US2672541A - Electric circuit interrupter - Google Patents

Description

March 16, 1954 w. E. PAUL 2,672,541

ELECTRIC CIRCUIT INTERRUPTER Filed Dec. 2'7, 1951 IMSM/IT/fl/Y 29 o o 29 as 6 5 1 40 32 1 a9 46- 45L... 4755: 48 1 I 38 Z7 44 43 26 a L z 25 24 Inventor; William 15. Paul,

His A51: orney.

Patented Mar. 16, 1954 ELECT-RIC CIRCUIT IN'ZIERRUP'IER William E. Paul, Schenectady, N. Y., assignor to General Electric Company, a corporation of New York Application December 27, 1951, Serial No. 263,616

14 Claims.

'My invention relates to electric circuit interrupters and, more particularly, to a blast control arrangement for used in conjunction with circuit interrupters of the fluid-blast type.

In circuit breakers of the gas or liquid blast type, it is the present practice to separate the contacts and to supply :a blast of fluid such as gas or liquid to the space in which the arc is drawn for the purpose of aiding in the extinguishment or the arc. No provision is made in present breaker constructions for controlling the particular instant at which the blast is supplied to the are relative to the instantaneous alternating current value thereof. Thus if the tinstantaneous value of current is of a high order of magnitude at the particular instant when the blast is supplied to'the arc, there will be a tendency for the gas or liquid to choke the breaker since the presence of the high current are raises the pressure of the fluid and interferes with the exhaust thereof from the interrupting chamber. Since the blast supplied to the are is normally ineifective to extinguish the arc until a current zero of the alternating current wave occurs, it is logical that more efiicient interruption could be accomplished suitable fluid control means were provided for directing a blast at the are only when the instantaneous current is at or approaching a zero value.

A principal object of this invention is "to provide fluid blast controlling means for use in conjunction with electric circuit breakers which blasts the are only when the current is at or approaching a zero instantaneous value.

Another object of this invention is to improve the interrupting performance and capacity of circuit breakers by preventing the choking of the breaker due to a blast of fluid supplied prematurely to the int-errupting chamber.

A further object of this invention is to provide an improved circuit interrupter wherein suitable venting means relieves the pressure generated within the interrupting chamber due to the formation of an arc therein and wherein a cross blast is directed at the arc to extinguish the arc at or near a current zero.

Th invention in one form as applied to a fluid blast circuit breaker having normally closed valve means arranged to control the fluid blast comprises resilient energy-storing means biasing the valve means toward the open position, magnetic holding means respcnsive to the instantaneous magnitude of current through the breaker for opposing the action of the resilient means,

and mechanical restraining means normally cperative to maintain the valve closed is released in response to :an opening operation of "the breaker so as to place the valve means briefly under the control of the resilient means and the magnetic means. When the instantaneous value of current approaches a small value or becomes zero, the resilient energy-storing means overcome the action of the magnetic holding means so as to open the valve means thereby to supply a blast of fluid to the arc and to effect its extinguishment. According to one feature of the invention, a movable one of the contacts is of a hollow construction and hence serves as a pressure-relieving vent for pressure built up within the interrupting unit due to the presence of the arc therein after the contacts have separated and before the valve means has opened. According to still another feature of the invention, the hollow contact is operated through a tubular operating rod by the operating mechanism thereby to facilitate the direct venting of such excessive arc-generated pressures.

While the invention is described herein in conjunction with a circuit interrupter of the gas blast type, it will be understood that it is not limited to such a circuit breaker and that the principles thereof are also applicable to interrupters of the liquid blast type.

For a better understanding of my invention; reference may be had to the following description taken in conjunction with the accompanying drawing in which Fig. 1 is a side view partially in section of a gas blast circuit breaker embodying the invention and in which Fig. 2 is a View along the line 2-2 of Fig. 1.

With reference to Fig. 1, which may be considered as being a single pole element of a multiple pole air blast breaker, a frame structure or housing I is supported upon bushing type in sulators 2. Mounted on the frame structure I is a pressure reservoir 3 to which is connected a blast conduit 4 having therein a valve 5. Conduit 4 is connected to the interrupting unit generally designated by the numeral E5. interrupter unit 6 is provided with an inlet port "I and an outlet port 8 and the arcing chamber 9 formed within the interrupter unit 5 contains fixed contact elements it and a tubular hollow movable contact element '1 I. Arc divider means 12 is disposed downstream from the outlet 8. An exhaust conduit l3 leads from the outlet 8 to the expansion chamber M which dissipates the heated arc vapors to atmosphere through the louvers i5. Interrupting unit 6 and parts associated therewith is of the general type disclosed in Patent 3 2,453,317 to Dell K. Tower et al., granted January 4, 1949, and assigned to the assignee of this invention.

An adapter member I3 is aiiixed to the upper end of the tubular contact II so as to afford a connection between contact I I and an insulating tubular operating rod I! which is in communication with an expansion chamber I3 which dissipates to atmosphere through the louvers I5.

For the purpose of operating the tubular contact I I by means of its associated tubular operating rod II, a pair of connecting rods or links I9 are pivotally connected at 20 to the front and rear of the tubular exhaust member I! and are pivotally connected at 2i to the front and rear operating crank arms 22 which are secured to and rotatable with an operating shaft 23, which may, of course, carry other similar cranks for the other two poles of the breaker, only th rear crank 22 being shown in the drawing. Rotation of shaft 23 and opening of valve could be effected by an operating mechanism of the type disclosed in Patent 2,436,191 to Julius W. Timmerman, Jr., granted February 17, 1948, and assigned to the assignee of this application. Since the particular operating mechanism for reciprocating the tubular contact I I and for opening the valve 5 forms no part of the present invention, the details of this structure have been omitted from the drawing for the sake of simplicity.

As is indicated in Fig. l, the inlet port 1 and the outlet port 8 are respectively closed by gate valve members 24 and 25. While both the inlet and outlet ports I and 8 are shown provided with valves such as 24 and 25, it will be understood that it is within the province of the invention to us only one such valve. For example, the principles of the invention would be applicable if only the gate valve 24 were utilized.

Both the gat valves 24 and 25 are mechanically coupled through the platelike cross head 23 which encircles the tubular contact II and to which is connected at either side thereof a ver tically disposed valve lift rod 21. This pair of valve lift rods 21 is normally biased downwardly toward the valve closed position by the mechanical restraining means comprising compressional springs 28 and plunger members 29 each having a shoulder 29a and disposed for vertical reciprocation through openings 30 formed in a housing structure 3| secured to each side of the tubular exhaust operating member I1 in any suitable manner. Each plunger 29 engages, but is separ2131; from the associated valve operating rod 2! a External connection to the movable contact I I is afforded by the terminal conductor 33 disposed within a bushing 34 constructed of insulating material and secured in any suitable manner to the frame I. nected by a conventional conductor stud which is disposed within the insulating bushing 2,

In accordance with one feature of th invention, the conductor 33 is split longitudinally into two parallel current-carrying parts. an upper part 35 which is fixed in position within the insulating bushing 34 and a lower resilient part 3'! which constitutes the resilient stored energy means for operating the valve. A fixed contact block 38 is secured to the upper fixed part 35 of the conducting stud 33 by any suitabl means such as by the weld indicated at 39. The tubular contact II is reciprocable within an opening formed in the fixed contact block 38 and is ar- The fixed contact ill is com 4 l J ranged in sliding contact therewith, e. g. comparable to the method disclosed in Patent 2,283,657 to Thumim which is assigned to the assignce of this invention. For making the split bushing stud constitute an effective parallelcurrent-path conductor, a strip of insulating material 4i divides the upper fixed part 35 from the lower resilient part 31, being preferably secured to the fixed leg 35 of the stud by means of a suitable cement.

At this point, it should be understood that the bifurcated stud 33 is preferably of some good electrically conducting metal or alloy having resiliency such, e. g. as beryllium copper. The stud may be assumed to be of square section and fitting into bushing 34 which has a square-sew tioned bore. Further, the resilient leg 31 normally lies flat and horizontal along the bottom of the bore, but is shown in its flexed upward position in Fig. 1 which, as will later become evident, corresponds to the valve-closed position. In other words, the flexible arm 3'! of the bushing stud 33"constitutes spring means biasing the blast control valves 24 and to their open position. From the drawings it will be seen that an extension arm 42 is secured to opposite sides of the left-hand end of flexible portion 3'! of conductor stud 33 by bolts 43 or by any other suitable means. As is clearly indicated in Fig. 2 the pair of arms 42 widely embrace the conducting contact block 38 which is suitably recessed at 44 to accommodate the angle bends of the arms during their flexing movement with the resilient stud leg 31. Pivotally connected to the left-hand ends of the arms 42 at 45 are a pair of levers 46 which are supported at their mid-points by a fixed pivot 41 mounted on the contact block 38. Each of the levers 46 is pivoted at 43 to one of the valve lift rods 21. Extension 42 is electrically connected with the contact block 38 by means of a flexible strap 40.

From the description above, it will be understood that the circuit through the breaker comprises the terminal of conductor 33, parallel conductors and 31 of the bushing stud 33 including conducting strap 40, contact block 38, tubular contact II, fixed contacts I0, and the conducting stud of the electric bushing 2,

From the above description, it will be obvious that the spring means 28 through the plungers 29 normally hold the valve lift rods 21 and the valves 24 and 25 downwardly to the closed position so that when the breaker is closed, as shown in the drawings, the valves 24 and 25 are closed since the springs 28 are constructed to preponderate over the valve-operating spring means constituted by the resilient stud leg 31.

'When the main blast valve5 is opened and when operating crank 23 is rotated clockwise as viewed in Fig. 1, pressure gas is supplied through conduit 4 to valve 24 and simultaneously the tubular contact I I is moved upwardly just to take up the contact wipe and then to draw an arc between its arcing tip and the fixed finger contacts I0. Such an arc will develop heat and pressure within the arcing chamber 9 and, until the valve '24 and 25 open, such ionized are products are vented upwardly through the tubular contact I I, the tubular operating member I I, the expansion chamber I8 and diffuse through the louvers [5 to atmosphere. After the initial upward movement of tubular contact II has taken up the contact wipe so that the contacts are in the act of separating, theshoulder 29a. of the plunger 9 is picked up by the lower end of the I accuser housing 31 so that the plungers 2-9 may move up out of engagement withthe valve rods 21. Ks previously mentioned, the springs 28 preponderate over the upward lift of the valve-operating resilient leg 31 so that not until after sepnation of the plungers from the valve rods 2-! do the valves 24 and 25 come under the control of the current-carrying resilient leg 3'? and-parts associated therewith.

"Since the spring leg 31 normally is biasing the valves 2! and S25 upwardly, these valves will open unless held momentarily in the closed position by a greater opposing force due to the electromagnetic attraction between theparallel currentcarrying paths of upper part 35 and the lower leg 31'o'f conductor 33 which is induced during :p'ortions of the alternating current wave when the instantaneous current value is in excess at a predetermined value. Such electro-magnetic interaction between a pair of closely-coupled parallel current paths through which current flows in the same direction so as to produce an attractive force therebetween is well known. Furthermore, the -condi-ictors and the tubular contact I! form a right-angled eledtro-magnetic loop circuit which inherently tends to expand as is Well known. Thus a component of this magnetic loop force acts upwardly on the part :91 and thereiore augments the aforesaid elective-magnetic par-a1- lel-curre'nt effect tending to hold the valve memi Thus, when the alternating current approaches an instan'taneous zero value, these electro mag netic holding forces decrease proportionately so that the spring force of leg 31 will become eifective to open the blast control valves 24 and 25 for anticipating the approaching current 'zero. Accordingly, a sudden cross blast of cool unionizcd arc-extinguishing air or gas is directed across the separated contacts at the most favorable in figuration of the tubular ope-rating rod H and cranks 2 2 in Fig. '1.

Upon closure o'ithe break-er, the operating shaft 2c is rotated counterclockwise turn, causes the tubular operating rod l the tubular contact ll to move downwardly. such time during the closing movement as the lower ends of plungers '2'9 engage the upper ends of valve lift rods '21, the preponderating springs 28 will become effective to close the valves 2s and 25 against the bias of their opening spring constituted by the resilient leg 3"! and, as the closing movement proceeds, this action will be fol lowed by the compression of the ,preponderating springs 28 due to the relative upward movement of the plungers 2%] within their housings 31 as the hollow contact [I travels down through its wipe distance into the fixed contact fingers 40.

While I have shown and described a, particular embodiment of the invention, 1 do not wish to be limited thereto and intend in the appended claims to cover all such changes and modifications as Obviously, exhaust from this cross ran within the true spirit and scope of the inventicn.

What I claim as :new and desire to secure by Letters Patent oi the United states is:

l. An alternating current electric circuit breaker of the fluid blast type comprising means defining an arcing chamber, a pair of relatively movable contacts arranged to separate and draw an are within said chamber, means including normally close-d valve means for supplying a blast of fluid to :an are drawn between said contacts upon separation thereof, and resilient means normally tending to open said valve means, said resilient means being magnetically restrained from opening said valve means by instantaneous values of current through the breaker in excess of a predetermined value.

2. An alternating current electric circuit breaker of the fluid blast type comprising means defining an arcing chamber, a pair of relatively movable contacts arranged to separate and draw an are within said chamber, means including normally closed valve means for supplying a blast of fluid to an are drawn between said contacts upon separation thereof, and resilient means normally tending to open said valve means, said resilient means being magnetically restrained from opening .said valve means by instantaneous values of current through the breaker in excess of a predetermined value, said resilient means being efiectiv-e to open said valve means for instantaneous currents through "the breaker which are below a predetermined value.

3. An alternating current electric circuit breaker of the fluid blast type comprising means defining :an arcing chamber, a pair of relatively movable contacts arranged to separate and draw an are within said chamber, means including normally closed valve means for supplying a blast of fluid to an arc drawn between said contacts upon separation thereof, resilient means normally tending to open said valve means, and mechanical restraining means normally arranged to prevent said resilient means from opening said valve means, said restraining means being rendered ineiiectivc to prevent said resilient means from opening said valve means in response to opening movement of said contacts and said resilient means bein magnetically restrained from opening said valve means by instantaneous values of current through the breaker in excess of a predetermined value.

a. An alternating current electric circuit breaker 'of the fluid blast type comprising means defining an arcing chamber, a pair of relatively movable contacts arranged to separate and draw an are within said chamber, means including normally closed valve means for supplying a blast of fluid to an are drawn between said contacts upon separation thereof, resilient means normally tending to open said valve means, and mechanical restraining means normally arranged to prevent said resilient means from opening said valve means, said restraining means being renderedi-neffective to prevent said resilient means from opening said valve in response to opening movement of said contacts and said resilient means being magnetically restrained from openin; :said valve means by instantaneous values of current through the breaker in excess of a predeter-minedvalue, said resilient means being eftective to open said valve means for instantaneous currents through the breaker which are below a predetermined value.

5. An alternating current electric circuit breaker of the fluid blast type comprising means defining an arcing chamber having an inlet and an outlet, a pair of relatively movable contacts arranged to separate within said chamber, one of said contacts being hollow and being arranged so as to define a pressure relieving passage for the escape of pressure from within said chamber due to an are drawn between said contacts upon separation thereof, valve means normally closing said inlet, resilient means normally tending to open said valve means, said resilient means being magnetically restrained from opening said valve means by instantaneous values of current through the breaker in excess of a predetermined value, and means for supplying a blast of fluid through said inlet and into said arcing chamber in response to opening of said valve means.

6. An alternating current electric circuit breaker of the gas blast type comprising means defining an arcing chamber having an inlet port and an outlet port, a pair of relatively movable contacts arranged to separate in said chamber, one of said contacts being hollow so as to define a pressure relieving passage for the escape of pressure from within said chamber due to an are drawn between said contacts upon separation thereof, and means including current responsive valve means for supplying a cross blast of gas to said chamber through said inlet port in response to an opening operation of the breaker,

said valve means being magnetically restrained in the closed position by instantaneous currents through the breaker in excess of a predetermined value and being biased toward the open position.

7. An electric circuit breaker of the gas blast type comprising means defining an arcing chamber having an inlet port and an outlet port, a pair of relatively movable contacts arranged to separate in said chamber, a movable one of said contacts being hollow so as to define a pressure relieving passage for the escape of pressure from within said chamber due to an are drawn between said contacts upon separation thereof, an operating mechanism operably related with said hollow contact for imparting operating movement thereto, and means including current responsive valve means for supplying a cross blast of gas to said chamber through said inlet port rendered operable in response to an opening operation of the breaker, said valve means being magnetically restrained in the closed position by instantaneous currents through the breaker in excess of a predetermined value and being biased toward the open position.

8. An alternating current electric circuit breaker of the gas blast type comprising means defining an arcing chamber having an inlet and an outlet, a pair of relatively movable contacts arranged to separate within said chamber, valve means normally closing said inlet, a conductor in series with said contacts, said conductor forming two parallel paths along a portion of its length, and a strip of insulating material interposed between said paths, one of said paths being fixed in position and the other of said paths being operably related with said valve means and being stressed so as to tend to impart opening movement to said valve means, the magnetic attraction between said paths being effective to prevent opening of said valve means for instantaneous currents through the breaker in excess of a predetermined value and being ineffective to prevent opening of said valve means for instantaneous currents through the breaker below a predetermined value during an opening operation of said contacts.

9. An alternating current electric circuit breaker of the gas blast type comprising means defining an arcing chamber having an inlet and an outlet, a pair of relatively movable contacts arranged to separate within said chamber, valve means normally closing said inlet, a conductor in series with said contacts, said conductor being split into two parallel parts along a portion of its length, and a strip of insulating material interposed between said parts. one of said parts being fixed in position and the other of said parts being resilient and operably related with said valve means and being stressed so as to bias said valve means toward the open position, the magnetic attraction between said parts being efiective to prevent opening or said valve means for instantaneous currents through the breaker in excess of a predetermined value and being inefiective to prevent opening of said valve means for instantaneous current through the breaker below a predetermined value during an opening operation of said contacts, and holding means for maintaining said valve means closed during ,only the initial portion of an opening operation of the breaker.

10. An alternating current electric circuit breaker of the gas blast type comprising a frame structure, means defining an arcing chamber having an inlet and an outlet, a pair of relatively movable contacts arranged to separate within said chamber, valve means normally closing said inlet, a conductor in series with said contacts, said conductor being split into two parallel parts along a portion of its length, a strip of insulating material interposed between said parts, and a bushing of insulating material mounted on said frame and in which said split conductor and said strip of insulating material are disposed, one of said parts being fixed in position and the other of said parts being resilient and operably related with said valve means and being stressed so as to bias said valve means open, the magnetic attraction between said parts being effective to prevent opening of said valve means for instantaneous currents through the breaker in excess of a predetermined value and being ineffective to prevent opening of said valve means for instantaneous current through the breaker below a predetermined value during an opening operation of said contacts.

11. An alternating current electric circuit breaker of the gas blast type comprising a frame structure, means defining an arcing chamber havsaid conductor being split into two parallel parts along a portion of its length, a strip of insulating material interposed between said parts, and a bushing of insulating material mounted on said frame and in which said split conductor and said strip of insulating material are disposed, one of said parts being fixed-in position and the other of said parts being operably related with said valve means and being stressed so as to tend to impart opening movement to said valve means, the magnetic attraction between said parts being effective to prevent opening of said valve means for instantaneous currents through the breaker in excess of a predetermined value and being ineffective to prevent opening of said valve means for instantaneous current through the breaker below a predetermined value during an opening operation of said contacts, and holding means for maintaining said valve means closed during only the initial portion of an opening operation of the breaker.

12. An alternating current electric circuit breaker of the gas blast type comprising means defining an arcing chamber having an inlet and an outlet, a pair of relatively movable contacts arranged to separate within said chamber, valve means normally closing said inlet, resilient means normally tending to open said valve means, and mechanical holding means normally arranged to prevent said resilient means from opening said valve means, said holding means being rendered ineffective to prevent said resilient means from opening said valve means in response to opening movement of said contacts and said resilient means being magnetically restrained from opening said valve means by instantaneous values of current in excess of a predetermined value.

13. An alternating current electric circuit breaker of the gas blast type comprising means defining an arcing chamber having an inlet and an outlet, a pair of relatively movabl contacts arranged to separate Within said chamber, one of said contacts being hollow and being arranged so as to define a, pressure relieving passage for the escape of pressure from within said chamber due to an are drawn between said contacts upon separation thereof, an operating mechanism operably related with said hollow contact for imparting operating movement thereto, valve means normally closing said inlet, resilient means normally tending to open said valve means, and mechanical holding means normally arranged to prevent said resilient means from opening said valve means, said holding means being rendered ineffective to prevent said resilient mean from opening said valve means in response to opening movement of said contacts and said resilient means being magnetically restrained from opening said valve means by instantaneous values of current in excess of a predetermined value.

14. An alternating current circuit breaker including an electric bushing in the interrupting circuit, conductor stud structure disposed in said bushing comp-rising parallel current paths including a rigid member and a resilient member, interrupting means including separable contacts for drawing an arc to be extinguished, currentresponsive means for controlling the extinguishment of said are, said current-responsive means responding to the varying magnetic interaction between said parallel current paths.

WILLIAM E. PAUL.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,298,778 Thumim et a1 Oct. 13, 1942 2,428,482 Wilcox et a1 Oct. 7, 1947 2,440,995 Wilcox May 4, 1948 2,456,965 Leitzel Dec. 21, 1948 2,561,486 Thibaudat July 24, 1951

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