US2875368A - Electrode control - Google Patents

Description

Feb. 24, 1959 w. M. JONES ETAL 2,875,368

7 ELECTRODE CONTROL Filed Jan. 10, 1957 I I i INVENTORS WITNESSES Wallace M. Jones and Francis M.Coin,Jr.

WW2; 2 MI ZMM ATTORNEY United States Patent ELECTRODE CONTROL Wallace M. Jones, Clairton, and Francis M. Cain, Jr.,

Washington, Pa., assignors to Westinghouse Electric Corporation, East Pittsburgh, Pa a corporation of Pennsylvania Application January 10, 1957, Serial No. 633,455 8 Claims. (Cl. 314-74) automatic control of the spacing of electrodes for an electric arc which is responsive to the unbalance between the arc voltage and a fixed reference voltage for correspondingly moving the electrodes.

' A more specific object of this invention is to control a reversible motor driving at least one electrode of an, electric are by a novel arrangement including a polarized relay, having its coil subjected to the voltage of the arc in opposition to a fixed predetermined reference voltage.

These and other objects of this invention will become more apparent upon consideration of the following detailed description of one embodiment thereof, when taken in connection with the attached drawing in which the single figure illustrates diagrammatically, apparatus for operating an electric arc lamp including the circuit con-,

nections therefor.

The electric arc lamp control apparatus illustrated on the drawing is adapted to be energized by a pair of alternating current supply conductors 2, which may be connected to a double pole switch 4 for selectively ener gizing and deenergizing the apparatus. The switchv 4 may be connected to a pair of conductors 6, which may in turn be connected to fuses 8 for interrupting the supply of current in the event of an overload or short circuit in the apparatus. The fuses 8 are connected by conductors-10 to a full-wave rectifier 12, to provide a source of direct current power at the positive terminal 14 and negative terminal 16. Preferably, a capacitor 13 is connected across the rectifier terminals to smooth the rectifier Output.

The are light is adapted to be energized from the direct, current source, and for this purpose there is provided a conductor 18 leading from one terminal 16 of the rectifier l2 and it is connected With a conductor 20, having a flexible portion 22, connected to the movable electrode 24 of the are light. The electrode 24' may be of any suitable material such, for example, as carbon or the like. A second conductor 26 including a regulating resistor 28 is connected from the other direct current output terminal him the other electrode 30 .of the are light. The electrode 3t) may be mounted on a suitable fixed support 32, whereas the movable electrode 24 is mounted on a support 34 which is mountedfor movement in a rectilinear direction toward and away from the fixed electrode 30. Any suitable mechanical arrangement may be employed for moving the movable electrode 24 audits support 34, preferably a movement reducing means, for

for example, by a spring 51.

example, the movable support 34 may have rack teeth formed thereon for engagement with a pinion gear 36.

The movable electrode 24, and in this illustrative emhodiment of the invention, the pinion 36, is adapted to be actuated by a reversible alternating current motor 38. While the motor 38 may be of any desired type, there is illustratively depicted on the drawing a capacitor type of motor having stator windings 40 and 42 directly connected together at one end of each winding. The other ends of the windings are joined by a conductor 62 which includes a capacitor 60, for a purpose to be described. The motor 38 is adapted to be energized from the alternating current source by a means of one conductor 44 connected to one of the fuses 8 and to the directly connected ends of motor windings 40 and 42. The other side of the alternating current source of supply is connected by means of a conductor 46 connected to the other of the fuses 8, and to the movable confact 43 of a polarized relay 50. The movable relay contact 48 is biased to the intermediate position shown, It will be noted that the relay 50 has one stationary contact 52 which is connected by means of a conductor 54 directly to one of the motor windings 40, and a second stationary contact 56 is con nected by means of a conductor 58 directly to the other of the motor windings 42.

The energizing circuit for the motor 48 will now be apparent as being under the control of the relay 50 so that when the movable contact 48 of the relay is in engagement with the stationary contact 52, the motor winding 40 will be directly connected across the alternating current source Of supply, whereas the winding 42 will be connected in series with the capacitor 60 across the alternating current source of supply. This will cause the motor to operate in one direction and to drive the movable electrode 24 in one direction, for example in a direction toward the stationary electrode 30. When the movable contact 48 of the relay is in engagement with the stationary contact 56, then the motor coil 42 will be directly connected across the alternating current source of supply, whereas the coil 49 will be connected in series with the capacitor 69 across the same source to thus cause operation of the motor in the reverse direction, and movement of the movable electrode 24 in the reverse direction, for example, in the direction away from the stationary electrode 30.

In order to operate the moving contact 48 of the relay, the relay includes a stationary magnetic core 64 adapted to be energized by a winding 66. As is Wellknown in the art, the movable contact 48 of the relay 50 isalso of a magnetic material, and is polarized so that the direction of how of current through the winding 66 will determine the position of movable contact 48. The relay winding 66 is connected at one end by means of a conductor 68 to the stationary electrode 30, so as to be at the same potential as the electrode 30, A conductor 70 connects the other end of the relay coil 66 to the movable element of a potentiometer 72 which is connected through a resistor 74 to the conductor 18, previously described as being directly connected to one of the direct current output terminals 16, and by a conductor 78 to the other of the direct current Output terminals 14 through a resistor 76. The conductor 78 thus acts to connect the coil to a potential determined by the setting of the potentiometer 72. Both potentials applied to'opposite ends of winding 66 are of the same polarity so that current flow through this winding will beproportional to applies to winding 66 will electrode 30 when the arc is at optimum length.

While a relatively high direct current voltage may be required to form andsustain an electric are between the electrodes 24 and 39, the actual voltage drop across the are for optimum spacing of the electrodes will be a lesser value, and the arc voltage will vary with variations in spacing of the arc electrodes and such voltage variations will be reflected at the end of winding 66 connected to the conductor 68.

Now if it be assumed that the lamp is not in operation, but the electrodes are separated from each other, if it is desired to operate the arc, the switch 4 may be closed, thus energizing the circuit. This will apply a voltage to the winding 66 of relay 5e by way of conductor 70 which is determined by the setting of the potentiometer 72, and this will be continuously applied to the winding 66 so long as the switch 4 is closed. At the same time, the winding 66 of the relay 50 is subjected to the voltage of the electrode 30, and since the electrodes are now separated and no current flow occurs, this voltage drop will be considerably higher than that referred to above as being continuously applied to the winding 66, to cause a resultant current through the coil in a direction to operate the movable contact 48 into engagement with the stationary contact 52 to cause operation of the motor 38 in a direction to move the movable electrode 24 toward the stationary electrode 30 and ultimately into engagement therewith. At the time the electrodes 24 and 30 engage, the voltagedrop thereacross will decrease to substantially zero, at which time the continuously applied predetermined voltage due to conductor 70 will become effective to cause current to flow in the relay winding 66 in the opposite direction to thus reverse the flux in core 64 and operate the movable contact 48 of the relay 50 into engagement with the other stationary contact 56 and thus cause operation of the motor 38 in the reverse direction to move the electrode 24 away from the stationary electrode 36. As this separating movement of the electrodes 24 and 36 occurs, the voltage drop across the electrodes will gradually increase, thus increasing the voltage applied to the winding 66 by the conductor 68, and at the optimum spacing of the electrodes 24 and 30 for light producing purposes, this voltage will then be equal to the voltage continually imposed on the winding 66 by the conductor 70 in the manner previously indicated, and the relay contacts will open and the motor 38 will stop. In this way the relay 50 can operate to automatically initiate operation of the are light, and to automatically maintain an optimum spacing of the electrodes 24 and 39. The use of a polarized relay results in relay operation without chatter of the relay contacts, and eliminates hunting.

Having described a preferred embodiment of the invention in accordance with the patent statutes, it is desired to point out that the invention is not to be limited to the specific circuit and construction disclosed herein,

as it will be apparent to persons skilled in the art that certain modifications and changes may be made in this particular arrangement without departing from the broad spirit and scope of the invention. Thus, the motor 38 may be connected to both electrodes 24 and 36 to simultaneously move them toward and away from each other. Similarly, instead of using a rectifier 12 to supply direct current, a motor-generator set could he used instead in which case the capacitor 13 will not be needed. Accordingly, it ,is desired that the invention be interpreted as broadly as possible in accordance with the appended claims.

We claim as'our invention:

' 1. Apparatus for operating an electric'arc lamp com: prising, a pair of lamp electrodes at least one of which is mounted for movement toward and away from the other, reversible motor operated means for moving at least said one electrode in both directions, a polarized relay be equal to that applied from having an operating coil and contacts controlling the energization'of said motor operated means to thus control the direction of electrode movement, the aforesaid operating coil of said relay being connected across said electrodes so as to be subjected to the voltage drop across said arc, and means for applying a predetermined reference voltage of the same polarity to said relay coil and of a value corresponding to the voltage drop across the are for the optimum length of are.

2. Apparatus for operating an electric arc lamp comprising, a pair of lamp electrodes at least one of which is mounted for movement toward and away from the other, reversible motor operated means for moving at least said one electrode in both directions, a polarized relay having an operating coil and contacts controlling the energization of said motor operated to thus control s the direction of electrode movement, the aforesaid 09g." crating coil of said relay being connected across {s id electrodes so as to be subjected to the voltage dropjicross said are, asource of direct current also connected! across said electrodes, and connections from said sq iirce for applying a predetermined voltage from said source to said coil of a polarity the same as that due to tlhe voltage drop across the electrodes and of a value corresponding to the voltage drop across the are for the optimum length of are. l s' l 3. Apparatus for operating an electric arc lamp comprising, a pair of lamp electrodes at least one of which is mounted for movement other, reversible motor means for moving at least said one electrode in both directions adapted to be connected to a source of alternating current, a polarized relay con trolling the energization of said motor to thus control the direction of rotation thereof, the operating coil of said relay being connected across said electrodes so as to be subjected to the voltage drop across said are, a rectifier also adapted to be connected to said source of alternating current, means connecting the direct current output of said rectifier across said electrodes, and connections from the direct current output of said rectifier for applying a predetermined direct voltage to said coil of a polarity the same as that due to the voltage drop across the electrodes and of a value corresponding to the voltage drop across the are for the optimum length of are.

4. Apparatus for operating an electric arc lamp comprising, a pair of lamp electrodes at least one of which is mounted for movement toward and away from the other, reversible motor operated means for moving at least said one electrode in both directions, a polarized relay having an operating coil and contacts controlling the energization of said motor operated means to thus control the direction of electrode movement, the aforesaid operating coil of said relay being connected across said electrodes so as to be subjected to the voltage drop across said arc, a source of direct current also connected across said electrodes, voltage dividing means also connected across said source of direct current, and means connecting said coil to said voltage dividing means in a manner to apply a predetermined voltage fromsaid source to said coil of a polarity the same as that due to the voltage drop across the electrodes and of a value corresponding to the voltage drop across the are for the optimum length of arc.

5. Apparatus for operating an electric arc lamp comprising, a pair of lamp electrodes at least one of which is mounted for movement toward and away from the other, reversible motor operated means for moving at least said one electrode in both directions, a polarized relay having an operating coil and contacts controlling the energization of said motor operated means to thus control the direction of electrode movement, the aforesaid operating coil of said relay being connected across said electrodes so as to be subjected to the voltage drop across said are, a source of direct current also connected across said electrodes, voltage dividing'means also connected toward and away from theacross said source of direct current and including a variable part, and means connecting said coil to the variable part of said voltage dividing means in a manner to apply a predetermined voltage from said source to said coil of a polarity the same as that due to the voltage drop across the electrodes and of a value corresponding to the voltage drop across the are for the optimum length of arc.

6. Apparatus for operating an electric arc lamp comprising, a pair of lamp electrodes at least one of which is mounted for movement toward and away from the other, reversible motor operated means for moving at least said one electrode in both directions, a polarized relay having an operating coil and contacts controlling the energization of said motor operated means to thus control the direction of electrode movement, the aforesaid operating coil of said relay being connected across said electrodes so as to be subjected to the voltage drop across said arc, a source of direct current also connected across said electrodes, resistance means also connected across said source of direct current, and means connecting said coil to an intermediate point of said resistance means to apply a predetermined voltage from said source to said coil of a polarity the same as that due to the voltage drop across the electrodes and of a value corresponding to the voltage drop across the are for the optimum length of arc.

7. Apparatus for operating an electric arc lamp com prising, a pair of lamp electrodes at least one of which is mounted for movement toward and away from the other, reversible motor operated means for moving at least said one electrode in both directions, a polarized relay having an operating coil and contacts controlling the energization of said motor operated means to thus control the direction of electrode movement, the aforesaid operating coil of said relay being connected across said electrodes so as to be subjected to the voltage drop across said arc, a

" is mounted for movement toward and away from the other,

reversible motor operated means for moving at least said one electrode in both directions, a polarized relay including an operating coil and spaced contacts adapted to be engaged by a movable contact in response to current flow through said coil in opposite directions, respectively, means biasing said movable contact to an intermediate open circuit position, the operating coil of said relay being connected across said electrodes so as to be subjected to the voltage drop across said arc, and means for applying a predetermined reference voltage of the same polarity to said relay coil and of a value corresponding to the voltage drop across the arc for the optimum length of arc.

Sandelowsky Apr. 18, 1933 Gilbert Jan. 2, 1934

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