Performance Comparison of a Freeform Lens and a CDTIRO When Combined With an LED

Babadi, Sina; Ramirez-Iniguez, Roberto; Boutaleb, Tuleen; Mallick, Tapas K.

doi:10.1109/jphot.2017.2728701

Cited by 7 publications

(3 citation statements)

References 10 publications

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“…The sample was immersed in transformer oil within the test vessel to prevent possible corona discharges or flashover. Additionally, the oil helps augmenting the microscope's resolution due to its high refractive index [25,26]. In order to detect the PD signals, an induction based sensor, known as High Frequency Current Transformer (HFCT), was appropriately clamped around the earth connection of the vessel.…”

Section: Experiments Setup and Test Proceduresmentioning

confidence: 99%

Electrical Treeing in Power Cable Insulation under Harmonics Superimposed on Unfiltered HVDC Voltages

et al. 2019

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Insulation degradation is an irreversible phenomenon that can potentially lead to failure of power cable systems. This paper describes the results of an experimental investigation into the influence of direct current (DC) superimposed with harmonic voltages on both partial discharge (PD) activity and electrical tree (ET) phenomena within polymeric insulations. The test samples were prepared from a high voltage direct current (HVDC) cross linked polyethylene (XLPE) power cable. A double electrode arrangement was employed to produce divergent electric fields within the test samples that could possibly result in formation of electrical trees. The developed ETs were observed via an optical method and, at the same time, the emanating PD pulses were measured using conventional techniques. The results show a tenable relation between ETs, PD activities, and the level of harmonic voltages. An increase in harmonic levels has a marked effect on development of electrical trees as the firing angle increases, which also leads to higher activity of partial discharges. This study of the influencing operational parameters of HVDC converters on power cable insulation is predicted to contribute to enhancements in cable design and progressive advancement in condition monitoring and insulation diagnostic techniques that can lead to more effective asset management in HVDC systems.

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Section: Experiments Setup and Test Proceduresmentioning

confidence: 99%

Electrical Treeing in Power Cable Insulation under Harmonics Superimposed on Unfiltered HVDC Voltages

et al. 2019

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“…The sample within the vessel was immersed in transformer oil to prevent possible corona discharges or flashover. In addition, the transformer oil helps in increasing the resolving power of the microscope due to its high refractive index [17,18]. The microscope was arranged in a direction towards the test sample, as shown in the schematic, with its objective lens in a proper clearance from the test sample.…”

Section: Electrical Treeing Under Pure Hvdcmentioning

confidence: 99%

Electrical Treeing in Cable Insulation under Different HVDC Operational Conditions

et al. 2018

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Electrical treeing (ET) can irreversibly deteriorate the insulation of polymeric power cables leading to a complete failure. This paper presents the results of an experimental investigation into the effects of unipolar and polarity reversing DC voltages on electrical tree (ET) and partial discharge (PD) behavior within high voltage direct current (HVDC) cross linked polyethylene (XLPE) cable insulation. A double needle configuration was adopted to produce non-uniform electric fields within the insulation samples, potentially leading to electrical trees. The development of trees was monitored through an optical method and the associated partial discharge signals were measured through an electrical detection technique, simultaneously. The analysis of the results shows reasonable relation between the formation of ETs and the type of the applied voltages. The polarity reversing attribute of the test voltages has a pronounced effect on formation and growth of electrical trees. This implicates an interaction between the space charges that accumulate within polymeric materials and the operational polarity reversing electric fields, which causes insulation degradation. Therefore, study of influencing HVDC operational parameters on insulation degradations can contribute to improvements in cable design and advancement in insulation diagnostic strategies applicable in HVDC systems leading to more effective asset management.

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“…Shaoulov proposed using micro-lenslet arrays to overcome the restriction in the size of optical systems [2]. Babadi proposed a novel circular dielectric internally reflecting optic, which can produce over 95% uniformity within an illuminated area [3]. Mashaal presented a promising representative design for LED collimation [4].…”

Section: Introductionmentioning

confidence: 99%

Fabrication of Cylindrical Microlens Array on RB-SiC Moulds by Precision Grinding with MAWJ-Textured Diamond Wheels

Zhang

Yao

et al. 2022

Applied Sciences

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Cylindrical microlens array (CMA) is applied widely in imaging, sensing, and laser machining fields. Among the many techniques for machining CMA, moulding is considered a mass-production method with low-cost and good accuracy. Aimed at the present problems in the machining of CMA moulds, which include low processing efficiency and the prediction of the surface topography, this paper focused on the fabrication of CMA on RB-SiC moulds by precision grinding with micro-abrasive water jet (MAWJ) textured diamond wheels. The combined rough–fine grinding strategy for ceramic mould materials was proposed. The grinding experiments of CMA were carried out. The ultra-precision grinding method was optimized to obtain high shape accuracy and a high-quality surface of RB-SiC moulds. It was found that by using MAWJ-textured diamond wheels, the profile error in the peak-to-valley value (PV) of the CMA moulds can be further reduced to 6.7 μm by using the combined rough–fine strategy grinding process.

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Performance Comparison of a Freeform Lens and a CDTIRO When Combined With an LED

Cited by 7 publications

References 10 publications

Electrical Treeing in Power Cable Insulation under Harmonics Superimposed on Unfiltered HVDC Voltages

Electrical Treeing in Power Cable Insulation under Harmonics Superimposed on Unfiltered HVDC Voltages

Electrical Treeing in Cable Insulation under Different HVDC Operational Conditions

Fabrication of Cylindrical Microlens Array on RB-SiC Moulds by Precision Grinding with MAWJ-Textured Diamond Wheels

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