VOLTAGE MULTIPLIER DEVICE FOR HIGH TENSION EQUIPMENT, IN PARTICULAR FOR APPLICATIONS IN SPACE.

Abstract: The invention relates generally to voltage multiplier devices, and in particular, to devices for use in spatial applications. The technical problem coped with concerns the provi­ sion of voltage multiplier devices of relatively small size and weight, and high reliability in operation. The problem has been solved by controlling the electric field on the multiplier device through an electrostatic screen, and by optimizing the potential gradient existing between the individual components of the voltage multiplier by means of a reduction in the electric field where the voltage is highest and partial discharges are more likely to occur.

Description: This invention relates to a voltage multiplier device for high tension equipment, in particular for spatial applications. As is known, satellite equipment, owing to the high costs of satellite launching and orbiting, as well as the difficulty or even impossibility of effecting component replacements, pose strict and often conflicting requirements. As an example, to reduce the launching cost, the weight and size of the equipment installed have to be minimized, while owing to the difficulties encountered, in replacing components, it is necessary that the latter be reliable and durable. On the other hand, size reduction, especially with high tension equipment, makes the insulation problems more keenly felt and increases the likelihood of the so-called corona effect occurring,with partial discharges which do not shortcircuit the electrodes. Such partial discharges occur inside cavities or inclusions in a dielectric, which grow larger with time owing to the wall being eroded away by the discharges. Consequently, within a more or less short time, this will result in a destructive discharge taking place and failure of the equipment. In particular with voltage multipliers, to achieve good reliability of the apparata, qualified components (capacitors, diodes, and resistors) must be selected, along with a good circuit arrangement of such components in order to minimize stray capacities, and a good insulation, In general, insulation is the most critical factor and requires a careful study of the potential distribution. In view of the foregoing situation, it is a primary object of this invention to provide a voltage multiplier which is compact in size and highly reliable in operation. A further object of the invention is to provide a voltage multiplier, wherein the likelihood of partial or destructive discharges occurring is minimized, thereby improving the apparatus durability. Another object of this invention is to provide a voltage multiplier as indicated, which features good insulation, both outside and inside between the individual components thereof. These and other objects, such as will be apparent hereinafter, are achieved by a voltage multiplier device for high tension equipment, in particular for spatial applications, according to the invention, comprising a first section including such circuit components as resistors, capacitors, and diodes operatively and function-wise interconnected together and being carried on a common mounting base, said first section being adapted to supply a high voltage, and a second driving section, and characterized in that electrostatic screens external to said first section are provided for controlling the present electrio field, and in that it comprises a means of optimizing the potential gradient present between the components making up said first section. Further features and advantages will be more clearly understood from the following description of a preferred, though not limitative, embodiment of this device, as illustrated by way of example only in the accompanying drawings, where: Figure 1 is a general perspective view of the voltage multiplier device according to the invention; Figure 2 is a schematical detail view of the device of Figure 1; Figure 3 is a side view of the detail shown in Figure 2; Figure 4 is a further detail view of the device of Figure 1, in schematical form; Figure 5 is a side view of the detail shown in Figure 4; and Figures 6 to 12 illustrate assembling details of the electric components of the voltage multiplier section according to the invention. With reference to Figure 1, indicated at 1 is the "main voltage multiplier" device. Said device 1 comprises two sections, of which a first section, designated with the reference numeral 2, constitutes the voltage multiplier proper, and a second section, designated with the reference numeral , constitutes the drive section of the final stage or voltage multiplier. The voltage multiplier 2 is divided, in turn, into a first element 2a and second element 2b, forming a multiplier by twelve and multiplier br thirty six, respectively. As may be seen in Figure 1, both the element 2a and element 2b of this invention are completely enclosed by a screen 14 formed from a wire mesh which is grounded. Figure 2 illustrates schematically the multiplier by thirty six. Said multiplier comprises a base 4 having holes 5 (represented as thin line circles). hick line circles represent the weld points 6 for assembling the components. mounted on the base 4 are capacitors 7 (welded in the way shove in Figure 7), diodes 8 (Figure 10), and a resistor 9 (Figure 8). Figure 3 shows a side view of the multiplier 36 of Figure 2, where the capacitors 7, diodes 8, and output cable 10 for the 36 kVolt high tension (welded as shown in Figure 9) may be seen. Figure 4 illustrates the multiplier-by-twelve element which, similarly to the multiplier-by-thirty six element shown in Figure 2, comprises a base 4' having holes 5' and weld points 6'. Welded to the base 4' are capacitors 7', diodes 8', resistors 91, resistors 11 (welded as shows in Figure 11), and a component 12 (assembled as shown in Figure 12). Shown in thick dash lines, both in Figure 2 and Figure 4, are components 7, 7', 9, 9', 111 and 12, which are all welded on the sane side of the base, 4 or 41, and in thin dash lines, the components 8 and 8' welded to the other side of the base. Figure 5 is a side view of the multiplier by twelve according to Figure 4. Said side view shows the capacitors 7', output cable 13 for the 12 kVolt high tension, and output cable 10' for the 36 kVolt high tension. Figures 6-12 illustrate the welding of the components and high tension cables, whereby a reduction in the applied electric field can be achieved, i.e. the optimization of the potential gradient. According to this invention, metal surfaces of various sizes, such as balls or small cylinders 15, are provided. The dimensions of the metal surfaces 15 must be carefully determined, as is obvious to a person skilled in the art, to each time provide the best distribution. The method for manufacturing the voltage multiplier device of this invention is also of essential import and advantageous per se. In accordance with said method, bases are press formed with holes, onto which bases the components are then assembled while inserting at the same time the metal balls or cylinders 15. Thereafter, the thusly assembled bases are placed within electrostatic screens, wherefrom air is drawn out prior to casting the insulating polyurethane resins. The insulating polyurethane resins are cast, according to the invention, under a vacuum, in order to prevent the formation of air bubbles within the insulating dielectric which would represent weakening areas. In fact, there would otherwise be generated at said bubbles high potential differences, with attendant increased likelihood of destructive discharges taking place. It will be appreciated from the foregoing description that the invention fully achieves its objects. In particular, that the voltage multiplier device is highly reliable, by virtue of metal surfaces being inserted therein which afford an improved distribution of the potential existing between the components, with attendant reduction of the electric field where the tension is highest. Furthermore, the provision of holes in the component mounting bases is extremely advantageous. In fact, such holes, by extending the path of any surface discharges reduce the likelihood of such discharges occurring between components at different potentials. Of fundamental importance to the reliability of the system is the fact that a control of the electric field has been provided in the form of screens which completely enclose the voltage multiplier section and are grounded electrically. Advantageously, such screens may be formed from wire mesh, thereby facilitating adhesion of the screen onto the insulating resins, and reducing the likelihood of air bubbles highly susceptible to discharging being formed between the screen snd external surface of the dielectric. Moreover, the insulating resins are cast under a vacuum to prevent the formation of air bubbles within the dielectric. The invention as described is susceptible to many modifications and variations, without departing from the scope of the instant inventive concept. In practicing the invention, the materials, as well as shapes and dimensions, may be any ones meeting individual application requirements.

Claims: CLAIMS 1. A voltage multiplier device for high tension equipment, in particular for spatial applications, comprising a first section (2) including such circuit components as resistors, capacitors, and diodes (7-9,7'-9', 11,12) operatively and function-wise interconnected together and being carried on a common mounting base (4,4'), said section (2) being adapted to supply a high voltage, and a driver section (3), characterized in that electrostatic screens (14) external to said first section (2) are provided for controlling the electric field present, and in that it comprises means (5,T',15) of optimizing the potential gradient present between the components making up said first section (2). 2. A device according to Claim 1, characterized in that said electrostatic screens (14) comprise a wire mesh completely enclosing said first voltage multiplier section (2). 3. A device according to Claims 1 and 2, characterized in that said electrostatic screens (14) controlling the electric field are kept at ground potential. 4. A device according to Claim 1, characterized in that said mounting base (4,4') for the circuit components (7-9,7'-9',11,12) making up said first voltage multiplier section (2) is formed with plural holes (5,5') for opti mi zing the potential gradient. 5. A device according to Claim 1, characterized in that located at terminals of said circuit components (7-9,7'-9',11,12) and at interconnection and weld points (6,6r) to the common mounting base (4,4') are metal surfaces (15) effective to provide an improved distribution and reduction of the electric field present within said first voltage multiplier section (2). 6. A voltage device according to Claim 5 characterized in that said metal surfaces (15) are in the form of small balls or cylinders welded to the terminals of said circuit components and said base (4,4'). 7. A device according to Claim 1, characterized in that said first voltage multiplier section (2) is impregnated with polyurethane resins having a high dielectric constant and being adapted to provide adequate insulation between points at different potentials for optimizing the applied electric field. 8. A method of manufacturing the voltage multiplier device for high tension equipment, in particular for spatial applications, characterized in that it comprises the steps of: - press forming a mounting base for circuit components with holes interrupting the electric path of discharges and the like; - assembling said circuit components by inserting and welding to the terminals of said components metal surfaces such as small balls and cylinders of a suitable size; - enclosing said base with said circuit components by means of a wire mesh electrostatic screen; - casting liquid state polyurethane resins into the enclosure formed by said screen either under a very low pressure or a vacuum; and - allowing said resins to solidify. 9. A voltage multiplier device for high tension equipment, in particular for spatial applications, substantially as herein described and illustrated.

Inventors: VOLONTIERI, ANTONIO
Applicants: FIAR S.P.A.
Application year: 1983
Main classification: H05K9
IPC codes: H05K9