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# IEEE Transactions on Dielectrics and Electrical Insulation

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Displaying Results 1 - 25 of 28
• ### Comments on "Dielectric breakdown characteristics of cryogenic nitrogen gas above liquid nitrogen surface" [with reply]

Publication Year: 1994
Cited by:  Papers (2)
| | PDF (86 KB)

For the original article see ibid., vol. 1, no. 3, p. 538-43 (1994). In the commenter's experience, a needle electrode in mist, just over the surface of the liquid, collects liquid droplets especially under voltage stress, which cause the test results to be very variable. This situation has been found not only with liquid nitrogen, liquid hydrogen and especially liquid helium, but also in air clos... View full abstract»

• ### Optical investigation of high-field conduction and prebreakdown in a dielectric liquid

Publication Year: 1994, Page(s):397 - 402
Cited by:  Papers (9)
| | PDF (420 KB)

Light emission studies of the high-field conduction and prebreakdown phenomena in a mixture of mono and dibenzyl-toluene (M/DBT), used as polypropylene impregnant in the all-film capacitor technology, have been undertaken to gain insight into the underlying physical mechanisms responsible for these processes. The absorption spectrum of this fluid, in the UV region, shows the appearance of structur... View full abstract»

• ### Pulse measurements using LED in dielectric liquids under impulse voltages

Publication Year: 1994, Page(s):391 - 396
Cited by:  Papers (14)
| | PDF (368 KB)

Current pulses, in the form of partial discharges, are known to be precursors of electrical breakdown in dielectric liquids. The precise measurement of these pulses is of great value for the understanding of the breakdown mechanism. The measurement of current pulses under impulse voltage is very difficult when using conventional electrical measurement systems. To overcome this difficulty, a novel ... View full abstract»

• ### Effects of additives on prebreakdown phenomena in n-hexane

Publication Year: 1994, Page(s):383 - 389
Cited by:  Papers (29)
| | PDF (468 KB)

Prebreakdown phenomena in n-hexane are observed in detail for positive and negative polarities by using simultaneously a high speed schlieren technique and an LED current measuring system, when an impulse voltage (1.1/225 μs) is applied to a point-to-plane electrode gap. Furthermore, the effects of several additives on the streamer propagation are investigated. Especially the effects of electro... View full abstract»

• ### Aging and related phenomena in modern electric power systems [comment and reply]

Publication Year: 1994, Page(s):548 - 549
Cited by:  Papers (5)
| | PDF (172 KB)

For original paper see ibid., vol. 28, no. 5, p. 826-844 (1993). Of all the highly interesting aspects of insulation aging which have been studied in this paper, we would like to comment on the detection of cavities in epoxy samples with the aid of the X-ray technique. The cavity irradiation must not be too weak since this may lead to intermittent partial discharges (PD). A too strong irradiation,... View full abstract»

• ### Breakdown and prebreakdown phenomena in liquids under positive impulse voltages

Publication Year: 1994, Page(s):377 - 382
Cited by:  Papers (12)
| | PDF (384 KB)

We examine the breakdown and prebreakdown behavior of two insulating liquids: benzyl-toluene and mineral oil in a nonuniform electric field at large distances (up to 20 cm) under a positive impulse voltage. We evaluate and compare the breakdown strengths of both liquids in these conditions as a function of interelectrode distance via Weibull type plots, a method commonly used when dealing with ins... View full abstract»

• ### Sparks in a small gap between HV spherical metal electrode and corona-charged organic film

Publication Year: 1994, Page(s):503 - 508
| | PDF (392 KB)

Sparks between a spherical metal electrode and corona-charged organic film were studied in air at room temperature. dc and impulse high voltages (HV) were applied to the spherical metal electrode, the polarity of which was opposite to that of the charge on the film. The maximum surface voltage of the corona-charged film was ±2 kV. The gap length was studied in the range 0.2 to 2.5 mm. Films... View full abstract»

• ### Thermally-stimulated current and dielectric loss measurement of polypropylene and Teflon-FEP films immersed in diarylethane

Publication Year: 1994, Page(s):487 - 495
Cited by:  Papers (5)
| | PDF (568 KB)

Some properties of oil/PP (biaxially stretched polypropylene) and oil/FEP (Teflon FEP) composite insulators have been investigated with TSC (thermally stimulated current) techniques. The oil/PP system showed three TSC peaks originating from carriers captured in the swollen surface region of the PP. The TSC spectra depended strongly on the polarity of the poling voltage and on the impregnating temp... View full abstract»

• ### Hot electron phenomena in liquid and gaseous Ar and N2 in divergent electric fields

Publication Year: 1994, Page(s):412 - 418
Cited by:  Papers (24)
| | PDF (476 KB)

A comparative study of electrical conduction and emitted light in an atomic (Ar) and a molecular liquid (N2) is presented as a function of various parameters. From the spectroscopic analysis of emitted light (in the range 200 to 850 nm), the energy of the hot electrons in these liquids may be measured. A simultaneous study was carried out on dense gases as a function of the applied pres... View full abstract»

• ### Simulation of corona discharge. Positive corona in SF6

Publication Year: 1994, Page(s):530 - 537
Cited by:  Papers (8)
| | PDF (384 KB)

Positive coronas in SF6 under three voltage levels, 3.0, 3.5 and 4.0 kV, are studied for a 0.5 cm gap between a hyperboloid needle and a plane electrode at a gas number density N=2.12×1018 cm3. The current in the form of a burst of pulses is found to increase with increasing voltage. The initiation and development of successive avalanches are traced as functi... View full abstract»

• ### Liquid helium breakdown as function of temperature and electrode roughness

Publication Year: 1994, Page(s):432 - 439
Cited by:  Papers (10)
| | PDF (432 KB)

The high dielectric dc strength of liquid helium can be explained by the effect of an energetic barrier against germinal vapor bubble elongation and runaway up to vapor discharge. The barrier normally rises in front of any cathode asperity where a germinal bubble may be produced from a collapsing vacuous cavity. After reaching a peak, the barrier changes into a decreasing tail, caused by significa... View full abstract»

• ### Generalization of the method of maximum likelihood [comment and reply]

Publication Year: 1994, Page(s):545 - 547
Cited by:  Papers (2)
| | PDF (184 KB)

For original paper see ibid., vol. 28, p. 65-72 (1993). The approximations connected with the ML in its classic' form (hrMLH) are very well pointed out, introducing the terms S1 and S2 which provide a generalized, unbiased form of the maximum likelihood method, called grMLH. The original author replies to the discussion View full abstract»

• ### Effect of frequency on heat transfer enhancement in temperature-induced electrohydrodynamic pumping

Publication Year: 1994, Page(s):468 - 473
Cited by:  Papers (3)
| | PDF (396 KB)

An induction electrohydrodynamic (EHD) pump in an axisymmetric configuration was designed and built to examine the heat transfer enhancement which accompanies fluid pumping under laminar flow conditions. The apparatus was operated at several tilt angles between 0 (horizontal) and 90° while the augmentation of heat transfer was measured and compared to typical forced pumping and natural circula... View full abstract»

• ### The dynamics of DC predisruption in liquid insulating media

Publication Year: 1994, Page(s):371 - 376
Cited by:  Papers (1)
| | PDF (440 KB)

Results of predisruptive current, light and electrical charge measurements are presented for the liquids tetraester, transformer oil and cyclohexane, under point-plane electrode arrangements with negative and positive high DC voltages. Observed current and light pulses existed both in the kHz and the MHz frequency ranges for both polarities of the point electrode. The electrical charge for the cur... View full abstract»

• ### Pulsed electrical breakdown in liquid helium in the μs range

Publication Year: 1994, Page(s):403 - 406
Cited by:  Papers (6)
| | PDF (216 KB)

Information about breakdown time-lags under pulsed voltage stress is prerequisite to the insulation design of superconducting devices. Experiments have been carried out using a pulse generator which provides a step voltage with 200 ns rise time and a long decay time constant of more than 1 ms. The present experiments may bridge the information gap between time lag measurements in the ns range usin... View full abstract»

• ### Corona characteristics for free conducting particles in various SF 6-gas mixtures

Publication Year: 1994, Page(s):509 - 519
Cited by:  Papers (6)
| | PDF (716 KB)

This paper reports on experimental investigations concerning the behavior of pulsative corona discharges from free conducting wire particles of different sizes in parallel plane and concave electrode systems, insulated with SF6 and its mixtures with nitrogen N 2, triethylamine (C2H5)3N and perfluorocarbon C8F16O gases. Co... View full abstract»

• ### Dynamics of prebreakdown phenomena in a uniform field in water

Publication Year: 1994, Page(s):496 - 502
Cited by:  Papers (23)
| | PDF (472 KB)

For a breakdown time lag of 10-7 to 10-3, both slow subsonic and thin supersonic streamers were found to emanate from a point electrode in deionized water (σ=5×10-5 S/m). The slow streamer-formed dendrite probably consists of gaseous microbubbles. Relaxation of the slow streamers was studied. The development of fast streamers resulted from kinetic phas... View full abstract»

• ### Initiation and formation of partial discharges in mineral-based insulating oil

Publication Year: 1994, Page(s):419 - 425
Cited by:  Papers (11)  |  Patents (1)
| | PDF (452 KB)

This paper reports the results of fundamental investigations concerning the behavior of partial discharges (PD) in mineral-based oil with the aim of characterizing the physical mechanisms that lead to the initiation and formation of PD pulses. First the influence of the parameters temperature, moisture, pressure and oil condition on the PD inception voltage, the apparent charge and the number of P... View full abstract»

• ### Dielectric breakdown characteristics of cryogenic nitrogen gas above liquid nitrogen

Publication Year: 1994, Page(s):538 - 543
Cited by:  Papers (16)
| | PDF (396 KB)

We measured the DC dielectric breakdown characteristics of cryogenic nitrogen gas above a liquid nitrogen surface for needle-to-plane and sphere-to-plane electrode configurations. Experimental results revealed that the DC breakdown voltage of cryogenic nitrogen gas increased, as the distance from the gap axis to the liquid nitrogen surface diminished, i.e. as the liquid nitrogen surface got closer... View full abstract»

• ### The effect of the electrode gap on breakdown in liquid dielectrics

Publication Year: 1994, Page(s):440 - 446
Cited by:  Papers (16)
| | PDF (440 KB)

It is a well known fact that the breakdown voltage of an insulating liquid increases nonlinearly with increasing electrode gap. Under nonuniform field dc conditions two breakdown voltages are determined depending on the electrode polarity. Using point-plane geometries, with gaps of 5 mm or larger, one finds that typical transformer oils have higher breakdown voltages when the point is negative tha... View full abstract»

• ### A discharge-avalanche theory for the propagation of electrical trees. A physical basis for their voltage dependence

Publication Year: 1994, Page(s):474 - 486
Cited by:  Papers (64)
| | PDF (868 KB)

The voltage dependence of electrical tree propagation from both recessed voids and embedded needle electrodes is described in terms of a quantitatively expressed physical model. Voltage dependent changes in the fractal dimension of the trees are used to explain the nonmonotonic behavior observed in the embedded needle geometry. The relationship of the model to inverse power law and Z' lifeline ch... View full abstract»

• ### Measurement of electron transport in liquid argon in crossed electric and magnetic fields

Publication Year: 1994, Page(s):407 - 411
Cited by:  Papers (2)
| | PDF (280 KB)

We report on a measurement of excess electron drift properties in liquid argon in the presence of crossed electric and magnetic fields. The electric field strength was varied between 6 and 110 V/cm. Using a superconducting solenoid magnetic field strengths up to 5 T were achieved. The magnetic field B&oarr; oriented perpendicular to the electric field E&oarr; and the components of the drift veloci... View full abstract»

• ### Simulation of corona discharge. Negative corona in SF6

Publication Year: 1994, Page(s):520 - 529
Cited by:  Papers (18)
| | PDF (528 KB)

Negative coronas in SF6 under three voltage levels are investigated by Monte Carlo simulation. For the purpose of simulation, the gap between a hyperboloidal needle and a plane is divided into two regions: region I where the electric field is very steep and most electrons and ions are accumulated, and region II the rest of the gap. In region I electron motion is simulated by dividing th... View full abstract»

• ### Pulsed corona for breaking up air bubbles in water

Publication Year: 1994, Page(s):426 - 431
Cited by:  Papers (5)  |  Patents (1)
| | PDF (312 KB)

The injection of gas into water, through a hollow needle, gives a stream of bubbles. These bubbles can be effectively broken up by application of HV pulses. Our experimental work shows that this mechanism works in demineralized water and even in conducting tap water if the pulses have a short rise time. Bubble diameters are as low as 50 μm. Our pulse source uses either a HV tetrode or a spark g... View full abstract»

• ### Streamer propagation under impulse voltage in long point-plane oil gaps

Publication Year: 1994, Page(s):447 - 458
Cited by:  Papers (50)  |  Patents (1)
| | PDF (824 KB)

A 67 mm point-plane gap immersed in transformer oil, at atmospheric pressure, stressed with a 1/180 μs impulse, has been studied by recording gap current and light emission. Time-resolved images were obtained by use of an image converter camera. Minimum breakdown voltages were twice as high for negative as for positive points. All streamers at these and higher voltages were supersonic, with neg... View full abstract»

## Aims & Scope

IEEE Transactions on Dielectrics and Electrical Insulation contains topics that are concerned with dielectric phenomena and measurements, with development and characterization of gaseous, vacuum, liquid and solid electrical insulating materials and systems; and with utilization of these materials in circuits and systems under condition of use.

Full Aims & Scope

Editor-in-Chief
Reuben Hackam