Liquid dielectric

About: Liquid dielectric is a research topic. Over the lifetime, 3702 publications have been published within this topic receiving 45150 citations.

Process for producing a ferrofluid

Abstract: A ferrofluid comprised of composite particles comprised of polymer-enmeshed magnetic metallic particles in indefinite suspension in a carrier fluid is produced by providing a pair of electrodes formed of a composition which will produce the desired magnetic metallic particles, immersing the electrodes in an organic dielectric liquid, applying a pulsed electric potential between the electrodes, adjusting the gap therebetween until there is an electric discharge eroding an electrode producing magnetic metallic particles enmeshed in polymer, recovering the magnetic material from the dielectric liquid and dispersing the magnetic material in a carrier fluid producing ferrofluid.

A New method of aging assessment for XLPE cable insulation based on dielectric response

Abstract: In order to solve the problem of permanent damage caused by the traditional tensile strength test in insulation ageing assessment of XLPE (extrude low-density polyethylene) cables, this paper presents a new method of aging assessment for XLPE cables insulation based on ultra-low-frequency dielectric response measurements. On the basis of equivalent circuit, the measurement algorithm of dielectric response is analyzed, whereafter, the calculating formulas of dielectric parameters are obtained. In addition, XLPE cables samples were carried on accelerated thermal ageing under laboratory conditions. It is shown from the results that dielectric dissipation factor increases obviously at lower frequency range with the increasing aging time. The total FDS (frequency domain spectroscopy) curves shift towards the high frequency regions with the increase of test temperature. The minimum value of dielectric dissipation factor for XLPE cable samples is almost the same at different test temperatures and certain ageing time. Therefore, the minimum value of dielectric dissipation factor in frequency domain can be used as the reference criterion of insulation ageing status. The new dielectric response assessment method presented in this paper could be used as non-destructive ageing evaluation criterion of XLPE cables.

Discharge characteristics and mechanism of conductive metal particles in function of the oil flow under AC voltages

Abstract: To obtain the characteristics and mechanism of partial discharge caused by metal particles in function of the oil flow under AC voltages, the author established a mechanical model of metal particles motion in dielectric liquid. The motion trajectory and distribution regularities of metal particles in flowing transformer oil were simulated and calculated. The discharge phenomenon caused by metal particles was explained based on 4 discharge types and discharge mechanism was investigated. Additionally, Experiments were carried out to research the variation of Partial discharge inception voltage (PDIV) with velocity and temperature caused by metal particles. It was observed that discharge amplitude increased within a little scale and discharge number decreased significantly with the increase of velocity. Rise time increased with the increase of velocity while duration time decreased. It was proved that insulating property of transformer oil which was contaminated with metal particles could be improved by increasing the velocity of transformer oil.

Electric device and dielectric material therefor

Abstract: The present invention comprises a liquid dielectric and electrically insulating material. In my prior Patent 1,931,455, patented October 17, 1933, I have described various non-inflammable dielectric and insulating compositions which consist of one or more aromatic hydrocarbons containing combined...