• Progress in Superconductivity and Cryogenics
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• v.4 no.1
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• pp.105-109
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• 2002

The short-term AC breakdown strength of laminated polypropylene insulating Paper (PPLP) has been studied for cold dielectric of high temperature superconductivity power cables. The design and operating conditions of the electrode system for studying of short-term breakdown strength of one-layer and multi-layer PPLP samples are discussed in liquid nitrogen(LN2) state. The influence of various operating factors (geometry and dimension of electrodes, speed of tested voltage, thickness of test sample) on the value of short-term AC breakdown strength at cryogenic temperature has been established.

• Transactions on Electrical and Electronic Materials
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• v.13 no.5
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• pp.252-255
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• 2012

In order to characterize insulation properties of epoxy/micro-silica/nano-silicate composite (EMNC), long-term and short-term AC treeing tests were carried out undr non-uniform electric field generated between needle-plate electrodes. In a long-term test, a 10 kV (60 Hz) electrical field was applied to the specimen positioned between the electrodes with a distance of 2.7 mm in an insulating oil bath at $30^{\circ}C$, and a typical branch type electrical tree was observed in the neat epoxy resin and breakdown took place at 1,042 min after applying the 10 kVelectrical field. Meanwhile, the spherical tree with the tree length of $237{\mu}m$ was seen in EMNC-65-0.3 at 52,380 min (36.4 day) and then the test was stopped because the tree propagation rate was too low. In the short-term test, an electrial field was applied to a 3.5 mm-thick specimen at an increasing voltage rate of 0.5 kV/s until breakdown in insulating oil bath at $30^{\circ}C$ and $130^{\circ}C$, and the data was estimated by Weibull statistical analysis. The electrical insulation breakdown strength for neat epoxy resin was 1,763 kV/mm at $30^{\circ}C$, while that for EMNC-65-0.3 was 2,604 kV/mm, which was a modified value of 47%. As was expected, the breakdown strength decreased at higher test temperatures.

• Progress in Superconductivity and Cryogenics
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• v.5 no.1
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• pp.128-132
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• 2003

This paper discusses several electrical properties of tape-type insulation impregnated with liquid nitrogen ($LN_2$) in superconducting cable. Synthetic polypropylene laminated paper has been tested for its short-term breakdown strength and partial discharge(PD) characteristics under AC voltage. furthermore, the effect of winding parameter on breakdown strength, PD incepti on and extinction electrical stress with different test samples are discussed.

• The Proceedings of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.5 no.2
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• pp.77-83
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• 1991

In this study the investigation were carried out on short-term breakdown characteristics of the compound material dependent on change of filler quantity, ambient temperature(room temperature~[$190[^{\circ}C$]) and kinds of voltage sources for the compound materials of Bisphenol- A epoxy resins filled with $SiO_2$ particles. As the results, obtained the dielectric breakdown strength generally decrease as increasing the quantity of filler and the distance, spacing of each's particles, decrease as increasing the quantity of filler, when the distance is less than [$7.5\mu\textrm{m}$], dielectric breakdown strength is nearly constant. In the case on AC voltage dielectric strength of filled epoxy resins is stronger than nonfilled epoxy resins on temperature region more than $130[^{\circ}C$].