US2607024A - Automatic arc starting device - Google Patents

Description

g- 12, 1952 E. M. MARWELL ET AL 2,607,024

AUTOMATIC ARC STARTING DEVICE Filed Jan. 27, 1951 P015527 L. KEN/V5077" W/ Wg Patented Aug. 12, 1952 AUTOMATIC ARC STARTING DEVICE Edward M. Marwell, Mount Kisco, and Robert L. Kenngott, Pleasantville, N. Y., assignors, by mesne assignments, to the United States of America Application January 27, 1951, Serial No. 208,218

Claims. 1

This invention pertains to an automatic arc starting device for employment as a lamp or furnace and more specifically to a high intensity electric; arc device started by means of an auxiliary electrode.

The usual method of starting an arc by the use of a third or auxiliary electrode is to connect the auxiliary electrode electrically to one main electrode and. to position it in mechanical and electrical contact with the other electrode. The position of the auxiliary electrode is controlled mechanically by a retracting solenoid. When the arc switch is closed, the arc current passes. through the auxiliary electrode and the ,main electrode which it touches and also through the. retracting solenoid. The, latter instantly retracts the auxiliary electrode which draws an arc from the main electrode as it leaves it. The arc then transfers itself to the other main electrode, and is established between the main electrodes and, because the main current still flows through the retracting solenoid, the auxiliary electrode is maintained in its fully retracted position.

This mechanism is not wholly satisfactory for all purposes. For instance, if" for any reason the auxiliary arc should fail to establish. the main are as the auxiliary electrode is swept back, the operation must be manually or automatically repeated, and this may occur repeatedly until the main arc is established. The basic reason why the main arc is not invariably established on initial actuation of the auxiliary electrode is that the two distinct operations of starting the are and of moving the auxiliary electrode out of the Way are merged and both are accomplished with one single uninterrupted motion of the auxiliary'electrode. The described conventional type of automatically started arc is additionally not suitable for use when great heat exists in the vicinity of the main arc, the auxiliary electrode holder being close enough thereto even in its retracted position to he dam agedor even destroyed.

The instant invention overcomes both of these objections. It segregates the two functions of starting the main arc and of removing the auxiliary electrode by separating its motion into two steps, the first designed to start the main are positively, and the second delayed until the arc has been started, so that the auxilairy electrode cannot be moved to its stored position until the main arc has started. The secondobjection is overcome. by movement of the auxiliary electrode to a position quite remote from the vicinity of the main arc. Failure of the main are for any cause will, nevertheless, cause the auxiliary electrode automatically to restart the arc and again withdraw.

The first objective of this invention then is to provide are starting means of superior positiveness by maintaining an auxiliary arc untilv the main arc shall have been ignited thereby.

The second objective is to provide a mechanism whereby the auxiliary electrode. and holder are positioned at a location distant from the main arc in order to prevent injury to the auxiliary electrode holder and its attached parts.

A further understanding of this invention may be secured from the detailed description and the accompanying drawings, in which:

Figure 1 depicts the arc-starting mechanism and its associated electrical circuit in the position when no current is flowing either in the main or auxiliary arc circuits.

Figure 2 illustrates the intermediate linkage position of the arc-starting mechanism, an are having been established between the auxiliary electrode and the cathode but the main are not having as yet been established.

Figure 3 a view of the arc-starting mechanism with the auxiliary electrode in the stored position, the main are having been ignited.

Referring now to Fig. l, the positive electrode or anode of a high intensity carbon arc is in dicated by the numeral ii and the corresponding negativeelectrode or cathode by the numeral 12. Apparatus for advancing these electrodes is not shown but may be of any conventional manual or automatic type. The main arc is energized from supply conductors l3 through a switch It, ballast resistor l6, and the winding of a plunger solenoid type of electromagnet H. A third or auxiliary carbon electrode [8 is supported by a mechanical linkage in such manner that it may swing into physical and electrical contact with the negative electrode [2, and

in Fig. 1 the auxiliary electrode is so depicted. Electrically the auxiliary electrode [8 is also connected by means of a flexible conductor [9 and through an auxiliary or striker ballast resistor 2| to the positive electrode H.

The auxiliary electrode I8 is affixed to one end of a lever 2d pivotally connected at 25 to one.

end of a lever 26. The lever 26 is pivoted adjacent its other end at 22 to the frame and an arm 36 extending beyond the pivot point 22 is connected to one end of a tension spring 31, the other end of which is fastened to the frame 38. A connecting bar 21 is pivoted at one end to the lever 24 at a pivot point 43 located adiacent to the pivot 25 but at a greater distance from the auxiliary electrode It! so that actuation of the connecting bar 21 results in rotation of the lever 24 about the point 25 as a fulcrum.

The connecting bar 2'? is provided with a stop 35 which cooperates with an extension 42 on the lever 2d limiting the amount of rotation of 'he lever 2 3 as respects the lever 26.

The other end of the connecting bar 2? is pivoted to one arm of a bell crank 26 at the point id and the bell crank itself is pivoted to the frame at 23. The other arm 29 of the bell crank is loosely pivoted to the armature 3! of a solenoid l'n' by a slotted pivot connection M.

The lever 28 is limited in its amount or rotational movement by stops it?! and 33 fixed to the frame.

It will be obvious from this linkage arrangement that rotation of the bell crank 28 exerting a tensile force on the connecting bar 2'! will result in a limited rotation of the lever E l about the pivot 25 without disturbing the rotational position of the lever 26 and hence such limited rotation is unrestrained by the spring 31. When, however, the extension 22 of the lever 2 abuts against the stop 34 on the connecting bar 2? any further movement of the lever 2 must be accomplished by rotation of the lever 26 about its pivot 22 which rotation is of course restrained by the spring 3?.

There are thus three positions which the auxiliary electrode 58 may assume depending on the force exerted by the solenoid on the bell crank 28. The first where no force is exerted permitting the auxiliary electrode to fall into contact with the electrode l2 under the force of the spring 3?. The second where an intermediate force is applied rotating the lever about the pivot 25 restained from further movement by the stops 5?. and 3d and the tension of the spring 3? so that the auxiliary electrode 58 is separated from the electrode I2 by a relatively small distance. Finally in the third position where full force is applied the lever 2: 3 is rotated together with the lever 25 as a unit about the pivot 22 against the action of the spring 37 and the auxiliary electrode I8 is thus moved to a position remote from the vicinity of the electrodes H and H2.

The procedure of starting the arc is initiated by closing the switch id manually. The are then is automatically drawn and established between the two main electrodes in the following manner. The arc current passes from the power source through the main ballast resistor 56, auxiliary ballast resistor 23, flexible conductor 52, auxiliary electrode it, negative electrode 12, conductor 3i solenoid ill and conductor 4! back to the power source. The passage of the current through the solenoid ll draws the armature 35 toward the right, rotating the bell crank lever 28 in a counterclockwise direction around its pivot pin 23, and drawing the connecting bar 2'? downward. The action in turn rotates the electrode holding lever 24 about the pivot 25, raising the left end thereof and separating the carbon 88 from the carbon l2. An arc follows the moving carbon 18 and is established between these two carbon electrodes. The movement of the lever 24 and of its carbon electrode it continues until the right end 42 or" the lever 24 comes into contact with the stop 34. This position of the linkage and of the auxiliary electrode carried thereby is termed the intermediate position. The action then stops, because the strength of the solenoid current is not sufficient to overcome the retractile force of the spring 31, the positions of the several levers then being as depicted in Fig. 2.

As the arc is drawn between electrodes 38 and E2, the latter, being the cathode, if it carries suincient current instantly becomes incandescent and emits electrons, which are expelled outward from the tip thereof in a sheaf or cone of flame having a wide apex angle because the electrons are mutually repellant. Many of the electrons, therefore, are expelled from the cathode in the direction of the positive electrode or anode H, and ionize the air path between electrodes l2 and H Moreover, the anode H being charged positively with respect to the charged electrons, tends to attract all that are emitted from the cathode, so that many more strike the anode than otherwise would. In addition, the anode l i being more positively energized than the auxiliary electrode l8 because of the voltage drop existing in the auxiliary ballast 2 I, there is more attractive force to draw electrons to the anode than there is to draw them to the auxiliary electrode. Due to all of these reasons the path from the cathode l2 to the anode I l becomes so highly ionized that appreciable current commences to flow between them. This reduces the amount of current that can flow to the auxiliary electrode [3, reducing the conductivity of the path thereto, thus increasing the relative conductivity of the main path, so that this transfer action quickly proceeds to completion, with all of the current passing to the anode II and with the arc to the auxiliary electrode is substantially extinguished.

.Because of the described emission of electrons from the cathode the precise location of the auxiliary electrode i3 is not of great importance, the described electrical and electronic conditions being paramount in importance in starting the are between electrodes H and i2.

In the described action the amount of current permitted to flow through the auxiliary arc is important, for if too little current flows the arc is not of the type termed high intensity and electrons are not generated at the cathode and shot into the surrounding space therefrom, or are generated and discharged in insignificant quantity. Specifically, the auxiliary arc current should be not less than 4C0 amperes. If the auxiliary arc current is less than this amount, the main arc may not start, or may not start promptly.

The resistor 2! has a, resistance several times that of the resistor it, so that the current drawn by the main arc between electrodes I! and i2 is at least several times that drawn by the auxiliary are between electrodes l8 and I2. The strength of the spring 31 is so designed that the operation of the solenoid IT is marginal in the sense that during the burning of the lower power auxiliary or starting arc the solenoid i? carries a relatively light current and cannot overcome the tension of the spring 31, but that when the heavy current of the higher power main arc flows the solenoid H is strongly energized and is able to overcome the tension of the spring 3?.

When, therefore, the main arc is established the following actions occur. The armature 3-! is drawn further into the solenoid l'i, rotating the bell crank lever 28 further in the counterclockwise direction. The connecting bar 2? is drawn down thereby and since the electrode holding lever 24 is already against its stop 34, the action causes the lever 26 to rotate clockwise'until it abuts against the stop 33. The movement of lever 26 carries the electrode-holding lever 24 with it, so that the auxiliary electrode I8 is transported to a position relatively distant from the main electrodes and completely away from their vicinity. This stored position is shown in Fig. 3.

Thus the three distinct positions of the arc starting mechanism are produced automatically by three current magnitudes inherently produced in operation. The transitions from the first to the second positions and current magnitudes and from the second to third are separate and distinct transitions although whether or not they are separated in time by a period of dwell in the second position is dependent upon the specific design, but does not change the theoretical basis of operation of the components. In the first position (Fig. I), the current flow is zero, the armature 3| is fully deenergized, the retractile spring 31 is retracted and brings the auxiliary electrode [8 into contact with the cathode electrode I2. In passing to the second position (Fig. 2) and in that position, the current flow through solenoid ll attributable to the current flow between electrode l2 and the auxiliary electrode l8 and a circuit including both resistors l6 and 2| may be of the order of 100 amperes. The solenoid is designed to overcome the weight of the electrode-holding lever 24 at, say so amperes current flow, and therefore, at say 100 amperes positively moves its armature 3| to the intermediate position and the lever 24 to the position shown in Fig. 2, and the retractile spring 31 remains retracted because its force cannot be overcome by the solenoid [1 at this 100 amperes current flow. In order to pass from the second to the third position the solenoid I! must, in example here given, be energized at 250 amperes or over, for instance at 500 amperes. the establishment of the main are as the mechanism attains its second position when the current through the solenoid constitutes the current though the main arc, flowing only through resistor 16. The solenoid armature Si is thereupon drawn into its fully operated position because the current is more than its pick-up value of 250 amperes, the force of the retractile spring 3? is overcome, the lever 26 is moved to its operated stop 33 and the electrode-holding lever 24 carrying its auxiliary electrode I8 is moved to the stored position shown in Fig. 3.

When the circuit is interrupted by opening the switch M, the electromagnet I l is deenergized, and the retractile spring 3? and the retractile efiect of the Weight of the electrode-holding lever 24 both cooperate to return the electrode holding-lever 24 into contact with the cathode electrode [2.

It is obvious that the plunger type electromagnet II can be replaced with any other type of electromagnet appropriately connected to actuate the linkage, or with a two-winding electromagnet or with two or more separate electromagnets. For example, the plunger type electromagnet I! can be replaced by a rotary type electromagnet disposed on the bell crank lever 28 about its fixed pivot 23.

What is claimed is:

1. In a high power are device, anode, cathode and auxiliary electrodes, said auxiliary electrode being positioned to contact said cathode, circuit means for energizing said electrodes, means responsive to the current flow between said cathode and auxiliary electrode for moving said This occurs upon .6 A auxiliary electrode to a first position adjacent said cathode but out of contact therewith to establish an arc therebetween, said are having such strength as to ignite an arc between said anode and cathode, and means responsive to the current flow between said anode and cathode when said are is ignited to move said auxiliary electrode to a position remote from the are between said cathode and anode.

2. In a high power arc device, anode, cathode and auxiliary electrodes, said'auxiliary electrode being positioned to contact saidcathode, an electric circuit including a ballast resistor connected between said anode and cathode, a circuit including a ballast resistor of higher resistance than said first mentioned ballast resistor connected between said anode and auxiliary resistor, means responsive to the current flow between said cathode andauxiliary electrode to movesaid auxiliary electrode out of contact with said cathode and to maintain a striking arc therebetween, said striking are being of such an intensity as to ignite an are between said anode and cathode, and means responsive to the current; flow in said last mentioned are to move said auxiliary electrode to position remote from said anode and cathode.

3. In a high power are device, anode, cathode and auxiliary electrodes, .said auxiliary electrode being positioned to contact said cathode, a circuit including electric motive means connected between said anode and cathode, a second circuit including current limiting means connected between said anode ,and auxiliary electrode whereby the power exerted by said electric motive means as a result of limited current flow between said auxiliary electrode and cathode is a fraction of the power exerted thereby as a result of current flow between said anode and cathode, first linkage means responsive to the fractional power exerted by said motive means for movingsaid auxiliary electrode out of contact with said cathode into a position to draw an arc therebetween, the are so formed being of sufficient intensity to ignite an are between said cathode and anode, and second linkage means responsive to the full power exerted by said motive means as a result of ignition of the are between said anode and cathode for moving said auxiliary electrode to aposition remote from said last mentioned are.

4. In a high power arc device, anode, cathode and auxiliary electrodes, said auxiliary electrode being positioned to contact said cathode, a circuit including a solenoid connected between saic anode and cathode, a second circuit including a ballast resistor connected between said anode and auxiliary electrode whereby the current flow through said solenoid as a result of conduction between said auxiliary electrode and cathode is less than the current flow produced therein as a result of conduction between said anode and cathode, a first linkage means operated by said solenoid moving said auxiliary electrode a limited distance from said cathode, a second linkage means operated by said solenoid only during maximum current flow therethrough for moving said auxiliary electrode to a position remote from said anode and cathode.

5. In a high power are device, anode, cathode and auxiliary electrodes, said auxiliary electrode being positioned to contact said cathode, a circuit including a solenoid connected between said anode and cathode, a second circuit including a ballast resistor connected between said anode and auxiliary electrode whereby current fiow through said solenoid as a result of conduction between said auxiliary electrode and cathode is limited to a lesser amount than the current fiow produced therein as a result of conduction between said anode and cathode, a first linkage means connected to said solenoid operative by the energy produced by said limited current fiow to withdraw said auxiliary electrode to a position spaced from but adjacent said cathode, a second linkage means connected to said solenoid and operated thereby to withdraw said auxiliary electrode to a position remote from said anode and cathode, and means inhibiting operation of said second linkage means in the absence of maximum current flow through said solenoid.

6. In a high power are device, anode, cathode and auxiliary electrodes, a holder for said auxiliary electrode, a linkage for rotating said holder and auxiliary electrode about a pivot point to move said auxiliary electrode into and out of contact with said cathode, means for limiting the amount of rotation of said holder about said pivot point, a second linkage for rotating said holder and said auxiliary electrode about a sec-- ond pivot point spaced from said auxiliary electrode by a greater distance than said first pivot point, and restraining means associated with said second linkage for preventing operation thereof by a force sufiicient to operate said first mentioned linkage.

'7. In a high power are device, anode, cathode and auxiliary electrodes, a holder for said auxiliary electrode, a linkage connected thereto for rotating said holder and said auxiliary electrode about a pivot point to move said auxiliary electrode into and out of contact with said cathode, means for limiting the amount of rotation of said holder about said pivot point, a second linkage connected to said holder for rotating said holder about a second pivot point spaced from said auxiliary holder by a greater distance than said first pivot point, restraining means associated with said second linkage for preventing operation thereof by a force suiilcient to operate said first mentioned linkage, a circuit for energizing said cathode and anode electrodes including a solenoid, a circuit for energizing said auxiliary electrode including said first circuit and a ballast resistor connected between said anode and auxiliary electrode, and means connecting said solenoid and said first and second linkage.

8. In a high power are device, anode, cathode and auxiliary electrodes, a holder for said auxiliary electrode, a linkage connected thereto for rotating said holder and said auxiliary electrode about a pivot point to move said auxiliary electrode into and out of contact with said cathode, means for limiting the amount of rotation of said holder about said pivot point to limit the separation of said cathode and auxiliary electrode, a second linkage connected to said holder for rotating said holder about a second pivot point placed at a greater distance from said auxiliary electrode than said first pivot point, restoring means connected to said second linkage for preventing operation thereof by a force suificient to operate said first mentioned linkage, a circuit for energizing said cathode and anode electrodes including a solenoid and a ballast impedance connected in series, a circuit for energizing said auxiliary electrode including a second ballast impedance connected betwen said anode and auxiliary electrode said second impedance having a higher value than said first mentioned ballast resistor and said solenoid being connected to operate said first and second linkages.

9. In a high power direct-current arc device, an anode, a cathode, a first ballast impedance connected in the anode-cathode circuit, an auxiliary electrode, the auxiliary electrode being movable and so disposed that it can touch the cathode only, a second ballast impedance connected directly to said auxiliary electrode, a first electrical circuit including said auxiliary electrode and having a selected range of impedance and current strength, a first mechanical linkage electromagnetically connected to said first electrical circuit for movement thereby and mechanically connected to said auxiliary electrode for motion thereof from a position in contact with the cathode to an intermediate position, out of contact therewith, a second electrical circuit including said anode having a selected range of impedance and current strength, and a second mechanical linkage electromagnetically connected to said second electrical circuit for actuation thereby and mechanically connected to said auxiliary electrode for motion thereof from the intermediate position to a stored position.

10. In a high power direct-current arc device, an anode, a cathode, power supply terminals, a first ballast impedance connected in series with said anode said cathode and said power supply terminals, an auxiliary electrode, the auxiliary electrode being movable and so disposed that it can touch the cathode only, a second ballast impedance connected directly to said auxiliary electrode, connection means for applying power from said power supply terminals to said auxiliary electrode said second ballast impedance and said cathode in series, moving means for moving said auxiliary electrode away from said cathode in first and second distinct motions, and electromagnetic means for applying the current through said auxiliary electrode to actuate said moving means in said first distinct motion to separate the auxiliary electrode from contact with said cathode to give rise to a strikin arc between the auxiliary electrode and the cathode, the striking are having such strentgh that the negative flame emanating from the cathode reaches the anode and causes the ignition without the auxiliary electrode touching the anode, said electromagnetic means additionally after the anode cathode current has commenced to flow applying said anode-cathode current to actuate said moving means in said second distinct motion to separate REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 743,241 Bremer Nov. 3, 1903 1,968,011 Beck July 31, 1934 2,186,063 Clouston Jan. 9, 1940

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