US1821813A - Circuit making and breaking device - Google Patents

Description

Sept. 1, 1931. c. A. NICKLE CIRCUIT MAKING AND BREAKING DEVICE CliFForcl A.NicKley Hus AbbOPneg Filed March 23, 1928 Patented Sept. 1, 1931 UNITED. STATES PATENT OFFICE CLIFFORD A. NICKLE, 0F SCHENECTADY, NEW YORK, ASSIGNOR TO GENERAL ELECTRIC COMPANY, A CORPORATION OF NEW YORK CIRCUIT MAKING AND BREAKING DEVICE Application filed March 23, 1928. Serial No. 264,210.

My invention relates to circuit making and breaking devices and more particularly to circuit interrupters for direct current circuits, vibratory contact devicesfor voltage regulators, and similar apparatus.

An object of my invention is to provide means for interrupting electrical circuits without sparking or arcing at the points of interruption when interrupting the flow of 0 an electric current having a value which would ordinarily cause injurious sparking and arcing, or for permitting the interruption of larger values of current than has been heretofore possible without subjecting I the contacts of the interrupter to injurious sparking or arcing.

Another object of my invention is'to provide an improved arrangement for interrupting an electric circuit in a highly evacuated 0 envelope or in a medium which tends to cause deleterious electronic emission at the contact points of interruption upon the occurrence of arcing or sparking.

It has heretofore been customary to connect a condenser in a parallel circuit to the contacts of an interrupter for reducing arcing at the contacts during the period when the contacts are separated. In the application of condensers in shunt ,to interrupter contacts the selection of the condenser for a particular interrupter has been made in accordance with experience with similar devices or initially according to a trial and error method by which a condenser capacity is selected to give minimum arcing during disengagement of the contacts and minimum arcing during reengagement of the contacts. That is, the application of condensers heretofore has not resulted in the elimination of arcing but has merely resulted in reducing the duration of the are so that the are becomes a spark. Increasing the size of the condenser to any great extent becomes im- 3 practical. Furthermore, a large capacity condenser causes a discharge upon reengagement-which causes depositing and pitting of the metal contacts. Thus, with the arrangements which have been used arcing and sparking and consequent pitting and burning of the contacts has not been entirely avoided.

Further phenomena other than pittingand burning of the contacts due to arcing and sparking have been observed when a current is interrupted in a high vacuum. hen an electric circuit is interrupted by means of electrodes separated in a highl evacuated envelope any are or spark whic is formed when the electrodes are moved into spaced relation causes heating of the contact surfaces and thereby develops regions which may become sources of electronic emission. If the contact surface is heated to the point where the electrons therein have suflicient energy to break through the metal boundary into space one type of thermionic emission results. Another type of thermionic emission may result from the formation of what may be termed a cathode spot. If the con tact material is of some suitable low melting point material, such as copper, and separation of the contacts while current is flowing is initiated, the last point in contact will be vaporized by the current flowing. That is, as long as the current is spread over the entire surface no point is' seriously heated. But just before the final separation the points in contact are so limited in area that the current brings them up to a point where the metal melts and vaporizes. At the same time that the contacts are separating but are still very close together the potential drop between the two contacts although quite small is still millions of volts per centimeter. A gradient of the order of millions of volts per centimeter will draw electrons from a relatively cold metal and electronic emission takes place even though the contacts are not heated to a degree sufiicient to cause electronic emission of the first type referred to above. These electrons will form collisions with the vaporized metal in the space between the contacts. These collisions will ionize some of the metal vapor thus producing additional electrons which join those already formed and travel toward the anode or positive electrode, The positive ions travel toward the. cathode or negatively charged electrode and due to their much greater mass their motion is relativelyslow so that positive charges accumulate in the region adjacent to the cathode. These positive charges produce a very high potential gradient at the cathode surface, thus-continuing to pull out electrons even though the anode meanwhile has been with drawn to a considerable distance.

By my invention, low melting point materials, such as copper, become more suitable for the electrodes of direct circuit interrupters of the vacuum type by suppressing the tendency to form cathode spots. IVith such materials a cathode spot is easily maintained for an indefinite period with a voltage of the order of volts and currents as low as 50 or amperes. On the other hand. metals which do not favor the formation and maintenance of cathode spots, such as tungsten, may be chosen but it is desirable to suppress arcing or sparking in order to eliminate the formation of projections which may favor the formation of regions of electronic emission. By my invention high voltage gradients are eliminated or reduced to so low a value that the cathode spot effect is negligible. Also the hot cathode or thermionic emission of electrons is reduced to a negligible value.

Now I have found from theoretical and practical investigations that sparking and arcing at interrupter contacts may be eliminated when interrupting an electric current having a value which ordinarily causes vicious sparking, and that circuits may be interrupted without vicious sparking at the point of interruption when carrying a current having a value which ordinarily could not be safely interrupted by the same contact device. My investigations have shown that in order entirely to eliminate an arc bet-ween contacts paralleled by an absorbing circuit when interrupting an electric circuit in which said contacts are connected in series of separation and is directly proportional to the current of the circuit to be interrupted and inversely proportional .to the velocity of separation of the contacts and the size of the condenser in the absorbing circuit. In accordance with my invention, for a given current the velocity of separation of the contacts and the size of the condenser are so chosen as to make the rupturing potential gradient, that is the maximum voltage per unit thickness which the dielectric. between the contacts can stand before it breaks down electrically, greater at any instant than the voltage built up across the absorbing circuit at the same instant.

My invention will be better understood from the following description taken in connection with the accompanying drawings and its scope will be pointed out in the appended claims.

In the accompanying drawings, Fig. 1 is a diagrammatic representation of an embodiment of my invention in a voltage regulating system, Fig. 2 shows a modification of the contact arrangement shown in Fig. 1, Fig. 3 shows a further modification of the regulating system and actuating means for the contact arrangement shown in Fig. 1, and Fig. 4 is a diagrammaticrepresentation of another embodiment of my invention more particularly adapted for interrupting power circuits.

In Fig. 1 of the drawings an embodiment of my invention is shown in the excitation circuit of a dynamo-electric machine diagrammatically represented by a three phase alternator 1 which is connected to a distribution circuit 2. The alternator 1 is provided with a field winding 3 which is connected to be energized from a direct current exciter 4 which is provided with a shunt connected field winding 5. A resistor 6 connected in series with field winding 5 is arranged to be alternately cut into and out of the field circuit with such rapidity and at such varying time intervals as to produce a resulting mean current of the value necessary to secure the desired regulation of alternator 1. For effecting this control of resistor 6 any suitable type of vibratory regulator. examples of which are well known, mav be used and as here shown may be of the Tirrill type which comprises two relativelv movable cooperating contacts 7 and8, which are actuated respectively by electroresponsive means 9 .connected to be energized from the circuit 2 and by electroresponsive means 10 connected to be energized in accordance with the voltage of exciter 4. The contacts 7 and 8 are arranged to control a contact arrangement in the form of an intermediate relay 11 which embodies my invention. This relay comprises two relatively movable cooperating contacts 12 and 13 which are arranged to be brought into engagement or disengagement in conformity ,with the engagement and disengagement of contacts 7 and S. An energy absorbing circuit is connected in parallel relation to contaets 12 and 13 and as shown preferably includes a capacitance device such as the condenser 14, although any other suitable device possessing capacitance or the ability to absorb the energy of a circuit after separation of contacts therein, such as a polarization cell may be used if preferred without departing from my invention in its broader aspects. Now in order to use a condenser having a capacity small enough to prevent objectionable sparking when the contacts are brought into engagement and at the same time prevent the voltage builtup across the condenser from exceeding the rupturing voltage gradient of the dielectric between the contacts upon disengagement, a high speed of separation of the contacts becomes necessary. In order to obtain the desired speed of separation relative to the size of condenser suitable for the type of contact arrangement shown here it has been found advantageous to impart an initial velocity of the same value to bothcontacts and maintain an engagement therebetween, and then abruptly stop one of the contacts while pern'iitt-ing the other contactto continue its movement in the same direction and at the same velocity, or with acceleration, to effect disengagement between the contacts. In the arrangement shown, contact 12 is mounted on a contact support 15 which is attached to a pivoted contact arm 16 biased to a contact disengaging position by a spring 17. The contact 13 is mounted on a resilient support shown as a plate spring 18 which is utilized to urge or bias contact 13 to a position of engagement with contact 12. The contact 13 is mounted on a contact supporting member 19 which is utilized to engage a fixed stop 20. In the particular arrangement shown stop 20 also acts as a support for spring 18 and is provided with a suitable opening 21 through which contact support 15 and contact 12 carried thereby extends to engage contact 13.

While I now prefer to use the particular arrangement shown in connection with contacts 12 and 13 and stop 20 various modifications, wherein the contact 13 instead of con tact 12 extends through the stop 20 and wherein the particular structure of stop 20 is eliminated and a simple pin stop in the path of spring 18 is used, will occur to those skilled in the art, and may be used, if preferred, without departing from my invention in its broader aspects.

The actuation of contact arm 16 and thereby contact 12 may be controlled by any suitable means. As shown an electromagnet comprising a coreinember 22 is arranged to cooperate with an armature 23 on contact arm 16. The core member 22 is energized by a winding 24 having in circuit therewith the contacts 7 and 8 and being connected across the exciter 4. When contacts 7 and 8 are closed, contacts 12 and 13 will be closed toshort circuit the resistor 6; and vice versa, when contacts 7 and 8 are open contacts 12 and 13 will be opento introduce a break in the. circuit in shunt to resistor 6.

. The operation of the regulator comprising contacts 7 and 8 as hereinbefore described is well known in the art and it is believeda very brief description will sutlice to convey an understanding of its operation relative to the operation of circuit interrupting device 11. It is evident that the exciter voltage is controlled by the rapid opening and closing of the contacts 7 and 8 and that the value of the exciter voltage depends upon the length of time the contacts 7 and 8, and consequently contacts 12 and .13. remain in engagement. Furthermore, it is evident that the length of time the contacts 7 and 8 remain in engagement depends upon the position of contact 7, which in turn depends upon the voltage of circuit 2.- At an constant voltage Contact 7 remains stationary and the contact 8 Vibrates so that the regulator acts as a direct current regulator to maintain the proper exciter voltage to produce the desired alternating voltage. \Yhen the voltage of alternator 1 tends to decrease contact 7 moves toward contact 8. Consequently the contacts 7 and 8 are in engagement a greater portion of the time during each vibration of contact 8. Therefore resistor 6 through the intermediary of contact device 11 is short circuited more of the time which in turn causes the alternator voltage to increase. \Vhen the exciter voltage reaches a value corresponding to that required to give normal alternating voltage the alternating current magnet 9 remains stationary in its new position and the direct current magnet 10 operates to maintain the excitcr voltage at this higher value in order to hold the desired alternating voltage.

In describing the operation of contact device 11 it will be. assumed that for the moment contacts 7 and 8 are in engagement. Under this assumption the energizing. circuit of winding 24 is completed across the exciter 4 and contact arm 16 is pulled down against the action of spring 17 so that contact support 15 and consequently contact 12 extend through the opening 21 in the fixed stop 20 to engage contact 13 and deflect spring 18 and thereby contact support 19 away from fixed stop 20. Under these conditions resistor 6 is short circuited. Now assume that contacts 7 and 8 are disengaged. Upon disengagement of contacts 7 and 8 winding 24 is deenergized and spring 17 quickly moves contact 12 in a direction to effect disengagement with contact 13. Prior to disengagement of contact 12 with contact 13, both contacts move at substantially the same velocity under the action of spring 18 until contact support 19 of contact 13 strikes stop 20, whereupdn contact 13 is abruptly stopped and contact 12 continues its motionto effect disengagement under the action of spring l7. It will thus be observed that instead of starting with an initial velocity of zero at the stant of disengagement contact 12 is given an appreciable velocity and a high speed 01 separation between the contacts 12 and 13, ,iS

obtained at the first instant of disengagement.

\Vhen it becomes impractical, because of thevalue of the current which is to be interrupted. to obtain the proper relation between the speed of separation of the contacts and the size of condenser which may be used without causing sparking andpitting 011 disengagement or reengagement of the contacts, it is :ulvantageous to increase the dielectric strength of the dielectric medium between the contacts. For this purpose I have found it desirable to place contacts 12 and 13in a sealed envelope, as shown in Fig. 2, in which a medium of a higher dielectric strength than air at atmospheric pressure is maintained. The contact arrangement shown in Fig. 2 is substantially the same as the arrangement shown in Fig. 1 and like numerals have been used to indicate like parts. In addition the contacts 12 and 13 and the contact supporting means 16 and stop 20 are enclosed in a sealed envelope 25 which may be formed either of glass as shown, or of metal. This envelope is preferably highly evacuated but it may contain air under pressure, an inert gas. or any suitable medium which will increase the dielectric strength of the dielectric between the contacts upon separation. If the envelope is evacuated it is preferable to secure a very high vacuum which can be maintained and which may be obtained by methods of evacuation and removal of occluded gases of the contents within the envelope in accordance with methods now well known in the art and explained in more detail hereinafter in connection with the description of Fig. 4. In the highly evacuated envelope the contacts 12 and 13 may be of any suitable material and contacts of silver and also of tungsten have shown satisfactory results in operating embodiments of my invention. Any suitable contact material may be used in air; silver is satisfactory here also. The pivoted arm 16 is supported by a member 26 which extends through the tubular extension 27 of the envelope 25. The tubular extension 27 is sealed to the support 26. preferably by means of a yielding sylphon bellows 28, which prevents transmission of jars or shocks to the envelope 25. The stop 20 extends through the opposite end of envelope 25 which is sealed thereto in any suitable manner but preferably, as shown. by means of a yielding sylphon bellows 29. The spring 17 which biases the pivoted arm 16 to a contact disengaging position is suitably supported by a member 30 which is sealed in the envelope 25. The electromagnetic operating mechanism comprising the core 22 and the winding 24 is preferably positioned outside the envelope but in operative relation With the armature 23.

\Vhen it becomes desirable to use a number of intermediate interrupting devices having electromagnetic operating means, as

shown in connection with device 11 in Figs. 1 and 2, the current required to operate the relays may overload the main contacts of the regulator and cause undesirable"arcing. In order that this current may be reduced without sacrificing the speed of operation of the intermediate devices and still permit the use of a standard main contact control device the operating mechanism shown in Fig. 3 may be used. In this figure so much of the apparatus and parts of the contact devices of the regulating system as are common to Figs. 1 and 2 are designated by like numerals. Any desired number of devices may be used to control a given section of resistor 6, but for purposes of simplification I show but two intermediate circuit interrupting devices designated as 31 and 32. The contacts 12 and 13 of device 31 control a portion of resistor 6 and a condenser 14' of suitable capacity relative to the speed of separation of the contacts is connected in shunt thereto. Similarly, the contacts 12 and 13 of device 32 control the remaining desired portion of resistor 6 and have a condenser 14" of suitable capacity connected in shunt thereto. Each of the contact mechanisms of devices 31 and 32 may be placed in a suitable envelope 25 in the same. manner as shown and described in detail in Fig. 2.

Since the circuit interrupting devices 31 and 32 are exactly similar the detail description of these devices will be directed to the device 31. The contact 12 is carried by the pivoted arm 16 in the same manner as previously described but instead of carrying the armature 23 the arm 16 may be constructed wholly or partly, as shown, of magnetic material designated by the enlarged portion 33. The portion 33 is subje ted to a substantially constant magnet field having opposite directions at the respective ends thereof. For this purpose a magnetic U- shaped structure 34 which may be either permanently magnetized or polarized by an energizing winding 35 positioned thereon is placed in operative relation on one side of the member 33, and an electromagnet comprising a U-shaped core member 36 and having a polarizing winding 37 positioned thereon is placed in operative relation on the opposite side of member 33. The windings 35 and 37 are energized in a manner to obtain polar areas of opposite polarity and in the reverse order at opposite ends of the member 33 as indicated by N and S in the drawing. Thus, in the arrangement shown the left-hand end -member 33 is positioned between a north pole which is on one side and a south pole which is directly opposite, while the right-hand end is positioned between a south pole on the same side as the north pole at the other end and a north pole directly opposite. A winding 38 surrounds member 33 and is connected in series with the contacts 7 and 8 across exciter'4 to establish an appropriate polarity at the ends of member 33 when it is desired to move the pivoted arm 16 in a given direction In the particular arrangementshown winding 38 is energized by a current in a direction to establish a north pole at the left-hand end and a south pole at the right-hand end in order to provide a torque to move contact 12 into engagement with contact 13.

In operation the regulating system shown in Fig. 3 functions generally in the same manner as previously described. It is therefore believed desirable to describe'merely the operation of the circuit interrupting device 31 which description will apply in all respects to the circuit interrupting device 32. First assume that contacts 7 and 8 are disengaged so that winding 38 is deenergized. Under this assumption the pivoted arm 16 will assume a position to maintain contact 12 out of engagement with contact 13 under the influence of spring 17 and occupying a position closer to the polar extremities of the upper magnetic member 34. Now if con tacts 7 and 8 come into engagement an energizing circuit is completed for winding 38 which in turn establishes magnetic poles at the polar extremities of the magnetic portion 33 of pivoted arm 16. For purposes of explanation and in keeping with the previous polarities assumedfor cores 34 and 36 the left-hand end of the magnetic portion 33 is assumed to become of north polarity and the right-hand end of south polarity. Under these conditions av torque is exerted on pivoted arm 16 due to the joint action of themagnetic members 34 and 36 on the magnetic member 33 to move pivoted arm 16 against the pull of spring 17 and thereby bring contact 12 into engagement with contact 13.

Now if contacts 7 and 8 are disengaged winding 38 is deenergized and spring 1'? quickly moves contact 12 in a direction to effect disengagement with contact 13. Prior to disengagement of contact 12 with contact 13, both contacts move at substantially the same velocity while in engagement under the action of spring 18 until contact 13 is abruptly stopped by stop 20. 'Whereupon contact 12 continues its motion in the same direction with an appreciable velocity of separation just as in the previously described arrangement shown in Figs. 1 and It to be noted. however. in the arrangement shown in Fig. 3, that the relays 31 and 32 have a much greater sensitivity per watt than the type of relay shown in Fig. 1 or the well known differential type of relay in which upon closure of the main regulator contacts an opposing field must be built up equal to the permanent field which is maintained in the core of the intermediate relay.

Consequently, a large number of relays may be controlled with the type of relay shown in Fig. 3 without overloading the main contacts 7 and 8 of the regulator.

In Fig. 4, I have shown an embodiment of my invention for use more particularly in. power circuits. 1 have shown an improved form of a vacuum switch which is described and claimed in an application of David s. Prince, Serial No. 264,116, filed March 23, 1928, and assigned to the same assignee as this application. The switch is connected in a circuit indicated by the conductors 48 and 4t) and comprises a. highly evacuated envelope 50 which may be formed either of glass, as shown, or of metal to enclose the circuit interrupting electrodes 51 and 52. Suitable means. such as the tube extension 50 is provided to enable the envelope to be exhausted and sealed ofi when desired. A suitable pump of the type mentioned hereinafter or other suitable means may be permanently connected to the extension 50 to remove gases which may be evolved during operation of the interrupter. The electrode 51 is secured to a suitable insulating support 53, or insulated therefrom, and extends through the tubuiar extension 54 of the envelope 50 into the central bulb portion of the envelope. The end of the tubular extension 54 is sealed to the electrode 51, preferably by means of a yielding sylphon bellows 55, which prevents transmission of jars or shocks to the envelope 50. The electrode 52 is movable into and out of circuit closing engagement with the electrode 51 and extends through the lower tubular extension 56 and'tlie sylphon bellows 5? at the end thereof. The flexibility of the-sylphon bellows 57 readily permits the electrode 52 to be moved into and out of circuit closing engagement with the electrode 51. The electrode 52 is maintained in alignment with the-electrode 51 by means of a suitable guide member 58 through which the end of the electrode 52-is adapted to slide.

Because the voltage required to break down a gap decreases as the pressure 'is decreased in the envelope and reaches a minimum at pressures of the order of a few inicrons and thereafter steadily rises until values of the order of millions of volts per centimeter potential gradient are required in a perfect vacuum. it is preferable to maintain the order of the vacuum extremely high. The vacuum preferably should be more perfect than a fraction-of a micron, a vacuum of one tenth of a micron has been found suitable for commercial voltages. Suitable exhaustion may be obtained by any wellknown means. such as Gaede or molecular pumpor a condensation pump of the Langmuir type. The contents of the envelope before assembly are to be suitably treated to remove occluded gases in accordance with well kn own processes for the production of high vacuum apparatus, which for example, may consist in heating the metal parts to a suitable temperature approaching the melting point for a suflicient time to remove the gases. After assembly the envelope and contents may be heated again in an oven in order to remove residual and occluded gases while the evacuation is taking place. Instead of placing the envelope and contacts in an oven the metallic portions may be subjected to a high frequency magnetic field in order to heat the parts and remove any residual gases during evacuation before the envelope is completely exhausted and sealed off.

The engagement-and disengagement of the electrode 52 with the electrode 51 is accomplished by suitable means shown as an electroresponsive mechanism 59. This mechanism as shown diagrammatically in the drawings is of the type described and claimed in Letters Patent No. 1,560,440 of J. F. Tritle, issued November, 3, 1925, and assigned to the assignee of my present invention. As shown, this mechanism comprises a pivoted arm carrying an armature 61 in attractive relation with a control magnet 62. The arm 60 is pivotally connected with an operating lever 63 which, in turn, is connected to operate the electrode 52 through the connecting link 64. The link 64 is preferably of insulating material so as to insulate the operating mechanism from the potential impressed upon the electrode 52. A heavy biasing spring 65 is connected to operating lever 63 so as strongly to bias the electrode 52 out of engagement with electrode 51. The electrode 52 is operated into engagement with electrode 51 by means of the pivoted bell crank closing lever 66 connected to the closing electromagnet 67 which is energized by closing a push button 68. The switch contacts 51 and 52 are held closed by the attraction between the armature 61 and the electromagnet 62. The electromagnet 62is provided with a holding winding 69 which is normally energized from the supply source indicated on the drawing by plus and minus signs. A push button 70 is connected in series relation in a normally closed position with winding 69 to provide a means for deenergizing winding 69 when it is desired manually to interrupt the circuit 4849. An overload tripping winding 71 is associated with the magnetic extensions 72 between the poles of electromagnet 62. The tripping winding 71 is shown connected in series relation with electrodes 51 and 52 and the conductors 48 and 49 of the circuit to be controlled.

In accordance with my invention an energy absorbing circuit is connected in parallel relation to electrodes 51 and 52 and as shown preferably includes a condenser 73, although any other suitable capacitance device such as a polarization cell or any circuit capable of absorbing the magnetic energy of circuit 48-49, when the circuit is interrupted, may be used without departing from my invention in its broader aspects.

As previously pointed out the absorbing circuit should hzwe such characteristics as will permit an absorption of all or substantially all of the stored magnetic energy of the circuit which is to be interrupted at such a rate relative to the voltage built up across the electrodes that at any instant the buildup voltage will be less than the voltage required to break down the dielectric between the electrodes at the same instant. Thus when utilizing a condenser in the absorbing circuit the capacity of the condenser must be chosen with respectto the speed of separation available with the particular type of switch used. Since the maximum potential gradient usually occurs at the instant of separation and is directly proportional to the current to be interrupted and inversely proportional to the speed of separation and capacity of the condenser a proper arrange ment may be readily obtained in accordance with the foregoing principles.

The operation of the circuit interrupter is substantially as follows: Closure of switch 68 energizes the closing electromagnet 67 with the resulting operation of the roller bell crank 66 into engagement with the operating arm 63. This operates arm 63 about its pivotal connection with the lever 60 and moves armature 61 into abutting engagement with the holding electromagnet 62. lVith the holding winding 69 energized, the armature 61 is firmly held in position. However, the electrode 52 is not moved into engagement with electrode 51 until after the closing electromagnet 67 is deenergized by opening switch 68. Thereupon, the spring 65 rotates the operating lever 63 about its pivotal connection to raise electrode 52 into engagement with the electrode 51. lVith electrode 52 thus brought into engagement with electrode 51 the circuit isclosed, and the operating lever 63 is free'to be released by the controlling electromagnet 62. The electromagnet 62 will normally hold the armature 61 in the attracted position as long as the conditions in the electric circuit are normal, or as long as holding coil 69 is ener ized.

In case an a normal circuit condition should arise, such for instance, as an overload, the magnetic field set up by the winding 71 will cause the flux set up by the electromagnet 62 to be shunted away from the armature 61 thereby releasing the armature and permitting the switch to open. The characteristic feature of this type of switch which provides a quick release, coupled with the fact that light parts may be used when the contacts are separated in a vacuum and that a strong biasing spring may be used, permits a high speed of separation of the contacts not filed concurrently with this application,

acetate;

only after the electrodes have started moving but at the first instant of separation. Thus, with an absorbing circuit of proper characteristics and in this case with a condenser of proper capacity chosen in accordance with v the velocity of separation obtainable with this arran ement, a substantially sparkless break maydJe efiected for Very large currents. A similar opening cycle of operation may be effected by actuating switch to its open position thereby dcenergizing holding Wind-v ing 69 which permits armature 61 to be released and contacts 51 and 52 to be separated in the same manner as previously described.

T he embodiment of my invention illustrated in Fig. 4 is disclosed and claimed in my copending application Serial No. 264,211, and assigned to the same assignee as this application.

While I have shown and described my invention as embodying various devices diagrammatically shown, it will be obvious to those skilled in the art that changes and modifications may be made without departing from my invention, and I, therefore, aim'in the appended claims to cover all such changes and modifications as fall within the true spirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent ot' the United States, is

1. In an electric circuit, a circuit interrupter comprising relatively movable contacts, an energy absorbing circuit in parallel relation to said contacts, and means for separating said contacts at such a rate relative to the value of voltage built up in said energy absorbing circuit that at each instant the rupturing voltage of the dielectric between said contacts shall be greater than the voltage built up at the same instant in said energy absorbing circuit.

2. In an electric circuit, a circuit interrupter comprising relatively movable con tests, a circuit including a capacitance connected in parallel relation to said contacts, and means for separating said contacts at such a rate relative to the capacity of said capacitance that at each instant the rupturing voltage of the dielectric between stud outacts shall be greater than the voltage built up at the same instant in said parallel circuit.

3. In an electric circuit, a circuit interrupter comprising relatively movable contacts, means for mcreasmg therupturmg Voltage gradient of the dielectric between said contacts when separated, a circuit including a condenser connected in parallel to said contacts, and means for separating said contacts at a velocity of separation relative to the capacity of said condenser such that the rupturing voltage gradient of the dielectric between said contacts at each iu stant of separation shall be greater than the voltage built up across said condenser at the same instant.

4. In an electric circuit, a, circuit interrupter comprising relatively movable contacts, a sealed envelope for enclosing said contacts in a medium of higher dielectric strength than air at atmospheric pressure, a circuit including a condenser connectcdin parallel to said contacts, and means for separating said contacts at a velocity of separation relative to the capacity of said condenser such that the rupturing voltage gradient of the dielectric between said contacts at each instant of separation shall be. greater than the voltage built up across said condenser at the same instant.

5. A circuit interrupter coinprisii'lg an evacuated envelope, cooperating circuit interrupting electrodes within said envelope, and means comprising an energy absorbing circuit in parallel relation to said electrodes for preventing formation of electron emitting regions on one or the other of said electrodes upon operation of said interrupter to effect separation between said electrodes.

6. A circuit interrupter comprising an evacuated envelope, cooperating circuit interrupting electrodes within said envelope, and means comprising a capacitance in parallel relation to said electrodes for preventing formation of electron emitting regions on one or the other of said electrodes upon separation of said interrupter to ei'lect separation between said electrodes.

7. A circuit interrupter comprising an e 'acuai ed envelope, cooperating circuit interrupting electrodes within said envelope, and means comprising a condenser in parallel relation to said electrodes for preventing "formation of electron emitting regions 011 one or the other of said electrodes upon separation of said interrupter to effect separation between said electrodes.

8. ln an electric circuit, a circuit interrupter compri ing relatively movable coopcrating electrodes, an evacuated envelope for enclosing said electrodes, a circuit including a condenser connected in parallel relation to said electrodes and adapted to absorb the magnetic energy of said circuit upon separation or" said electrodes, and means for separating said electrodes at such a velocity-relative to the capacity of said condenser as to prevent the formation of electron emitting regions on said electrodes.

9. In an electric circuit, a circuit interrupter comprising relatively movable contacts, a capacitance circuit in parallel to said contacts and adapted to absorb substantially all of the magnetic energy of said circuit when said contacts are separated, and means for imparting an initial velocity to said contacts before disengagement therebetween.

' 10. In an electric circuit, a circuit interrupter comprising relatively movable contacts, a circuit including a condenser in parallel relation to said contacts, means for periodically causing engagement and disengagement of said contacts, and means for moving said contacts in unison at an appreciable velocity effecting disengagement therebetween.

11. In an electric circuit, a circuit interrupter comprising relatively movable. con- 1 tacts, a circuit including a condenser in parallel relation to said contacts. an arm for supporting one of said contacts, electromagnetic means for vibrating said arm, resilient means for supporting the other of said contacts and for biasing said contact toward said first mentioned contact whereby said contacts move in unison-over a portion of the range of travel of said first mentioned contact, and means for abruptly stopping the motion of said sec- 0nd mentioned contact after said first mentioned contact has moved a predetermined distance in a direction to effect disengagement between said contacts.

12. In an electric circuit. a circuit interrupter comprising relatively movable contacts, a circuit including a condenser in parallel relation to said contacts, an arm including a magnetic structure for supporting one of Said contacts, means for subjecting opposite extremities of said magnetic structure to magnetic fields in opposite directions, means associated with said magnetic structure for magnetizing the respective polar extremities thereof in a direction opposite to the magnetic fields to which they are. subjected in accordance withvariations inan electrical characteristic of said circuit, a spring for supporting the other of said contacts and for biasing said contact toward said first mentioned con tact. and means for abruptly stopping tllu motion of said second mentioned contact after said first mentioned contact has moved a predetermined distance in a direction to effect disengagement between said contacts.

13. In an electric circuit. a circuit in errupter comprising relatively movable contacts. a circuit including a condenser aparallel relation to said contacts, an arm for supporting one of said contacts, a polarized relay for actuating said arm. resilient means for supporting the other of said contacts and for urging said contact toward said first mentioned contact, and means interposed in the path of travel of said second mentioned c011- t-act for arresting the movement thereof after said first mentioned contact and said second mentioned contact have moved in a direction to effect disengagement between said contacts.

In witness whereof, I have hereunto set my 60 hand this 13th day of March, 1928.

CLIFFORD A. NICKLE.

CERHFHCATE era eetteee'ttemo Fatent Nee E 82L8l3. (Granted September 11, 39311 t0 CMFFJRD A NECKLE.

It is hereby certified that error appears in the printed speeitication 0f the aheve mtmhered patent requiring correction as follows: Page 4, tine 123, after the were "end" insert the word of; page 5, Kine 78, strike out the article "the"' and time 25, after "as" insert the article a; page 8, time 6, claim 10, after' "veleetty" insert the word before, and line 47, claim 113, fer the article "a" third. eeetmence read in; and that the said Letters Patent shoufld he read with these cett'eetions therein that the same may conform to the recent 0? the case in the Patent @tfficec Signed and sealed this 27th day of @etehter, A. D. 39%,

M, J. Moore,

(Seat) Acting Commissienerfif Patents.

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