AC and DC House Wiring Efficiency Estimations Using a Fast Extensive Measurements Approach

DC-based appliances are exponentially increasing in the present market. This scenario opens the opportunity to utilize the DC electricity produced by the PV panels directly without going through the conversion stages. Due to high penetration of DC electricity sources, it is timely to utilize DC electricity directly. Several research works have been reported in the literature to experimentally test and compare AC and DC wiring options. Accurate and precise experimental measurements are vital to establish a sound theoretical basis. However, this is difficult due to cost and time constraints. Therefore, to avoid costly measurements, this paper develops a mathematical model based on measurements on selected AC and DC wiring at four voltage levels (12 V DC, 24 V DC, 48 V DC, and 230 V AC). A digital simulation calibration using DigSilent is conducted to validate the proposed mathematical model. This paper proposed to utilize the simulation calibration approach that is a cost-effective and timesaving option to perform extensive measurements accurately

EQ-5D-3L Derived Population Norms for Health Related Quality of Life in Sri Lanka

Background Health Related Quality of Life (HRQoL) is an important outcome measure in health economic evaluation that guides health resource allocations. Population norms for HRQoL are an essential ingredient in health economics and in the evaluation of population health. The aim of this study was to produce EQ-5D-3L-derived population norms for Sri Lanka. Method A population sample (n =  780) was selected from four districts of Sri Lanka. A stratified cluster sampling approach with probability proportionate to size was employed. Twenty six clusters of 30 participants each were selected; each participant completed the EQ-5D-3L in a face-to-face interview. Utility weights for their EQ-5D-3L health states were assigned using the Sri Lankan EQ-5D-3L algorithm. The population norms are reported by age and socio-economic variables. Results The EQ-5D-3L was completed by 736 people, representing a 94% response rate. Sixty per cent of the sample reported being in full health. The percentage of people responding to any problems in the five EQ-5D-3L dimensions increased with age. The mean EQ-5D-3L weight was 0.85 (SD 0.008; 95%CI 0.84-0.87). The mean EQ-5D-3L weight was significantly associated with age, housing type, disease experience and religiosity. People above 70 years of age were 7.5 times more likely to report mobility problems and 3.7 times more likely to report pain/discomfort than those aged 18-29 years. Those with a tertiary education were five times less likely to report any HRQoL problems than those without a tertiary education. A person living in a shanty was 4.3 more likely to have problems in usual activities than a person living in a single house. Conclusion The population norms in Sri Lanka vary with socio-demographic characteristics. The socioeconomically disadvantaged have a lower HRQoL. The trends of population norms observed in this lower middle income country were generally similar to those previously reported in high income countries

Magnetic Design Aspects of Coupled-Inductor Topologies for Transient Suppression

Based on the discovery of the surge absorption capability of supercapacitors, a transient protector named supercapacitor-assisted surge absorber (SCASA) was designed and implemented in a commercial device. Despite its simplicity, the circuit topology consisted of a coupled inductor wound around a specially selected magnetic core. This paper elucidates the design aspects of SCASA coupled-inductor topologies with a special focus on the magnetic action of core windings during transient propagation. The non-ideal operation of the SCASA transformer was studied based on a semi-empirical approach with predictions made by using magnetizing and leakage permeances. The toroidal flux distribution through the transformer was also determined for a 6 kV/3 kA combinational surge, and these findings were validated by using a lightning surge simulator. In predicting the possible effects of magnetic saturation, the hysteresis properties of different powdered-iron and ferrite core types were considered to select the optimal design for surge absorption. The test results presented in this research revealed that X-Flux powdered-iron toroid and air-gapped EER ferrite yielded exceptional performance with ∼10% and ∼20% lower load–voltage clamping compared to that of the existing Kool μu design. These prototypes further demonstrated a remarkable surge endurance, withstanding over 250 consecutive transients. This paper also covers details of three-winding design optimizations of SCASA and LTSpice simulations under the IEC 61000/IEEE C62.45 standard transient conditions.</jats:p

Permeance based model for the coupled-inductor utilized in the supercapacitor assisted surge absorber (SCASA) and its experimental validation

Transient-surge absorption capability of small/low cost supercapacitors (SCs) is already published. SCASA is a patented technique that led to the development of a high performance commercial surge protector which adheres to UL-1449 3rd edition test protocols. The commercial implementation comprises a coupled-inductor, two metal oxide varistors (MOVs) and a SC sub-circuit. This paper presents a permeance based model for the coupled-inductor of SCASA topology in predicting its operation under contrasting voltage conditions. In validating the circuit operation with regard to its surge absorption capability versus 50 Hz AC power transfer, a lightning surge simulator (LSS-6230) was utilized. We discuss this comparison based on the standard IEEE C62.41 surge waveforms up to a maximum of 6.6 kV

Investigating the impact of ferrite magnetic cores on the performance of supercapacitor assisted surge absorber (SCASA) technique

Supercapacitor assisted surge absorber (SCASA) is a patented technique developed by the University of Waikato. One noticeable attribute of this design is the inclusion of a coupledinductor which improves its capability of surge absorption. This paper mainly focuses on investigating the usability of ferrite iron for the core of the coupled-inductor, and attempts to explain how to minimize the effects of a negative voltage peak that arise during SCASA operation. Four ferrite cores with different geometries and material compositions (W-ferrite and J-ferrite) are subjected to 6.6 kV surge hits. Experimental outcomes demanded the need of inserting air-gaps inside these ferrite toroids. High magnetic permeability of ferrite results in a low energy storage capability; this limits their suitability in surge absorption related applications. To overcome the issues of high permeability we modified the cores with thin cuts through the surfaces. Experimental work is facilitated by lightning surge simulators (LSS-6110 and LSS-6230) coupled with the utility main to generate surge waveforms defined by the IEEE C62.41. The analysis of test results encourages us to justify the gappedcore approach, and to further verify, performance of SCASA is empirically compared for both powdered-iron cores and modified ferrite cores using international protocols of UL-1449

Optimization of Supercapacitor Assisted Surge Absorber (SCASA) Technique: A New Approach to Improve Surge Endurance Using Air-Gapped Ferrite Cores

SCASA is a patented technique commercialized as a surge protector device (SPD) that adheres to UL-1449 test standards. Apart from the novel use of supercapacitors, SCASA design incorporates a coupled-inductor wound to a specially selected magnetic material of powdered-iron. In this study, we investigate the limitations of the present design under transient operation and elucidate ways to eliminate them with the use of air-gapped ferrite cores. In modelling the operation under 50 Hz AC and transient conditions, a permeance-based approach is used; in addition, non-ideal characteristics of the transformer core are emphasized and discussed with empirical validations. The experimental work was facilitated using a lightning surge simulator coupled with the 230 V AC utility mains; combinational surge-waveforms (6 kV/3 kA) defined by IEEE C62.41 standards were continuously injected into SPD prototypes during destructive testing. Such procedures substantiate the overall surge-endurance capabilities of the different core types under testing. With regard to optimizations, we validated a 95% depletion of a negative-surge effect that would otherwise pass to the load-end, and another 13–16% reduction of the clamping voltage verified the effectiveness of the methods undertaken. In conclusion, SCASA prototypes that utilized air-gapped cores revealed a greater surge endurance with improved load-end characteristics.</jats:p

Importance of Leakage Magnetic Field and Fringing Flux in Surge Protector Design

Transient surge absorption capability of su percapacitors is practically implemented in a commercial surge protector known as supercapacitor assisted surge absorber (SCASA). It is a low component count high per formance circuit design which utilizes a coupled inductor topology wound to a powdered-iron magnetic core. This paper investigates non-ideal characteristics of the SCASA transformer designed using various air-gapped ferrites such as manually gapped toroids and mass-produced com mercially available EER cores. Emphasis is given to exam ine surge energy losses associated with leakage magnetic field and fringing flux of gapped transformer prototypes. In predicting effects of an air gap in ferrite materials, an analytical approach based on effective-permeance is used with validations based on SCASA inductance properties. Experimental work presented in this paper are carried out using a Noiseken lightning surge simulator adhering to IEC 60038 and IEEE C62.41 standards. In addition, SCASA pro totypes were subjected to surge immunity tests specified by UL-1449 Underwriters’ laboratory procedures, where a 10% reduction of load-voltage was recorded outperforming the present design

On the relevance of the polar β-phase of poly(vinylidene fluoride) for high performance lithium-Ion battery separators

Separator membranes based on poly(vinylidene fluoride), PVDF, poly(vinylidene fluoride-co-trifluoroethylene), PVDF-TrFE, poly(vinylidene fluoride-co-hexafluropropylene), PVDF-HFP and poly(vinylidene fluoride-co-chlorotrifluoroethylene), PVDF-CTFE were prepared by solvent casting method using N,N-dimethylformamide (DMF) as solvent. In all cases, the same polymer/solvent ratio and solvent evaporation temperature were used. For all membranes, porous microstructure is achieved with a degree of porosity larger than 50%. The β-phase content as well as degree of crystallinity were different for each membrane, which were lower for the co-polymer membranes when compared with PVDF. On the other hand, the observed ionic conductivity values, electrolyte uptake, tortuosity and MacMullin number were similar for all membranes. The electrochemical performance of the separator membranes was evaluated in Li/C–LiFePO4 half-cell configuration showing good cyclability and rate capability for all membranes. Among the all separator membranes, PVDF-TrFE demonstrate the best electrochemical performance, with a discharge capacity value of 87 mAh.g-1 after 50 cycles with a capacity retention of 78 % at 2C.Finally, the correlation between the β-phase content in the membranes and the cycling performance was demonstrated (which was significant at high-C rates): larger β-phase contents, leading higher polarity, facilitates faster lithium ion migration within the separator for similar microstructures.This work was supported by the Portuguese Foundation for Science and Technology (FCT) in the framework of the Strategic Funding UID/FIS/04650/2013. The authors thank FEDER funds through the COMPETE 2020 Programme and National Funds through FCT under the projects PTDC/CTM-ENE/5387/2014 and UID/CTM/50025/2013 and grants SFRH/BD/90215/2012 (J.C.D.) and SFRH/BPD/112547/2015 (C.M.C.). The authors acknowledge funding by the Spanish Ministry of Economy and Competitiveness (MINECO) through the project MAT2016-76039-C4-3-R (AEI/FEDER, UE) (including the FEDER financial support) and from the Basque Government Industry Department under the ELKARTEK Program. Authors are grateful to the Government of the Basque Country for financial support (Grupos de Investigación, IT718-13). The authors thank Solvay, Timcal and Phostech for kindly supplying the high quality materials.info:eu-repo/semantics/publishedVersio

Supercapacitor assisted surge absorber (SCASA) technique: selection of magnetic components based on permeance

Supercapacitors help building long time constant resistor-capacitor circuits. This property helps them withstand high voltage transient surges and dissipate transient energy in the resistive element of the circuit without exceeding the supercapacitor’s DC voltage rating, which is usually between 2.5 to 4 V. SCASA is a patented technique, which was commercialized within the last five years. Successful implementation of this circuit topology, despite its simplicity, is quite dependent on the selection of the core of the coupled inductor utilized. This paper provides the essential details of the process of selecting the core for the magnetic component required, with a brief comparison of SCASA technique with a traditional surge protector, without any supercapacitors