Electricity: measuring and testing – Electrostatic field
Reexamination Certificate
2000-07-19
2003-04-08
Sherry, Michael (Department: 2829)
Electricity: measuring and testing
Electrostatic field
C324S459000, C324S537000, C324S464000
Reexamination Certificate
active
06545480
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to testing techniques and is designed to be used, for example, in researching the dielectric strength of high-voltage equipment in an environment of gaseous insulation.
2. Description of the Prior Art
Any construction of this kind of testing equipment must consider the necessity of making a higher voltage power supply unit with considerably higher power. This causes some difficulties in manufacturing, and results in unsatisfactory weight and dimensions for such equipment.
In implementing various technical solutions to the problem herein, attempts have been made to perform the gaseous dielectric breakdown with a power supply unit of relatively low voltage. Among those methods that provide the abovementioned effect are found (1) a technical solution that provides for the injection of hot gases into a discharge gap (SU, 232358, H01 H, Nov. 12, 1968); (2) a technical solution that provides for the injection of gaseous bubbles of cavitation origin (SU, 1072166, H01 T 1/20, Feb. 7, 1984); and a technical solution that provides for covering one of the electrodes with an activating layer (DE, 3621254, H01 T 1/20, Jan. 7, 1988).
All the known methods, however, based as they are only on the redistribution of a space charge within a discharge gap, are ineffective and do not allow a considerable decrease of the power supply voltage.
The closest method to the one proposed in the subject invention is the method of performing the electrical breakdown of a gaseous dielectric in a highly non-uniform field. In accordance with this method the initial voltage, which provides a self-maintained discharge, is first supplied to the electrodes defining the discharge gap, and then a voltage pulse base is generated as additional electromotive force is induced in the leads. It finally results in the complete breakdown of the dielectric (SU, 913494, H01 T 3/00, Mar. 15, 1982).
One major shortcoming of the prior art, with its emphasis only on increasing the testing voltage with the help of a voltage pulse base, is its complete inability to cause any considerable decrease in the power supply unit output voltage.
SUMMARY OF THE INVENTION
One object of the present invention is to provide the ability to carry out the electrical breakdown of a gaseous dielectric using a power supply unit with a reduced voltage caused by the application of both methods discussed above, at the same time—using both the preliminary redistribution of a space charge and the further generation of a voltage pulse base in the supply circuit. This permits gaseous insulation and its diagnosis using a power supply unit with a relatively low output voltage.
In accordance with the subject method of the invention, the initial voltage, a voltage sufficient for producing a self-maintained discharge, is first supplied to electrodes that define the discharge gap. The voltage pulse base is then supplied to provide, together with the initial voltage, the complete breakdown of the dielectric. A corona discharge is generated by supplying the initial voltage to the electrodes defining the discharge gap so as to ensure a space charge at the corona-producing electrode. Before the voltage pulse base is generated, the space charge load is uniformly redistributed along the discharge gap by lowering the corona discharge current. Simultaneously, the decrease of the corona discharge current and the formation of the voltage pulse base occurs through the use of a dynamic discharge device, which is integrated to the supply circuit and has its electrodes switched from a closed state into an open one before being bridged by the electrical arc.
REFERENCES:
patent: 3639831 (1972-02-01), Cushman
patent: 3801899 (1974-04-01), Liao
patent: 4245187 (1981-01-01), Wagner
patent: 4742427 (1988-05-01), Richman
patent: 0 458 505 (1991-05-01), None
patent: 2109455 (1970-10-01), None
patent: 590588 (1976-10-01), None
patent: 913494 (1980-07-01), None
patent: 1665855 (1989-08-01), None
Lackenbach & Siegel LLP
Nguyen Trung
Sherry Michael
Valery Venginovich Starikov
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