US2213658A

US2213658A - Circuit breaker control system

Info

Publication number: US2213658A
Application number: US249687A
Authority: US
Inventors: Thommen Hans
Original assignee: BBC Brown Boveri France SA
Current assignee: BBC Brown Boveri AG Germany; BBC Brown Boveri France SA
Priority date: 1938-01-14
Filing date: 1939-01-07
Publication date: 1940-09-03
Anticipated expiration: 1957-09-03
Also published as: FR848830A; BE432154A; CH207920A; GB523956A

Description

Sept. 3, 1940.

H. THOMMEN Filed Jan. 7. 1939 3 Sheets-Sheet 1 i a I 4 r I W ll \j/ 47 44 45 Sep&. 3, iQQ-Q. H THQMMEN f/zz'lws CIRCUIT BREAKER CONTROL SYSTEM Filed Jan. 7, 1939 3 Sheets-Sheet 2 Sept. 3, 1940. H. THOMMEN CIRCUIT BREAKER CONTROL SYSTEM Filed Jan. 7, 1939 rub-r 3 Sheets-Sheet 3 Patented Sept. 3, 1940 UNITED STATES PATENT OFFICE CIRCUIT BREAKER CONTROL SYSTEM Application January 7, 1939, Serial No. 249,687 In Germany January 14, 1938 9 Claims.

This invention relates in general to improvements in circuit breaker control systems, and more particularly to a control system for a circuit breaker comprising arcing contacts which are immediately reclosed upon opening thereof and disconnecting contacts which are opened only upon repeated operation of the arcing contacts.

It is frequently desired to control a circuit breaker in such manner that the circuit breaker contacts reclose immediately upon interrupting operation thereof, the contacts thereafter reopening and remaining open if the operating condition causing the first opening of the contacts isstill present. It is, however, desirable to shorten as much as possible the time required for the entire sequence of operations of the circuit breaker to reduce the disturbing effects of such operations on the performance.of electric motors and other apparatus connected with the circuit controlled by the circuit breaker. To obtain such result the circuit breaker preferably comprises fluid actuated arcing contacts which are light in weight and which travel only a short distance while being swept by a blast of fluid to momentarily interrupt the flow of current therethrough. The circuit breaker is also provided with disconnecting contacts which are suitably interlocked with the arcing contacts to open only during a predetermined time interval following at least one reclosing and reopening of the arcing contacts and to thereafter maintain the circuit open.

If the circuit breaker is of large dimensions, the arcing contacts are preferably provided with fluid actuated reclosing means operable while the contact opening means are still acting to reduce the time required for reclosing and reopening the arcing contacts. If the circuit to be controlled is a polyphase circuit the different pole portions of the circuit breaker may be actuated independently of one another in dependence upon the occurrence of disturbances in the circuit conductors associated therewith, butit is generally preferable to cause all pole portions of the circuit breaker to function simultaneously to avoid continued operation of the circuit as a single phase circuit.

It is therefore one of the objects of the present invention to provide a control system for a circuit breaker operable to control positively the opening and closing operations of the arcing contacts of the circuit breaker and to cause the disconnecting contacts of the circuit breaker to be opened upon reopening of the arcing contacts.

Another object of the present invention is to provide a control system for a multipole circuit breaker operable to cause the disconnecting contacts of all pole portions of the circuit breaker to be opened upon repeated opening of the circuit breaker arcing contacts.

Another object of the present invention is to provide a control system for a circuit breaker for causing the arcing contacts of the circuit breaker to be opened by fluid under pressure and to be reclosed while the contact opening operation is continued.

Objects and advantages other than those above set forth will be apparent from the following description when read in connection with the accompanying drawings, in which:

Fig. l diagrammatically illustrates one embodiment of the present invention in which the operation of the disconnecting contacts is controlled through a pneumatic relay responsive to redosure of the arcing contacts;

Fig. 2 diagrammatically illustrates a modified embodiment of the present invention in which the operation of the disconnecting contacts is controlled through an electromagnetic relay;

Fig. 3 is a diagram of the connections of the circuit breaker contacts in a polyphase electric circuit;

Fig. 4 is a chart of the operation of the embodiment illustrated in Fig. 1; and

Fig. 5 is a chart of the operation of the embodiment illustrated in Fig. 2.

Referring more particularly to the drawings by characters of reference, reference numeral 6 generally designates a circuit breaker of the fluid actuated type comprising cooperating arcing contacts l, 8 serially connected with cooperating disconnecting contacts 9, ill in an electric circuit I I. Circuit breaker 6 may be of the single pole type, as illustrated in Fig. 1 to simplify the drawing, but if circuit H is a polyphase circuit, circuit breaker 6 will comprise a plurality of pole portions equal in number to the number of phase conductors of circuit H as illustrated in Fig. 3. The diiferent pole portions may be independently controlled, but it is generally preferable to jointly control all the pole portions to avoid continued operation of circuit H as a single phase circuit upon opening of less than all the pole portions of circuit breaker 6.

Circuit breaker 6 comprises a reservoir i2 serving as a source of supply of fluid under pressure and preferably also serving as support for the circuit breaker contacts. The fluid utilized for actuation of the circuit breaker is assumed to be compressed air supplied to reservoir l2 and main- ,rotated by suitable contact separating means such as an air motor ll of any suitable known type to cause opening of the disconnecting contacts. The disconnecting contacts may be closed by another air motor I3.

Insulator It is hollow and defines part of the arcing chamber I9 of the circuit breaker which motor 23 acting against a spring 25. Contact T is hollow and is provided with a spring 26 continuously tending to maintain contacts I and 8 closed. The contacts are provided with fluid actuated contact separating means such as a piston 21 adapted to be displaced in a cylindrical chamber of cap 22 also serving for the passage of the air discharged from the arcing chamber through contact 7. Air under pressure may be admitted under the lower face of piston 21 from arcing chamber l9 through a check valve 28 and-through a pneumatically actuable slide valve 29. Piston 27 also controls the admission of air under pressure under the lower face of an annular slide valve 3| having a cylindrical portion adapted to abut against a plate 32 to close the passage for the flow of air issuing from the bore of contact '1.

Opening operation of circuit-breaker is controlled in response to an operating condition of circuit such as the magnitude of the flow otf current therethrough by means of a current transformer 33 connected in circuit H and supplying current to the coil of a relay 3%. Relay 33 controls the connection of a. suitable auxiliary current source such as. a battery 38 with the coil 31 of a magnet valve 38 through an auxiliary switch 39 mounted on the shaft of contact 9. Valve 38 connects motor 29. with atmosphere when the valve coil is deenergized and connectsmotor 24 with reservoir I 2 170 cause opening of valve 23 and opening of contact I when the valve coil is energized.

Another magnet valve ll naving a coil 32 is arranged similarly to valve 38 to supply air under pressure from reservoir I 2 to the left side of a piston 43 slidable in the cylindrical bore oif an air relay 69. A second piston 35 of relay 5% controls the supply of air from arcing chamber 19 to motor H. A third piston 46 mounted on the shaft of

pistons

33 and 45 controls the supply of air from reservoir l2 through valve 23 and arcing chamber 89 to the space below slide valve 29 to control reopening of contactl. Piston 43 is also operable to close a plurality of contacts 41 controlling'the energiration of coils 37v and 42. A push button switch 58 is connected across those contacts 91 which control coil 92,

operable to open the valve for causing reclosureof contact 1. Valve 5| is provided with a relatively large second piston 53 operable toreclose the valve under the control of valve 3|. Air is admitted through valve 5| to a reservoir 56 and to the right hand side of a fourth piston 55 of relay 44 integral with a fifth piston 56 operable to open arcing chamber l9 and motor 23 to atmosphere. Piston 55 is of smaller diameter than piston 43 and normally closes a set of contacts 5'! connected in series with the contacts of an air relay 58 and controlling a holding circuit for coil 31. Air relay 58 is arranged to be responsive tomthe pressure within arcing chamber 59 and is provideFTvith suitable means for delaying opening of the contacts thereof for a predetermined length of time after return of the pressure within arcing chamber l9 to atmospheric value.

Another air relay 59 similar to relay 58 controls the connections of coil 31 in response to the pressure in reservoir 56. The pistons of air relay 4 3 are normally maintained in the positions shown by means of a spring 60. Motor l8 may receive air under pressure from reservoir l2 through a magnet valve 6|, the coil 62 of which may be connected with battery 36 through a push button switch 63. This connection preferably includes the contacts of an air relay 6% responsive to-the air pressure in the cylinder of motor ll to render the circuit breaker trip free.

Fig. 1 illustrates circuit breaker 6 in the normal operating condition thereof, contacts i, 8 and 9, It being closed to complete circuit ll. Upon occurrence of an operating condition such as an overload or short circuit in circuit H, resulting in an excessive fiow of current therethrough, current transformer 33 supplies suificient current to the coil of relay 34 to cause the relay contacts to close. A circuit is thereby completed from battery 36 through the contacts of relays 34 and 59, coil 31 and switch 39 back to the battery, and valve 38 is actuated to admit air from reservoir l2 to motor 24. Valve 23 is thereby opened to admit air from reservoir I2 into arcing chamber l9. After the pressure within arcing chamber [9 has built up to a suflicient value, valve 28 opens to admit air from arcing chamber l9 through valve 28 and silde valve 29 to the space adjacent the lower face of piston 21. Piston 21 rises and separates contact 1 from contact 8 against the action of spring 23. An arc is drawn between contacts 1 and B and is extinguished by the air blast escaping from chamber l9 through contact 1 and between plate 32 and slide valve 3l. The flow of current through circuit II' is interrupted and relay 34 returns to the position shown.

When piston 21 approaches the upper end of its stroke, a port 39 is uncovered thereby, through which space below the lower *iface of slide valve 3|. Slide valve 3| is raised into engagement with plate 32 to close the outlet from the arcing chamber. The space adjacent contacts I and 8 is accordingly filled with air at the pressure of plied on both faces of piston 27. spring 26 canair under pressure is admitted into the .coil 42 instead of coil 3?.

not reclose contact 1 because valve 28 prevents return of air from the space below piston 21 to chamber l9.

During the above contact opening operation and before return of relay 34 to the position shown, air is admitted from chamber Hi to relay 58 which thereupon connects coil 31 with battery 36 through a holding circuit independent of relay 34. Air is also admitted from arcing chamber l9 through relay 44 into reservoir 49 and under piston 52 of valve 5|. After a predetermined time delay depending upon the capacity of reservoir 49, the pressure under piston 52 becomes sumcient to lift the piston, which opens V valve 5! and closes a port normally discharging reservoir 54 to atmosphere. Valve 5! admits air under pressure to relay 59 which is actuated thereby to cause relay 34 to thereafter control Air pressure is also applied to the lower face of slide valve 29 to actuate the slide valve to the upper position thereof. Slide valve 29 places the lower faces of piston 27 and of slide valve 3i in communication with atmosphere and also applies air pressure to the upper face of slide valve M to cause slide valve iii to reopen. The contact opening action of piston 27 is terminated, and the decreasing air pressure on the upper face of piston 2'! causes the piston to cooperate with spring 26 to return contact l to the position shown. Reclosing of contact 7 takes place after a predetermined time delay while valve 23 is still open as a result of the connection of valve 23 with valve 5i through arcing chamber l9 and reservoir 49 forming a pneumatic interlock therebetween.

The above described portion of the operation of the circuit breaker takes place regardless of whether or not the disturbance in circuit H has been terminated by opening of contacts 7, 8. Upon reclosure of these contacts, three diiferent sequences of operation may take place. Let it first be assumed that the disturbance was of transient nature, such as an arc to ground from an otherwise sound conductor of circuit ll following a stroke of lightning and that the disturbance is terminated by opening of contacts l, Upon reclosure of contact l in the manner above described, the operation of circuit 5 l is restored to its normal condition and relay 34 re mains in the position shown.

After a predetermined time delay depending upon the capacity of reservoir 54, the pressure within this reservoir rises to a suficient value to cause piston 55 to be displaced to the left against the action of spring 64. Contacts 5'! open the holding circuit for coil 37, thus causing valve 38 to return to the position shown and to discharge the air previously admitted into motor 24. Valve 23 closes to disconnect arcing chamber l9 from reservoir l2. The air contained within the arcing chamber is discharged to atmosphere between

pistons

55 and 56 of valve 44 which also assist in discharging the air from motor 24. Piston 56v also releases the air contained within reservoir The pressure within reservoir 49 decreases and piston 52 of relay Si is returned to the position shown, opening a port placing reservoir 54, relay 59 andslide valve 29 in communication with atmosphere. Relay 59 and slide valve 29 immediatelyreturn to the positions shown. Reservoir 54 gradually discharges to atmospheric pressure and permits piston 55 of relay 44 to return to position shown after a time delay. Relay 58 returns to the position shown after a time delay depending upon the adjustment thereof.

.cuit Ii.

The system is then again in the normal operating condition thereof and is again ready to function as if contact 'I had not been opened. The above sequence of operations is represented by the chart Fig. 4a. in which the different columns represent successivearbitrary intervals of time reading from left to right. The diiferent members of the system are listed in a column at the left side of the chart and a circle in any column indicates that the element listed on the same line is displaced from the position shown. Elements which are always actuated together are listed on the same line to simplify the chart.

Let it next be assumed that the disturbance is of the type which is not removed upon opening of circuit breaker 6, such as a permanent short circuit resulting from rupture of a conductor of cir- Upon reclosure of contact I, as above described, the excessive flow of current through circuit 11 l is immediately reestablished and relay 34 is again actuated in response thereto. Relay 34 connects battery 36 with coil 42 through the contacts of relay 59, which is then maintained in the depressed position under the control of the reclosing system of contact I. The purpose of this connection is to render relay 34 operable during a predetermined period following reclosure of contact 7! to cause reclosure of valve 5! and opening of all the contacts of the circm't breaker. Coil 42 causes opening of valve 4i which admits air under pressure from reservoir i2 to the left sideof piston 43 and to the space above piston 53. Valve M is thus reclosed and

pistons

43, 45 and 45 are displaced to the right. Contacts 417 are closed to complete a holding circuit for coil 42 independently of relay 34. Piston 46 and valve 5! cooperate to discharge the air contained in relay 59 and below slide valve 24. The slide valve returns to the position shown, removes the pressure applied to the upper face of slide valve ill, and reestablishes the connection between piston 2! and chamber l9 through check valve 23.

At this moment coil 3? is still energized from battery 34 through contacts 57 and through the contacts of relay 58 so that valve 23 is still open and piston 21 may reopen contact 7 to again interrupt the flow of current through circuit 5 l Slide valve 3i is again raised to close arcing chamber l9. At the same time, piston 45 admits air from arcing chamber iii to motor ll which opens contact 9 of the disconnecting switch, leaving circuit it permanently open at contacts 9, M3. Auxiliary switch 39 opens the circuit of the coils 31 and 42, causing valve 23 and piston 43 to return to the positions shown. Arcing chamber !9 is then still filled with air under pressure.

After a time delay, valve 5i opens and slide valve 29 is raised in the manner above described to cause slide valve 3! to drop, thereby releasing the air contained within arcing chamber i9 and causing contact 7 to reclose. Reservoir 49 discharges into the arcing chamber and when the pressure in the reservoir has decreased sufficiently, valve 5i returns to the position shown to discharge the air contained within reservoir 54. If desired, such action may be accelerated by dimensioning piston 46 to have a loose fit in relay 44 to permit some of the air contained in

reservoirs

49 and 54 to leak through the piston clearance. Relay 58 finally returns to the position shown and the entire system is then returned to the position shown with the exception of contact 9. The entire sequence of operations in this case is diagrammatically represented by the chart Fig. 4b.

Let it finally be assumed that the disturbance in circuit II has been removed by opening of contact 1 in the manner above set forth, but that the disturbance again becomes effective between the time of reclosure of contact 1 and the time of return of relay 59 and of slide valve 29 to the positions shown at the end of a predetermined period following reclosure of contact 1. Valves 29, 8|, 5| and 99 are then still under the direct control of relay 38. The operation of the system, accordingly, remains the same as the operation resulting from the occurrence of a permanent short circuit as above described if piston 58 has not yet opened contacts 51 at the time of reestablishment of the disturbance. If piston 58 has already been displaced to the left, the piston is returned to the position shown by the extension of the shaft of piston 95 which is then moving to the right and the operation of the system is again completed as above described to cause opening of all the contacts of the circuit breaker. If, however, relay 39 recloses the contacts thereof after relay 59 has already returned to the position shown, the operation of the circuit breaker will be reinitiated in the manner above described .as if contacts 1, 8 have not previously been opened.

After opening of contact 9 and removal of the fault in circuit ii, the circuit breaker may be closed manually by closing switch 83. This switch connects coil 82 with battery 38 to cause opening of valve 8!. This valve connects motor i8 with reservoir l2 and the motor thereupon closes contact 9.

The circuit breaker may also be opened manually by momentarily closing switch 88 to cause actuation of valve 91. Valve 9i .admits air from reservoir 12 to the left side of piston 83 which is displaced to the right with pistons 95 and 98 to close contacts 91. The latter complete a holding circuit for coil 92 and also connect coil 31 with battery 36. Valve 38 opens and causes opening of valve 23 which admits air from reservoir i2 into arcing chamber 19. Contact 1 opens in the manner outlined aboveand interrupts any current which may be flowing through circuit II. At the same time piston 85 admits air from chamber 19 to motor 11 to cause opening of contact 9 and of auxiliary switch 39. The latter opens the circuit of coils 31 and 42 and causes the circuit breaker, with the exception of contact 9, to return to the position shown. This.

operation is represented by the chart Fig. 40.

In the embodiment illustrated in Fig. 2, circuit breaker 8 is assumed. to be simplified by the omission of slide valves 29 and 3| and of check valve 28. Contact 1 may then be reclosed by admission of air from reservoir I2 to the space above piston 21 through an air relay 58 similar to relay 69 but comprising a stepped piston 81 forming a valve integral with a second piston 98 and acting against another piston 69 through a spring 1|. Piston 81 is controlled by avalve 12 provided with an actuating coil 13 and controls in turn a plurality of contacts 14, 15. Piston 89 is controlled by a valve 18 having an actuating coil 11 and controls a plurality of contacts 18, 19.

Motor I1 is controlled by a second air relay 8| provided with a stepped piston 82 integral with another piston 83 and maintained in a neutral position by a pair of

springs

84, 85. Movement of piston 82 is controlled by a valve 88 having a coil 81 and by a valve 88 having a coil 89.

Piston 82 controls a plurality of contacts 9|, 92

- step in the operation thereof.

99, 95. The diflerent coils and contacts above described cooperate with a reclosing relay 98 provided with normally closed contacts 91, instantaneously closing contacts 98, and contacts 99 closing with a time delay. In particular, relay 98 forms an interlock between

valves

23 and 81 to cause reclosure of contact 1 while valve 23 is still open. Opening operation of the circuit breaker may be controlled manually by means of a pushbutton switchiflll.

The operation of circuitbreaker 8 will be described following the same procedure as with respect to the embodiment illustrated in Fig. 1. Upon occurrence of any disturbance in circuit ll resulting in an excessive flow of current therethrough, relay 38 closes the contacts thereof to connect coil 31 with battery 38 through contacts 91 of relay 98 and through auxiliary switch 39. Coil 31 opens valve 38 which in turn causes opening of valve 23 and actuation of contact 1.

After a predetermined time delay, relay 98 closes contacts '99 which connect coil 13 with battery 38 through contacts 18 and 93 and through switch 39. Valve 12 is thereby opened 1 and admits air from reservoir 12 to the left side of piston 81. The piston is displaced to the right and admits air under pressure from reservoir 12 to the upper face of piston 21 to cooperate with spring 26 in reclosing contact 1 against the action of the air from chamber 19 on the lower face of piston 21. Piston 81 also closes contacts 15 which complete a holding circuit for the coil of relay 96 independently of contacts 95,

and closes contacts 15 which connect coil 81 with battery38. I

Assuming first that opening of contact 1 has removed the disturbance from circuit ll, upon reclosure of contact 1 relay 38 remains in the position shown. Coil 81, which is then energized,

opens valve 88 which. admits air from reservoir i2 to the left side of piston 82. Piston 82 is displaced to the right, closes contacts 92 and opens contacts 9| to cause deenergization of coil 31. Valve 38 closes and causes reclosure of valve 23. The air contained within chamber 19 escapes to atmosphere between contacts 1 and 8, which are not in gas tight engagement. Piston 82 also opens contacts 93 to deenergize coil 13. Valve 12 recloses and permits piston 81 to return to the position shown and to discharge the air entrapped above piston 21. The circuit of coil 81 is opened by contacts 15 to cause piston 82 to return to the position shown. Contacts 14 and 95 being open, relay 98 returns to the position shown and the entire system is returned to the normal operating condition thereof. The entire operation is represented by the chart Fig. 5a.

Assuming next that opening of contact 1 has not removed the disturbance from circuit II, upon reclosure of contact 1 relay 34 closes the contacts thereof to connect battery 38 with coil 11 through contacts 98 of relay 98. Coil 11 opens valve 18 which admits air from reservoir 12 to the right hand side of piston 69. Piston 69 is displacedto the left to opencontacts 18 and to close contacts 19. Opening of contacts 18 causes deenergization of coil 13 which permits piston 61 to return to the position shown to discharge the air contained within the space above piston 21. This action is accelerated by mechanical action'of piston 69 on the extension of the shaft of piston 51. position shown, contacts 15 connect coil 81 with battery 36 to cause opening of valve 86. Piston 92 was accordingly displaced to the right to open contacts 9!, but a circuit for coil 31 was then closed through the contacts of relay 34 and through contacts 92. Valve 23 is thus maintained open through the above operation.

When piston 61 returns to the position shown, arcing chamber I9 is still filled with compressed air which opens contact 1 and blows out the are drawn between contacts I and 8. Piston 6'! also opens contacts l5, and coil 81 is deenergized. Valve 86 recloses to cause piston 82 to return to the position shown, Closure of contacts l9 by piston (59 energizes coil 89 which admits air from I, reservoir ii. to the right side of piston 89 to disrepresented by chart Fig. 5b.

Assuming finally that the disturbancein circuit ll again becomes effective between the time of opening of contacts M by piston 82 and the time of return of relay 96 to the position shown, the circuit of coil 3?! is momentarily opened at contacts til and valve 23 may be reclosed. Upon reclosure of contact "l, however, relay 3 3i again connects coil 3i with battery 36 through contacts 92, valve 23 opens again and the operation of the system is completed as above described.

The circuit breaker may be opened manually by closing switch Mm to connect coils 3i and H with battery 38. Coil 37 actuates valve 33 and causes opening of valve 28. Air is admitted from reservoir it into arcing chamber it to open contact l and to interrupt any current which might be flowing through circuit ll. Coil ll actuates valve 76, which admits air from reservoir it. to the right hand side of piston 69. The latter closes contacts 39 to energize coil 89. Valve 88 is actuated to admit air from reservoir 52 to the right hand side of piston 83, which displaces piston 82 and causes air to be admitted thereby from arcing chamber 99 to motor ll. Motor ill opens contact 9 and also actuates switch 39 to cause the remainder of the system to return to the position shown in the manner outlined above. This operation is represented by the chart Fig. 50.

Although but two embodiments of the present invention have been illustrated and described, it

-will be 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 combination, a 'polyphase electric circuit comprising a plurality of phase conductors, a circuit breaker comprising a plurality of pole portions in number equal to the number of said phase conductors and each comprising cooperat- Until return of piston 61 to the" ing arcing contacts and cooperating disconnecting contacts serially connected with said arcing contacts in a different one of the said phase conductors, means responsive to an operating condition of said circuit for opening said arcing contacts, time delay means responsive to initiation of the opening operation of said arcing contacts for causing said arcing contacts to reclose, and means responsive to a continuance or reoccurrence of said operating condition and controlled by said contact reclosing means for causing opening of all said contacts, 1

2. In combination, an electric circuit, a circuit breaker comprising cooperating arcing contacts and cooperating disconnecting contacts serially connected with said arcing contacts in said circuit, means continuously tending to maintain said arcing contacts closed, means responsive to an operating condition of said circuit for opening said arcing contacts against the action of the first said means, means responsive to the initiation of the operation of said contact opening means for terminating the action of said contact opening means and cooperating with the first said means to cause said arcing contacts to reclose, and means responsive to said operating condition during a predetermined period following reclosure of said arcing contacts to cause opening of all said contacts.

3. In combination, an electric circuit, a circuit breaker comprising cooperating arcing contacts and cooperating disconnecting contacts serially connected with said arcing contacts in said circuit, means for causing opening of said arcing contacts comprising a source of fluid under pressure, contact separating means and a valve for connecting said source with said contact separating means, means responsive to an operating condition of said circuit for opening said valve to cause opening of said are contacts, means for causing opening of said disconnecting contacts comprising a second contact separating means and a second valve for connecting said source with said second contact separating means, and means comprising said operating condition responsive means and means controlled by the first said valve to cause the second said valve to open after opening of said arcing contacts.

4. In combination, an electric circuit, a circuit breaker comprising cooperating arcing contacts and cooperating disconnecting contacts serially connected with said arcing contacts in said circuit, means for causing opening of said arcing contacts comprising a source of fluid under pressure,-contact separating means and a valve for connecting said source with said contact separating means, means responsive to an operating condition of said circuit for opening said valve to cause opening of said arcing contacts, means for causing reclosure of said arcing contacts comprising contact closing means and a second valve connected with said source, means responsive to initiation of opening operation of said arcing contacts for actuating the second said valve to cause reclosure of said arcing contacts, means for causing opening of said disconnecting contacts comprising a second contact separating means and a third valve for connecting said source with said second contact separating means, and means responsive to said operating condition during a predetermined period following reclosure of said arcing contacts for causing opening of all said contacts.

5. In combination, an electric circuit, a circuit breaker-comprising cooperating arcing contacts and cooperating disconnecting contacts serially connected with said arcing contacts in said circuit, means for causing opening of said arcing contacts comprising a source of fluid under pressure, contact separating means and a valve for connecting said source with said contact separating means, means responsive to an operating condition of said circuit for opening said valve to cause opening of said arcing contacts, -means for causing reclosure of said arcing contacts comprising contact closing means and a second valve connected with said source, means responsive to initiation of said opening operation of said arcing contacts for actuating the second said valve to cause reclosure of said arcing contacts, means for causing opening of said disconnecting contacts comprising a second contact separating means and a third valve for connecting said source with said second contact separating means, and means responsive to a continuance or reaccurrence of said operating condition and controlled by said contact reclosing means to cause opening of all said contacts.

6. In combination, an electric circuit, a circuit breaker comprising cooperating arcing contacts and cooperating disconnecting contacts serially connected with said arcing contacts in said circuit, means for causing opening of said arcing contacts comprising a source of fluid under pressure, contact separating means and a valve for connecting said source with said contact separating means, means responsive to an operating.

condition of said circuit for opening said valve to cause opening of said arcing contacts, means for causing reclosure of said arcing contacts comprising contact closing means and a valve connected with said source, means responsive to initiation of said opening operation of said arcing contacts for actuating the second said valve to cause reclosure of said arcing contacts, means for causing opening of said disconnecting contacts comprising a second contact separating means and a third valve for connecting said source with said second contact separating means, and means responsive to a continuance or reoccurrence of said operating condition for opening the said third valve to cause opening of said disconnecting contacts between an opening operation 02, said arcing contacts and the following reclosing operation of said arcing contacts.

'7. In combination, an electric circuit, a circuit breaker comprising cooperating arcing contacts and cooperating disconnecting contacts serially connected with said arcing contacts in said circuit, means for causing opening of said arcing contacts comprising a source of fluid under pressure, contact separating means and a valve for connecting said source with said contact separating means, means responsive to an operating condition of said circuit for opening said valve to cause opening of said arcing contacts, means for causing reclosure of said arcing contacts comprising contact closing means and a. second valve connected" with said source, and an interlock between said valves to cause the second said valve to beactuated to cause reclosure of said arcing contacts while the first said valve is open.

8. In combination, an electric circuit, a circuit breaker comprising cooperating arcing contacts and cooperating disconnecting contacts serially connected with said arcing contacts in said circuit, means for causing opening of said arcing contacts comprising a source of fiuid under pressure, contact separating meansand a valve for connecting said source with said contact separating means, means responsive to an operating condition of said circuit for opening said valve to cause opening of said arcing contacts, means for causing reclosure of said arcing contacts comprising contact closing means and a second valve connected with said source, an interlock between said valves to cause the second said valve to be actuated to cause reclosure of said arcing contacts while the first said valve is open, means for causing opening of said disconnecting contacts comprising a second contact separating means and a third valve for connecting said source with said second contact separating means, and means responsive to said operating condition during a predetermined period fol-' lowing reclosure of said arcing contacts for causing opening of all said contacts.

9. In combination, an electric circuit, a circuit breaker comprising cooperating arcing contacts and cooperating disconnecting contacts serially connected with said arcing contacts in said circuit, means for causing opening of said arcing contacts comprising a source of fluid under pressure, contact separating means and a valve for connecting said source with said contact separating means, means responsive to an operating condition of said circuit for opening said valve to cause opening of said arcing contacts, means for causing reclosure of said arcing contacts comprising contact closing means-and a second valve connected with said source. means responsive to initiation of opening operation of said arcing contacts for opening the second said valve to cause reclosure of'said arcing contacts, means for causing opening of said disconnecting contacts comprising a. second contact separating means and a third valve for connecting said source with said second contact separating means, and means controlled by said contact reclosing means and cooperating with said operating condition responsive means for reclosing the second said valve and for opening of the third said valve to cause opening of all said contacts.

" HANS THQr'