By Topic

Electrical Insulation, IEEE Transactions on

Issue 2 • Date April 1981

Filter Results

Displaying Results 1 - 16 of 16
  • Table of contents

    Page(s): c1
    Save to Project icon | Request Permissions | PDF file iconPDF (834 KB)  
    Freely Available from IEEE
  • IEEE Electrical Insulation Society

    Page(s): c2
    Save to Project icon | Request Permissions | PDF file iconPDF (214 KB)  
    Freely Available from IEEE
  • Full text access may be available. Click article title to sign in or learn about subscription options.
  • The Ageing of Electrical Insulation at Cryogenic Temperatures

    Page(s): 83 - 88
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (739 KB)  

    This paper presents some theoretical and experimental evidence that, under certain conditions, the transient voltage characteristics of electrical insulation impregnated with liquid nitrogen become the limiting factor in determining the normal operating stress. The life of the insulation is assumed to obey the well known life equation: (stress)n x time = conatant. It will be shown that the operating stress will depend upon the switching and lightning impulse strengths of the insulation, if the exponent n is above a critical value. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • The Impulse Characteristics of Electrical Insulation Operating at Cryogenic Temperatures

    Page(s): 89 - 96
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (906 KB)  

    This paper reports the transient voltage breakdown characteristics of electrical insulation operating at cryogenic temperatures. Nomex®e, Tyvek® and polypropylene film/cellulose paper laminate (PPLP) specimens impregnated with liquid nitrogen (LN2) and containing cavities of known dimensions were subjected to either 1.2/50 or 250/2500 ps impulses of increasing amplitude until breakdown. The effect of repeated impulses of constant amplitude, hydrostatic pressure, cavity location, and polarity reversal were also investigated. Of the three materials examined, PPLP exhibited the highest impulse strength, but also showed deterioration with repeated impulses above 150 kV/mm. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Power Frequency and Impulse Voltage Breakdown along Silicone Oil/Xlpe Interface

    Page(s): 97 - 104
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1303 KB)  

    Power frequency (60 Hz) and Impulse Voltage breakdown characteristics of Silicone Oil (PDMS) with and without cross-linked polyethylene (XLPE) spacers have been studied. The electrode geometries were designed to simulate a high voltage cable termination. In the presence of a spacer, the breakdown stress under 60. Hz voltage remained nearly independent of gap length over the range of gaps studied. The results showed that the risk of discharge inception is low if the tangential stress, along the PDMS/ XLPE interface of a cable termination, does not exceed 1 kV/mm. Under impulse voltage the breakdown values for the liquid gaps with and without the spacers were approximately equal. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Photo-Inspection between Cross-Linked Polyethylene and a Semiconducting Layer

    Page(s): 105 - 110
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1669 KB)  

    Compatibility between a cross-linked polyethylene layer and a semiconducting polyethylene layer in a block sample, simulating a solid dielectric cable, is investigated by use of a photo-multiplier to detect light emission at the interface. The application of a photo-multiplier to detect the quality of contact at the interface provides superior sensitivity to the conventional discharge detection method which, itself, is sensitive only to actual treeing discharges and consequently is valid as a detector only after the start of electrical treeing. The semiconducting polyethylene layer used as an electrode in the experiments is sandwiched between sheets of low-density polyethylene (M. I. = 1.0) and heated with dicumyl peroxide to achieve chemical cross-linking. As determined from the output of the photo-multiplier, the treeing inception voltage increases with the quality of the contact. A temperature dependency of the contact is also detected by the photo-multiplier in the range above room temperature where light emission shows a maximum at about 60°C, suggesting that contact becomes poorest at about that temperature. The effect that mechanical drawing of the test samples has on light emission at the interface is also investigated at various temperatures by means of the photo-multiplier. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Experimental Study of the Breakdown Characteristics of a Gas-Insulated Bus

    Page(s): 111 - 117
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1680 KB)  

    The area effect in gas-insulated systems on the breakdown voltages and V-t characteristics is studied, using a model bus section of 84 kV single-phase SF6 gas-insulated substation. The model bus, stretched along a straight line, has a number of conical spacers. The breakdowns occur at the shielding electrodes arranged near the spacers. Increasing the number of spacers means an increased chance of breakdown at these shielding electrodes. When switching impulse and ac voltage are applied to the above system including many spacers, the breakdown voltage distribution has a range somewhat lower than that of one spacer. This phenomenon is caused by the increase of weak points on the electrodes. When steep front impulse voltages are applied, the breakdown distribution of many spacers is very similar to that of one spacer, in contrast to the cases of switching impulse and ac voltage. This relative insensitivity of breakdown voltage to the system scale suggests a mechanism other than the statistics of weak points. The experimentally obtained overall V-t characteristic of this system is found to conform to the empirical formula proposed from small scale experiments. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Correlations between Nondestructive and Destructive Tests on High-Voltage Coil Insulations for Rotating Miachines

    Page(s): 118 - 127
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1226 KB)  

    The correlations between results of nondestructive and destructive tests on high-voltage coil insulations for rotating machines were investigated and the following findings were obtained. Breakdown voltage on application of a commercial line voltage (50 Hz) is correlated to the voltage at which a partial discharge bridges the insulation layer. Breakdown voltage on application of a direct voltage is correlated with the discharge magnitude, dielectric constant and dielectric loss tangent corresponding to void discharge in the insulation layer. Breakdown under an impulse waveform voltage is in some respects similar to that under commercial frequency but, because of the short duration of voltage application, it is correlated with the magnitude of electrical resistance, and this correlation is related to the ease with which the bridge phenomenon of discharge in the insulation layer propagates. Thus, the correlation between breakdown voltage and electrical characteristics in nondestructive tests varies with the voltage waveform involved. In tapewound laminated structures, as in micaceous insulatopms, breakdown occurs along the lap of tape, so that characteristic phenomena of the breakdown process for various voltage waveforms combining mutually correlated characteristics, are observed. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Surface Discharge Studies with Uniform Field Electrodes at Low Pressures

    Page(s): 128 - 133
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (866 KB)  

    An investigation of power frequency (50 Hz) surface partial discharges in dry air, using 21r/3 Rogowski profile electrodes in the low pressure range of 0.067 to 91.333 kPa, shows that for the discharges occurring symmetrically around the electrodes and just outside the uniform field region, the breakdown voltages are 20 to 30% lower than those accounted for by the usual Paschen values. Emphasis, therefore, has been given to modified values of breakdown voltages for any useful calculations. The effect of reduced pressure on inception voltage has been discussed and an attempt has been made to explain the difference between the observed and calculated values on the basis of a pressure-dependent secondary ionization coefficient. It is shown that increasing the insulation thickness in a critical pressure range (0.067 to 0.400 kPa) does not allow any significant increase in the discharge free working stress of the insulation system. At higher pressures (>0.400 kPa) the increase in inception voltage with thickness and pressure follows an equation which is expected to hold for other insulating materials as well. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Impulse Breakdown of Polymer Dielectrics in the NS Range in Divergent Fields

    Page(s): 134 - 139
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (736 KB)  

    The short time impulse breakdown of polymer dielectrics, polyethylene (PE), polyethylene terephthalate (PET), polycarbonate (PC), polystyrene (PS), and polymethyl methacrylate (PMMA) in a pointplane electrode system has been studied using a ns rise time pulser. A polarity effect was found in all polymers: a highet voltage is required to induce breakdown for a negative point than for a positive point. This effect usually increases with increasing gap distance except for PMMA, in which the ratio of the negative to the positive breakdown voltage is small even for longer gap distances. There is much difference in the results of the 50% breakdown voltage Vb for pulses of 100 ns duration for each polymer. Vb for PS is the very highest among polymers tested in both negative and positve points. Vb for PET and Vb for PMMA are the lowest in the positive point and in the negative point, respectively, in the thicker gap region. The formative time lag is, in most cases, less than about 10 ns. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Evaluation of a New Material for Semiconducting Layer in XLPE Power Cables

    Page(s): 140 - 143
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (977 KB)  

    A new material for the semiconducting layer on crosslinked polyethylene (XLPE) power cable was evaluated through water treeing tests. Since the new material contains only fifteen percent carbon black by weight, it can be cleaned by screening. Thus the material has less contaminants at the semiconducting-insulating layer interface. Water treeing tests showed that the number of water trees grown in the new material was one hundredth of those in the conventional material. Addition of a curing agent to the new material decreased the water tree number another one tenth. The new material with curing agent should prevent water tree growth in XLPE power cables. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Laboratory Testing of a Sensor for Hydrogen Dissolved in Transformer Oil

    Page(s): 144 - 148
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (617 KB)  

    A new device based on the electrochemical oxidation of hydrogen diffusing through a Teflon(R) membrane has been tested over a range of conditions in the laboratory. The device is aimed at measuring the hydrogen content of transformer oil in situ and on a continuous basis. The sensor consists of a metallic body screwed directly on the transformer in an appropriate opening and a second removable metallic casing that includes the electrochemical cell. This device was temperature cycled from -30 to 70°C. The diffusion of hydrogen from the bulk of the oil to the membrane is the slowest step and determines the resulting signal. Agitation of the oil is an important factor in the operation of the sensor; thermally induced convection as present in operating equipment is sufficient to improve the behavior of the sensor. A temperature compensating circuit was devised to eliminate the thermal factor from the observed signal; the results with this compensating circuit are presented. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • The Interpretation of Current Transients in Dielectrics

    Page(s): 149 - 152
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (499 KB)  

    It is shown that a peak in a transient current following a step voltage application generally does not represent the carrier transit time in some dielectrics. Different mechanisms leading to almost similar transient currents are discussed. It is shown that current transient peaks can have different significance depending on the mechanisms of charge generation, transport and recombination. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • IEEE Electrical Insulation Society

    Page(s): 152-a
    Save to Project icon | Request Permissions | PDF file iconPDF (208 KB)  
    Freely Available from IEEE
  • Information for authors

    Page(s): 152b
    Save to Project icon | Request Permissions | PDF file iconPDF (944 KB)  
    Freely Available from IEEE

Aims & Scope

This Transactions ceased production in 1993. The current retitled publication is  IEEE Transactions on Dielectrics and Electrical Insulation.

Full Aims & Scope