CS237059B1 - Insulating system for flat high-voltage electrodes - Google Patents

Abstract

The insulation system is designed to increase electrical strength and reduction of discharge. The essence of the isolation system is that between the first and second electrodes are adjacent disc insulators placed with each other ribs that are aligned with each other in two planes parallel to both electrodes. The insulation system is designed for high-voltage cabinets electron optical sources instruments.

Description

(54)

BUFiTVAL ZDENEK ing.CSc., SAW VOJTĚCH ing.,

GATEWAY EMIL ing., BRNO, KUNZ IVO, ŘÍČANY.

Insulation system between two high voltage surface electrodes

The insulation system is designed to increase electrical strength and reduce discharge. The essence of the insulating system is that between the first and second electrodes are located side-by-side disc insulators with prominent ribs, which are arranged with respect to one another in two planes parallel to the two electrodes.

The insulation system is designed for high voltage power supply cabinets of electron optical devices.

237 059

237 059

BACKGROUND OF THE INVENTION The present invention relates to an insulating casing between two high voltage surface electrodes designed to increase electrical strength and reduce the occurrence of discharges of various origins and types.

Improved regulation of the sources of accelerating voltages of electroptic devices has reduced a significant proportion of high voltage failures, but has also excelled in various types of discharges and pre-stress phenomena affecting the nature of high voltage. The influence of electric discharges on the character of high voltage cannot be limited by regulation. Discharges reduce the resolution of electron microscopes, sometimes completely disabling their function. They limit the life of integrated electronic circuits and cause the degradation of insulating dielectric materials. The magnitude and amount of discharges, whether gliding over the surface of insulators, or so-called partial discharges in the micro- or macroscopic cavities of insulators, can be limited by design modifications or improved technology for processing insulating materials such as epoxy encapsulating resins. These structural modifications usually increase the insulation distances, or increase the thickness and thus the amount of insulation materials, among other technological measures. A disadvantage of the air insulation provided in the usual way is, in particular, that dust and dirt grains are grouped in the air path of the field lines, on which a sliding discharge is easily formed. The probability of a sliding discharge of this type is given, among other things, by the size of the insulated surface, the macro and microscopic irregularities of the electrode surface, the amount of dust and dirt grains, and the degree of ionization of the insulating environment. The disadvantage of the insulation provided by the casting insulating resins is the technological difficulty in the first place. Watering larger

- 3,237 OSS surfaces with insulating resins are technologically difficult and lead to microscopic cracks that significantly reduce electrical and mechanical strength. · Larger amounts of dielectric insulating material increase the level of partial discharges, lead to an increase in parasitic capacities and an unwanted increase in stored energy. Partial and moving discharges degrade the insulating material, reduce the lifetime of the integrated circuits, increase the noise level in the feedback circuits, and thus prevent proper operation of the control.

These previous drawbacks are overcome by an insulating system located between two surface electrodes designed to increase electrical strength and reduce the occurrence of discharges and micro-discharges of different origins. The essence of this system is that disc insulators with prominent ribs are arranged side by side between the first and second surface electrodes. The ribs are disposed relative to each other in two planes parallel to the surface of the two electrodes.

The main advantage of this insulation system is that it allows to increase the electrical strength between two flat electrodes in a simple technological and economical way.

BRIEF DESCRIPTION OF THE DRAWINGS The invention is illustrated in greater detail in the accompanying drawing, in which: FIG. 1 is an axial section and FIG. 2 is a plan view of an exemplary embodiment of an insulating system.

The insulating system comprises first and second surface electrodes 1 and 2, between which disc insulators with prominent ribs 6 are arranged. In the isolation environment between the two surface electrodes 1 and 2, the elongated field lines E _Q and the permittivity E _{p of the} disk insulators are indicated. In our case, it is a voltage between the surface electrodes, under which the jump or discharge does not occur safely under the given conditions.

The holding voltage can be expressed by the equation:

E _d = ^e f. k _t . E _diZA where ... E _d ... is the withstand voltage

E _f ... is a coefficient involving the influence of microscopic roughness and cleanliness of the electrode surface as well as the dust-free environment

4 ... the time factor ^{E is called an} inherent electrical strength at which the ionization and electron capture factors are equal

The holding voltage E _d is not only of a nature characterizing the quality of an insulating environment, such as a gas, but also characterizes its behavior over a certain exposure time, expressed as a time factor k ^, in an insulating system characterized by a factor e ^. The probability of the discharge is thus proportional to the size of the insulated surface, in our case the electrodes ia 2, their surface quality, the dustiness of the environment and the time during which there is an appropriate electric gradient in the space between the electrodes JL and 2. Increasing the electrical strength is achieved by extending the insulator surface path. The excellent ribs 4 of the disk insulators shape and extend the path of the field lines, which would otherwise be directed in the shortest way from one surface electrode 1 to the other surface electrode 2. Dust and dirt grains are also grouped into the extended field lines. and will not hold it. The part of the surface area of the electrodes i and 2, in which the field lines are straight, is so small compared to the original surface without disc insulators that the likelihood of discharges is virtually eliminated.

The insulation system is designed especially for high voltage acceleration voltage cabinets.

Claims (1)

SUBJECT OF THE INVENTION 237 059 Insulation system between two high-voltage surface electrodes, intended to increase the electrical strength, characterized in that between the first and second surface electrodes (1,2), disc insulators (3) are arranged next to each other with prominent ribs (4) arranged with respect to each other in two planes parallel to the two surface electrodes (1,2).