US2633512A - Device for interlocking arcing and disconnect contacts - Google Patents

Description

IIMarCh 3 G. E. JANSSON F iled Feb. 15, 1949 DEVICE FOR INTERLOCKING ARCING AND DISCONNECT CONTACTS Patented Mar. 31, 1953 DEVICE FOR INTERLOGKING ARCING AND DISCONNECT CONTACTS Gustav E. Jansson, North Quincy, Mass, assignor to Allis-Chalmers Manufacturing Company, Milwaukee, Wis., a corporation of Delaware Application February 15, 1949, Serial No. 76,482

This invention relates to switching devices such as electric circuit breakers of the fluid blast type and more particularly to means for controlling the sequence of operation of separable contacts embodied therein.

In circuit breakers of the fluid blast type, it has been discovered that current or are interruption takes place under the most advantageous conditions when the arcing contacts are rapidly separated to a distance permitting the flow of a blast of fluid transversely of the arc and contacts. This blast of air or other fluid cooperating with a suitable bafile structure causes rapid circuit interruption. However, in order to be sure that restriking of the arc does not occur, isolating or disconnect contacts are usually provided in addition to the arcing contacts and are opened after the arc has been extinguished but while the fluid blast is still being maintained. In order to obtain the proper relationship and sequential operation of the arcing and disconnect contacts, separate actuating means for the two sets of contacts have been provided which heretofore have been interlocked by complicated arrangements so as to insure consecutive operation.

It is therefore one object of the present invention to provide a new and improved means for controlling the sequence of operation of separable contacts embodied in switching devices of the fluid blast type.

Another object of the invention is to provide a new and improved circuit breaker oi the fluid blast type in which the interlocking means preventing the disconnect contacts from separating before arcing contacts in series therewith does not physically-contact the disconnect contacts upon proper sequential operation of the separable contacts. r

A further object of the invention is to reduce the cost of manufacturing and simplify the design of the means for controlling the sequence of operation of separable contacts embodied in a circuit breaker of the fluid blast type.

Objects and advantages other than those set forth will'beapparent fromthc following description when read in connection with the accompanying drawing in which the single figure is a diagrammatic showing of a circuit breaker and pneumatic control system therefor embodying the present invention.

Referring moreparticularly to the drawing by,

4 Claims. (01.200-82) sumed herein to be compressed air, supplied from a suitable compressor (not shown). Although in general, circuit breakers of the type herein considered are provided with a plurality of similar pole structures, one for each phase of a polyphase electric circuit, only one such pole structure or pole unit is shown in the figure and the circuit breaker will be described in detail as if it were of the single pole unit type.

The circuit breaker, for example, may comprise a fixed arcing contact 3 and a cooperating movable arcing contact 4 connected in series with a disconnecting switch comprising a fixed disconnect contact 5 and a cooperating movable disconnect contact 6 in an electric circuit through stud terminals '1 and 8. The arcing contacts 3 and i are housed in a tubular arcing chamber 9, having a metallic sleeve shaped wall [0 axially aligned with and supporting an insulating sleeve i l and an insulating sleeve 12. The metallic sleeve ii! of chamber 9 constitutes a conductive connection between the fixed arcing contact 3 and an extension of terminal 8. Sleeve ll constitutes a discharge passage for chamber 9.

Sleeve 18 is provided with an inwardly extending bracket l3 upon which is arranged a contact constituting the fixed arcing contact 3 of the circuit-breaker. The cooperating movable arcing contact i, which may be in the form of a streamlined solid of revolution, is actuated by a fluid motor l8 comprising a piston slidable in insulating sleeve l2 and secured to a stud H5. The piston of fluid motor !8 comprises a metallic sleeve member 28, an insulating hub 2| secured to member 28 at the upper end thereof, and a hub ll secured to member 28 and stud 16 at the lower end-thereof. Arcing contact 4 is suitably secured to a stud 2a which is slidably mounted in insulating hub 2i and biased to closed position by a spring 22 acting between a bushing 23 secured to stud 2c and an extension 24 of hub IT. The stud 2D is conductively connected to the stud It by means of flexible conductors 25.

A pair of main or current carrying contacts 26 and 27 are. in parallel with the arcing contacts 3 and :3. Contacts 25 is preferably made in a series of segments resiliently mounted to form an anriular stationary contact. The movable current carrying contact 2? is diagrammatically represented as a part of metallic sleeve member 28 which is secured to insulating hub 2i and hub I! so as to move with the piston upon actuation thereof. Thus, current entering from terminal 8, flows through metallic sleeve Ill, main or current carrying contacts 26 and 2?, sliding contacts l4 and disconnect contacts and 6 to the terminal l. Although the arcing contacts when closed are in parallel with the main or current carrying contacts, the flow of current will generally pass almost entirely through the main contacts because of the relatively small area of the cooperating surfaces of the arcing contacts and because of the higher resistance thereof.

The movable current carrying contact 2'! is urged into engagement with the fixed current carrying contact 25 by resilient means such as a spring 29 acting between hub ll and a metallic washer 33 which is resiliently supported in a metallic sleeve portion 3|. The metallic sleeve portion 3! is supported by insulating sleeve I2 at the free end thereof. Sleeve portion 3| is axially aligned with sleeves Hi, I! and i2. In addition sleeve portion 3i is provided with an extension arm 52 which supports the fixed disconnect contact 5. l

The insulating sleeve portion ll communicates with a cooling chamber 33. The sleeve portion l i may contain an auxiliary arcing electrode 34 which is usually aflixed thereto and coaxially aligned therewith. The auxiliary arcing electrode 34 is connected with the disconnect contacts 5 and 5 and a current limiting resistor 35 by means of conductor l5.

The movable disconnect contact 5 may be piv- I tact 6, and the other end of rod 31 may be conneoted to an arm 39 of a bell crank 45. A second arm M of bell crank 40 may be connected to the piston rod 42 of a fluid motor 45. The rod 42 protrudes through and beyond the ends of a cylinder 44 of motor 45. Motor 45 actuates the bell crank 40 which, in turn, actuates the connecting rod 31'. A predetermined movement of connecting rod 3? actuates the movable disconnect contact 5 and moves it to its open and closed positions. A pair of regulating or needle valves 46 and 4? may be utilized for regulating the supply of fluid from reservoir 2 to motor 55.

In accordance with the present invention, a

mechanical interlocking device precludes improper sequence of operation of the disconnect con- I tacts 5 and 6 with reference to the arcing contacts 3 and 4. The mechanical interlocking device comprises a means such as an abutment or bent lever 48 which is pivotally mounted at 5! on a bracket 49 and is arranged to lie within the path of relative movement of the arcing contacts, which, in the embodiment shown, is the path oi. movement of contact 4 or of the rod or stud l6 which is actuated with arcing contact 4. Lever 48 also lies in the path of relative movement of the disconnect contacts which, in the embodiment shown, is the path of movement of contact 6, for preventing separation of the disconnect contacts 5 and 6 prior to opening of arcing contacts 3 and t. A biasing means, such as a spring 50, pivots the lever 48 into the path of movement oi the movable disconnect contact 6 and precludes separation thereof from the stationary or fixed disconnect contact 5 prior to separation of arcing contacts 3 and 5 which would occur in case of maladjustment of the pneumatic sequence control means for motor 45, i. e. needle valve 46.

As long as the disconnecting switch is closed there is no engagement between the lever 48 and the movable disconnect contact 6. If the circuit breaker opens, lever 43 will be pivoted out of the path of movement of the movable contact 6 of the disconnecting switch by the arcing contact operating fluid motor I8 and by stud l5. If arcing contacts 3,4 are fully separated, the disconnecting switch can open without ever being engaged by the lever 48. If, however, the fluid motors i8 and 45, are not so adjusted as to result in proper sequential operation of the arcing contacts 3 and 4 and the disconnect contacts 5 and 6, lever 48 will stop the movable disconnect contact 6 and preclude its separation from the stationary disconnect contact 5 as long as the arcing contacts 3 and 4 have not fully parted.

The compressed air for operating the control system and the arcing contacts is derived from the reservoir 2. The air under pressure in reservoir 2 also produces the arc extinguishing blast across the gap formed between the pair of cooperating arcing contacts 3, 4 upon separation thereof. The are extinguishing blast from reservoir 2 to the arcing contacts 3, 4 is controlled by a blast valve 52 which provides a connection between the reservoir 2 and an insulating conduit 53 which is connected to the metallic sleeve portion I0 of chamber 9.

Differential type blast valve 52 employing a pilot valve therefor comprises fluid motors 54 and 55 for controlling a blast inlet port 56. Motor 54 comprises a cylinder 51, a piston 58, a spring 59, and an inlet port 60. Motor 55 comprises a cylinder 6|, a piston 62, a return spring 63 for piston 62, an exhaust port 64. Valve 65 for closing exhaust port 66 is arranged to be operated by motor 55. A cylinder 61 surrounds cylinder iii of motor 55 coaxially therewith. Cylinder 61 is provided with an exhaust port 58. Piston 32, when actuated by air under pressure, actuates valve 65 and opens exhaust port 66 against the action of spring 33. As long as exhaust port 65 remains closed, air under pressure supplied from reservoir 2 through inlet port 60 cooperates with spring 53 to maintain the valve 65 in the position shown.

Inlet port ll of blast valve 52 supplies fluid motor 55 with operating fluid under pressure for actuating piston 32. Inlet port 1!, however, is controlled by a slide valve E2 which opens and closes port H upon a predetermined movement of piston 43 of fluid motor 45. Connecting rods 73 and 34, interconnected by link I5 and of which the former is connected to slide valve 12 by means of link 16, forms a mechanical connection between .rod 42 of piston 43 to slide valve 12.

piston type interlocking valve 83 is provided and arranged in a conduit 84, 84' for connecting the closing valve '79 and the fluid operated motor 45. Valve 83 comprises a cylindrical valve housing 85 defining a passage interconnecting conduit portions 84, 84', a valve element 86, and biasing means such as a spring acting upon valve element 85 in a direction longitudinally thereof and tending to maintain valve element 85 in its open position. Element 85 is adapted to be moved selectively to the open position shown and to a closed position and may comprise axially aligned pistons 81 and 88 which are slidable into valve housin 135 and are joined by a stem portion 89. Fluid under pressure is enabled to flow through valve housing 85 when valve element 85 is in open position.

Valve housing 85 defines means such as a first port 93 for admitting therein fluid under pressure from a conduit 94 which is connected to conduit 53. Valve housing 85, in addition, comprises means such as a second port 96 for admitting fluid under pressure from conduit section 84, means defining a third port 9'! for interconnecting housing 85 and motor means 45, and means defining a fourth port 98 and fifth port 98. Port 98 serves the purpose of exhausting residual air trapped in cylinder 44 on the right side of piston 4'3 and in conduit 84, while port 98 serves the purpose of venting compressed air that may leak between the pistons 87, 88 and the walls of valve 83 to the lower end of valve housing 85. In its open position shown, piston 31 is situated between the first port 93 and the second port 95. When valve element 86 is in its closed position, piston 87 is situated between the second port 95 and the third port 91. Port 9'! is always situated between pistons 8'1 and .88.

The piston type interlocking valve 33 may be mechanically operated to lockout position if the circuit breaker is removed from its cell 99. Rod I69, which may press on piston 2'! of valve element 85, is actuated in an upward direction when the circuit breaker, which forms part of a vertical lift arrangement, is in position in cell 99. This actuation of rod I09, upward, frees valve element 85 and permits it to assume its open position. Rod Hill is actuated upward when the circuit breaker is raised into position in cell 99 by abutment of a connecting rod I83 against a structural member M4. The abutment of rod I93 against member I'M results in rotation of a link I 35 in a counterclockwise direction and thus applies tension to a helical spring I96. Lowering of the circuit breaker to permit removal thereof from cell 99 permits spring IE6 to contract. Spring I95 is stronger than spring 99 located within valve 83 and hence when the breaker is lowered from its cell 99, spring H36 actuate-s valve element 85 to its closed position.

The circuit breaker illustrated in the drawing is shown with the disconnect contacts in the open circuit position and the pneumatic control system in the corresponding position, A closing operation is initiated by energization of the closing solenoid valve 19, thereby causing air under pressure from reservoir 2 to pass through conduit 89, valve 19, conduit 84', valve 83, conduit 84 to fluid motor 45. Operation of solenoid valve 19 results in piston 53 of motor 45 moving from right to left to actuate rod 42,, bell crank 49, and connecting rod 31, thus closing the disconnect contacts 5 and 6. The movement of piston 43 of motor 45 from right to left rotates link '15 clockwise, and this results in an upward movement of connecting rod 14 which in turn rotates link '78 in a. clockwise direction. The clockwise rotation of link 16 a'c'tuates slide valve 12 in an upward direction, thus opening port H and closing exhaust ports TI.

The passage of air through ports 95 and i l of valve 83 during a closing operation of the circuit breaker does not actuate valve element 85, because the pressures applied thereby to pistons a! and 88 are equal.

When the solenoid trip valve 13 is energized, compressed air flows from reservoir 2, through conduit 80, trip valve '18, a conduit 197,, and inlet port H ofslide valve l2. causes .air from reservoir 2 to move piston 62 of motor 55 against the action of spring 63. The movement of piston 82 under the action of air pressure from reservoir 2 moves valve 65 and opens port 65 in cylinder 67. Upon opening of port 56, air under pressure trapped in cylinder t? exhausts to the atmosphere through port 58. This exhausting action rvduces the pressure behind piston 53 of motor 54 and enables the air under pressure in reservoir 2 acting on the portion of the left side of piston 53 surrounding the seat of the blast valve to overcome the action of spring 59. A blast of air under pressure then flows through cylinder .51 of motor 54 left of piston 58, inlet port 56, conduit .53, and an inlet port I it in sleeve portion 19 of chamber 9. Air under pressure in chamber 9 acting on insulating hub 2! actuates the piston of motor !8 and, the piston sequentially opens the current carrying contacts 26 and 2? and the arcing contacts .3 and 6. Insulating hub 21,, being secured to sleeve member 28, moves sleeve member 28, hub H, and stud It in contact opening direction, thereby separating first the current carrying contacts 25 and 2? and shortly thereafter (upon the engagement of hub 21 and bushing 23) the arcing contacts 3 and 4. The air blast extinguishes the arc that occurs upon separation of the arcing contacts 3 and 2-.

Upon a predetermined travel of stud l E, which is actuated by the piston of motor It, a portion thereof abuts against lever 48. The movement of lever 48 moves one arm thereof out of the path of movement of the movable disconnect contact 6. The proper sequence is assured by interlock lever 48 but timing is governed by rate of flow of air controlled by valve 45.

Upon the flow of the air blast through conduit 53, air under pressure therefrom is transmitted through a conduit Hi8 connected thereto and to an inlet port its in motor 45. This pressure pulse moves piston 43 of motor 45 from left to right, thus resulting in the separation of the di connect contacts 5 and 6. If the desired predetermined sequence of operation of fluid motor is resulting in separation of the arcin contacts 3 and 3, and of fluid motor 45 resulting in separation of the disconnect contacts 5 and 5, does not occur, the lever :38 will prevent disconnect contacts 5 and 6 from separating as long as arcin contacts 3, 4 are not fully separated. However, if fluid motors I8 and 45 operate in the proper sequence, lever 48 will be moved out of the path of movement of disconnect contact 5 without physical engagement thereof before fluid motor 45 actuates disconnect contact 5.

Upon the flow of an air blast through conduit 53, air under pressure therefrom is transmitted through conduit 94, through inlet port 93, to valve 83. This pressure impulse moves valve element 86 into the closed position thereof against the action of spring 96. Such movement of valve element 86 brings piston 81' below port as, whereby the connection between port 96 and port or is interrupted. The closing of the connection preeludes the possibility of air under pressure being supplied through port 91 to motor 55, which might result in closing the disconnect contacts.

Opening of disconnect contacts 5, 6 effects resetting of blast valve 52 by cutting or]? of air feed through port I! by positioning of slide valve 12 and simultaneous venting of the actuating air from chamber of piston 62 throughport ll. Blast valve 52 closes and stops the how of fluid through conduit 53 and adjacent the arcing contacts 3 and 4. The action of spring 25 then closes the arc-' ing contacts 3 and 4 and the main current carrying contacts 25, 21. The reduction of pressure in conduit 94 enables spring 9i to return valve element at to its open position.

If opening and closing impulses are substantially simultaneously initiated by valves 53 and #9, respectively, air under pressure from conduit 53 again moves valve element 86, against the action of spring Bil. This prevents the closin impulse from flowing through valve 78, valve 83, conduit 84 to fluid motor 45. Disconnect cntacts 5 and 6 cannot be closed during the period of time a tripping impulse prevails. The lockout feature of valve 83 is aided by the action of the closing impulse which flows through valve is a d port 96 into the space in valve 83, above piston 33. This closing impulse thus aids the blast air from conduit 53 in looking valve 83 in its closed position. Once actuated to closed position, no closing impulse can be passed through valve 53 as long as either closing valve lid or blast valve remains open since either or both will feed air to chamber above piston 37, thereby holding valve 85 in closed position. In the lockout position of valve element 8%, ports in and 558 are in communication, resulting in venting of the conduit which connects valve 83 and fluid motor Port 98' is provided to vent air which might leak by piston 88, thereby preventing resetting of valve 33 due to build-up of pressure behind piston In the lookout position of valve element 88 fluid under pressure from conduit 66' maintains valve element as in its lockout position even though admission of fluid under pressure through port 93 has ceased.

While the embodiment shows how the present invention may be applied to a circuit breaker having separate arcing contacts and disconnect contacts, it will be apparent that the invention is not limited to circuit breakers of this particular type. It is equally applicable to circuit breakers which have but one single set of contacts serving the purpose of forming an arc gap for nitial circuit interruption as well as the purpose of increasing the amount of circuit insulation upon interruption of the circuit at that are gap. It is also apparent to those skilled in the art that various changes and modifications may be made therein without departing from the spirit of the invention or from the scope of the appended claims.

It is claimed and desired to secure by-Letters Patent:

1. In an electric switching device the combination of a plurality of relatively movable cooperating arcing contacts in series with a plurality of relatively movable cooperating disconnect contacts, a first separating means for actuatin at least one of said arcing contacts, a second 861 rating means for actuating at least one of said disconnect contacts, control means for causing a predetermined sequence of operation of said first and second separating means, and pivotally mounted lever means actuated responsive to 0105-. ing movement of said arcing contacts to lie within the path of movement of said one of said disconnect contacts for preventing separation of said disconnect contacts and actuated by said first separating means to move out of the Path O movement of said one of said disconnect contacts without physical contact therewith responsive to. opening movement of said first separatingm ans, said second separatingmeans maintaining said one of said disconnect contacts at a mode- 8. termined distance away from said lever means when said disconnect contacts are in closed position.

2. In an electric switching device the combination of a plurality of relativelymovable coopcrating arcing contacts in series with a plurality of relatively movable cooperating disconnect contacts, a first separating means for actuating at least one of said arcing contacts, a second separating means for actuating at least one of said disconnect contacts, means for producing a blast of fluid under pressure adjacent said arcing contacts for extinguishing the are formed upon separation thereof, control means for causing a predetermined sequence of operation of said first and second separating means, and pivotally mounted lever means actuated responsive to closing movement of said arcing contacts to lie within the path of movement of said one of said disconnect contacts for preventing separation of said disconnect contacts and actuated by said first separating means to move out of the path of movement of said one of said disconnect contacts without physical contact therewith responsive to opening movement of said arcing contacts, said second separating means maintaining said one of said disconnect contacts at a predetermined distance away from said lever means when said disconnect contacts are in closed Position.

3. In an electric switching device, the combination of fixed and movable cooperating arcing contacts in series with fixed and movable cooperating disconnect contacts, a support for mounting said fixed disconnect contact and conductively connecting said fixed disconnect contact to said movable arcing contact, a source of fluid under pressure, a first motor means oper-.

ated by fluid under pressure from said source for,

actuating said movable arcing contact, a second motor means operated by fiuid under pressure from said source for actuating said movable disconnect contact, means for producing a blast of fluid under pressure from said source adjacent said arcing contacts for extinguishing the are formed upon separation thereof, an adjustable control means for causing a predetermined se quence of operation of said first and second motor means, and a lever mounted on said support and actuated responsive to closing movement of said movable arcing contact to lie Within the path of movement of said movabledisconnect contact to prevent separation of said disconnect contacts in case of maladjustment of said motor sequence control means and actuated out of the said path of movement without physical contact with said disconnect contacts responsive to opening movement of said movable arcing contact, said second motor means maintaining said movable disconnect contact at a predetermined distance away from said lever when said movable disconnect contact is in closed position. i

a. In an electric switching device, the combination of fixed and movable cooperating arcing contacts in series with fixed and movable coopcrating disconnect contacts, a support for mounting said fixed disconnect contact and conduc-' tively connecting said fixed disconnect contact to said movable arcing contact, a source of fluid under pressure, a first motor means operated by fluid under pressure from said source for actuating said movable arcing contact, a second motor means operated by fluid under pressure from said source for actuating said movable disconnect contact, means for producing a blast of fluid under pressure from said source adjacent said arcing contacts for extinguishing the are formed upon separation thereof, an adjustable control means for causing a predetermined sequence of operation of said first and second motor means, and a lever mounted on said support and actuated responsive to closing movement of said movable arcing contact to lie within the path of movement of said movable disconnect contact to prevent separation of said disconnect contacts in case of maladjustment of said motor sequence control means, said lever being actuated by said first motor means out of the said path of movement without physical contact with said disconnect contacts responsive to opening movement of said movable arcing contact, said second motor means maintaining said movable disconnect contact at a predetermined. distance away from said lever when said movable disconnect contact is in closed position.

' GUSTAV E. JANSSON.

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

UNITED STATES PATENTS

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