Mechanism of charge accumulation at flowing oil/pressboard interface based on optical measurement of electric field

Inoue, Naohisa; Katō, K.; Shimizu, Ryo; Nakagami, Yoshitake; Iwai, Hideyuki; Ōkubo, H.

doi:10.1109/ceidp.2001.963599

Cited by 7 publications

(6 citation statements)

References 4 publications

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“…The improved calculation method of the electric field is described as follows: knowing the light intensity distribution and the sequence n of light and dark lines, the electric fields between electrodes can then be calculated from Figure 6b and equations (11)(12)(13)(14). For example, the light intensity goes downward between n=15 and n=16 when the electric field increases from the upper side of line "V" to the middle point of line "V" shown in Figure 5b, which means equation (12) and n=15 are used to calculate the electric field.…”

Section: Comparison Resultsmentioning

confidence: 99%

“…Note that only the situation with two crossed λ/4 wave plates is given in equation (10) (11)(12)(13)(14).…”

Section: Deducing the Electric Fieldmentioning

confidence: 99%

“…where n is the sequence space (0, 1, 2…n max ) of dark fringes or light fringes on CCD images which are counted from outmost where n=0 (generally, the electric field is also approximately 0), and the value n in situation "a)" always increases by 1 with the changing states in equations (11)(12).…”

Section: Deducing the Electric Fieldmentioning

confidence: 99%

“…As seen from equations (11)(12)(13)(14), the distribution of the electric field and space charge can be determined by the light intensity distribution and the sequence n and l of light lines and dark lines, where light intensity distribution is processed as described in Sections 3.2.1 to 3.2.2. Defining the paramount parameter n is critical.…”

Section: Definition Of Nmentioning

confidence: 99%

“…Moreover, the electric field distribution can hardly be determined in the dielectric bulk, because the electric field cannot be easily calculated from the geometries alone when space charge appears. The Kerr electro-optic space charge measurement method can be used to measure space charge/electric field interactions in high voltage stressed liquid dielectrics [10][11][12][13]. Such as in the early 1980's, Kelley and Hebner [14]] used a CCD array to record the intensity variations, synchronized the detection interval to different times in the waveform, and made some explanation of space charge dynamics.…”

Section: Introductionmentioning

confidence: 99%

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Space charge dynamics investigation based on Kerr electro-optic measurements and processing of CCD images

Shi

Yang

Sima

et al. 2013

IEEE Trans. Dielect. Electr. Insul.

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The Kerr electro-optic technique is used to investigate electric field and space charge effects using large Kerr constant propylene carbonate as the dielectric liquid with Kerr constant B≈1.22×10 -12 m/V 2 . However, improved accuracy of this technique to measure space charge distributions remains an important goal. This paper describes inversion algorithm research on obtaining accurate space charge distributions from Kerr measurements. The original charge-coupled device (CCD) image of light intensity was converted into grayscale values for improved calculation. The grayscale CCD image was transformed into the frequency domain through a two-dimensional Fourier transformation. Butterworth filtering techniques were employed for edge enhancement algorithms. The most important parameter for calculation of space charge distributions are the integer fringe numbers n in the sequence of light and dark fringes measured by the CCD camera. Comparison of the improved algorithm and traditional methods for calculating electric field and space charge distributions between a pair of stainless steel parallel plate electrodes was investigated. The space charge dynamics were also calculated after processing the CCD images with some improvements. The results showed the electric field was essentially uniform at early times of pulsed high voltages. This uniformity indicated the absence of space charge during the early transient interval, while a bipolar charge injection was found in the central region between electrodes at later times. For longer times the electric field and space charge distributions slowly became uniform again. Grayscale processing and Butterworth filtering played an important role in the improvement of the algorithm for better image quality and edge enhancement.

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