US3400353A

US3400353A - Metal enclosed switchgear with series connected switch means, circuit interrupter means, current responsive means and operating means mounted on door

Info

Publication number: US3400353A
Application number: US561839A
Authority: US
Inventors: Guenther G Schockelt
Original assignee: S&C Electric Co
Current assignee: S&C Electric Co
Priority date: 1966-06-30
Filing date: 1966-06-30
Publication date: 1968-09-03
Anticipated expiration: 1985-09-03
Also published as: GB1135169A

Description

p 1968 G. G. SCHOCKELT METAL ENCLOSED SWITCHGEAR WITH SERIES CONNECTED SWITCH MEANS, CIRCUIT INTERRUPTER MEANS, CURRENT RESPONSIVE MEANS AND OPERATING MEANS MOUNTED ON DOOR Filed June so, 1966 7 Sheets-Sheet 1 49 12 y LINK/76E FROM 22 3 00/? 7'0 5m TIONHRY INSULATING BARR/El? P 3, 1968 5. G. SCHOCKELT 3,400,353

METAL ENCLOSED SWITCHGEAR WITH SERIES CONNECTED SWITCH MEANS, CIRCUIT INTERRUPTER MEANS, CURRENT RESPONSIVE MEANS AND OPERATING MEANS MOUNTED ON DOOR Filed June 30, 1966 7 Sheets-Sheet 2 w' INSULATING p 1968 G. 5. SCHOCKELT 3,400,353

CTED SWITCH METAL ENCLOSED SWITCHGEAR WITH SERIES CONNE MEANS CIRCUIT INTERRUPTER MEANS, CURRENT RESPONSIVE MEANS AND OPERATING MEANS MOUNTED ON DOOR 7 Sheets-Sheet 5 Filed June 30, 1966 Sept- 3, 1968 G. G. SCHOCKELT 3, 0 ,3

METAL ENCLOSED SWITCHGEAR WITH SERIES CONNECTED SWITCH MEANS. CIRCUIT INTERRUPTER MEANS. CURRENT RESPONSIVE MEANS AND OPERATING MEANS MOUNTED ON DOOR Filed June 50, 1966 7 Sheets-Sheet 4 ML 00%7 /AJ 3. G. SCHOCKELT 3,400,353

CHGEAR WITH SERIES CONNECTED SWITCH UIT INTERRUPTER MEANS CURRENT RESPONSIVE AND OPERATING MEANS MOUNTED 0N DOOR Sept. 3, 1968 METAL ENCLOSED SWIT MEANS CIRC MEANS P 3, 1968 G. G. SCHOCKELT 3,400,353

METAL ENCLOSED SWITCHGEAR WITH SERIES CONNECTED SWITCH 'MEANS, CIRCUIT INTERRUPTER MEANS, CURRENT RESPONSIVE MEANS AND OPERATING MEANS MOUNTED ON DOOR Filed June 30, 1966 '7 Sheets-Sheet 6 Sept. 3, 1968 SCHOCKELT 3,400,353

METAL ENCLOSED SWITCHGEAR WITH SERIES CONNECTED SWITCH MEANS. CIRCUIT INTERRUPTER MEANS, CURRENT RESPONSIVE MEANS AND OPERATING MEANS MOUNTED on DOOR Filed June 30, 1966 7 Sheets-Sheet 7 f? 19 kg 20 F M? 5' "a United States Patent METAL ENCLOSED SWITCHGEAR WITH SERIES CONNECTED SWITCH MEANS, CIRCUIT IN- TERRUPTER MEANS, CURRENT RESPONSIVE MEANS AND OPERATING MEANS MOUNTED ON DOOR Guenther G. Schockelt, Skokie, Ill., assignor to S & C Electric Company, Chicago, III., a corporation of Delaware Filed June 30, 1966, Ser. No. 561,839 Claims. (Cl. 337-7) ABSTRACT OF THE DISCLOSURE Safe metal enclosed switchgear in which the switchgear is enclosed in a metal housing provided with a door to permit access thereto. Mounted on the door and connected in series are a switch blade, a vacuum type circuit interrupter and a fuse with shunting contacts. Also mounted on the door is a stored energy mechanism operated by the blowing of the fuse for opening the switch blade and circuit interrupter together and a manually operated stored energy mechanism arranged to open the switch blade and circuit interrupter. Interloeks operate between the switch blade and door to prevent opening of the door when the switch blade is closed and between the fuse and a manually operated handle to prevent operation of the handle until the fuse is replaced. There is another interlock which prevents closure of the door once it has been opened after operation of the fuse.

This invention relates to metal enclosed switchgear for application to alternating current circuits operating at voltages of the order of 13.2 kv. It can be employed for circuits operating at higher or lower voltages and for different current ranges as may be required. It constitutes an improvement over the constructions disclosed in US. Beebe et al. Patent Serial No. 552,282, filed May 23, 1966, now US. Lindell Patent 3,327,076, issued June 20, 1967 and Schockelt Ser. No. 558,165, filed May 23, 1966.

For electric power distribution at various locations, such as shopping centers, high rise buildings, industrial plants, etc., and at relatively high voltage, for example 13.2 kv, switching equipment is provided that must be reliable and safe. Such equipment is arranged for normal supervision and operation by personnel of limited skill whose capabilities extend only to routine operations involving opening and closing a circuit, changing blown current responsive means, such as fuse devices, etc. Because of competitive conditions, the cost of this switching apparatus is required to be held to a minimum consistent with proper and safe operation.

0 Among the objects of this invention are: To provide new, improved and safe metal enclosed switchgear; to mount a series connected switch blade and separable contact circuit interrupter together with operating means therefor on a door of metal enclosed switchgear which is provided with stationary contacts in insulated spaced relation which are interconnected when the door is closed and the switch blade and interrupter are closed; to interlock the switch blade and the door to permit opening of the door only when the switch blade is open; to prevent exposure of the stationary contacts when the door is 'open; to operate the current interrupter, such as a vacuum switch, in response to flow of current of predetermined value therethrough; to open the circuit followed by movement of the switch blade to open position; to shunt the current sensing means substantially at the same time it operates to limit arcing at its terminals; to prevent opening of a current interrupter as long as the cur- 3,400,353 Patented Sept. 3, 1968 rent flow exceeds a predetermined value; to provide one stored energy mechanism for opening the current interrupter and switch blade in response to current flow of predetermined value and another stored energy mechanism operating through the one stored energy mechanism for operating the current interrupter and the switch blade to perform normal switching functions; to employ the one stored energy mechanism to provide for trip free operation if the circuit is closed on a fault; to provide a polyphase switching arrangement with the current responsive means of any one phase arranged to open all phases and with the operating means arranged to open and close all phases simultaneously; to employ a current sensor with fusible means capable of carrying full load current continuously and arranged to blow on flow of excess current therethrough in accordance with the timecurrent characteristic of a fuse to release an operating member for opening the current interrupter; to shunt the blown fusible means to maintain circuit continuity with respect only to the blown fusible means to permit opening of the circuit by the circuit interrupter unless such operation is prevented by the excess current flow respon sive means; to provide, in combination with a suitable current interrupter, switching means that responds in accordance with a time-current characteristic of a fuse for clearing fault currents up to the limit of the current interrupter employed; and to prevent reclosure of the circuit interrupter and switch blade opened in response to blowing of the fusible means until the current sensor is restored to normal current carrying condition.

According to this invention, metal enclosed switchgear is provided which includes a metallic housing having a door in at least one wall to permit access to the switchgear therein which may be single phase or polyphase depending upon the number of circuits to be switched. Each phase includes a pair of stationary contacts in insulated spaced relation with an apertured insulating barrier between them and the door. A movable insulating shutter, operated by the door, closes the apertures in the stationary insulating barrier when the door is opened. Mounted on the door and connected in series are a switch blade movable through an opening in the stationary insulating barrier to engage one of the stationary contacts, a separable contact circuit interrupter, preferably of the vacuum type, and a current sensor with shunting contacts, there being a contact plate extending from the current sensor through another opening in the stationary insulating barrier for connection with the other stationary contact. Also mounted on the door is a stored energy mechanism operated by blowing of the fusible element of the current sensor for opening the circuit interrupter and the switch blade together with a manually operable stored energy mechanism arranged to operate through the stored energy mechanism to open and close the current interrupter and the switch blade. Separate interlocks operate between the switch blade and the door and prevent opening of the latter when the switch blade is closed. Another interlock, between the current sensor and the manually operable handle used for charging the stored energy mechanism, prevents such operation after the current sensor has been operated and until it is re placed. Also another interlock prevents closure of the door once it has been opened after operation of the current sensor, until it has been replaced. Alternatively, instead of the current sensor and shunting contacts, a conventional solid material fuse or a current limiting fuse can be used and mounted on the door in series with the series connected switch blade and separable contact circuit interrupter.

In the drawings: FIG. 1 is a view, in front elevation, of metal enclosed switchgear embodying this invention. FIG. 2 is a vertical sectional view, at an enlarged scale, taken generally along the line 22 of FIG. 1, certain parts he ing broken away in order to show certain details of construction. FIG. 3 is a view, taken generally along the line 33 of FIG. 2. FIG. 4, sheet 1, is a vertical sectional view, at an enlarged scale, taken generally along the line 44 of FIG. 2. FIGS. 5, 6 and 7 show different operating positions of the first stored energy or spring biased linkage means and second stored energy or overcenter spring means employed for operating the separable contact circuit interrupter and switch blade from and to the circuit closed positions. FIG. 8 is a view, partly in side elevation and partly in section, of a portion of the stored energy or spring means shown in FIGS. 5, 6 and 7. FIG. 9 is a longitudinal sectional view, at an enlarged scale, of the current sensor. FIG. 10 is a vertical sectional view, taken generally along the line 10-10 of FIG. 9. FIG. 11 is a view in end elevation, looking from right to left, of the terminal member employed in the current sensor shown in FIG. 9. FIG. 12, sheet 4, is a view at a reduced scale and somewhat similar to FIG. 9 to show the current sensor-in the operated condition. FIG. 13, sheet 5, is a perspective view showing the shaft that is mounted on the rear side of the door for mounting the several targets and associated equipment. FIG. l4-is a view, somewhat diagrammatic in character, showing the manner in which the current sensor is related to the operating mechanism. FIG. is a view, similar to FIG. 14, but showing the operated position of the current sensor and related parts, FIGS. 16, 17 and 18 are views of the current sensor and show how it is prevented from operating to trip the operating mechanism when the current flow in the circuit exceeds a predetermined value. FIG. 19 is a vertical sectional view, at an enlarged scale, showing the latch mechanism for preventing closure of the door once it has been opened after operation of the current sensor, the illustration he-re showing the latch mechanism in normal operating condition with the current sensor functioning normally. FIG. is a view, in side elevation, taken generally along the line 20-20 of FIG. 19 to show the latch mechanism. FIG. 21 is a view, similar to FIG. 19, but showing the door closed and the current sensor operated. FIG. 22 is a view, similar to FIGS. 19 and 21, showing the manner in which the latch mechanism prevents closure of the door once the current sensor has operated and the door has been opened. FIG. 23 is a view, similar to the lower right corner of FIG. 2, and shows how a conventional fuse can be employed in lieu of the current sensor shown in FIG. 2

Referring now to FIGS. 1, 2 and 3, the reference character 10 designates, generally, metal enclosed switchgear embodying this invention. The switchgear 10 includes a metallic housing 11 that is formed of sheet steel and it has rear and

front walls

12 and 13 with an opening 14 in the front wall 13 that is arranged to be closed by a door 15 which is hinged as indicated at 16. There will be described hereinafter the manner in which the door 15 is latched in the closed position. The metallic housing 11 also includes

side walls

17 and 18 and top and

bottom walls

19 and 20, the latter having suitable openings to per mit the positioning of energized conductors therethrough in accordance with conventional practice.

The external connections are made to upper and

lower terminal pads

21 and 22 which form parts of upper and lower stationary main contacts, shown generally at 23 and 24, and mounted on

suitable insulators

25 and 26 respectively. The

insulators

25 and 26 are stationarily mounted on

channels

27 and 28 that extend between the

side walls

17 and 18 and are suitably welded in position.

Forwardly of the upper and lower stationary main contacts 23 and 24 is a stationary insulating barrier 31 that is suitably apertured by the provision of upper and lower apertures 32 and 33 in alignment with the upper and lower stationary main contacts 23 and 24. A movable insulating shutter 34, having upper and

lower apertures

35 and 36 therein, is suitably mounted on the stationary insulating 4' barrier 31. The shutter 34 is arranged to be moved transversely of the stationary insulating barrier 31 in the manner described in the above identified Schockelt application for closing off the upper and lower apertures 32 and 33 when the door 15 is opened in order to prevent accidental engagement with the stationary main contacts 23 and 24 both of which may be energized. For moving the insulating shutter 34 in accordance with the movement of the door 15 a linkage, indicated at 37, can be employed. The linkage 37 is indicated diagrammatcially and may be constructed as described in the above identified Schockelt application.

Mounted on the door 15 for movement therewith are a switch blade 38, a separable contact circuit interrupter 39, and a current sensor indicated, generally, at 40. The switch blade 38, interrupter 39 and current sensor 40 are arranged to be connected in series circuit relation and, when the door 15 is closed, to interconnect the upper and lower main contacts 23 and 24. The separable contact circuit interrupter 39 is shown as being of the vacuum type. However, it will be understood that other types of separable contact circuit interrupters can be employed. Upper and

lower insulators

41 and 42, mounted on the inside of the door 15, serve to mount the switch blade 38, circuit interrupter 39 and current sensor 40 thereon.

The switch blade 38 comprises a pair of blade members 43, the distal ends of which are turned inwardly as indicated at 44 for cooperating with an ancuate flange 45 on the upper main contact 23 when the switch blade 38 is in the switch closed position. This arrangement provides one interlock which prevents opening of the door 15 when the switch blade 38 is in the closed position. It will be understood that the

upper apertures

32 and 35 in the insulating barrier 31 and movable shutter 34, when they are in alignment, permit swinging movement of the switch blade 38 therethrough from a position in front of the insulating barrier 31 to the switch closed position shown in FIG. 2. The pair of blade members 43 is suitably secured to opposite sides of a metallic plate 46 which is secured to a short shaft 47 for rotation therewith. The arrangement is shown more clearly in FIG. 3 where it will be observed that a polyphase switch construction is employed although it will be understood that the present invention can be employed for a single phase operation. Each short shaft 47 is journaled in suitable bearing support arms 49 that extend upwardly from a bearing support 50 which is suitably secured to the upper insulator 41 that is carried by the inside of the door 15. Contact engagement with the plate 46 is provided by contact fingers 53, FIG. 2, that extend upwardly from a contact fitting 54, FIG. 4, which is secured to the upper end of a movable contact rod that extends through a suitable bellows 56 into a vacuum housing 57 that may be formed of glass or other suitable insulating material. At its lower end the contact rod 55 carries a spring loaded movable contact 58 that is arranged to engage a stationary contact 59 mounted on the upper end of a stationary contact rod 60 which extends downwardly through the lower end of the vacuum housing 57 in suitable sealed relation thereto.

For moving the spring loaded contact 58 into and out of engagement with the stationary contact 59 only a slight translatory movement of the contact rod '55 is required. For this purpose an arcuate slot 63 is provided in the plate 46 which rotates with the switch blade 38 and, as shown in FIG. 4, is arranged to receive a roller 64 that is carried by a transverse pin 65 the ends of which project through slots 66 in the contact fitting 54. The ends of the transverse pin 65 are positioned between the lower end of adjusting screws 67 and arched leaf springs 68 the ends of which bear against the lower surfaces 69 of the slots 66. In this manner a resilient connection is provided between the switch blade 38 and the spring loaded movable contact 58 so that the latter is moved into good contact engagement with the stationary contact 59 without requiring precise movement of the plate 46 for effecting this operation. The arrangement is such that the spring loaded contact 58 is moved out of engagement with the stationary contact 59 to open the circuit between the upper and lower stationary contacts 23 and 24 before the switch blade 38 moves out of engagement with the upper stationary contact 23 and to close this circuit after the switch blade has moved into engagement with upper stationary contact 23.

A conductor 73, preferably in the form of a copper bus bar, is arranged to interconnect the stationary contact rod extending downwardly from the circuit interrupter 39 and the current sensor 40. The lower plate-like end 74 of the conductor 73 is arranged to have the current sensor 40 mounted thereon. The current sensor 40 is mounted directly on an upper contact plate 75 which has a plate 76 of insulation between it and the plate-like lower end 74 of the conductor 73. The reason for this construction will be apparent presently. A contact tongue 77, FIG. 2, extends from the upper contact plate 75 through the registering openings or apertures 33 and 36 in the stationary insulating barrier 31 and in the movable insulating shutter 34 to snake contact engagement with a bifurcated contact extension 78 from the lower line contact 24.

As shown in FIG. 3, for polyphase operation, insulating barriers 81 are suitably mounted on the inside of the door 15 to move therewith for increasing the insulation between the several phases and between them and ground. If desired, another insulating barrier can be employed to the left of the left phase here shown and between it and the adjacent side 17 of the metallic housing 11, if this additional insulation is deemed to be necessary.

The several short shafts 47 on which the switch blades 38 are mounted are arranged to be interconnected by corrugated insulators 82 and the insulator 82 at the right side of the polyphase installation is connected to an operating shaft 83. It will be understood that rotation of the operating shaft 83 effects conjoint rotation of the corrugated insulators 82 and of the switch blades 38 together with corresponding movement of the respective movable contact rods 55 and the movable contacts 58 of the several circuit interrupters 39. As will be described in more detail hereinafter, provision is made for rotating the operating shaft 83 by a first stored energy means or spring biased linkage means, indicated generally at 84, 'and by a second stored energy ,means or overcenter spring means, indicated generally at 85. The overcenter spring means 85 is mounted on a shaft 86 that is journaled by bearings 87, FIG. 3, on the rear side of the door 15. Secured to the shaft 83 is a sprocket 88 and trained over it is a chain 89 that is also trained over a sprocket 90 which is secured to a shaft 91 suitably journaled on the rear side of the door 15 and to which a manually operable handle 93 is secured. The handle 93 has a hand grip 94 and, as shown in FIG. 1, it is arranged to be located in a recess 95 in the door 15 when the handle 93 is in its uppermost position, as shown in FIGS. 1 and 2. The recess 95 also is arranged to receive it when it is rotated to its lowermost position.

FIGS. 5, 6, 7, and 8 show in more detail the arrangement, construction and operation of the spring biased linkage means 84 and the overcenter spring means 85. In these figures the manually operable handle 93, which is connected by the chain 89 to rotate the shaft 86, is shown as being mounted directly on the shaft 86 for rotation therewith. This is for illustrative purposes and to make more clear the functioning of the operating mechanism for the switch blade 38 and the circuit interrupter 39. Also for illustrative purposes the switch blade 38 is shown as being mounted on operating shaft 83, although it will be recalled that it is connected thereto mechanically through one or more of the corrugated insulators 82.

Mounted for rotation with the switch blade 38 and with shaft 83 is a pair of L-shaped switch levers 98.

They are pivotally connected at 99 to a pair of toggle links '100 which, as shown in FIG. 8, are arranged to straddle the L-shaped switch levers 98. The pair of toggle links 100 is pivotally connected at 101 to another pair of toggle links 102 which are pivotally connected at 103 to the upper end of an elongated guide member 104 which is provided with an elongated slot 105 along which the pivot 99 is arranged to move and to be guided thereby. A coil compression auxiliary spring 106 is interposed between a shoulder 107 at the lower end of the elongated guide member 104 and a washer 108 that is slidable on the guide member 104 and bears against the lower ends of the pair of toggle links 100. In order to limit the overcenter movement of the pairs of

toggle links

100 and 102 to their position as shown in FIG. 5, stop means '109 extend from the toggle links 100 in overlying relation to the toggle links 102. The toggle links 100 and 102 are biased to the right as viewed in FIG. 5 by a torsion or link spring 110 which, as shown in FIG. 8, is positioned around the pivot 101 with one end 111 reacting against the toggle links 100 and the other end 112 reacting against the toggle links 102. As long as the toggle joint, formed by the toggle links "100 and 102 in conjunction withthe guide member 104 and the coil compression spring 106, remains in the condition shown in FIG. 5, the entire spring biased linkage means 84 acts as a strut or lever for transmitting operating force to the switch levers 98 as provided by the overcenter spring means 85 under the control of the manually operable handle 93. As will appear hereinafter, provision is made for breaking the toggle joint and releasing the coil compression spring 106 to rotate the switch blade 38 to the open position after the circuit has been opened by the circuit interrupter 39 in response to operation of the current sensor 40.

The overcenter spring means 85 includes a drive lever 113 that is freely rotatable on the shaft 86 from a position against a stop 114 to an alternate position shown in FIG. 6. At one end the drive lever 113 is pivotally connected to the pivotal connection 103 at the upper end of the elongated guide member 104 and thereby is arranged to apply force thereto for rotating the shaft 83. The other end of the drive lever 113 comprises an extension 115. Freely rotatably mounted on the shaft 86 is a toggle lever 116 that is provided with laterally extending

pins

117 and 118 which are arranged to engage the drive levers 113 and the extensions thereof in a manner 'to be described. One end of the toggle lever 116 is pivotally connected at 119 to one end of a main spring guide tube 120 that is movable through a guide sleeve 121, FIG. 2, which is pivoted at 122 to an abutment 123 on the rear side of the door 15. A coil compression spring 124 surrounds the guide tube 120 and one end reacts against a shoulder 125 thereon while the other end reacts against a shoulder 126 that is carried by the guide sleeve 121. An operating arm 127, secured to the shaft 86 and, for illustrative purposes, shown as an extension of the manually operable handle 93 is arranged to engage one or the other of the

pins

117 or 118 for rotating the toggle lever 116 to a position slightly past the center position for charging the coil compression spring 124 to rotate the switch blade 38 through the spring biased linkage means 84 from the switch closed position shown by full lines in FIG. 5 to the switch open position shown by full lines in FIG. 6 and against a stop 128.

The switch blade 38 can be rotated from the switch closed position shown in FIG. 5 to the switch open posi tion shown in FIG. 6 either by operation of the spring biased linkage means 84 accompanied by discharge of energy stored in coil compression spring 106 or by operation of the overcenter spring means 85 accompanied by discharge of energy in the coil compression spring 124 which spring is substantially stronger than the spring 106.

In a manner to be described, the current sensor 40 is arranged to effect the opening of the switch blade 38 by breaking the toggle joint formed by the

links

100 and 102. For this purpose, an operating force is applied along the pair of toggle links 100 in a direction opposite to the direction in which the torsion spring 110 acts with the result that after the pairs of

toggle links

100 and 102 have been moved past their in line or center position, the coil compression spring 106 is permitted to expand, as shown in FIG. 7, with the toggle lever 116 remaining stationary as held by coil compression spring 124. The pivot 99 moves upwardly in the slot 105 and rotates the switch levers 98 to rotate the switch blade 38 to the open position and against the stop 128.

When the switch blade 38 is to be rotated to the open position by operation of the overcenter spring means 85 from the position shown in FIG. to the position shown in FIG. 6, the shaft 86 is rotated by the manually operable handle 93 through the agency of the chain 89. As described above, for illustrative purposes, the manually operable handle 93 is shown here as being connected directly tothe shaft 86. On rotation of the manually operable handle 93 in a clockwise direction, FIG. 5, the operating arm 127 is caused to engage the pin 117 and continued rotation rotates the toggle lever 116 and compresses the spring 124. The operation continues until the toggle lever 116 has been rotated slightly past the center position, shown by broken lines in FIG. 6, whereupon the spring 124 expands and rapidly rotates the toggle lever 116. The pin 117 engages the extension 115 of the drive levers 113 and rotates them away from stop 114. Under the assumed conditions the spring biased linkage means 84 remains in the condition shown in FIG. 5 so that the drive levers 113 are able to operate therethrough and to rotate the switch levers 98 in a clockwise direction and therewith the switch blade 38 to the open position against stop 128. The final position of the spring biased linkage means 84 and overcenter spring means 85 together with the manually operable handle 93 is shown by full lines in FIG. 6.

When it is desired to operate the switch blade 38 to the switch closed position, after it has been operated to the open position as described and as shown in FIG. 6, the manually operable handle 93 is rotated in a counterclockwise direction to bring the operating arm 127 into engagement with the pin 118. The toggle lever 116 then is rotated in a counterclockwise direction again to compress the spring 124. This operation continues until the pivot 119 is moved slightly past its center or in line position whereupon the spring 124 expands to continue the rotation of the toggle lever 116 in a counterclockwise direction. The pin 117 engages the juxtaposed side of drive levers 113 and thereby exerts a downward force on pivot 103 to operate through the spring biased linkage means 84 and rotate the switch levers 98 and therewith the switch blade 38 to the switch closed position. The manually operable handle 93 then is rotated to the uppermost position as shown in FIG. 1.

In the event that the switch blade 38 has been rotated to the open position by discharge of the energy of the spring 106 which forms a part of the spring biased linkage means 84 so that the mechanism occupies the position shown in FIG. 7, the next operation is to recharge spring 105 without causing any operation of the switch blade 38. This is accomplished by rotating the manually operable handle 93 in a clockwise direction for charging the spring 124 in the same way that it is charged for moving the switch blade 38 to the open position as above described. After the toggle lever 116 has been rotated past its center or in line position, as shown in FIG. 6, the spring 124 discharges to rotate the toggle lever 116 in the clockwise direction with the pin 118 picking up the drive levers 113 and rotating them in a clockwise direction to move pivot 103 upwardly and recharge or recompress spring 106. This is permitted since pivot 99 is held stationary by the switch levers 98 which are connected to the switch blade 38 and it is held against rotation by stop 128. The recharging of the spring 106 takes place because it is weaker than spring 124. The continued operation of the manually operable handle 93 to the lower position in the recess 95, FIG. 1, places the operating mechanism in the position illustrated by full lines in FIG. 6, corresponding to the open position of the switch blade 38.

In describing the operation of the switch blade 33 from and to the switch closed position, it will be tinderstood that, where a polyphase switch construction is employed, all three switch blades 38 are rotated simultaneors ly. Also, the arrangement is such that, in swinging the switch blade 38 or switch blades 38 to the open position, the circuit first is opened by the respective circuit inter rupter 39. When the switch blade or blades 38 are to tated toward the switch closed position, the arrangement is such that the switch blade or blades 38 engage the respective upper main stationary contact 23 and then the circuit is completed by closure of the respective circuit interrupter 39.

The details of construction of the current sensor 40 are shown in FIGS. 9, 10, 11 and 12. Here it will be observed that the

conductor plates

74 and 75, with the insulating plate 76 therebetween, are held together by flat head screws 131 which extend through insulating bushings 132 in the conductor plate 74. An internally threaded metallic guide bushing 133, preferably formed of copper, is secured to the upper contact plate and has threaded therein one end of a tubular metallic housing 134 that also is formed preferably of copper. At its distal end the tub ular metallic housing 134 is provided with a cap 135 of copper and it has an inwardly extending annular contact portion 136 that is arranged to be engaged, in a manner to be described, by contact fingers 137 which ext-end from a contact tube 138 that preferably is formed of copper and makes contact with the conductor plate 74. An insulating sleeve 139 serves to space the tubular metallic housing 134 from the contact tube 138.

In order to insulate normally the annular contact portion 136 from the contact fingers 137, an internal layer of insulation 140 is formed at one end of a metallic tension tube 141 which is slidably mounted within the contact tube 138 and extends outwardly therefrom. The metallic tension tube could be formed wholly of insulation. However, in order to provide the requisite strength within the limited confines of the contact tube 138, it has been found desirable to employ the metallic tension tube 141, preferably formed of steel, with the internal layer of insulation 140 in the manner described. Slotted openings 142 are located in diametrically opposite sides of the tension tube 141 and at the end opposite the layer of insulation 140. The inner ends of the slotted openings 142 form shoulders 143, FIG. 12, that are arranged to engage inner sides 144 of an end portion 145 of a terminal member 146, FIG. 11, which has a press fit with the outer end of the contact tube 138. The terminal member 146 preferably is formed of copper. The tension tube 141 extends past the end portion 145 of the terminal member 146 and through an opening 147 in the conductor plate 74. Its outer end is closed by a metallic end plug 148 that may be formed of aluminum. A coil compression spring 149 reacts between a shoulder 150 and the end surface of the end portion 145 for normally biasing the tension tube 141 outwardly.

In order to restrain the outward movement of the tension tube 141 as urged by coil compression spring 149, fusible means, shown generally at 152, are employed. Under normal operating conditions the fusible means 152 shunts the contact portion 135 and the contact fingers 137 extending from the contact tube 138. The fusible means 152 includes a fusible element 153 which may be a coil of silver wire. One end of the fusible element 153 is secured to the inner end of a terminal member 154, preferably in the form of a copper rod, which extends through the cap 135 and contact portion 136 and is secure-d thereto by a set screw 155. The other end of the fusible element 153 is secured to a hexagonal hea d 156 of a fuse element fitting, shown generally at 157, which is threaded at 158 into the adjacent end of a stem 159 which forms a part of the terminal member 146. The fusible means 152 also includes a strain element 160, preferably in the form of Nichrome wire, with one end being secured to the terminal member 154 and the other end extending through the fitting 157 and through the terminal member 146. The outer end of the strain element 160 extends through the metallic end plug 148 and is secured thereto by a set screw 161. Extending outwardly from the end plug 148 is a quick detachable fitting 162 the purpose of which will be described presently.

Normally the current path from the conductor plate to the conductor plate 74 is as indicated by the line with arrow heads and extends through the metallic guide bushing 133, tubular metallic housing 134, cap 135, terminal member 154, fusible means 152, fuse element fitting 157, terminal member 146, and contact tube 138 to the conductor plate 74'. The fusible means 152 are arranged and constructed to carry the normal current flow of the circuit in which the current sensor 40 is connected and also to withstand the flow of overload current in accordance with conventional fuse practice. The time-current characteristic for the fusible means 152 is selected in accordance with the circuit requirements. When the current flow exceeds the rating of the current sensor 40, the fusible element 153 melts and the entire current flow then is transferred to the strain element 160 which promptly melts and releases the end plug 148 for movement outwardly to the position shown by broken lines in FIG. 9 under the infiuence of the coil compression spring 149. This is accompanied by endwise movement Of the tension tube 141 and by withdrawal of the layer of insulation 140 from between the annular contact portion and the adjacent ends of the contact fingers 137. Their inherent resiliency is sufficient to move them into contact engagement with the contact portion 136, aided by the magnetic forces generated by current flow in the closely adjacent housing 134 and contact fingers 137, with the result that the gap formed by blowing of the fusible means 152 is promptly shunted. The reason for this shunting arrangement is that the current sensor 40 is not intended to have any current interrupting capacity. The current flow then, as shown by the broken line in FIG. 12, is transferred to flow directly from the conductor plate 75 through the metallic housing 134 and the contact fingers 137 of the contact tube 138 to the conductor plate 74. Here the tension tube 141 is moved to its outermost position as limited by engagement of the shoulders 143 with the inner sides 144 of the end portion 145.

Instead of providing the layer of insulation on the inside of metallic tension tube 141, the outer surface of the contact portion 136 can be coated with a suitable insulating material which can be readily punctured when the voltage resulting from the blowing of the fusible means 152 is applied between the contact portion 135 and the contact fingers 137. However, the tension tube 141 still is employed, although not of the same length, to provide a member that moves from one position to another as a result of blowing of the fusible means 152.

As shown in FIGS. 13 to 18, use is made of the blowing of the fusible means 152 in the current sensor 40 for tripping the spring 'biased linkage means 84 to open the circuit interrupter 39, followed by opening of its switch blade 38. Again only the switch blade 38 is referred to but it will be understood that the sequence of operations is as previously described and that the circuit interrupter 39 first is opened, followed by movement of the switch blade 38 out of contact engagement with the respective upper stationary contact 23. Referring specifically to FIG. 14, the quick detachable fitting 162 is shown as restraining downward movement of a link 166 that is pivoted at 167 on an car 168 which is carried by the underside of the conductor plate 75. Pivoted at to the other end of the link 166 is a rod 170 that is formed of insulation and is pivoted at 171 at its upper end to a lever 172 which is rotat-ably mounted on a shaft 173, FIG. 13, that is journaled in suitable bearings 174,

FIG. 3, on the inside of the door 15. A coil tension spring 175 serves to bias the lever 172 in a counter clockwise direction. This is the same direction in which the lever 172 is rotated by the coil compression spring 149 of the current sensor 40 on blowing of the fusible means 152. The upper end of the coil tension spring 175 is anchored to an arm 176 that extends rearwardly from the inner side of the door 15. A target 177, carried by the lever 172, moves with respect to a window 178 in the door 15, FIGS. 1 and 2, and it carries suitable indicia to indicate the condition of the current sensor 40 associated therewith and whether or not it is in the operating or the blown condition.

Rotation of the lever 172, on blowing of the current r sensor 40, causes rotation of a detent 180 which is carried by an arm 181 that is secured to the shaft 173 for rotation therewith. In this manner on blowing of any one of the three current sensors 40, the shaft 173 will be rotated and, as will be described presently, all of the switch blades 38 and associated circuit interrupters 39 are opened.

It may be desirable to prevent, momentarily, the opening of any of the circuit interrupters 39 followed by opening of the associated switch blade 38 when the current flow exceeds the interrupting capacity of the circuit interrupter 39. For this purpose a magnetic latch mechanism, shown generally at 184, is employed. Its operation is shown more clearly in FIGS. 16, 17 and 18. The magnetic latch mechanism 184 includes a latch arm 185 that is pivoted at 186 to the conductor 73 from which the conductor plate 74 extends underneath the current sensor 40. A detent 187 at the lower end of the latch arm 185 is arranged to underlie the outer end 188 of the link 166 and it is held out of underlying engagement therewith by a coil compression spring 189 which is mounted on a guide bolt 190 that extends through the lower end of the conductor 73. The distal end 191 of the guide bolt 190 extends through the distal end of a lever 192 which is pivoted at 193 to the latch arm 185 intermediate its ends. The lever 193 carries a plate 194 of magnetic material that is located close to the conductor 73 and is arranged to be attracted by the magnetic field generated by current flow therethrough. The arrangement is such that the spring 189 holds the plate 194 of magnetic material away from the conductor 73 and thus the detent 187 is held out of underlying relation to the outer end 188 of the link 166 until the force exerted by the magnetic field generated by flow of current through the conductor 73 is sufiicient to attract the plate 194. When this occurs on flow of predetermined current in excess of that capable of being interrupted by the circuit interrupter 39, the detent 187 is swung underneath the outer end 188 of the link 166 and it is prevented, as shown in FIG. 17, from moving downwardly sufiiciently far to rotate the lever 172 and cause rotation of the shaft 173. However, the tension tube 141 is permitted to move outwardly under the influence of spring 149 to the position shown in FIG. 17 which movement is sufiicient to remove the layer 140 of insulation from between the contact portion 135 and the contact fingers 137 and they are permitted to shunt the gap formed by blowing of the fusible means 152. As soon as the circuit is opened by some external circuit interrupting means, such as a high duty circuit breaker, and the current flow through the conductor 73 is reduced, the plate 194 of magnetic material no longer is attracted and the spring 189 expands to move the latch arm 185 so that the detent 187 no longer underlies the outer end 188 of the link 166. Then, as shown in FIG. 18, the link 166 is permitted to move downwardly to its full extent under the influence of the coil compression spring 149. The lever 172 then is effective to rotate the shaft 173 aided by spring 175.

The rotation of the shaft 173 in response to operation of any one of the current sensors 40 is arranged to effect the opening of all of the switch blades 38 after the respective circuit interrupters 39 have opened. For this purpose, as shown in FIG. 13, a bell crank 197 is secured to the shaft 173 for rotation therewith. One arm 198 of the bell crank 197 is pivotally connected at 199 to the lower end of a link 200, the upper end of which is pivotally connected at 201, FIG. 14, to an operating lever 202 which is freely rotatably mounted on the shaft 83. At its other end the operating lever 202 carries a roller 203 that is arranged to engage the pair of toggle links 100 of the spring biased linkage means 83 and to move the

links

100 and 102 past their center position whereupon, as previously described, the energy stored in the coil compression spring 106' is released to rotate the switch levers 98 and effect operation of the circuit interrupters 39 followed by the opening of the switch blades 38.

The other arm 204 of the bell crank lever 197 is arranged to be operated by a reset button 205 which is located in the door 15, FIG. 1. When the reset button 205 is depressed, the bell crank 197 is rotated to return the operating lever 202 to the position shown in FIG. 14 from the operated position shown in FIG. 15 where the toggle links 100 and 102 are shown in the operated position which corresponds to the open position of the switch blade 38.

It is desirable to prevent manual operation of the handle 93 from its uppermost position until the operating linkage has been reset by operation of the reset button 205 which is permitted only when all of the current sensors are in place and in proper operating condition.

For this purpose an arm 208, FIG. 13, is secured to the shaft 173 for rotation therewith. At its distal end the arm 208 is pivotally connected at 209 to a link 210, FIGS. 14 and 15, the upper end of which is pivotally connected at 211 to a lever 212 which is pivoted intermediate its ends at 213 on the rear of the door 15. A detent 214 carried by the other end of the lever 212 is arranged to enter a notch 215 in a disc 216 which is mounted on and is rotatable with the shaft 91 on which the handle 93 is mounted for rotation therewith.

As shown in FIGS. 3 and 19 to 22, a latch mechanism, illustrated generally at 220, is employed for preventing closure of the door 15 once it has been opened after any one of the current sensors 40 has operated and the shaft 173 has been rotated in the manner described for tripping the spring biased linkage means 84 to the operation position shown in FIG. 7. The latch mechanism 220 includes an arm 221 that is secured to the shaft 173 for rotation therewith. The arm 221 carries a detent 222 that is arranged to be connected by a coil tension spring 223 to a latch lever 224 and also to underlie it. The latch lever 224 is freely rotatably mounted on the shaft 173 and it has a nose portion 225 that is arranged to project through an opening 226 in a housing flange 227, FIG. 3, that forms a part of the metallic housing 11. At its opposite end the latch lever 224 has a cam surface 228 that cooperates with the adjacent inner surface of the door 15.

In FIG. 19 the normal position of the latch mechanism 220 is shown. Here the nose portion 225 of the latch lever 224 extends through the opening 226 in the housing flange 227 and the detent 222 underlies the latch lever 224 since the shaft 173 is assumed to be in the normal non-operated position. FIG. 21 shows the operation that results from rotation of the shaft 173 in the manner above described. The arm 221 rotates with the shaft 173 and tensions the spring 223. However, the latch lever 224 remains in the previous position, as shown in FIG. 19, since its nose portion 225 extends through the opening 226 in the housing flange 227. Now, when the door 15 is moved to the open position, as shown in FIG. 22, it carries with it the shaft 173 and withdraws the nose portion 227 from the opening 226 in the housing flange 227. The spring 223 then rotates the latch lever 224 to the position here shown where the nose portion 225 lies below the opening 226 and the cam surface 228 wedges 12 against the juxtaposed inner surface of the door 15. If an attempt is made to close the door 15, the nose portion 225 engages the housing flange 227 and prevents the closure of the door 15.

It is desirable that provision be made for preventing rotation of the switch blade 38 or the switch blades 38 when the door is opened. For this purpose the interlocking mechanism disclosed in the Beebe et al. patent above referred to can be employed. As shown in FIG. 1 the door 15 is provided with a door handle 231 that is arranged to move a latch bar 232 at the ends of which latch members 233 are connected for rotation into and out of engagement with fixed latch members 234 that are suitably mounted on the metallic housing 11. The interlocking mechanism is provided by a pivotally mounted pawl 235 that is biased by a spring 236 and is controlled by a flexible wire 237 which forms a part of a control cable that is indicated, generally, at 238. The control cable 238 also includes a stationary sleeve 239 which, as shown in FIG. 14, has the flexible wire 237 projecting therefrom for connection at 240 to a locking lever 241 which is pivotally mounted intermediate its ends at 242 on the side wall 18. The locking lever 241 is arranged to cooperate with a cam 243 which is mounted on the shaft 83 for rotation therewith. The arrangement is such that, when the door 15 is open, the spring 236 is effective through the flexible wire 237 to rotate the locking lever 241 into engagement with the cam 243 and thus prevent rotation of the switch blade or blades 238.

Windows 245 are provided in the door 15, FIG. 1, to permit visual inspection of the switch blades 38 and the upper stationary contacts 23 through the

upper apertures

32 and 35 in the stationary insulating barrier 31 and in the movable insulating shutter 34 without requiring that the door 15 be opened.

As shown in FIG. 23, instead of employing the current sensor for interconnecting the circuit interrupter 39 and the respective lower line contact 24, a solid material fuse, shown generally at 248, can be employed. Also a current limiting fuse can be used, if desired. The fuse 248 is mounted in suitable fuse. clips on the upper and

lower insulators

41 and 42 that are carried by the door 15. A relatively short conductor 249 interconnects the upper end of the fuse 248 with the contact rod of the respective circuit interrupter 39. A contact tongue 250 extends from the lower fuse terminal through the openings 33 and 36 in the stationary insulating barrier 31 and in the movable shutter 34 for contact engagement with the bifurcated contact extension 78 from the lower line contact 24. A mufller or condenser 251 is located at the lower end of the fuse 248, if it is of the solid material type, for condensing and confining the arc blast therefrom. a

What is claimed as new is:

1. Metal enclosed switchgear comprising a metallic housing having walls with at least one wall including a door,

means mounting said door on said housing for movement between open and closed positions,

a pair of stationary contacts mounted in said housing in insulated spaced relation,

switch blade means in said housing for engaging and disengaging one of said stationary contacts, a means rotatably mounting said switch blade means on said door,

circuit means including separable contact arc extinguishing circuit interrupter means on said door interconnecting said switch blade means and the other stationary contact, and

operating means on said door for rotating a distal end of said switch blade means into and out of engagement with said one stationary contact and for opening and closing the contacts of said separable contact are extinguishing circuit interrupter means in predetermined sequence with rotation of said switch blade.

2. Metal enclosed switchgear according to claim 1 wherein means interconnect said operating means and said separable contact circuit interrupter means to open the circuit between 'said stationary contacts before said one stationary contact is disengaged by said switch blade means and to close said circuit after said one stationary contact has been engaged by said switch blade means.

' 3. Metal enclosed switchgear according to claim 2 wherein said circuit means also includes current responsive means in series with said separable contact circuit interrupter means, and 7 means is responsive to operation of said current responsive means on flow of predetermined current through said circuit means for opening the contacts of said circuit interrupter means and disengaging said switch blade means from said one stationary contact.

4. Metal enclosed switchgear according to claim 3 wherein said current responsive means includes fusible means interconnecting a pair of fuse terminals, and

means are provided for shunting said fuse terminals after blowing of said fusible means.

5. Metal enclosed switchgear according to claim 3 wherein means responsive to flow of current in said circuit means in excess of a predetermined value prevent Opening of said contacts of said circuit interrupter means until after said current flow is reduced below said predetermined value.

6. Metal enclosed switchgear according to claim 3 wherein locking means on said metallic housing cooperate with said door to prevent closure thereof after said current responsive means has operated and said door has been opened until said current responsive means has been restored to operative condition.

7. Metal enclosed switchgear according to claim 3 wherein said operating means includes first stored energy means operated in response to said current responsive means for opening the contacts of said circuit interrupter means and opening said switch blade means,

second stored energy means arranged to operate through said first stored energy means, and

means for charging said second stored energy means to operate said separable contact circuit interrupter means, to move said switch blade means to and from engagement with said one stationary contact, and to return said first stored energy means to charged condition after the same has operated.

8. Metal enclosed switchgear according to claim 7 wherein two additional pairs of stationary contacts are mounted in insulated spaced relation in said housing and thereby provide a polyphase arrangement,

two additional switch blade means, separable contact circuit interrupter means, and current responsive means are mounted on said door for interconnecting the respective additional pairs of stationary contacts, and

said operating means is common to all of said switch blade means, said separable contact circuit interrupter means, and said current responsive means.

9. Metal enclosed switchgear according to claim 2 wherein said circuit means also includes a fuse device in series with said separable contact circuit interrupter means.

10. Metal enclosed switchgear according to claim 1 wherein means interlock said door and said switch blade means and includes shoulder means on said one stationary contact, and

shoulder means on said switch blade means arranged to cooperate with said shoulder means on said one stationary contact at least when said switch blade means is in the switch closed position.

11. Metal enclosed switchgear according to claim 1 wherein means interlock said door and said switch blade means and includes locking cam means movable with said switch blade means,

manually operable latch means on said door and cooperable latch means on said metallic housing, and

means interconnecting said cam means and said latch means on said door and preventing operation thereof to unlatch said door when said switch blade means is in the switch closed position.

12. Metal enclosed switchgear according to claim 1 wherein a stationary insulating barrier is positioned in said housing between said wall including said door and said pair of stationary contacts, said barrier being apertured to receive therethrough said switch blade means for connection to said one stationary contact,

an insulating shutter is movable with respect to said stationary insulating barrier, and

means interconnect said door and said insulating shutter to move the latter and close off said apertured barrier when said door is opened.

13. Switchgear comprising a pair of stationary contacts in insulated spaced relation;

means interconnecting said stationary contacts including in series switch blade means,

current interrupter means, and

fusible means having contact means in parallel therewith for shunting the same on blowing thereof; and

operating means responsive to blowing of said fusible means for opening said current interrupter means and subsequently opening said switch blade means.

14. Switchgear according to claim 13 wherein said current interrupter means is a vacuum type interrupter.

15. Switchgear according to claim 13 wherein means are provided for opening and closing said switch blade means and said current interrupting means with the connection between the last named means and said switch blade means and said current interrupting means being trip free in the event that the circuit is completed on a fault suflicient to blow said fusible means.

16. Switchgear comprising a pair of stationary contacts in insulated spaced relation;

current interrupter means, and

operating means responsive to blowing of said fusible means for opening said current interrupter means and subsequently opening said switch blade means,

said operating means including first stored energy means operated in response to blowing of said fusible means for opening said load current interrupter means and thereafter said switch blade means,

means for charging said second stored energy means to operate said current interrupter means and said switch blade means, and to return said first stored energy means to charged condition after the same has operated.

17. Switchgear according to claim 16 wherein means responsive to flow of current in said means interconnecting said stationary contacts in excess of a predetermined value prevent opening of said current interrupter means and of said switch blade means by said first stored energy means until after said current flow is reduced below said predetermined value.

18. Switchgear according to claim 16 wherein said switch blade means includes a switch blade rotatable about a fixed axis;

said first stored energy means includes a switch lever connected to said switch blade,

a guide member movably mounted on the distal end of said switch lever,

an auxiliary spring reacting between said guide member and said switch lever and biasing it toward switch open position,

a pair of toggle links pivoted together at one end and at their other ends to said switch lever and to said guide member respectively,

stop means on one of said toggle links cooperating with the other toggle link to limit relative movement thereof in one direction to a position slightly past the center position, and, p

a link spring biasing said links against said stop means.

19. The switchgear according to claim 18 wherein said second stored energy means includes a drive lever rotatable about a fixed axis and pivotally connected to said guide member and to that one of said links pivoted thereto,

a toggle lever rotatable about said axis about which said drive lever is rotatable,

an overcenter spring mechanism connected to said toggle lever,

means for rotating said toggle lever to charge said overcenter spring mechanism by moving the same from either side of its center position to slightly past said center position thereof whereupon it discharges energy stored therein and rotates said toggle lever, and

means on said toggle lever engageable with said drive lever to move said guide member and links generally endwise to rotate said switch blade from and to switch closed position depending upon the direction of rotation of said toggle lever; and

spring biased linkage means interconnecting said fusible means and said pair of toggle links and acting to move the same in the direction in which said link spring acts and past said center position of said links whereupon said auxiliary spring rotates said switch blade to open position,

rotation of said toggle lever by said overcenter spring mechanism after said switch blade has been moved to open position acting to return said toggle links to said position thereof slightly past their center position and to recharge said auxiliary spring.

20. Switchgear according to claim 16 wherein means responsive to blowing of said fusible means prevents operation of said second stored energy means to return said first stored eenrgy means to charged condition until after the blown fusible means has been replaced.

References Cited UNITED STATES PATENTS 974,109 11/1910 Avel et al. 1,292,807 1/ 1919 Krantz. 1,352,044 9/1920 Baruch. 2,400,408 5/ 1946 Haefelfinger 200-1 18 2,636,955 4/1953 George 2001l4 2,810,805 10/1957 Schwager. 2,914,635 11/1959 Lester et al. 3,055,996 9/1962 Beebe et a1. 3,238,332 3/1966 Mikulecky 200 3,268,696 8/1966 Lindell. 3,280,282 10/1966 Rodeseike et al.

FOREIGN PATENTS 421,416 12/1934 Great Britain.

BERNARD A. GILHEANY, Primary Examiner.

GEORGE HARRIS, J 11., Assistant Examiner.