US1930545A - Current-controlling apparatus - Google Patents

Description

Oct. 17, 1933. w sL 1,930,545

CURRENT CONTROLLING APPARATUS Filed Nov. 15, 1929 2 Sheets-Sheet l 9 ft?- 59 J5 INVENTOR Roy J wensley ATTo'RNEY Oct. 1-7, 1 933. R WENSLEY 1,930,545

CURRENT CONTROLLING APPARATUS Filed Nov. 13, 1929 2 Sheets-Sheet 2 lll III[ INVENTOR RoyJWensley ATTORNEY Patented Oct. 17, 1933 UNITED STATES 1,930,545 CURRENT-CONTRQLLING APPARATUS Roy J. Wensley, Pittsburgh, Pa., assignor, to

Westinghouse Electric & Manufacturing Company, a corporation of Pennsylvania Application November 13, 1929 Serial No. 406,965

Claims.

My invention relates to current-controlling apparatus and particularly to apparatus for controlling the illumination intensity of lighting circuits used in theaters and auditoriums and in 5 interior and exterior ornamental lighting.

An object of my invention is to provide a circuit-controlling apparatus wherein the intensity of illumination may be predetermined for a selected scene of a theatrical production or for any selected period of time and wherein the apparatus may be pre-set to produce predetermined illuminating intensities at any predetermined time, during a plurality of scenes of a theatrical production or during a plurality of selected time intervals.

Another object of my invention is to provide a current-controlling apparatus for theatre-lighting circuits or for ornamental-lighting circuits wherein such circuits are controlled by reactors and wherein the current necessary for control of the reactors is substantially less than that usually required.

A further object of my invention is to provide a current-controlling apparatus for theatrelighting and like circuits wherein the control winding of the reactor is supplied through the medium of a resistance-controlled thermionic device, thereby enabling the use of a relatively small resistance unit and reducing the space required upon the switchboard.

A further object of my invention is to provide'a compact and relatively inexpensive cirwit-controlling apparatus wherein the abovenoted results may be accomplished by means of apparatus having a minimum numberof moving These and other objects that will be made apparent'throughout the further description of my invention are obtained by means of the apparatus hereinabove described, and illustrated in the accompanying drawings, wherein,

Figure 1 diagrammatically illustrates the apnaratus and wiring connections employed in the circuit-controlling apparatus or system, and

Fig. 2 is a diagram, similar to that of Fig. 1, illustrating a modified form of current-controlling apparatus.

Referring particularly to Fig. 1, a single illuminating circuit 3 is shown in which a plurality of electric lamps 4 are provided. It will be understood that the ordinary theatre and ornamental-lighting requirements demand a large number of individually and collectively controlled lighting circuits divided into groups of circuits having lamps of different colors.

The lamp circuit 3, comprising conductors 5 and 6, is supplied with electric current from the main alternating-current feed conductors 7 and 8 through the medium of an inductive winding 9 of a reactor 11. The reactor 11 comprises an 5 iron core 12 having legs 13, 14 and 15, the inductive winding 9 being wound about the legs 13 and 14.

The reactor is provided with a direct or unidirectional current-control winding 16 that is 5 wound about the central leg 15 of the core and serves to saturate the core and thereby reduce .the impedance of the coils 9 substantially in proportion to the current flowing through the control The normal impedance of the 7 reactor prevents suflicient current from flowing through the coils 9 to cause incandescence of the lamp filaments.

The degree of illumination of the lamps in the light circuit 3 is substantially proportional to the amount of current passing through the control winding 16, and this latter current need be only a very small proportion of that flowing through the inductive winding 9 and the lamp circuit.

The source of energy for current supplied to the control winding 16 is a thermionic device 17 comprising a filament 18, a plate 19 and a grid 21, the filament being energized by means of a direct-current source of supply, such as a battery 5 22.

The plate circuit 23 is provided with a transformer 24 having a primary winding 25 that is connected to a source of direct current, such as a battery 26. 'The transformer 24, which is of the iron-core type, is provided with a secondary winding 27 that is connected across the terminals 28 and 29 of a rectifier 31, as indicated in Fig. 1, and the control winding 16 is connected to the terminals 32 and 33 of the 96 rectifier, the connections being such that the pulsating or alternating current set-up in the plate circuit, as a result of a pulsating-current potential imposed upon the grid, in a manner to be hereinafter described, are translated, 100 through the medium of the rectifier 31, in the form of a pulsating uni-directional current in the control winding 16.

The apparatus for providing a pulsating or altemating-current potential on the grid 21 comprises a current regulator 34, of the constant-current type, having a stationary primary winding 35 connected, through the medium of conductors 36 and 3'7, to the feed conductors 7 and 8 of the alternating-current source. The

regulator is provided with the usual floating secondary winding 38 that is movably mounted upon a rocking arm 39 having a counter balance 41. The regulator is of standard construction and no claim is made to the regulator shown for the purpose of illustrating its application.

A resistance element or unit 42, having a winding 43, preferably of resistance material, such as nickel-chromium alloy or the like, is connected to the secondary winding 38 of the regulator through the medium of conductors 44' and 45, the former having a fixed resistance 46 in series with the resistance winding 43.

The winding 43 is of uniform resistance throughout its length, and a plurality of resistor sections 47, 48, 49, 51, 52, 53, 54, 55, 56, and 57 are connected, at spaced intervals, to the resistance winding 43 by means of conductors 58. The points of connection or terminals 69 are spaced uniformly along the winding 43 and at each terminal 69, a flexible conductor 59 is connected to the winding 43 and is provided with a contact brush 61 which slidably engages the resistor sections 47 to 57, respectively.

A master contact arm 62, having spaced contact brushes 63 and 64, is so pivotally mounted, that, when it is rotated, the contact brushes 63 and 64 engage the resistance winding 43, the contact brushes 63 and 64 being preferably spaced apart a distance equivalent to the distance between the terminals 69.

The contact brush 63 is connected to the grid 21 of the thermionic device through the medium of a conductor 65, and the contact 64 is connected to the negative terminal of a source of direct current, such as a battery 66, for the purpose of imposing a negative potential bias upon the grid 21.

It will be understood that the purpose of the regulator 34 is to maintain a substantially uniform current flow through the resistance element 42, regardless of the total resistance thereof, which varies in accordance with the positions of the contact brushes 61 engaging the resistance elements 47 to 57.

It will be understood also that the potential diiference between the ends of any sections of the resistance winding 43 that are of equal length is substantially equal and uniform, so that, ordinarily, regardless of the position of the resistance arm 62 and its contact brushes 63 and 64, the potential difference between the brushes will remain the same.

Assuming that there is a potential difference of volts across the conductors 44 and 45 at the terminals 67 and 68, respectively, the potential difference between any two terminals 69 will be 10 volts, since the resistance winding 43 is divided into 10 sections of equal length.

When the resistance arm 62 is so positioned, as indicated in dotted lines, that the contact brushes 64 and 63 engage, respectively, the extreme terminal 68 and the adjacent connection joint 69 and, when the contact brush 61 of the resistor section 47 is in the position indicated, the resistor section between the points 68 and 69 is completely short-circuited by the flexible conductors 59 and contact brushes 61. Therefore, there is no potential drop between the contacts 63 and 64 and, as a result thereof, no current will flow in the plate circuit.

However, if the contact brush 61 oi the resistor section 47 is moved to the position indicated in dotted lines, a portion of the resistor section 47 will be interposed in the circuit, and the potential diflerence between the contact brushes 63 and 64 will be proportional to resistance of the section 47 that is included in the circuit.

It will be understood that a resistor section 47, 48, etc., is, for instance, provided for each scene to be enacted in a theatrical production and the degree of illumination for a selected scene is predetermined by positioning the contact brush 61 upon the resistor section 47, 48, etc. It will be apparent from the foregoing that, as the resistance arm 62 is rotated in a clockwise direction, the potential diil'erence between the contacts 63 and 64 will vary in proportion to the combined resistance in the circuit between the contact brushes 63 and 64 and the resistance of the sections 47 or 48, etc. that is connected to the resistance element 43 between the contact brushes 63 and 64.

From the foregoing, it is also apparent that the degree of illumination of a circuit may be increased or decreased from the illuminating intensity determined by the position of the contact brush 61 by moving the resistance arm 62 in a clockwise or contraclockwise direction.

If the potential imposed upon the grid 21 100 varies, the current in the plate circuit will correspondingly vary and will alter the current flow through the transformer 24 and, subsequently, through the control winding 16. It is apparent I therefore, that I have provided a simple and extremely flexible apparatus whereby the current intensity of a light circuit may be predetermined by a simple apparatus which may be pre-set to produce predetermined illuminating results, and that the amount of current for controlling the thermionic device is a very small fraction of the current controlled. Consequently, the resistance unit may be relatively small and occupy very little space upon the switchboard.

In Fig. 2, I have disclosed a modified form of apparatus wherein the various control units are identical with the apparatus disclosed, with the exception that the resistance element is modifled to obviate the necessity of a current regulator, the modification of the resistance element being of such character that, regardless of the position of the contact brush 61 upon its resistor section 47, 48, etc., the total resistance of the element or unit remains unchanged. For this reason, since the resistance does not change, the current through the resistance unit remains the same, provided, of course, that the voltage of the current source remains constant.

It will be noted that, in addition to the resistance winding 43, I have provided an auxiliary resistance winding 71 which comprises resistance sections 72, 73, 74, 75, 76, 77, 78, 79, 81 and 82, all of which, are connected in series. One end of the resistance element 71 is connected to the terminal 68 by a conductor 83, and the other terminal 84 of the resistance element 71 is connected to the feed conductor 8 of the current-supply circuit. The conductor 7 of the current-supply circuit that is connected to the inductive winding 9 of the reactor 11 is also connected to the terminal 67 of the resistance winding 43.

The resistor sections 72, 73, etc. are disposed adjacent to resistor sections 47, 48, etc. respectively, in such manner that both oi. the resistance sections may be simultaneously engaged by sliding contact bars 85 which carry the contact brushes 61 and 86 that are connected to the resistance element 71, at equally spaced intervals by means of flexible connectors 87.

It is apparent from the foregoing that, when a contact brush 61 on a sliding bar 85 is moved to include, in the circuit across the brushes 63 and 64, resistance of the resistance section 47, a corresponding amount of resistance in the section 72 is shunted from the circuit by the flexible conductor 87 and its contact 86, it being understood that the resistor sections 4'7 and '12 are all of substantially the same length and of equal and uniform resistance. Since any movement of the sliding contact 85 shunts from the resistance element exactly the same amount of resistance as is included by the contact 61, the total resistance of the unit 42 remains unchanged and, consequently, the current flow through the unit remains unaltered. I

The operation of the contact arm 62 and its brush contacts 63 and 64 is identical with the operation described with reference to the device illustrated in Fig. 1, since the potential difference between the contact 63 and 64 depends, in the same way, upon the position of the contact 61 on its resistance sections 4'1, 48, etc. and upon the position of the contact arm relative to terminals 69 to which the flexible conductors 59 are connected to the resistance winding 43.

While I have described two embodiments of my invention, changes may be eflected therein without departing from the spirit and scope thereof, as set forth in the appended claims.

I claim as my invention:

1. In an illumination-control system, means, including a thermionic device for deriving an alternating-current potential substantially corresponding to a desired degree of illumination and means, including a transformer, connected resistance of predetermined sections of the resistance element, and means for maintaining a substantially uniform current flow through the resistance element regardless of variations in the total resistance thereof.

3. In an electrical system, means for supplying a presettable variable potential to the system comprising a resistance element having a plurality of portions or substantially equal and fixed resistance and a plurality of portions having variable resistance for varying the total resistance of predetermined sections of the resistance element, means for maintaining a substantially uniform current flow through the resistance element regardless of variations in the total resistance thereof, and means for impressing on the electrical system a potential substantially corresponding to the potential difference between sections of the resistance element.

4. In an electrical system, means for supplying a presettable variable potential to the system comprising a resistance element having a plurality of portions of substantially equal and fixed resistance, and a plurality of portions having variable resistance for varying the total resistance of predetermined sections of the resistance element, said portions of variable resistance being so connected as to maintain the total resistance of the resistance element substantially constant, and meansfor impressing on the electrical system a potential substantially corresponding to the potential difference between sections of the resistance element. 5'. In an electrical system, means for supplying a presettable variable potential to the system comprising a resistance element having a plurality of portions of substantially equal and fixed resistance, a plurality of portions having variable resistance for varying the total resistance of predetermined sections of the resistance element, means .for simultaneously engaging portions of the variable resistance in a manner to maintain the total resistance of the resistance element substantially constant, and means for impressing on the electrical system a potential substantially corresponding to the potential difference between sections of the resistance element.

ROY J. WENSLEY.

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