US3141942A - Control means for air blast circuit breakers - Google Patents

Description

July 21, 1964 H. FORWALD 3,141,942

CONTROL MEANS FOR AIR BLAST CIRCUIT BREAKERS Filed Aug. 1, 1960 3 Sheets-Sheet 1 I /Z% I 2 L 22 INV EN TOR.

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CONTROL MEANS FOR AIR BLAST cmcurr BREAKERS Filed Aug. 1, 1960 Q 3 Sheets-Sheet 2 July 21, 1964 v H. FORWALD 3,141,942

CONTROL MEANS FOR AIR BLAST CIRCUIT BREAKERS Filed Aug. 1, 1960 3 Sheets-Sheet 3 705 I16 I06 I76 1/4 Z- f z5 4..

i x w INVENTOR. AMI/(0N Folk/410 United States Patent 3,141,942 CUNTRQL MEANS FOR AER BLAST CIRCUIT BREAKERS Haakon For-Wald, Ludvika, Sweden, assignor to Allmanna Svenska Elektrislra Aktieholaget, Vasteras, Sweden, a corporation of Sweden Filed Aug. 1, 19nd, Ser. No. 46,659 Claims priority, application Sweden May 7, 1960 6 Claims. (Cl. 2(i0148) This invention relates to air blast circuit breakers and more specifically relates to a control for a high pressure air cut-off means for normally isolating a source of compressed air from an interrupter structure and its support so that compressed air will not be lost in the event of a leak in the interrupter or its support.

Air blast circuit breakers are well known in the art, wherein compressed air is supplied to an interrupter or are extinguishing chamber through a support pillar insulator. The insulators are filled with compressed air when the contacts of the interrupter are in the open as well as the closed position. During an opening operation the compressed air within the insulator and are extinguishing chamber supplies an air blast for extinguishing the arc drawn by the contacts.

If there is a leak somewhere within the insulator or are extinguishing chamber, the high pressure air required for the blast will be lost. Furthermore, if the contacts are open, the loss of pressure may cause an unintentional closing of the contacts. Where a plurality of individual interrupters are mounted on separate pillar insulators with a common supply of high pressure air, it is clear that a fault in any portion of the high pressure system will permit reclosing of all of the interrupters.

In order to prevent loss of high pressure gas and unintentional reclosing, the individual pillar insulators have heretofore been provided each with its individual reservoir of high pressure gas, these reservoirs being connected to the main source of high pressure through small orifices. Thus, if there is a break in one of the pillar insulators, the main pressure source, and the reservoirs, for the other pillar insulators, drain through the restrictive orifices whereby repairs can be effective before a serious pressure loss occurs.

This system is subject to the disadvantage that, after contact operation and air blast, the compressed air for the various reservoirs is drained and is not quickly replen ished. If the pressure level falls too low, it is possible for the contacts to reclose unintentionally, so that the orifices for this reason should preferably be large. On the other hand, for the orifice to be operable to isolate the main pressure source from a broken pillar insulator, it is preferably small.

In accordance with the present invention, the orifice is (ept small while quick replenishing of high pressure gas after contact operation is provided. Thus, the orifice is placed in a valve type structure which is momentarily opened during blast operation and is thereafter closed. This permits a quick replenishing of high pressure gas to the individual reservoirs and, if one of the insulators is broken, the high pressure source is directly exposed to this break for only the very short time that the valve is open.

However, the above described arrangement is hardly suitable when filling the circuit breaker with compressed air at the time of initially putting it into service, because when the restrictive orifices are opened the outlet valves of the interrupting chambers are also opened so that a large amount of the air supplied is conducted directly out to the open air. To avoid this disadvantage the present invention provides means whereby the restrictive orifices of such a system may be controllably opened during times other than the contact operation time so that, for example, the auxiliary pressure supplies may be supplied at any desired time other than contact operating time and when the unit is initially placed in service.

Accordingly, a primary object of this invention is to provide a novel pressure supply control system for air blast circuit breakers wherein each of a plurality of series connected interrupters are pneumatically isolated from one another.

Another object of this invention is to isolate pneumatically a number of series connected interrupters from one another and from a main source of high pressure air so that a leak in any one of the interrupter systems will not cause a drain of high pressure air from either the remaining systems or the main source of supply.

Another object of this invention is to provide a restrictive orifice between a compressed air reservoir or chamber which supplies the air blast for an interrupter chamher and the main source of high pressure air wherein the orifice is temporarily opened during the opening operation of the interrupter to replenish the supply of air in the compressed air reservoir.

A further object of this invention is to provide a novel control system for normally isolated auxiliary pressure supplies of a gas blast circuit breaker wherein the restrictive orifice may be defeated at any desired time.

Other objects of this invention will become apparent from the following description when taken in connection with the drawings in which:

FIGURE 1 shows a side view of one pole of a circuit breaker having a plurality of series connected interrupters, and with a first embodiment of a restricted orifice defeating means for auxiliary pressure chambers which are normally-isolated from one another.

FIGURE 2 shows a second embodiment of the invention.

FIGURE 3 shows in part an interrupter with a pair of cooperating contacts in the closed position.

FIGURE 4 shows the same interrupter as FIGURE 3, with the contacts in the open position.

Referring now to FIGURE 1, the pole of the circuit breaker shown in this figure includes a first terminal 1 and a second terminal 2 which are connected in series with the four interrupting chambers or interrupters 3, 4, 5 and 6, which may be of the type shown in FIGURES 3 and 4. Each of interrupters 3, 4, 5 and 6 are mounted on hollow pillar insulators 7, 8, 9 and 10 respectively which are in turn mounted on compressed air reservoirs or containers 11, 12, 13 and 14 respectively which are in pneumatic communication with the interior of their respective pillar insulators and interrupter chambers. Each of compressed air containers 11 to 14 communicate with conduit 15 which is connected through valve 61 to a main source of high pressure air (not shown) as through passages 16, 17, 18 and 19 respectively. The main conduit 15 is provided with a plurality of cylindrical open ings 20, 21, 22 and 23 which receive pistons 24, 25, 26 and 27 respectively. Each of these pistons then carries a projecting nozzle such as nozzles 28, 29, 30 and 31 which seat in the openings of passages 16, 17, 18 and 19 respectively. Each of nozzles 28 to 31 are provided with orifices or controlled leaks 32, 33, 34 and 35 respectively where these controlled leaks are small enough to exert a substantial resistance to the flow of gas therethrough. Each of nozzles 28 to 31 are normally biased upwardly to restrict their respective orifices by biasing springs 36, 37, 38 and 39 respectively.

With the structure shown to this point, a relatively high pressure is maintained within containers 11 to 14, their individual pillar insulators 7 to 10 and their individual interrupter structures 3 to 6. This high pressure is used for obtaining a gas blast which extinguishes an arc 3 drawn by the contact within the arc extinguishers as has been described in connection with FIGURES 3 and 4.

In order to initiate operation of the contacts of the arc extinguishers, a control air system which includes feeders 40, 41, 42 and 43 of control conduit 44 are connected to the gas pressure responsive means within the interrupters 3 to 6. Thus, assuming that a relatively high pressure prevails in the interrupters 3 to 6, supplied through pillar insulators 7 to 10 by compressed air, so long as a relatively high pressure is applied to feeder conduits 4-9 to 43 respectively, the interrupter contacts will be moved to and retained in an open position. The opening will take place under the influence of a blast of air contained within containers 11 to 14.

The contacts of the interrupters are then reclosed by removing the pressure from conduits 40 to 43 through appropriate pressure control means.

In the event of a pressure leak in any of the pillar insulators 7 to 10 or interrupters 3 to 6, the blast pressure stored in the pressure reservoirs 11 to 14 will be lost. In the absence of the closures for passages 16 to 19, it will be apparent that pressure from the remaining pillar insulators and interrupters, as well as from the main pressure source, will also be lost. Furthermore, where the high pressure gas within the pillar insulators is used in part for holding the cooperating contacts open when they are moved to their open position, such a failure could cause the unintentional reclosing of the interrupter contacts. All of this is prevented by partially closing passages 16 to 19 whereby a failure in any one of the systems will not affect the remaining and isolated systems. Thus, if insulator 7 is broken, the remaining insulators and pressure containers 12 to 14 will be isolated therefrom as will the main pressure source so that a source of blast pressure remains for their respective in terrupters and, furthermore, their contacts will be retained opened even though the contacts of interrupter 3 close because of the failure of its insulator 7.

While the structure described to this point serves the isolating purposes required, it is disadvantageous in that during normal operation there is a substantial pressure decrease in containers 11 to 14 which must be quickly restored.

In accordance with the present invention, auxiliary operating means are provided whereby passages 16 to 19 are momentarily opened during air blast operations so that pressure in chambers 11 to 14 can be quickly restored. If, during this momentary operation, there is a leak in any one of the systems, the gas lost therethrough will be of a negligible amount because of the relatively short time that the orifice in front of it is opened.

The novel system includes a two-way valve structure 45 which comprises a cylinder 46 having a piston 47 movable therein.

The piston 47 has a stem 48 which carries a valve element 49. Valve element 49 normally seats against lower orifice 50 by virtue of biasing spring 51 within cylinder 46 which bears on piston 47. Conduit 44 which causes interrupter operation is connectable to the main source of operating pressure through a valve 52 having a valve member 53 which is movable upwardly to connect main conduit 15 directly to conduit 44. A further extension of conduit 44 introduces pressure below piston 47 whereupon valve element 49 is moved upwardly to seal off feeder conduit 54. A time delay pressure equalizing means is then provided for piston 47 by way of orifice 55 in piston 47. With valve 49 in its lower and normal position, feeder conduit 54 is normally in communication with conduit 56 and to auxiliary feeders 57, 58, 59 and 60 which produces pressure below pistons 24, 25, 26 and 27 respectively.

The operation of the system is as follows:

When the interrupter structures 3, 4, and 6 are closed the control valve 52 is in the position shown so that conduit 44 is vented to the external pressure and conduit 56 and its feeders 57, 58, 59 and 6d are connected to the pressure within main conduit 15. Thus, the pressure on the bottom of pistons 24 to 27 in combination with the biasing force of springs 36 to 39 overcomes the downward pressure applied to the upper surface of pistons 24 to 27 so that passages 16 to 19 remain substantially sealed.

Accordingly and as described above, each of the auxiliary pressure systems for each of the interrupters are isolated.

In order to cause the pole which includes interrupters 3 to 6 to open, valve member 53 is either manually or automatically moved upwardly to connect the relatively high pressure within main conduit 15 to conduit 44, whereby the interrupter structures are operated under the influence of the strong air blast derived from the high pressure air in containers 11 to 14. At the same time, a relatively high pressure is placed beneath piston 47 so that piston 47 moves upwardly whereby valve member 4-9 seals olf feeder conduit 54 and vents conduit 56 through opening 50 to the external atmosphere.

The relatively high pressure on the upper surface of pistons 24 to 27 is then high enough to overcome the biasing force of springs 36 to 39 so that these pistons are moved downwardly and the passages 16 to 19 are exposed to the relatively high pressure within main conduit 15 and the auxiliary pressure containers 11 to 14 are replenished.

After a predetermined time, which depends upon the size of orifice 55, a sufiicient amount of gas flows from the bottom of piston 47 to the top thereof so that spring 51 can begin to move valve member 49 downwardly to close off opening 50 and connect conduit 56 to the interior of conduit 15. At this point, pistons 24 to 27 are moved upwardly to again seal otf passages 16 to 19 and pressure reservoirs 11 to 14 which have been restored to their high gas pressure condition.

It is to be noted that if there is a break as in one of the pillar insulators 7 to 10, that the time that the passages 16 to 19 are opened is relatively short so that there will be only an unsubstantial drain from the high pressure source connected to conduit 15. Accordingly, the present invention makes it possible to substantially isolate the various interrupter structures from the other interrupter structures which are operated from a common pressure supply while still permitting a replenishing of the auxiliary pressure reservoirs.

In order to initially fill auxiliary pressure containers 11 to 14 with compressed air when the circuit breaker is put into service or when it is desired to increase the pressure of the auxiliary pressure containers 11 to 14, auxiliary means are provided in the auxiliary conduits such as conduit 16 which connect main conduit 15 to the auxiliary pressure containers such as container 11. These auxiliary means include auxiliary conduit 97 having branch feeders 63, 64, 65 and 66 which are connected to conduit 15 through a cut-off valve 99. Each of feeder conduits 63 to 66 are connectible to their respective conduits such as conduit 16 through a valve 100, 101, 102 or 103, which is normally closed and is opened when pressure is applied to conduit 97. The valve 99 is then operable to a position where it connects conduit 97 to conduit 15 so that, in the absence of any required operation for the circuit breaker interrupters or of the valve heads 28 to 31, pressure can be directly applied to the auxiliary pressure system. It will be noted that the valve structure including valves to 103 is required to prevent the flow of gas from the other auxiliary pressure systems when a failure occurs in one of them.

A second embodiment of the invention is set forth in FIGURE 2 wherein components identical to those of FIGURE 1 have been given the same identifying numerals.

It will be noted in FIGURE 2 that the conduit portion 15 which contains the movable pistons 24 to 27 is shown in a more compact form in contrast to the elongated form of FIGURE 1, although the valve heads and pistons and springs such as valve head 28, piston 24 and spring 36 serve the same functions described above. In FIGURE 2, however, the operation of the two-way valve 45 for controlling the pressure of conduit 56 is arranged in a difi'erent way.

The two-way valve 45 is normally biased to a position as by biasing spring 51 to permit communication between conduit 56 and conduit 15. The valve member 70, however, is movable to an upper position which closes off this connection and connects conduit 56 to the external atmosphere whereby the pressure on top of pistons 24 to 27 is sufficient to move the pistons 24 to 27 downwardly to connect the main pressure source to theauxiliary pressure containers such as container 11.

Valve member 70 is controlled by a piston 71 which is movable within a cylinder 72 and is connected to valve member 70 through the plunger 74 and pivotally mounted beam 75 is connected to piston 71 by link 76. The piston 71 is normally biased in its upper position by a spring 73 so that spring 51 normally holds valve member 7 0 in the lower position shown.

To control the position of piston 71, the space above in and below it are connected to one another through a conduit 77 which has a controlled bypass therein, including the ball-type back-valve 79. The upper surface of piston 71 is connected to conduit 15 by feeder conduits 80 which have a valve 81 connected therein which normally cuts ofi conduit 15 from piston 71.

As will be seen hereinafter, when the valve member of valve 81 moves upwardly to shut off the space above piston 71 from external atmosphere and to connect the pressure of conduit 15 thereto, piston 71 will move downwardly to move valve member 70 upwardly and, after a predetermined time given by valve 79, the pressure below piston 71 will be relatively equalized to permit its return to the position shown so that valve member 70 is reclosed.

The movable element of valve 81 is mechanically connected to ganged pistons 82, 83, 84 and 85 which are movable within their own respective cylinders.

Each of the poles of the circuit breaker of FIGURE 2, one of which has been described, is provided with a control device which includes electrically operated valves schematically illustrated as valves 86, 87 and 88, respectively. Valve 86 has an outlet 89 which is connected to control conduit 44 of the phase shown in FIGURE 2; while outlets 90 and 91 of valves 87 and 88 are connected to similar control conduits of the other two phases.

When valve 86, for example, is energized, the high pressure air of conduit 15 will be connected to conduit 44 to initiate the operation of each of the series connected circuit interrupters such as circuit interrupter 3 of the phase. These valves further serve to connect conduit 15 to spaces 92, 93 and 94 beneath pistons 82, 83 and 84 respectively over auxiliary conduit means as schematically illustrated.

A further auxiliary conduit is connectable to space 95 beneath piston 85 through manually controllable valve 96.

The operation of the embodiment of FIGURE 2 may now be considered as follows:

During contact operation and assuming that the auxiliary pressure containers 11 to 14 are filled to their required pressure, when one of the phases is actuated as due to a fault signal applied to valves 86, 87 and 88, or due to a manually introduced signal to these valves, the valves open so that the control conduit such as conduit 44 is connected to conduit 15. Thus, all of the interrupters of the pole are operated.

At the same time, compressed air from conduit 15 is connected in spaces 92, 93 and 94 beneath pistons 82, 83 and 84 respectively so that these pistons move upwardly to open valve 81. This connects the pressure in conduit 15 to the top of piston 71 so that piston 71 moves downwardly and valve member 70 moves upwardly to vent the pressure in conduit 56. This will cause each of the pistons such as piston 24 to move downwardly so that the conduits such as conduit 16 are connected to conduit 15 to permit a rapid refill of auxiliary compressed air containers 11 to 14 with compressed air from main conduit 15.

After a predetermined time, air flow through valve 79 will cause pressure equalization between the upper and lower surfaces of piston 71 so that spring 73 can move piston 71 back to the position shown to permit valve 70 to move downwardly to close off conduit 56 and connect it to conduit 15 and thus permit the reclosing of valve heads such as valve head 28 to isolate the various auxiliary pressure sources.

When the system is initially installed and put into service or the pressure in auxiliary containers such as container 11 has fallen below a required minimum value, the novel system can cause a replenishing of pressure to the auxiliary pressure systems without requiring a contact operation. Thus, the auxiliary valve 96 may be manually operated to cause connection of conduit 15 to space beneath piston 85. This will cause the operation of valve 81 and, as described above, a momentary opening of the valve heads such as valve head 28 in the absence of any contact operation.

If the full required pressure is not achieved with this operation, it can be repeated as often as necessary until a predetermined pressure is achieved for the auxiliary pressure containers.

An interrupter (see FIGURES 3 and 4) consists of a chamber 3 enclosing a fixed contact member and a moving contact member 106. The chamber is fitted with a bushing 104 carrying the fixed contact member 105. In addition, the interrupter includes sliding contacts 107, which transmit the current from the moving contact member, as well as a contact spring 108, which always tends to maintain the contacts in the closed position. A mechanism 109 is built onto the chamber for operating the contacts and for opening and closing the channels for the air flow.

The exhaust channel 110 of the chamber is sealed off by a valve disc 111, which is actuated by forces in the closing direction clue to the pressure in the chamber. When a breaking impulse is given to the circuit breaker, the control air conduit 40 is put under pressure. When the pressure in cylinder 112 increases as a result of the inflow of compressed air from the control air conduit 40, the piston 113 causes the valve disc 111 to open at the same time as the seat 114 is put in communication via the auxiliary valve 115 with the outside atmosphere. This passage remains open as long as pressure is maintained in the cylinder 112.

Since the compressed air is forced to flow through the moving contact member 106 before passing out through the exhaust channel 110, this will result in a force counteracting and exceeding that of the contact spring 108. The contact member consequently moves in the direction of the air flow until the cone 116 has reached the seat 114. At this juncture, the arc drawn by the contracts is subjected to a combined radial and axial blast of air. Arc extinction then occurs at the first current zero of the breaking current.

From the moment when the cylinder 112 is subjected to pressure, compressed air flows through the vent 117 in the piston 113 to the rear of the piston and the valve disc 111 returns to the closed position as soon as the opening force of the piston falls short of the forces actuating the valve disc in the closing direction. Part of these forces are now exerted by the cone of the moving contact, which is pressed against the seat of the valve disc by the pressure in the chamber. This results in the moving contact following the return motion of the valve disc so that, when this is completed and the exhaust channel has been closed again, it assumes the open position (FIGURE 4).

When a closing impulse is to be given to the circuit breaker, the control air conduit 40 is discharged. The auxiliary valve 115 changes position without, however,

the piston 113 being affected by the pressure in the cylinder 112 dropping to zero. This results in the seat 114 being subjected to pressure, and the holding action on the moving contact member ceases. The contact spring 108 then resets the contacts to the closed position.

The chamber 3 is kept continuously under pressure, whereas the control air conduit 40 is only put under pressure during opening operations. The circuit breaker remains in the open position of rest as long as the pressure is maintained, but moves over to the closed position when the control air conduit is being emptied.

In the foregoing the invention has been described only in connection with preferred embodiments thereof. Many variations and modifications of the principles of the invention within the scope of the description herein are obvious. Accordingly, it is preferred to be bound not by the specific disclosure herein but only by the appended claims.

I claim:

1. An air pressure control system for an air blast circuit breaker; said air pressure control system including a source of compressed air, a pillar insulator, said air blast circuit breaker including a circuit interrupting chamber carried on said pillar insulator, a pair of co-operating contacts enclosed in said chamber, said co-operating contacts being operable between a circuit closed and a circuit opened position, and said chamber being filled with compressed air in the closed as well as the opened position of said contacts, means pneumatically connecting said interrupting chamber to said pillar insulator, meansincluding an orifice pneumatically connecting said pillar insulator to said source of compressed air; a blocking means for said orifice movable between a blocking and an unblocking position, means normally holding said blocking means in said blocking position; a control means for said blocking means; means operatively connecting said control means to said co-operating contacts for operating said contacts between said circuit closed and said circuit opened position, said control means moving said blocking means to said unblocking position when said contacts are operated to said circuit opened position, and thereafter returning said blocking means to said blocking position, whereby said interrupting chamber is momentarily connected through said pillar insulator to said source of compressed air.

2. In a device as claimed in claim 1, said control means being manually operable to connect said interrupting chamber momentarily through said pillar insulator to said source of compressed air independently of operation of said contacts.

3. In a device as claimed in claim 1, said control means comprising a two-way valve operable between a first and a second position; said blocking means including a piston; an air pressure means to maintain an air pressure on said piston to hold said piston in said blocking position when said two-Way valve is in said first position; movement of said valve to said second position removing said pressure on said pistons to permit movement of said piston to said unblocking position.

4. In a device as claimed in claim 3, said two-Way valve having controlled leak means for automatically returning said valve to said first position after a predetermined time from the time said valve is moved to said second position.

5. In a device as claimed in claim 4, said control means being manually operable to connect said interrupting chamber momentarily through said pillar insulator to said source of compressed air independently of operation of said contacts.

6. In a device as claimed in claim 3, said control means being manually operable to connect said interrupting chamber momentarily through said pillar insulator to said source of compressed air independently of operation of said contacts.

References Cited in the file of this patent UNITED STATES PATENTS 2,964,605 Schulz Dec. 13, 1960 FOREIGN PATENTS 551,071 Belgium Sept. 29, 1956 1,073,578 Germany Jan. 21, 1960

Claims (1)

1. AN AIR PRESSURE CONTROL SYSTEM FOR AN AIR BLAST CIRCUIT BREAKER; SAID AIR PRESSURE CONTROL SYSTEM INCLUDING A SOURCE OF COMPRESSED AIR, A PILLAR INSULATOR, SAID AIR BLAST CIRCUIT BREAKER INCLUDING A CIRCUIT INTERRUPTING CHAMBER CARRIED ON SAID PILLAR INSULATOR, A PAIR OF CO-OPERATING CONTACTS ENCLOSED IN SAID CHAMBER, SAID CO-OPERATING CONTACTS BEING OPERABLE BETWEEN A CIRCUIT CLOSED AND A CIRCUIT OPENED POSITION, AND SAID CHAMBER BEING FILLED WITH COMPRESSED AIR IN THE CLOSED AS WELL AS THE OPENED POSITION OF SAID CONTACTS, MEANS PNEMATICALLY CONNECTING SAID INTERRUPTING CHAMBER TO SAID PILLAR INSULATOR, MEANS INCLUDING AN ORIFICE PNEUMATICALLY CONNECTING SAID PILLAR INSULATOR TO SAID SOURCE OF COMPRESSED AIR; A BLOCKING MEANS FOR SAID ORIFICE MOVABLE BETWEEN A BLOCKING AND AN UNBLOCKING POSITION, MEANS NORMALLY HOLDING SAID BLOCKING MEANS IN SAID BLOCKING POSITION; A CONTROL MEANS FOR SAID BLOCKING MEANS; MEANS OPERATIVELY CONNECTING SAID CONTROL MEANS TO SAID CO-OPERATING CONTACTS FOR OPERATING SAID CONTACTS BETWEEN SAID CIRCUIT CLOSED AND SAID CIRCUIT OPENED POSITION, SAID CONTROL MEANS MOVING SAID BLOCKING MEANS TO SAID UNBLOCKING POSITION WHEN SAID CONTACTS ARE OPERATED TO SAID CIRCUIT OPENED POSITION, AND THEREAFTER RETURNING SAID BLOCKING MEANS TO SAID BLOCKING POSITION, WHEREBY SAID INTERRUPTING CHAMBER IS MOMENTARILY CONNECTED THROUGH SAID PILLAR INSULATOR TO SAID SOURCE OF COMPRESSED AIR.

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