US2362798A - Electric switchgear - Google Patents

Description

Nov. 14, 1944. R. E. BOLD ELECTRIC SWITCHGEAR Filed June 30, 1942 2 Sheets-Sheet l R m M a u C m Inventor: Ralph E.;Bold,

a. 174 414 His Attorneylay R. E. BOLD ELECTRIC SWITCHGEAR Filed June 30, 1942 "i ov. 14, 1944.

2 Sheets-Sheet 2 Inventor. 7 Ralph E Bold, by His Attorney.

Patented Nov. 14, 1944 nmc'rarc swrrcnema 7 Ralph E. Bold, was run, Pa., assignor to General Electric Company, a corporation of New York Application June 30, 1942, Serial No. 449,111

10 Claims.

My invention relates to electric switchgear and more particularly to station type switchgear for gas blast circuit breakers wherein a circuit breaker, together with its gas supply tank, operating and control mechanism and conduits or fines for exhaust gases are mounted on a supporting frame orpllbicle so as to constitute a unit assembly.

My invention has for its principal object the provision of improved switchgear of the aforesaid type that provides ready accessibility to the unit without sacrificing simplicity in design and efficiency in operation that also provides for proper cooling and venting of the exhaust arc gases so as substantially to preclude danger of fiashover.

In the compact unit type switchgear above referred to, the disposal of highly heated arc gases ejected from the gas blast circuit breakers incident to large current interruptions presents certain problems, not only in respect to flashover but also in respect to the accessibility and maintenance of the switchgear unit. This is due to the comparatively long exhaust passages through which the hot arc gases must be directed and cooled before they can be vented in the vicinity of high tension electrical apparatus. If this were not done there would'be danger of voltage breakdown or flashover due to the presence of conducting gases near live conductors. Also attendants might be burned iftoo near the exhaust vents. The aforesaid exhaust passages are generally defined by insulating pipes or conduits extending for some distance from the circuit breakers. In one form of unit type switchgear the gas exhaust pipes extend vertically from the phase circuit breakers so as separately to exhaust at or beyond the top of the unit. Since the circuit breakers are generally at the front of the unit this arrangement interferes materially with the mechanism compartmerit, for example, thereby making inspection of the operating and control equipment practically.

impossible without disassembling and removing the gas exhaust pipes. I

In accordance with my invention the insulating passages directly connected to the phase circuit breakers lead into a cpmmon exhaust conduit o'r header having. in mm lateral extension passages, all provided with gas cooling means for preventing flashover between phases and for insuring arc gases before final venting. The exhaust conduit and its lateral passages are so located with respect to the essential appar'atusoi the switchgear unit that inspection and maintenance or the sumcient cooling'and Tie-ionization oi the.

equipment {are readily possible without disasembling the structure.

My invention will be more fully set forth in the following description referring to the accompanying drawings, and the features of novelty which characterize my invention will be pointed out with particularity in the claims annexed to and forming apart of this specification.

Referring to the drawings, Fig. 1 is a perspective view, partly in section, of a station type switchgear unit for gas blast circuit breakers embodying the present invention, Fig. 2 is a similar view showing another form of my invention, Fig. 3 is a partial perspective view of a switchgear unit showing a modification of the arrangement shown in- Fig. 1, and Fig. 4 is a partial view of another form my invention may assume.

The switchgear unit shown by Fig. 1 comprises a m'ainsupporting frame I forming a box-like metal housing or cubicle. The housing may comprise sheet metal and structural forms suitably fabricated to form a self-sustaining rigid unit. In the lower part of the housing at the front thereof are located the circuit breakers 2a, 2b and 20, a three-phase installation being illustrated. The circuit breakers per se which are of the gas blast type may be of any suitable construction such as that disclosed and claimed by Prince et a1, Patent No. 2,284,842 issued June 2, 1942, for Circuit breaking apparatus" and assigned to the same assignee as the present invention.

Each circuit breaker which comprises anenclosed chute-like structure 2 'of mechanically strong insulating material is supported on and insulated from the lower floor 3 of the grounded metal housing by insulators 4. The essential parts of each circuit breaker (taking the phase 2a, for example) comprises a gas supply pipe 5 for directing the are extinguishing gas under pressure to the arc chute 2, relatively movable contacts including a vertically movable blade contact 5 and a coacting fixed contact (not shown) within the chute connected to the fixed contact terminal 1 arranged so as to draw the arc, transj versely of the incoming gas blast from the pipe ll, suitable arc extinguishing structure (not shown) within the chute and an insulating as exhaust conduit 8 for leading. away harmlessly highly heated arc gases from the chute. The

electric circuit for the breaker includes the upper contact terminal 9 with which the movable blade 6 is in sliding conducting engagement and which is also electrically connected through the rear wall "I of the housingto the power line by an insulated lead-in-conductor indicated at H and the fixed contact terminal 7 which also is connected with the power line through the lower wall 3 of the housing.

The phase circuit breakers are separated by metal walls l2 thereby dividing the lower circuit breaker housing space into three separate compartments for the circuit breakers and the associated phase conductors. The upper part of the housing forms a mechanism and control compartment 13 in which are mounted the gas storage supply tank 14, a blast control valve l5 for controlling flow of the interrupting gas from the tank through the main gas supply conduit IE to the individual phase supply lines 5, and suitable operating mechanism (not shown) for the threephase circuit breaker. In certain cases it may be desirable to mount the gas supply tank l4 outside the compartment I3 011 the side of the frame. The operating mechanism which may be of the motor-cam or pneumatic types, for example, is connected to the movable contact insulating rod ll of each circuit breaker so that opening movement of the mechanism causes simultaneous upward movement of the blade contact 6 in proper relation to opening of the blast valve for opening the circuit. The circuit breaker is closed to the position shown by downward movement of the rods ll.

The mechanism and control compartment also houses the usual auxiliary devices and switches, relays, etc., for insuring proper operation of the circuit breaker mechanism and the blast valve Ii. Since my invention does not depend on either the form of operating mechanism or th particular type or design of such auxiliary devices, etc., I have not in the interests of clearness and simplicity shown them in the patent drawings. The front of the compartment I! may be provided with a detachable cover plate l8 so that inspection and maintenance of the equipment may readily and conveniently be had from the front of the housi g.

For the purpose of more eiilciently and completely cooling the arc chute'exhaust gases and for eliminating interference between the gas exhaust passages and the compartment I3, I provid a common exhaust header I! of comparatively large cross sectional area into which each of the exhaust conduits 8 directs the hot chute gases that accompany a heavy current interruption. The header I9 i horizontally located at the bottom of the compartment is along the front thereof and offset with respect to direct access to the equipment for operating the circuit breaker so as to leave substantially clear the space other wise occupied by the control equipment. This positioning of the header also provides for material spacing of the header from the arc chutes. The header is provided at its opposite sides with vertical extensions 2! and 2| which extend along the front inner sides of the compartment I! so as to leave clear the control equipment space. The extension passages 2| and 2| can thus vent harmlessly the exhaust gases as indicated at the top of the switchgear unit where, it will be noted, no high tension apparatus is located.

In addition to the long and comparatively spacious exhaust venting es, other means are provided for more intensively cooling the gases. For this purpose metallic cooling structures are located in the insulating conduits I at 22 and in the extension passages 20 and 2| at 28. These cooling structures may comprise, for example, corrugated metal sheets concentrically or 75 5 interfere with free venting while presenting a large heat transfer surface to the gases.

Two coolers in series in each chute exhaust pipe 8 serve sufliciently to cool the gas before reaching the metal header 19 to prevent an inter- 10 phase fault through the conducting structure thereof. The additional coolers 23 in the header extensions serve further to cool the gas to such extent that danger from flashover at adjacent equipment and injury to attendants are substantially precluded. In certain cases, it may be desirable to locate coolers in the header l 9 between the phase exhaust pipes 8, for example.

Where it is preferable to vent the gases at the rear of the unit, the arrangement of Fig. 1 may be modified as shown by Fig. 3. Here, the header is provided with horizontal lateral extensions 24 and 25 located along the bottom sides of the compartment l3 so as to vent the gases at the rear. Coolers 26 are also located in the extension pas- 5 sages as in the manner of Fig. 1. This arrangement also provides a free space for inspection and maintenance of equipment from the front without sacrificing efllciency and safety in the method of gas venting.

30 Fig. 2 illustrates substantially the same type switchgear as shown by Fig. 1 except that the high tension conductors a d the circuit breakers are disposed at the top of t e unit out of ordinary reach and the operating and control mechanisms are located in the lower part of the housing at ground potential. In this arrangement the circuit breakers are suspended from the top wall 21 of the breaker compartment by insulators 28 and the chute exhaust pipes 8 lead downward to a common header of large cross sectional area at 2!,

the header in this case being located at the top and front sides of the lower compartment.

A large single conduit 30 depending from the midsection of the header 28 directs the header gases downwardly to the bottom of the unit to a lateral extension II which forms with the conduit 3. an inverted T-section. The lateral extension II at its opposite ends along the front thereof is provided with vent openings in which 5 gas coolers I2 are located for insuring sufliciently complete cooling of the vented exhaust gases. In this case, a completely free space across the entire front of the lower compartment is unnecessary since the equipment to be inspected can in certain instances be grouped so that the pneumatic control devices, for example, may be located in space 33 and the electric auxiliary devices, etc., for breaker operation may be located in space 34, the gas storage supply tank then being located at the rear of the lower compartment In the type switchgear shown by Fig. 4 the header is located horizontally at 35 substantially at the same level as the phase are chutes 2. Here the interrupting duty is such that the chute exhaust tubes 38 can be comparatively short between the chutes and header. Extending laterally in a vertical direction from the header are exhaust venting pipes 31 which, as in the previous instance, can be provided with coolers and can be located at the sides of the supporting frame I for venting the gases harmlessly at the top of the switchgear. In the form of breaker shown, the lead-in conductor bushings I8 and 39 depend from the frame so that the lower terminal of the conductor at II is connected to the fixed contact (not shown) within the arc chute and the lower terminal of the conductor at H is electrically connected by sliding engagement to the movable blade contact 6. The blade 6 is movable horizontally through a side wall of the chute 2 to cooperate with the fixed contact by a suitably actuated crank arm 42. The are gap formed within the chute upon separation of the contacts is traversed by a gas blast from a supply pipe 43 as in the previous instance. The operating and control mechanism and the gas supply tank are not shown in the interest of simplicity and may be conveniently supported on the frame I at the pper or lateral sides thereof.

It will be noted that in each arrangement the chute exhaust gases are mixed and cooled in the comparatively large header space as indicated by the flow-direction arrows before being directed to the final exhaust passages wher they are again cooled and reduced in velocity to permit more efficient heat transfer. In addition to providing a more efficient switchgear unit from the standpoint of inspection and maintenance, the header and header extension spaces provide complete flame control since the velocity of the gases is so reduced that mixing of hot partially burned and combustible gases with the air takes place before final venting. Incandescent unburned carbon particles, for example, thus have an opportunity to unite with oxygen and to burn completely befor being vented in the form of flame to the atmosphere.

It should be understood that my invention is not hunted to specific details of construction and arrangement therebf herein illustrated, and that changes and modifications may occur to one skilled in the art without departing from the spirit of my invention.

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

1. Electric switchgear of the compact unit type comprising a supporting frame, a p01 phase circuit breaker of the gas blast type mounted in saidv frame at one end thereof, means for operating and controlling said circuit breaker mounted in said frame at the opposite end thereof in alignment with said first mentioned means, a gas storage supply tank mounted on said frame, said circuit breaker having separate phase units each arranged to be directly supplied with gas under pressure from said tank, an exhaust pipe for each unit for venting hot arc gases therefrom, an exhaust header common to and communicating with each of said exhaust pipes, said header being perpendicularly arranged with respect to said cuit breaker of the gas blast type mounted in said frame at one-end thereof, means for operating said circuit breaker including a gas storage supply tank mounted in said frame at the opposite end thereof and vertically spaced from said circuit breaker, said circuit breaker having separate phase units each arranged to be supplied with gas under pressure from said tank, an exhaust pipe for each unit for venting highly heated arc gases therefrom, an exhaust header common to and communicating with each of said exhaust pipes, said header being horizontally located at approximately the midsection of said supporting frame with reference to said ends thereof a material distance from said units and arranged so as to avoid obstructing access to said circuit breaker operating means, and additional venting passages having gas cooling structure communicating with said header for completely cooling the vented exhaust gases, said additional passages being arranged in said opposite end of said frame at either end of said header also so as sub stantially to avoid obstructing access to said oir cuit breaker operating means.

3. Electric switchgear of the compact unit type comprising a cubicle typ supporting frame, a polyphase gas blast circuit breaker mounted in said frame at the lower part thereof, means for operating said circuit breaker including a gas storage supply tank mounted in said frame at the upper part thereof, said circuit breaker hav ing separate phase units each arranged to be supplied with gas under pressure from said tank, an exhaust pipe extending vertically from each said unit for venting hot arc gases therefrom, an exhaust header'common to and communicating with each of said exhaust pipes, said header being located at an intermediate part of said supporting frame between said units and said circuit breaker operating means so as to avoid obstructing access to said circuit breaker operatin means, and extension passages extending from opposite ends of said header along the opposite sides of said frame at said upper part so as also to avoid obstructing access to said circuit breaker operating means, said header extension passages forming with said header a U-shaped section for venting said exhaust gases harmlessly at the upper part of said frame.

4. Electric switchgear of the compact unit type comprising a cubicle type supporting frame, a polyphase gas blast circuit breaker mounted in said frame at the lower part thereof, means for operating said circuit breaker including a. gas storage supply tank mounted in said frame at the upper part thereof, said circuit breaker having separate phase units each arranged to be supplied with gas under pressure from said tank, an exhaust pipe extending vertically from each unit for venting arc gases therefrom, an exhaust header common to and communicating with each of said exhaust pipes, said header being horizontally located at an intermediate part of said supporting frame so as to avoid obstructing access to said circuit breaker operating means, and an extension cooling passage extending vertically from each end of said header to the top of said frame along the opposite sides of said frame so as also to avoid obstructing access to said circuit breaker operating means.

5. Electric switchgear comprising a cubicle type supporting frame, a polyphase gas blast circuit breaker mounted in said frame at the upper part thereof, means for operating said circuit breaker includinga gas storage supply tank mounted in said frame at the lower part thereof, said circuit breaker having separate phase units each arranged to be supplied with gas under pressure from said tank, an exhaust pipe extending vertically downward from each unit for venting arc gases therefrom, an exhaust header common to and communicating with each of said exhaust pipes, said header being horizontally located at an intermediate part of said supporting frame so as to avoid obstructing access to said circuit breaker operating means, and aninverted T- shaped venting passage extending downward from said header for venting the exhaust gases at opposite sides of said frame at the bottom thereof, said inverted T-shaped passage arranged centrally of the lower part of said frame so as.

not materially to obstruct access to said circuit breaker operating means.

6. Electric switchgear of the compact unit type comprising a supporting frame, a polyphase circuit breaker of the gas blast type including operating means therefor mounted in said frame, said circuit breaker having separate phase units at the lower part of said frame each arranged to be supplied with gas under pressure from a pressure source, an exhaust pipe for each unit for venting arc gases therefrom extending horizontally from said unit, an exhaust header horizontally mounted on said frame common to and communicating with eachof said exhaust pipes, and means forming additional gas venting passages extending laterally from said header in aarc gases therefrom, said exhaust pipes being arranged in vertical alignment, an exhaust header common to and communicating with each of said exhaust pipes mounted on said frame intermediate said ends thereof, said header extending horizontally across said supporting frame,

and additionalventing means extending laterally I from said header for completely cooling the vented exhaust gases.

8. Electric switchgear comprising a cubicle type supporting frame, a polyphase gas blast circuit breaker mounted in said frame at the lower part thereof, means for operating said circuit breaker mounted in said frame at the upper part thereof,

communicating with each of said exhaust pipes, said header being horizontally located at an intermediate part of said supporting frame substantiaily between said units and said circuit breaker operating means, and extension passages extending from opposite ends of said header along the opposite sides of said frame at said upper part, said header extension passages forming with said header a U-shaped section for venting said exhaust gases harmlessly at the upper Dart of said frame.

9. Electric switchgear comprising a cubicle type supporting frame, a polyphase gas blast circuit breaker mounted in said frame at the lower part thereof, means for operating said circuit breaker mounted in said frame at the upper part thereof above said gas blast circuit breaker, a gas storage supply tank also mounted on said frame, said circuit breaker having separate phase units arranged horizontally side by side each arranged to be supplied with gas under pressure from said tank, an exhaust pipe extending vertically from each unit for venting arc gases therefrom, said exhaust pipes bein arranged in vertical alignment, an exhaust header common to and communicating with each of said exhaust pipes, said header being horizontally located substantially at an intermediat part of said supporting frame with reference to said lower and upper parts thereof, and an extension cooling passage extending vertically from each end of said header to the top of said frame along the opposite sides of a gas storage supply tank also mounted on said frame, said circuit breaker havin separate phase units arranged horizontally side by side each arranged to be supplied with gas under pressure from said tank, an exhaust pipe extending vertically from each unit for venting hot arc gases therefrom, an exhaust header common to and said frame for venting said gases harmlessly at the top of said frame.

10. Electric switchgear comprising a cubicle type supporting frame, a polyphase gas blast circuit breaker mounted in said frame at the upper part thereof, means for operating said circuit breaker mounted in said frame at the lower part thereof, a gas storage supply tank also mounted on said frame, said circuit breaker having separate phase units arranged horizontally side by side each arranged to be supplied with gas under pressure from said tank, an exhaust pipe extending vertically downwardfrom each unit for venting are gases therefrom, an exhaust header common to and communicating with each of said exhaust pipes, said header being horizontally located substantially at an intermediate .part of said supporting frame, and an inverted T-shaped venting passage extending downward from said header for venting the exhaust gases at opposite sides of said frame at the bottom thereof.

- RALPH E. BOLD.

Images