Showing papers on "Partial discharge published in 1974"
TL;DR: In this article, the breakdown characteristics of SF6 at pressures up to 15 kg/cm2 absolute at 20°C against power frequency, switching impulse and lightning impulse voltages in sphere and coaxial cylinder gaps.
Abstract: This paper describes the breakdown characteristics of SF6 at pressures up to 15 kg/cm2 absolute at 20°C against power frequency, switching impulse and lightning impulse voltages in sphere and coaxial cylinder gaps.
21 citations
01 Sep 1974
TL;DR: In this article, a real-time computational technique known as signal recovery has been used to detect the smallest discharge which may be detected during partial discharge tests on electrical equipment is usually determined by the levels of background interference.
Abstract: The smallest discharge which may be detected during partial discharge tests on electrical equipment is usually determined by the levels of background interference. To improve the signal/noise ratio the real-time computational technique known as signal recovery has been used. This has the additional advantage that the end result is a permanent record which will allow the user to reliably compare discharge characteristics throughout a component's life. While the approach is applicable to any component, the experimental evaluation programme was based on 11 kV polymer-insulated cable. This was tested in various situations, namely, as a short length in the laboratory, as drum lengths in several factories, and lengths (together with associated switchgear) installed in a number of power stations. In these conditions, discharges of 1 pC and less could be detected, even where the noise levels on conventional display-only equipment were tens of picocoulombs.
13 citations
Patent•
29 Mar 1974
TL;DR: In this article, a corona discharge device for charging the surface of a body, for example a photosensitive element utilized in the art of electrophotography, is described.
Abstract: In a corona discharge device for charging the surface of a body, for example a photosensitive element utilized in the art of electrophotography, the corona discharge current is controlled to vary at a predetermined rate at the commencement and termination of corona discharge so as to ensure uniform deposition of electric charge on the surface of the element.
10 citations
TL;DR: In this article, a test technique was developed for use in the field to detect internal partial discharges which may occur in high voltage potential transformers, which is done while the equipment is still energized by the system.
Abstract: This paper describes a test technique which has been developed for use in the field to detect internal partial discharges which may occur in high voltage potential transformers. The first stage consists of. detecting ultrasonic signals caused by the discharges. This is done while the equipment is still energized by the system. The second stage consists of removinj from service the transformers found to be producing high ultrasonic signal levels and then subjecting those transformers to tests to measure the partial discharge level.
8 citations
10 Jun 1974
TL;DR: In this article, a method for the design of a high-voltage solid insulation system used in airborne or satellite highvoltage components and systems is presented, and illustrated with a successful system now used in these applications.
Abstract: A method for the design of a high-voltage solid insulation system used in airborne or satellite high-voltage components and systems is presented, and illustrated with a successful system now used in these applications. The design is based on the elimination of corona in the solid, and principally involves making an insulation with a very high corona inception voltage and then controlling the electric field stress below that level. Examples of actual components and systems designed in this way are shown.
3 citations
01 Jan 1974
3 citations
TL;DR: In this paper, the strength of synthetic oil impregnated capacitor paper (Askarel) to dc and ac voltage 1.2/50-s voltage surges and switching surges of various wavefront duration are discussed.
Abstract: Based on measurements, the strength of synthetic oil impregnated capacitor paper (Askarel) to dc and ac voltage 1.2/50-?s voltage surges and switching surges of various wavefront duration are discussed. The results of measurements are compared with the performance figures of mineral oil impregnated capacitor paper. The diminishing effect of the number of lightning and switching surges and their amplitude upon electric strength and of initial voltage partial discharge is investigated.
3 citations
TL;DR: In this paper, the performance of laminated Kraft paper/oil dielectric (1.3 mm thick) was evaluated using a radio interference (RI) meter, which proved well suited for this purpose.
Abstract: Experiments have been carried out to determine the partial discharge performance of laminated Kraft paper/oil dielectric (1.3 mm thick). As with conventional corona pulse detection equipment, the pulses were measured on a radio interference (RI) meter which proved well suited for this purpose. The type of insulation investigated has high long-term electric strength if correctly assembled, even when small voids are present in the dielectric. If discharges do occur, a certain recovery interval is required to regain almost full electrical strength, because of the time needed to absorb gases formed by the discharge. The data obtained on the test specimens were confirmed by long-term tests carried out on oil-filled instrument transformers.
2 citations
2 citations
01 Oct 1974
TL;DR: The voltage endurance of liquid impregnated paper insulation is important in both test and service for high voltage equipment such as transformers, capacitors, and cable as mentioned in this paper, and it has been recognized for a long time that if electrical discharges occur, they may limit the life.
Abstract: The voltage endurance of liquid impregnated paper insulation is important in both test and service for high voltage equipment such as transformers, capacitors, and cable. It has been recognized for a long time that if electrical discharges occur, they may limit the life. Especially with cable, corona studies have been carried out for many years using both dielectric loss measurements (i. e., Schering Bridge) and several types of amplified band pass techniques for more direct measurement of corona pulses.
2 citations
TL;DR: In this paper, the site of a partial discharge within a dielectric can be determined by the use of localized fields using a new graphic corona display method, which can be used to detect partial discharge.
Abstract: The site of a partial discharge within a dielectric can be determined by the use of localized fields. An example is given of the technique using a new graphic corona display method.
TL;DR: In this paper, the effect of the reverse voltage on maximum power transfer to the discharge capacitor is discussed, and it is shown that the amplitude of this reverse voltage considerably reduces the power transferred to the capacitor per cycle.
Abstract: In the basic relaxation generator for electric discharge macchining, a reverse voltage usually appears across the discharge capacitor. The effect of this reverse voltage on maximum power transfer to the discharge capacitor is discussed. It is shown that the amplitude of the reverse voltage considerably reduces the power transferred to the capacitor per cycle Connecting a diode across the discharge capacitor results in better utilization of power. Resulting improvements in machining rate and tool wear are also explained.