation of the high voltage switch, so that the parts are in the positions indicated in Figs. 5 and 7 of the drawings. I

While there have been shown and described particular embodiments of .the present invention, it is not desired that the invention be limited to the construction shown and described, for it will, of course, be obvious to those skilled in the art that changes and modifications may be made without departing from the invention. It is, therefore, aimed in the appended claims to cover all such changes and modifications as fall withinthe true spirit and scope of this invention.

13 of the drawings,

1'83 returns the latch the throw lever 92 is rotated gagingthe other end of said member and movable'out "of engagement therewith to permit said member-to be moved by said resilient means to a displaced position in which said conductive member is spaced from said resilient means, and mean-s'for holding said member in said displaced position spaced from said resilient means.

2. In a circuit interrupter, structure defining spaced apart contacts, a movably mounted conductive member 'for completing a'circuit between'said contacts and having a displaced position in whichsaid'circuit is interrupted, an actuating means associated with saidrmember for 'moving said member'to saiddisplacedpositionin which said actuating means is spaced from said member, :means in engagement with said member for. securing said member in a circuit completing positionadjacent said'actuating means, said securing means being operable to permitsaid member to be moved to said displaced position by said actuating means, and latch means responsive to movement of said member to said displaced position for preventing movement thereof to said circuit completing position adjacent said actuating means.

'3. A-high voltage switch comprising a .fixed contact, contact means movable relativeto said fixed contact to complete and disconnect an electrical circuit, structure forming spaced contacts in said circuit, aconductive member for completingsaid circuit through said spaced contacts andv movable to a displaced position to interrupt said circuit, actuating means associated with said member 'tomove said member to said displaced position in which saidv member isv spaced from said actuating means, means controlled by movement of said movable contact nneans ffor..preventing. movement of said member to said dis- .placed position, and means also controlled by movement of said movable contact means for preventing movement ofsaid member from saiddisplaced. position. toward said actuating means.

-4. A high-voltageswitch. comprising a pair of relatively. movable contacts including a fixed contact and contact means movable relative to said fixed contact in arcuate and rectilinear movement to complete and interrupt anelectrical circuit, structure forming spacedcontacts connected inan auxiliary electrical circuit inparallel with said .relatively movable contacts, aconductive :member. positioned between-said spaced contacts and movable to a displaced .positionspaced from'said contacts, means .for moving said member, first latch means forpreventing movement of said member to said displaced position, means responsive=.to;=rectilinear movement of said..movablecontact means towardsaidfixed contact for rendering said first latch .means 7 effective, means responsive to rectilinear movement of said movable contact away from'said fixed contact for completing said auxiliarycircuit through said member,- means'responsive to arcuate movement ofsaid movable contact means away from said fixed "contact for releasing saidfirst latch means to permit said member to be moved to- :said displaced; position; second latch means forcholding'saidrnember in-said displaced position,-and means'responsive' to-arcuate movement of said movable contactmeans toward saidfixed contact for-rendering saidssecond latch means ineffective whereby said member is"returned' to a'position adjacent said spaced :contacts.

5. A high voltage. switch comprising-a pair ofrelatively movable contacts including va fixed contact and contact means movable relative to said fixed contact'to-complete and zdisconnectzan electrical :circuit, structureiorming spaced contacts connected in an auxiliary electricr'circuit in parallel with said relatively :movable con'tacts, a :conduc'tive member-positioned-between said spaced contacts and movable to a displaced positionspaced from said con- 21 tacts, means for moving said member, first latch means for preventing movement of said member to said displaced position, means responsive to movement of said movable contact means toward said fixed contact for rendering said first latch means effective, means responsive to movement of said movable contact away from said fixed contact for completing said auxiliary circuit through said member, means also responsive to movement of said movable contact means away from said fixed contact for releasing said first latch means to permit said member to be moved to said displaced position, and second latch means for holding said member in said displaced position.

6. A high voltage switch comprising a pair of relatively movable contacts including a fixed contact and contact means movable relative to said fixed contact to complete and disconnect an electrical circuit, structure forming spaced contacts connected in a branch circuit in parallel with said relatively movable contacts, a rod contact member for interconnecting said spaced contacts and movable to a displaced position remote from said con tacts, energy storage means for moving said member, latch means for preventing movement of said member to said displaced position, means responsive to movement of said movable contact means toward said fixed contact for sequentially rendering said latch means and said energy storage means efiective, and means responsive to movement of said movable contact away from said fixed contact for completing said branch circuit through said member and for releasing said latch means to permit said member to be moved to said displaced position.

7. A high voltage switch comprising relatively movable contacts including a fixed contact and a movable contact adapted to make and disconnect an electrical circuit, means including a pair of spaced interrupting contacts arranged in parallel circuit relationship with said relatively movable contacts, a conductive member positioned between said spaced contacts and movable to a position displaced therefrom to interrupt said circuit, first latch means for preventing movement of said member to the displaced position, second latch means for holding said member in said displaced position, means responsive to movement of said movable contact toward said fixed contact for sequentially rendering said second latch means ineffective and said first latch means effective, and means responsive to movement of said movable contact away from said fixed contact for completing said parallel circuit through said member and for releasing said first latch means to permit said member to be moved to said displaced position thereby to extinguish the are generated by movement of said member.

8. A high voltage switch comprising a fixed contact, contact means movable relative to said fixed contact to complete and interrupt an electrical circuit, structure providing contacts spaced by gas evolving material to form a parallel branch of said circuit, a conductive member bridging said spaced contacts and movable to a displaced position to open said branch circuit, means for moving said member, first latch means for preventing movement of said member to the displaced position, second latch means for holding said member in a displaced position, means responsive to rectilinear movement of said movable contact means toward said fixed contact for rendering said second latch means inefiective and said first latch means efiective, and means responsive to arcuate movement of said movable contact means away from said fixed contact for releasing said first latch means to permit said member to be moved to said displaced position.

9. A high voltage switch comprising a fixed contact, contact means movable relative to said fixed contact to complete and interrupt an electrical circuit, are extinguishing structure forming spaced contacts in a parallel branch of said circuit, a conductive member positioned between said spaced contacts and movable to a displaced position spaced from said contacts, a resiliently urged lever movable to a position conditioned for moving said member,

first latch means for preventing movement of said member to the displaced position, means responsive to movement of said movable contact means toward said fixed contact for rendering said first latch means effective and for moving said lever to the conditioned position, means responsive to movement of said movable contact means away from said fixed contact for releasing said first latch means to permit said conditioned lever to move the conductive member to said displaced position thereby to extinguish an arc formed by opening said switch.

it). A high voltage switch comprising a pair of relatively movable current carrying contacts, a pair of spaced interrupting contacts connected in parallel with said movable contacts, conductive means movable relative to said interrupting contacts to make and break the circuit through said interrupting contacts, a lever engageable with one end of the conductive means for propelling said conductive means, pivotally mounted means engaged by one of said relatively movable contacts during a circuit closing operation for conditioning said lever for operation, a latch for retaining said conductive means against movement, actuating means for rendering said latch effective, and timing means controlled by movement of said pivotally mounted means for delaying the operation of said actuating means until said lever is conditioned.

11. A high voltage switch comprising a fixed contact, movable contact means cooperating with said fixed contact to complete and interrupt an electrical circuit, are extinguishing structure defining spaced contacts forming a portion of said circuit, conductive means movable relative to said structure to complete and to interrupt said circuit, a pivotally mounted lever for moving said conductive means in a first direction to interrupt said circuit, means operated in accordance with movement of said movable contact means relative to said fixed contact for moving said lever in a direction to produce movement of said conductive means in a second direction opposite to said first direction thereby to condition said lever for impelling said conductive means, means for retaining said conductive means against movement in said first direction, and timing means controlled in accordance with relative movement between said fixed and movable contacts for delaying the effectiveness of said retaining means until said conductive means has been moved in said second direction.

12. A high voltage switch comprising a fixed contact, movable contact means cooperating with said fixed contact to complete and interrupt an electrical circuit, structure defining spaced contacts forming a portion of said circuit, conductive means movable relative to said structure to complete and interrupt said circuit, resilient means for moving said conductive means, means engaged by said movable contact means during movement thereof relative to said fixed contact for conditioning said resilient means for operation, means for retaining said conductive means against movement, means controlled by movement of said engaged means for rendering said retaining means effective, and timing means for delaying the effectiveness of said retaining means until said resilient means is conditioned.

13. A high voltage switch comprising a fixed contact, movable contact means cooperating with said fixed contact to complete and interrupt an electrical circuit, structure defining spaced contacts forming a portion of said circuit, conductive means movable relative to said structure to complete and to interrupt said circuit, spring urged lever means for propelling said conductive means, a pivotally mounted trip lever engaged at one end by said movable contact means during movement thereof for pivoting said lever means to a stressed condition of said spring, means for retaining said conductive means against movement, pivotally mounted means controlled by movement of said movable contact means for rendering said retaining means efiective, and timing means interposed between said pivotally mounted means and said retaining wardly therefrom; said auxiliary contact means including a freely propelled 5 vertically movable rod contact, actuating-means forpropellingsa-id rod'contact upwardly away from sard actuating means; holding means'posi-tioned'ad jacent the upper'end of-said rodcontactfor-holdingsaid' rod" contact in two" spaced positions, and control means responsive'to relative movement betweensaid fixed contactaneans and .said movable contact meansfor controlling said last mentioned means.

A- high voltage switchcomprising'terminal structure; including fixed contact'means, connecting structure movable rel-ativeto said terminal structure for completing-and interrupting an electrical circuit through said contactfmeans,- a chamber formedof gasevolving material having one end thereof positioned on saidterminal structure and.extendingupwardly therefrom, a freely movable conducting element positioned insaid chamber, an enclosure: above thetop of said chamber 'for receiving said element, movement controllin'g means positioned between said'chamberi and said enclosure for controlling the move= menttof said' element between said'chamber and-said en closure so that 1. saidfreelyv movable elementis disposed substantially entirely within enclosure, and means operated in accordance with the po-' sition of: the connectingstructurerelative to-the terminal structure'for actuating said movement controlling means.

16. A high voltage switch comprisinga-pair' of mu tively movable current carrying contacts and a pair of relatively movable circuit interrupting contacts capable of being connected in parallel with said current carrying contacts during a circuit interrupting operation, a latch control unit for controlling the operation of said circuit interrupting contacts including a trip rod, means for actuating said trip rod in response to relative movement between-said current carrying contacts, and means for maintaining said trip rod in a normal position comprising a pairof pivotal supports and a tightly coiled spring interposed between said supports.

17. The high voltage switch of claim 16 in which said pivotalsupports each are providedwith opposed recesses forfreceiving the ends of said spring.

18. The high voltage switch of claim 16 in which a weight is included in said latch control unit for rendering said means for maintaining said trip rod'in normal position nonoscillatory.

l9. A high voltage switch comprising a pair of relatively movable current carrying contacts and apair of relatively movable circuit interrupting contacts capable of being connected in parallel with said current carrying contacts during a circuit interrupting operation, a latch control unit for controlling the operation of said circuit interrupting contacts including a trip rod, a trip horn on one ofsaid relatively movable current carryingcontacts for actuating said trip rod in response to relative movement between said-current carrying contacts, spring-means for maintaining said triprod in a'norrnal position so as-to be actuated by relative separation or rel-ative'closing of-said current carrying contacts, a trip lever pivotallymountedin said latch control unit forlatching said circuit interrupting contacts in the closed position, a latch crank.

pivoted on said trip lever, a latch pivoted on said latch crankfor latching said circuit interrupting; contacts in the open position, said trip rod actuating, said trip lever means is moved toward said circuit auxiliary contact means either said chamber or said therefrom, said auxiliary contact'means including an electrically conductive element movable between a circuit completing position and a circuit interrupting position, means operatively-associated with saidmovable element in said-circuit completing positionfor moving said ele'-- men-t to said circuit interrupting position, said-moving means being moved outof operative association with said element in said circuit interrupting position, latch meansfor selectively maintaining said movableelement in either of said twopositions, and means controlling said latch means in accordance'with relative movement betweensaid fixed'contact means and said connecting structure.

22. A-high voltage switch comprising terminal structure including fixed contact means, connecting structure movable relative to said' terminal structure for completing and-interrupting'anelectrical circuit through said con, tact means, auxiliary contact means including aimovable: element having a:conductive-portion, said movable ele, ment being mov'ableitoa circuit completing position and; a circuit interruptingposition, means for moving said element from one of said positions to the other thereof, latch means engagingi one end of said. movable element for maintaining said element. in. a circuit completing posi tion'and for engaging :the other end of said element for maintaining said. movable element in a circuit interrupting position, and means selectively controlled in accordance with relative movement between said terminal structure and. said connecting structure for selectively render.- ing saidlatch means eiTec-tive to maintain said movable element in said positions.

23. The switch set forth in claim 14 in which the said control means'includes means for operating said holding; means to release said rod contact for propulsion by said actuating means during movement of said movable contact means'away from said fixed contact means and means for operatingthe said holding means to release said rod contact for-movement under the force of gravity during movement of said movable contact means toward said fixed contact means.

24. In a circuit interrupter, means defining an are extinguishing chamber having an open end, a conductive member movably mounted in said chamber in a circuit completing position, actuating means for moving said. member out of said chamber to a displaced circuit interrupting position, and detent means movably mounted adjacent one end of said chamber and extending across at least a portion of the open end of said chamber, said detent means being movable away from said open end to permit said member to be moved out of said chamber to said displaced position by said actuating means and being thereafter operable to a position interposed between. said member and said open end to prevent said member from moving into said chamber.

References-Cited in the file of this patent UNITED STATES PATENTS 1,963,418 Pittman et al June 19, 1934 2,458,800 Schultz. Jan. 11, 1949 2,658,976. Hoye Nov. 10, 1953 2,709,736 Schneider May 31, 1955'

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