Proceedings of the IEE - Part IIA: Insulating Materials

Issue 3 • March 1953

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Displaying Results 1 - 25 of 44
  • Proceedings at the Symposium of Papers on Insulating Materials

    Publication Year: 1953, Page(s):1 - 2
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  • Opening address

    Publication Year: 1953, Page(s):3 - 4
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  • A spectrometer for millimetre wavelengths

    Publication Year: 1953
    IEEE is not the copyright holder of this material | Click to expandAbstract | PDF file iconPDF (1422 KB)

    A free-space method for the measurement of permittivity at millimetre wavelengths is described. This method utilizes the microwave analogue of the optical spectrometer, electromagnetic horns with lenses taking the place of the collimator and telescope of the optical instrument. At these wavelengths aperture dimensions are necessarily comparable with the radiated wavelength, and diffraction effects... View full abstract»

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  • Dielectric behaviour of granular semi-conducting aggregates, with special reference to some magnesium ferrites

    Publication Year: 1953, Page(s):15 - 22
    IEEE is not the copyright holder of this material | Click to expandAbstract | PDF file iconPDF (951 KB)

    Aggregated granular semi-conductors can display high permittivities and dispersion effects which vary with temperature and voltage. This behaviour need not be characteristic of the granule material: can be a consequence of its conductivity and of a particular kind inhomogeneity of the aggregate arising from the contact structure the intergranular boundaries. The dielectric properties of certain si... View full abstract»

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  • The dielectric losses in some representative insulating materials

    Publication Year: 1953, Page(s):23 - 37
    IEEE is not the copyright holder of this material | Click to expandAbstract | PDF file iconPDF (1974 KB)

    A detailed study is made of the permittivity and power factor of a number of insulating materials over the whole range of conditions encountered in electrical practice, including frequencies from 10 c/s to 24 000 Mc/s and temperatures from -35° C to +240° C in appropriate cases. The materials fall into the following groups: (a) Silicones and other silicon-oxygen structures including mica and glass... View full abstract»

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  • Variation of capacitance with temperature in metallized-mica capacitors

    Publication Year: 1953, Page(s):38 - 40
    IEEE is not the copyright holder of this material | Click to expandAbstract | PDF file iconPDF (382 KB)

    The temperature coefficient of capacitance of a metallized-mica capacitor varies with frequency as a result of relaxation processes, and is therefore correlated with the power factor of the mica. The temperature coefficient of commercial capacitors ranges at least from -40 to +100 parts in a million per degree centigrade at 1 kc/s; it may be more negative, by about 40 parts in a million per degree... View full abstract»

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  • The dielectric properties of rubber

    Publication Year: 1953, Page(s):41 - 45
    IEEE is not the copyright holder of this material | Click to expandAbstract | PDF file iconPDF (592 KB)

    The paper describes the results of measurements of the power factor and relative permittivity of purified, uncompounded, natural rubber within the temperature range from -50 to +40° C and within the frequency range from 50c/s to 1 Mc/s. The effect of exposure to water vapour on the dielectric properties is contrasted with the effect of a similar exposure on the properties of crude rubber. The meth... View full abstract»

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  • The dielectric properties of certain benzene derivatives in the solid state

    Publication Year: 1953, Page(s):46 - 53
    IEEE is not the copyright holder of this material | Click to expandAbstract | PDF file iconPDF (869 KB)

    The paper gives the results of an investigation of the dielectric properties of two chlorine-methyl substituted benzenes, pentachlortoluene and 1,2,4-trimethyl 3,5,6-trichlorbenzene, and of pentaiodobenzene, over the frequency range 50-4.8×1010c/s, and discusses the observed behaviour in terms of modern dielectric theory. It was thought possible that these materials would exhibit resonance absorpt... View full abstract»

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  • Discussion on "Permittivity and dielectric losses in solids" before the Measurements Section, 16th March, 1953

    Publication Year: 1953, Page(s):54 - 59
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  • The authors' replies to the discussion on "Permittivity and dielectric losses in solids"

    Publication Year: 1953, Page(s):59 - 60
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  • Some aspects of the deterioration of insulating fluids

    Publication Year: 1953, Page(s):61 - 67
    Cited by:  Papers (2)
    IEEE is not the copyright holder of this material | Click to expandAbstract | PDF file iconPDF (888 KB)

    Acidity and resistivity measurements have been used to judge the condition of used oil and have revealed a few oils with conductivities which are abnormally high when compared with their low acidities. Examination of such oils by filtration, separation and chemical extraction, together with attempts to simulate the high conductivity by additions of pure substances to new oil, suggested that low re... View full abstract»

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  • The measurement of the power factors of insulating oils at 50 c/s

    Publication Year: 1953, Page(s):68 - 72
    Cited by:  Papers (2)
    IEEE is not the copyright holder of this material | Click to expandAbstract | PDF file iconPDF (770 KB)

    A modified Schering bridge which, whilst simple in operation, will measure the power factors of insulating oils with a high order of accuracy has been designed and constructed. The power factors of insulating oils are often very low, e.g. 0.00005 or less at room temperature, and considerable care must therefore be taken to avoid small errors which may arise from deficiencies in the electrical circ... View full abstract»

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  • Effect of humid air on power loss in pure and impure paraffin oil

    Publication Year: 1953, Page(s):73 - 80
    Cited by:  Papers (2)
    IEEE is not the copyright holder of this material | Click to expandAbstract | PDF file iconPDF (1040 KB)

    Measurements were made over the frequency range 50 c/s-30 Mc/s on a very pure paraffinic oil, and on the same oil containing a few parts per thousand of an ester of the type used in the plasticizer trade. Neither displayed a measurable power loss in the low-frequency region, the oil containing the ester showing the usual dipole loss in the megacycle region. Treatment with humid air had no effect o... View full abstract»

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  • Dielectric properties of oil-soaked pressboard as affected by water

    Publication Year: 1953, Page(s):81 - 88
    Cited by:  Papers (2)
    IEEE is not the copyright holder of this material | Click to expandAbstract | PDF file iconPDF (995 KB)

    The effect of water, in amounts capable of being absorbed from a normal atmosphere, upon the dielectric properties of oil-soaked pressboard has been investigated over the temperature range from 20° to 90° C. Curves relating loss tangent, permittivity and electric breakdown strength of 0.2-in thick material with absorbed moisture and temperature have been plotted, and from these a final relationshi... View full abstract»

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  • Dielectric loss of insulating oil

    Publication Year: 1953, Page(s):89 - 93
    Cited by:  Papers (3)
    IEEE is not the copyright holder of this material | Click to expandAbstract | PDF file iconPDF (606 KB)

    Considerable discrepancies between the results of different laboratories when measuring the dielectric loss of the same insulating oils has been reported in co-operative tests for C.I.G.R.É., Second Series, 1949-50. These can arise either from contamination of the oil sample with impurities or from the instability of the oil. Errors due to the first cause have been rendered negligible by evolving ... View full abstract»

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  • Symposium of papers on insulating materials session 2: permittivity and dielectric losses in liquids discussion before the measurements section, 17th march, 1953

    Publication Year: 1953
    IEEE is not the copyright holder of this material | PDF file iconPDF (1675 KB)
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  • The authors' replies to the discussion on "Permittivity and dielectric losses in liquids"

    Publication Year: 1953, Page(s):103 - 104
    IEEE is not the copyright holder of this material | PDF file iconPDF (390 KB)
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  • An experimental investigation of factors influencing the electric strength of potassium chloride crystals

    Publication Year: 1953, Page(s):105 - 110
    Cited by:  Papers (2)
    IEEE is not the copyright holder of this material | Click to expandAbstract | PDF file iconPDF (925 KB)

    Experiments with single crystals are described, showing that the electric strength of potassium chloride is not significantly affected by the choice of electrode material. It is, however, considerably increased by treatments that introduce the structural defects, associated with residual strains, caused by plastic deformation. This does not seem to have been appreciated in the past. Structural def... View full abstract»

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  • Some mechanisms of insulation failure

    Publication Year: 1953, Page(s):111 - 120
    Cited by:  Papers (4)
    IEEE is not the copyright holder of this material | Click to expandAbstract | PDF file iconPDF (1445 KB)

    The paper reports recent investigations into mechanisms of insulation failure. After a review of recent progress emphasizing that failure depends on a number of distinct factors which can be separated by suitable techniques, experimental results are given covering some theories recently established. These include: (a) Electrochemical attack on capacitor dielectrics, with results of life tests on c... View full abstract»

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  • Electric discharges in air-gaps facing solid insulation in high-voltage equipment

    Publication Year: 1953, Page(s):121 - 131
    IEEE is not the copyright holder of this material | Click to expandAbstract | PDF file iconPDF (1632 KB)

    The performance of high-voltage alternators under conditions of over-voltage is materially improved by the application of an insulating sheathing to exposed parts of the bare earthed metal. The authors first derive the physical explanation for this observation from experiments using auto-photographic recording methods. These experiments are then expanded to cover other phenomena observed with disc... View full abstract»

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  • The electrical breakdown of air between insulators

    Publication Year: 1953, Page(s):132 - 137
    Cited by:  Papers (4)
    IEEE is not the copyright holder of this material | Click to expandAbstract | PDF file iconPDF (646 KB)

    By the use of a cathode-ray tube it is shown that the a.c. breakdown current in a glass vessel with external electrodes, containing air at reduced pressures, consists of a number of separate pulses, the number in a half-cycle increasing with the excess voltage. The current flows in pulses because once a breakdown occurs in the gas, charges collect on the glass walls and produce reverse fields whic... View full abstract»

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  • Electrical breakdown in vacuum

    Publication Year: 1953, Page(s):138 - 140
    Cited by:  Papers (1)
    IEEE is not the copyright holder of this material | Click to expandAbstract | PDF file iconPDF (360 KB)

    Direct and impulse voltages were applied to an electrode system in a vacuum of the order of 10<sup>-5</sup> mm Hg. Of particular interest were the results obtained with a needle-and-sphere system, the breakdown voltage of which was considerably higher than that of a normal sphere-gap with the same electrode spacing, especially when a very fine needle was used. Oscillograms were taken o... View full abstract»

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  • Electrical breakdown in organic liquids

    Publication Year: 1953, Page(s):141 - 148
    Cited by:  Papers (1)
    IEEE is not the copyright holder of this material | Click to expandAbstract | PDF file iconPDF (1264 KB)

    The dispersion in the measurements of the electric strength of pure hydrocarbon liquids using direct voltage is significantly reduced using a hydrogen thyratron by-passing circuit. The damage due to discharge, mainly produced on the anode, is much less, and many more measurements on a particular sample are possible. Experiments with n-hexane show that the breakdown is practically independent of bo... View full abstract»

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  • Breakdown of insulation by discharges

    Publication Year: 1953, Page(s):149 - 158
    Cited by:  Papers (2)
    IEEE is not the copyright holder of this material | Click to expandAbstract | PDF file iconPDF (1548 KB)

    The principal factors limiting the safe working electric strength of modern low-loss insulation are electrochemical deterioration and breakdown caused by internal or surface discharges. In the paper the mechanisms of deterioration and breakdown by discharges are discussed in detail. Special consideration is given to the effects of the amplitude, frequency and waveform of the applied voltage on the... View full abstract»

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  • The a.c. breakdown of polythene and polystyrene

    Publication Year: 1953, Page(s):159 - 162
    IEEE is not the copyright holder of this material | Click to expandAbstract | PDF file iconPDF (490 KB)

    The electric strength of polythene when subjected to 50-c/s alternating electric stress has been measured for a range of ambient temperatures from -196° C to 17° C, and that of polystyrene for temperatures between -196° C and 70° C. The a.c. breakdown strengths are found to be lower than the corresponding intrinsic electric strengths at room temperature and above, particularly with polythene, but ... View full abstract»

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Aims & Scope

Published in 1953, the Proceedings of the IEE - Part IIA: Insulating Materials was a special volume of the Proceedings of the IEE - Part II: Power Engineering, covering the Symposium of Papers on Insulating Materials, which was held from 16th-18th March 1953.

Full Aims & Scope