RU2297064C2 - Capacitor for voltage measurements by means of capacitive voltage divider - Google Patents

Abstract

FIELD: electrical engineering; voltage measurements by means of capacitive voltage divider.

SUBSTANCE: capacitor has case mounted on cylindrical supporting shell filled with insulating medium; this case functions as first capacitor plate accommodating second capacitor plate in the form of horizontal metal tube attached to top end of supporting tube; it also has additional plate in the form of tube coaxially installed inside second plate and electrically connected to case. Bottom plate of supporting tube is secured on capacitor metal base in parallel with supporting tube axis. Supporting tube is assembled of metal tube sections fixed together by means of insulating tube section. Capacitor also has cylindrical column made of high-sensitivity material and mounted inside supporting shell coaxially with supporting tube.

EFFECT: enhanced capacitor rating and reliability.

1 cl, 1 dwg

Description

The invention relates to electrical engineering and can be used to measure voltage using a capacitive voltage divider.

Currently known methods of creating capacitive dividers for measuring voltage using capacitive voltage transformers type NDE. As a high-voltage arm of the capacitive divider, series-connected coupling capacitors are used, which have a significant capacitance, which allows additional power to be taken from the capacitive divider. At the same time, coupling capacitors are oil-filled equipment, that is, they are fire and explosive, and when these capacitors are connected in series, there is a high probability of obtaining a high-voltage arm capacitance that differs significantly from the calculated one. [one].

The closest in technical essence and the achieved result is a capacitive voltage divider used in gas-insulated switchgears in which a cylindrical capacitor of a high-voltage arm is formed by a cylindrical current lead and a metal cylindrical lining isolated from the grounded case. The value of the capacitance of the high-voltage arm depends on the ratio of the diameters of the current lead and the lining, as well as on the length of the lining [2].

Such a design with a grounded enclosure can only be used in SF6 gas-insulated switchgears, and in the case of an outdoor substation, this design must use a high-voltage input for connecting the current lead to high voltage wires.

The objective of the invention is to provide a design for a high voltage arm of a capacitive divider, which can be installed in an open substation without the use of a high voltage input and without serial connection of oil capacitors.

This problem is solved in such a way that a cylindrical metal casing, which is one of the plates of a high-voltage capacitor, filled with an insulating medium, mounted on an insulating supporting cylindrical casing, also filled with an insulating medium, contains a second lining of the high-voltage capacitor in the form of a metal pipe located horizontally, and an additional lining electrically connected to a metal casing and located coaxially with a metal pipe, which is a second capacitor plate. The second lining in the form of a metal pipe is mounted on the upper end of the support pipe, in the cavity of which there is a tap from the second lining of the high-voltage capacitor. The support pipe may consist of pieces of metal pipes rigidly connected to each other by means of a pipe made of insulating material or made entirely of insulating material. In this case, the support pipe is located inside the insulating cylindrical column of high-strength material, which is fixed inside the insulating support cylindrical casing coaxially with the support pipe.

The drawing shows a high-voltage capacitor in section, made according to this invention.

The outdoor high-voltage capacitor contains a metal casing 1, which is a capacitor plate made in the form of a cylinder, in which a second capacitor plate 2 is placed, made in the form of a metal pipe located horizontally, and also contains an additional cylindrical plate 3 connected coaxially with the metal pipe 2, connected electrically with the housing 1. The housing 1 is mounted on a supporting insulating cylindrical casing 4, which is separated from the remaining volume of the cylindrical capacitor a column of high-strength material 5. The casing 4 and column 5 rest on the metal base of the capacitor 6. The second lining of the capacitor 2 in the form of a pipe is mounted on a support pipe consisting of pieces of metal pipes 7 and 8 and a pipe section 9 of insulation material rigidly connecting them. The tap from the second lining 2 is made by a conductor 10 laid in the cavity of the support pipe and brought out through the bushing 11 mounted on a metal base 6.

A piece of pipe 9 made of insulating material, installed between the pieces of metal pipes 7 and 8, allows you to break the electrical connection between the second plate 2 of the high voltage capacitor and the grounded metal base 6 and to remove the tap from the second plate of the high voltage capacitor for connection with the capacitor of the low voltage arm of the capacitive voltage divider.

The insulation between the metal housing 1 and the additional lining 3 connected to the housing 1 and the metal pipe 2, as well as between the vertical support pipe, consisting of parts 7, 8, 9, and the metal housing 1, is made of gas or purely oil and does not contain elements of solid insulation, which provides in areas of maximum electrostatic field strength obtaining high dielectric strength insulation.

The introduction of a high-strength insulating column 5, dividing the capacitor volume into two parts, eliminates the effect of high pressure of the insulating gas or high gas pressure generated in the case of oil decomposition in the event of an arc fault inside the high-voltage capacitor on the walls of the insulating support casing 4 made of insulating material with a low mechanical strength, such as porcelain.

Information sources

1. Transformers. Issue 27. Voltage Transformers. A.M. Dymkov, V.M. Kibel, Yu.V. Tishenin. M .: Energy. 1975, pp. 81-90.

2. Design and calculation of gas-insulated high-voltage apparatus. A.I. Poltev. L .: Energy. Leningrad branch. 1975, S. 214-216 and 231-232.

Claims (1)

A high-voltage capacitor of an outdoor installation, comprising a metal case filled with an insulating medium mounted on a support insulating cylindrical casing, which is the first capacitor lining, which houses the second capacitor lining, made in the form of a metal pipe located horizontally, and an additional lining electrically connected to the metal case and located coaxially with the metal pipe, which is the second lining, the second lining mounted on the upper the end of the support pipe, the lower end of which is fixed to the metal base of the capacitor perpendicular to the axis of the support pipe, characterized in that the additional lining is made in the form of a metal cylinder located inside the second lining, and the supporting pipe consists of pieces of metal pipes and a pipe section rigidly connecting them from insulation material, in the cavities of which there is a tap from the second lining, brought out through the bushing.