Development of the DC superimposition bridge method for the measurement of high insulation resistance of medium voltage XLPE cables in operations

1996 ◽  
Vol 116 (5) ◽  
pp. 75-84 ◽  
Author(s):  
Takashi Shinmoto ◽  
Chiaki Kimura ◽  
Ken Yamamoto ◽  
Susumu Umeda
Keyword(s):  
Insulation Resistance ◽  
Medium Voltage ◽  
Bridge Method ◽  
High Insulation

The Microbiological Deterioration of Rubber Insulation

1953 ◽  
Vol 26 (4) ◽  
pp. 869-883
Author(s):  
John T. Blake ◽  
Donald W. Kitchin ◽  
Orison S. Pratt
Keyword(s):  
Dielectric Strength ◽  
Insulation Resistance ◽  
Great Care ◽  
Moist Air ◽  
Humid Atmosphere ◽  
Buried Cables ◽  
High Insulation ◽  
Pass Through ◽  
In Transit ◽  
Voltage Breakdown

Abstract Experiments on natural rubber and GR-S insulation in various forms have shown them to be inherently vulnerable to fungus attack unless made sufficiently fungitoxic. Stable fungitoxic GR-S compounds have been developed in this work which have invariably maintained normal high insulation resistance during four years in active soil. Thin Neoprene jackets may be permeable to fungi so that underlying insulation should be fungitoxic or inherently stable. A humid atmosphere as in a wet duct may be a dangerous environment. It has been shown that inoculated wire can fail in moist air due to fungus penetration. Parallel electrical tests on wire and culture tests on agar-filled tubes demonstrated that the electrical failures in soil were caused by fungus penetration. It was possible to detect and identify fungus in transit in thick walls of GR-S insulation. Three types of fungi which can pass through rubber insulation and thin Neoprene jackets have been identified, at least by genus. The most prevalent has been Spicaria violacea Abbott. The presence of fungus in insulation lowers the dielectric strength before the filaments have passed completely through the wall. Impending failure can be detected by voltage breakdown tests. Rubber insulation in buried cables must be sufficiently fungitoxic. Great care is required in formulating stable compounds to insure that other required properties are not harmed.

The Electrical Characteristics of Medium Voltage Insulators Against Contaminants at Coastal Area

2021 ◽  
Vol 13 (6) ◽  
Author(s):  
I Made Yulistya Negara ◽  
◽  
Dimas Anton Asfani ◽  
Daniar Fahmi ◽  
◽  
...  
Keyword(s):  
Leakage Current ◽  
Rural Areas ◽  
Coastal Area ◽  
Industrial Area ◽  
Mechanical Support ◽  
Insulation Resistance ◽  
Electrical Characteristics ◽  
Medium Voltage ◽  
Distribution Line ◽  
Current Value

Insulators have an important role in an electrical distribution line. They has a role as a mechanical support and on electrical insulation that isolate the live line and dead part of the electrical poles. Environmental factors will affect the performance of the insulator. Every area where the isolator was installed has a unique characteristics, therefore the electrical characteristics of each insulator will be differ from an area to others area. This study investigated the electrical characteristics of the 20 kV insulator for some feeder that representing all regions in coastal area. Coastal area has four types of areas, namely industrial, household, city, and rural areas. The leakage current of sample of these four area were measured and the Non-Soluble Deposite Density (NSDD) of each sample were also measured. The results show that the industrial area had the highest leakage current value of 1.22 mA while the lowest leakage current was observed in the household area of 0.44 mA. These were also confirmed that the industrial area had the highest NSDD value of 0.2412 mg/cm2 and the lowest NSDD in household areas of 0.0228 mg/cm2 were observed. Moreover, It was also observed that the highest flashover voltages and insulation resistance were in rural areas of about 53.4 kV and 261.33 GΩ, respectively and the lowest flashovers were in household areas of about 39.34 kV and 118.83 GΩ, respectively.

Prospects for convergent beam electron diffraction with a 200kV cold field-emission transmission electron microscope

1991 ◽  
Vol 49 ◽  
pp. 466-467
Author(s):  
J W Steeds ◽  
R Vincent
Keyword(s):  
Field Emission ◽  
High Performance ◽  
Small Diameter ◽  
Convergent Beam Electron Diffraction ◽  
Zone Axis ◽  
Medium Voltage ◽  
Transmission Electron ◽  
Good Crystallinity ◽  
Special Modification ◽  
Convergent Beam

We review the analytical powers which will become more widely available as medium voltage (200-300kV) TEMs with facilities for CBED on a nanometre scale come onto the market. Of course, high performance cold field emission STEMs have now been in operation for about twenty years, but it is only in relatively few laboratories that special modification has permitted the performance of CBED experiments. Most notable amongst these pioneering projects is the work in Arizona by Cowley and Spence and, more recently, that in Cambridge by Rodenburg and McMullan.There are a large number of potential advantages of a high intensity, small diameter, focussed probe. We discuss first the advantages for probes larger than the projected unit cell of the crystal under investigation. In this situation we are able to perform CBED on local regions of good crystallinity. Zone axis patterns often contain information which is very sensitive to thickness changes as small as 5nm. In conventional CBED, with a lOnm source, it is very likely that the information will be degraded by thickness averaging within the illuminated area.

Atomic structure imaging of the Si/SiO2 interface with high-resolution electron microscopy

1986 ◽  
Vol 44 ◽  
pp. 390-391
Author(s):  
J.L. Batstone ◽  
J.M. Gibson ◽  
Alice.E. White ◽  
K.T. Short
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
Atomic Structure ◽  
High Resolution Electron Microscopy ◽  
Medium Voltage ◽  
Voltage Electron ◽  
Resolution Electron ◽  
Structural Image ◽  
Electron Microscopes ◽  
Point To Point

High resolution electron microscopy (HREM) is a powerful tool for the determination of interface atomic structure. With the previous generation of HREM's of point-to-point resolution (rpp) >2.5Å, imaging of semiconductors in only <110> directions was possible. Useful imaging of other important zone axes became available with the advent of high voltage, high resolution microscopes with rpp <1.8Å, leading to a study of the NiSi2 interface. More recently, it was shown that images in <100>, <111> and <112> directions are easily obtainable from Si in the new medium voltage electron microscopes. We report here the examination of the important Si/Si02 interface with the use of a JEOL 4000EX HREM with rpp <1.8Å, in a <100> orientation. This represents a true structural image of this interface.

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