US2238184A - Electric switch - Google Patents

Description

April 15, 1941. v E 2,238,184

ELECTRIC SWITCH Filed March 51, 19157 4 Sheets-Sheet 1 31mm or Vz'clar I? BE E .2 attorney April 15, 1941. v. T. FARE 2,238,184

ELECTRIC SWITCH Filed March 31, 1 937 4 Sheets-Sheet 2 Zmnenior Cittorneg April 15, 1941. v. T. PARE 2,238,184

ELECTRIC SWITCH Filed March 51, 1937 4 Sheets-Sheet 5 3nnentor Gttorneg April 15, 1941. v. T. FARE ELECTRIC SWITCH 4 Sheets-Sheet 4 ZSnventor 222w Filed March 31, 1937 (Ittomeg Patented Apr. 15, 1 941 UNITED STATES PATENT OFFICE ELECTRIC SWITCH Victor T. Par, C'ollingswood, N. J., assignor to Radio Corporation of America, a corporation of Delaware Application March 31, 1937, Serial No. 133,965

1 Claim. (Cl. 290-147) This invention relates to electric switches, partional type of circuit breaker it may be said genticularly to switches designed to make and break orally that such arrangement is unsuited for circuits carrying large currents, and has special breaking a circuit subjected to large inductive reference to the provision of improvements in loads, for the reason that arcing will occur beswitches of the type having contacts immersed tween the opened primary contacts before the in a magnetic arc-quenching field. flux of the magnetic field has been built up to While the invention will be described as applied thedensity required to ensure proper quenching. to a current impulse transformer subjected to a Accordingly, an object of the present invention large inductive direct current load, it is to be is to provide a switch having contacts immersed understood that the invention is not limited to go in an arc-quenching magnetic field and includsuch application, as the disclosure in this respect ing means for delaying the opening of said s merely illustrative for p p of eXploining tacts until the flux density of said magnetic field the inventive concept. reaches a predetermined value.

Cu rent p s transformers Capable of Another object of the invention is to provide cratin r ativ ly h nt y va s of 1.; a circuit breaker for use in connection with iron rect current find use app for example, core transformers and including means for prein the art of ma ne i in Permanent magnets; venting the actuation of said circuit breaker until A rr impulse transformer may Compnse the energy in said core is built up to the value a primary winding of many turns, a secondary of required to accomplish a given task whereby few turns (usually one), and an intermediate 30 wastefuldissipation of energy is obviate iron core. Direct current is fed to the primary Another object f the invention is to provide Winding in amount sufiiclem'i sutstantlally t a circuit-breaker for use with current impulse saturate the iron core. If the c1rcu1t to the pritransformers of the type wherein direct current m Winding, now be Opened the energy stoted flowing in the primary circuit gives rise to stored m the Core W111 h suddenly released A portlpn 533 energy in the core of the transformer, said cirof this energy 5 appeardm secordary cuit breaker being adapted to open the primary cuit (if it is close as a irec curren impu se,

a circuit quickly and cleanly, whereby the energy and balance W111 appear m the form of an released upon the collapse of the magnetic forces f gfi gf g g fifig 33 2 3122; Q0 stored in the core may be emciently transformed C y into current of optimum value in the secondary the secondary circuit is usefully employed, it follows that the eficiency of the device is proporij i w z g the t t tional to the quantity of energy dissipated in the 0 er 0 J66 0 mven to plovlde form of an are between the open terminals of the 9 switch capable Clean primary Circuit, that is to say, the less energy break in a circuit carrying an inductive load of dissipated in the primary circuit, the more is the upwards of five thousand Watts and this too useful energy appearing in the secondary circ it, Within substantially two one-thousandths (.002) It is apparent from the foregoing that the more of a Second; rapidly the primary circuit is opened, and the other Oblects and advantages, together wlth more rapidly and completely the resulting arc is 4o Certain dttails o construction, Will be apparent quenched, the greater is the energy avail bl in and the invention itself will be best understood the form of a direct current impulse on the secby reference o the following pe fication and ondary side of the transformer. theoocomponylng w n s, wherein In order to ensure a rapid break and adequate Figure 1 is a partly schematic elevational view quenching of the developed arc, resort has here- 45 a simple embodiment of the invention as ptofore been had to circuit breakers of the type p d to a current Impulse transformer,

comprising a fast acting switch having contacts Figure 2 is 'a side elevation of anotherembodimmersed in an arc-quenching magnetic field. imont of the switch of invention,

The usual practice has been to provide a multiple Figure 3 is a front elevation of the device of contact switch and to so arrange the connections 59 Fig. showing the switch arms in the l d thereto that upon opening of the primary cirposition,

cuit the current from the line is switched to the Figure 4 is a Partial elevational view of the coils which then, and not until then, generate the device of Figs. 2 and 3, and showing the Swit arc-quenching magnetic field. Regardless of the arms in the open position, advantages claimed for the described conven- Figure 5 is a sectional elevation taken on the line 5-5 of Fig. 4 and showing an actuating device for the switch arms,

Figure 6 is a fragmentary sectional view taken on the line 6-6 of Fig. 3 and showing a clutch mechanism for operating the switch arms, and

Figure '7 is a detailed sectional view taken on the line of Fig. 6.

In Fig. 1, designates generally a current impulse transformer comprising a primary winding 3, an iron core 5 and a secondary winding 1. Winding 1 terminates in a pair of bus bars 9. By way of example, the primary winding 3 may comprise twenty-five hundred turns and the secondary "I but one turn. The energy applied to the primary 3 of transformer I may be obtained from a 220 volt 24 ampere source of direct current. Such source is indicated in the drawings by the conventional plus and minus symbols.

The application of direct current to the primary 3 stores up magnetic energy in the iron core 5. When this core becomes saturated, or

- substantially so, and the circuit supplying current to the primary is then broken, a momentary direct current surge or impulse will appear in the secondary 1, provided its terminals 9 are closed. This impulse may reach a value of, say fifty five thousand (55,000) amperes provided only that too much of the magnetic energy stored in core 5 is not dissipated in the form of an are between the points at which the primary circuit is broken. Current of the order or value mentioned may be utilized, for example, to permanently magnetize metal objects, in which case the object to be magnetized (not shown) may be removably clamped Y to bus bars 9.

A'switch, indicated generally at i, is provided for opening the circuit carrying current to the primary winding 3 of transformer I. Switch |l comprises a frame |3 which supports a fixed switch arm I5 and a movable switch arm ll. Arm I? is biased to open as by means of a spring l9 and may be heldin the closed position as by means of a pawl 2|, which is urged into engagement with arm H by means of a spring 23.

Switch arms i5 and I! are provided with contacts and 2'1, respectively. In order to quench or blow-out the arc incident to the opening of the switch, contacts 25 and 2? are immersed in a magnetic field which bridges the pole pieces 29 and. 3| of an electro-magnet M. The arrangement of these pole pieces may be similar in all respects to that shown in the later described side elevational view of the modified form of the invention shown in Fig. 2.

In order to prevent the opening of contacts 25 and 21 until the flux density of the magnetic field reaches a value sufficient to insure prompt and adequate quenching of the are between these contacts, a magnetically actuated mechanism is provided for releasing the pawl 2| which holds the movable switch arm in its illustrated closed position. Such mechanism may be constituted essentially of an armature 33 composed of a magnetically permeable material secured to a plunger 35 which is slidable in an extension 3'! in frame I3 and connected to pawl 2| by an adjusting screw 33. As illustrated the armature 33 and plunger 35 are in that position whereat pawl 2| holds switch arm closed against the tension of spring l3. It will be understood that spring 23 of the release mechanism is so adjusted that when the flux density of the magnetic field in which contacts 25 and 21 are immersed reaches a value sufficient to adequately quench the are developed upon opening of these contacts then armature 33 will be pulled down against the tension of spring 23 causing pawl 2| to pivot out of engagement with the end of switch arm l1 and permitting it to be instantly and forcibly pulled outwardly by spring l9. A switch handle 4| is provided for returning switch arm H to its illustrated closed position with respect to arm l5.

As previously set forth the surge of current across terminals 9 of the secondary I of transformer I when the magnetic energy stored in core 5 is released must be of a certain high value to perform its task. If the circuit to primary 3 were to be opened before core 5 stored up enough energy to provide secondary with current of a value less than that required, much energy, as well as the operators time, would be wasted. To obviate such waste an auxiliary control is provided in conjunction with the release mechanism of switch whereby premature opening of the circuit to the primary winding 3 of the transformer is prevented.

The illustrated auxiliary control comprises a pair of switches 43 and 59 connected in series in the circuit which provide energy for generating the arc-quenching magnetic field. Switch 43 may comprise a stationary arm 45 and a pivoted arm 41 shown biased to the open position by a spring 45. A separate pivoted arm 5| supports an armature 53 of magnetically permeable material adjacent and within the influence of the magnetic field generated about core 5. Arm 5i is provided with a snubber 55 and is normally held by a spring 51 in a position such that its armature 53 is out of the region of maximum intensity of the field adjacent core 5.

As the energy transferred to core 5 from primary is built up, armature 53 is gradually attracted thereto and pushes arm 4? over (to the left as viewed in Fig. 1) against the tension of spring 49. This brings arm 41 in contact with arm 45 and thereby completes the circuit to switch 59. Switch 59 may be of conventional design and-comprises a solenoid 6| which when energized attracts an armature 63 closing contacts 65 and 67.

In operating the device of Fig. 1 the switch arms l5 and ll of switch H are first closed by means of the switch handle 4|. Arm ll carrying contact 21 is'thus locked in its closed position by pawl 2|, and armature 33, which controls the release of pawl 2|, and hence of arm H, is in its idle or raised position. The circuit to this switch I I may now be traced from the positive side of the 220-volt line through lead a, primary winding 3, arm I5, contacts 25 and 21 to movable switch arm I? and through lead 17 to the negative side of the current source.

Current flowing through the primary winding 3 stores magnetic energy in core 5. When core 5 is saturated, or substantially so, it attracts the armature 53 of switch 43, and moves pivoted arm 5| which in turn moves contact 41 against the tension of spring 49 into contact with arm 45. Contacts 25, 41 being thus closed, the solenoid 6| of switch 59 is energized and its contacts 65 and 51 are closed. Current now flows through branch line 0 through contact 61 to the electro-magnet M, and through lead e to contacts 65 from whence it flows through wire 1 back to the return lead I) to the negative side of the direct current source.

Contacts 25 and 21 are maintained closed by pawl 2| until armature 33, on plunger 35, is

and duplicate parts.

pulled down. Armature 33 can be pulled down to release the pawl 2| and the spring biased switch arm ll only when the flux density of the magnetic field in which contacts 25 and 21 are immersed reaches a value sufiicient to quench the arc incident to the opening of these contacts. As previously set forth, prompt and adequate quenching of the arc between contacts 25 and 2'1, such as is provided by the improved mechanism of the present invention, ensures that energy released upon the collapse of the magnetic forces stored in the iron core will be converted into current of optimum value in thesecondary or output 3 of the current impulse transformer I.

Figs. 2 to '7, inclusive, show an alternative and completely automatic switch having contacts immersed in an arc-quenching magnetic field and including means, constructed in accordance with the invention, for delaying the opening of said contacts until the flux density of said magnetic field reaches a predetermined value. In Figs. 2 to 7, inclusive, like characters represent the same In these drawings, 2 designates a U-shaped base or frame, the upstanding arms of which support a pair of inwardly extending, axially spaced arms 4. Each arm or core 4 carries a magnet coil 6 and terminates within the U in a pole piece or plate 8. The terminals for these coils are shown at 10. They are series connected, as by lead i2.

Pole plates 8 are arranged in spaced parallel relation and the area therebetween is enclosed on all but its top side by sheets or boards l4 of asbestos composition which are joined together by bolts I6 to form a flat, rectangular box which will be understood to be permeated by the magnetic field generated by the coils 6. A pair of tie pieces l8 frame the upper end of this insulating box and support a pair of oppositely located lugs 20, each of which carries an inwardly directed bifurcated stop 22 (Figs. 3 and 4).

One of the upstanding arms of the U-frame 2 supports a panel of insulating material 24 in which two rods or axles 26 are J'Ournaled in fixed,

spaced parallel relation. Axles 26 extend inwardly and terminate above and slightly beyond the enclosed air gap between the magnet pole pieces 8. A switch arm 28 is revolubly mounted, in a manner later described, adjacent the end of each axle 26. Each switch arm 28 is curved slightly adjacent its free end (Fig. 2) to accommodate a contact 32. The ends of arms 28 which carry the contacts 32 are at all times contained within the space circumscribed by the asbestos boards l4 intermediate the magnet pole pieces 8.

As above indicated, the switch arms and the supports therefor are of duplicate construction. Fig. 6 is a sectional view showing details of the manner in which they are supported. Each axle 26 is fixed against rotation in supporting panel 24 as by lock nuts 34. Nuts 34 also serve to secure leads 36 which carry current for the switch arms 28 to axles 26. Current traversing axles 26 is transferred to the switch arms 28 through spiral springs 38. Each spring 38 is secured at one end to a collar 40, which is fixed on axle 26 by a pin 42, and is secured at the other end to its switch arm 28 by rivet 44, Each axle 26 carries two hubs 46 and 48. It is to the outer hubs 48 that switch arms 28 are secured as by screws 50. The inner hub 46 on each shaft has a closing arm 52 fixed thereto as by screws 54. The adjacent ends of hubs 46, 48 are provided with complementary clutch elements in the form of teeth 56, 58, respectively, whereby movement imparted to hubs 46 by closing arms 52 is transmitted to the hubs 48 to which switch arms 28 are afiixed. The center of axles 26 may be of increased diameter as indicated at 60, to prevent longitudinal movement of hubs 46, 49, along these axles.

As shown in Figs. 3 and 4, the closing arms 52 extend inwardly and their axes cross at a point along a vertical line midway between the axes of the hubs 46 to which they are respectively fixed. The intersecting end portions of the closing arms 52 are provided with elongated slots 62. As shown more clearly in Fig, 2, the closing arms 52 are behind switch arms 28 and are adapted to be moved by means of a plunger 64. This plunger 64 is shown in dotted lines in Fig. 4. It is provided with a pin 66 which extends outwardly therefrom and engages the elongated slots 62 in the crossed ends of the closing arms 52.

When plunger 64 is moved upwardly to the position shown in Figs. 2 and 3, the intersecting slotted ends of the closing arms engaged by pin 66 are moved in the same direction. This causes the sleeves 46 to which the opposite ends of these arms are afiixed to rotate on axles 26. Rotation of hubs 46 causes the clutch teeth 56 to engage the complementary teeth 58 on hubs 48. As hubs 48 rotate, they move the switch arms 28, which are aflixed thereto, inwardly to that position shown in Fig. 3 whereat contact members 32 are contiguous one another.

The mechanism for actuating plunger 64 is shown mounted upon a shelf 68 extending over the axles which carry the switch closing arms 52. Shelf 68 is mounted on the insulating panel 24 in which axles 26 are journaled. The device shown generally at 19 (Figs. 2, 3 and 4) and in detail in Fig. 5 is operated by compressed air from a tank or other source shown diagrammatically at 12. The device itself comprises a cylinder 14 in which are affixed a piston 16 to which plunger 64 is secured, a stop 18 and a spiral spring 88. Air entering the cylinder 14 at the bottom, through pipe 62 under control of a suitable valve 84 forces the piston 16, and hence plunger 64 upward, lifting the closing arms 52 to the closed position illustrated in Fig. 3. With closing arms 52 closed, valve 84 may be moved to that position whereat the air from cylinder I4 is exhausted through pipe 82 and outlet 86. Spring 86 then returns the piston 16 t0 the bottom of cylinder 14. The return movement of the piston is effected without altering the position of the switch arms 28; the previously described couplings on axles 46, 46 permitting this.

A locking mechanism is provided for maintaining the switch arms 28 in the closed position (Fig. 3) until the flux density of the magnetic field in which contacts 32 are immersed is suflicient to ensure prompt and adequate quenching of the are which is developed between these contacts at the instant they are opened. In Figs. 2, 3 and 4, 88 designates an insulating block positioned beneath shelf 68 and secured thereto and to the upright insulating panel 24, as by bolts 90. Secured to the front of the block as by pivots 92 are two pawls 94, one for each switch arm 28.

The outer end of each pawl 94 is provided with a roller 96 and a spring 98. Springs 98 urge rollers 96 into contact with the end surfaces of the switch arms 28, while these arms are being moved to the closed position. When switch arms adapted to be attracted by the magnetic field generated by coils 6. As clearly shown in Figs. 2 and 3, armature Hi6 terminates immediately above one of the pole plates 8 of the magnet, and

the top surface of this plate has a pair of pins I88 therein which fit into orifices IIU (Fig. 3) in the armature to guide its movement. Rod I04 is guided adjacent its upper end by a pin I I2 which is fitted into an orifice in an adjustable stop member or screw H4.

When the armature Hi6 and its supporting rod IM are pulled down, the inwardly extending pin [92 on the rod pulls the adjacent ends of pawls 94 down, causing them to pivot at 92 and lifting their outer ends out of engagement with the side end surfaces of switch arms 28. helical springs 38 is attached at one end to an axle 26 and at the other end to a switch arm 28,

bifurcated stops 22 are positioned in the path of ii.

the switch arms 23 and limit their range of movement.

When the device I0 which controls the closing of switch arms 23 is actuated, the outward movement of the ends of these arms urges the adjacent ends of pawls Q4 upwards. Since pawls 94 are pivoted at 92, intermediate their ends,- their rounded inner ends Iilt'i will move upwards in contact with pin Hi2 which, as previously described,

is secured to the rod I04 carrying armature I06. 1.,

The force exerted through pin Hi2 carries this rod IE4, and hence armature Hi6 upward to that position from whence it is pulled down (to permit the opening of switch arms 28) when the flux density of the magnetic field, in which switch contacts 32 are immersed, reaches a predetermined value.

Since each of the As previously indicated, the flux density required to actuate armature I05 corresponds, in accordance with the invention, to that required to ensure prompt and adequate quenching of the are developed between contacts 32 when they are being opened. Obviously, the greater the current load to be broken, the greater the flux density required to blow out or quench the resulting arc. Armature I06 may be adjusted to respond to fields of various intensities by adjusting the biasing force applied to the pawl springs 98. This may be simply accomplished by adjusting a pair of hollow set screws H6 in which pawl springs 98 are seated.

A switch substantially identical to that shown in Figs. 2 to '7, connected to a current impulse transformer in the manner indicated in Fig. 1 has been found capable of breaking an inductive load of five thousand, five hundred watts within substantially two one-thousandths (.002) of a second.

Reference is made to copending divisional application Ser. No. 321,545, filed February 29, 1940, which claims the current impulse transformer herein disclosed.

Various modifications of the invention will suggest themselves to those skilled in the art. It is to be understood therefore that the invention is not to be limited except as required by the prior art and the spirit of the appended claim.

What is claimed is:

A switch comprising a pair of axles mounted in spaced parallel relation, a clutch comprising driving and driven elements revolubly mounted on each axle, a switch arm fixed to each driven element and biased to the open position, a closing arm fixed to each driving element, means for applying torque to said clutch elements through said closing arms whereby to close said switch arms, a pair of pawls mounted adjacent said switch arms and biased to a position whereat said arms are maintained closed, an armature connected to said pawls, means for generating an arc-quenching magnetic field adjacent said switch arms and towards which said armature is adapted to be drawn to release the pawls holding said switch arms closed, and means for adjusting the bias on said pawls as determined by the flux density required to quench the arc incident to the opening of said switch arms.

VICTOR T. PARE'.

Images