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Subject: search.filters.subject.Dissipation factor

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    An experimental study on dielectric response of the crosslinked polyolefin (XLPO) insulation of the unshielded cable under electric field and heat flux
    (2021-05-19)
    Singhasivanon, Jakawan
    ;
    Jirasuwankul, Nirudh
    Nowadays, crosslinked polyolefin cables (XLPO cables) are more popular and more famous for electrical insulation. In order to study and analyze the characteristics of insulation. The polarization and depolarization of current measurements (PDC measurement) is one of the advance methods that can compute and provide dielectric reaction parameters. In this paper, aim to study dielectric response of the XLPO insulation of unshielded cables under electric fields and heat fluctuations by measuring permittivity (ϵ′, r), conductivity (σ) and dissipation factors (Tan δ). The experimental results indicate permittivity is rather constant at different field strengths and temperatures and are similarly to XLPE insulation. It is also found that the activation energy of XLPO insulation is 0.77 eV. Future more, action energy in this research can excite electrons or ions in valent band within insulations to change the state from non-conductivity to conductivity.
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    The effects of solvents on the properties of ultra-thin poly (methyl methacrylate) films prepared by spin coating
    (2013-11-01)
    Tippo, T.
    ;
    Thanachayanont, C.
    ;
    Muthitamongkol, P.
    ;
    Junin, C.
    ;
    Hietschold, M.
    Poly (methyl methacrylate) (PMMA) is extensively used as an insulating layer in organic electronic devices. In this study, spin coating method was used to cast thin layers of PMMA for dielectric application from solutions in three different solvents, namely dimethylformamide (DMF), n-butyl acetate and toluene. The solvent's vapor pressure causes the solvent to vaporize at different rates leading to layer's distortion and different surface roughnesses. Preparation of suitable surface morphologies, for example, pinhole-free and crack-freewas studied. A step profilometer was used to measure the film thicknesses. Alternatively an equation correlating final film thickness to spin speed and solution concentration was proposed. A metal/insulator/metal parallel plate capacitor structurewas fabricated and the current density dependence on the applied electric fieldwas measured. The resulting low surface roughness, low leakage currents, high breakdown voltage, and high dielectric constant were obtained for the 100 nm-thick PMMA film prepared with DMF. © 2013 Elsevier B.V.
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    Equivalent circuit approximation of transformer insulation by using PDC measurement
    (2008-10-06)
    Roongroj, Ch
    ;
    Pattanadech, N.
    ;
    Praisuwanna, P.
    ;
    Yutthagowith, P.
    ;
    Thongkaemkaew, K.
    This paper represents the insulation model of 3φ, 50 MVA, 132.8/13.8 kV power transformer. This model is developed from the polarization and depolarization current measurement (PDC). The insulation modeling consists of a parallel circuit among C<inf>50</inf> <inf>Hz</inf>, R<inf>0</inf>, R <inf>1</inf> and C<inf>1</inf> in series, R<inf>2</inf> and C<inf>2</inf> in series, R<inf>3</inf> and C<inf>3</inf> in series, and R<inf>4</inf> and C <inf>4</inf> in series. C<inf>50</inf> <inf>Hz</inf> is obtained from the conventional measurement method; whereas, the applied step voltage and the sum of PDC are calculated for R<inf>0</inf>. The individual elements (R<inf>1</inf> and C<inf>1</inf>) are determined from fitting technique employing MATLAB program. From experimental results of the tested transformer, the example of insulation model for Transformer No. 1 (T1) is created with C<inf>50</inf> <inf>Hz</inf> of 3.643 nF, R<inf>0</inf> of 334.8 GΩ. The values of R <inf>1</inf>-R<inf>4</inf> are 86.52, 110.5, 669.5 and 271.0 GΩ respectively; while, the values of C<inf>1</inf>-C<inf>4</inf> are 37.62, 6.047, 0.101 and 0.013 nF respectively. The proposed model is validated by calculating dissipation factor and measuring dissipation factor. The results show that the proposed model and experimental validation are good agreement with each others. © 2008 IEEE.