scholarly journals Ablation-assisted current interruption in medium voltage switchgear – Development and prospect

2017 ◽  
Author(s):  
Henning Taxt
Keyword(s):  
Global Warming ◽  
High Voltage ◽  
Global Warming Potential ◽  
Current Interruption ◽  
Medium Voltage ◽  
Insulation Materials ◽  
New Knowledge ◽  
Medium Voltage Switchgear

<p>SF6-gas is widely used in medium and high voltage<br />switchgear today because of its excellent insulation and<br />current interruption capabilities. However, due to its<br />high global warming potential, there is a political<br />pressure to replace it wherever possible, resulting in a<br />need for new solutions in the design of compact lowcost<br />switchgear. An evident response is to review and<br />further develop the technologies that were promising<br />before the entry of SF6. One of these was the application<br />of gas-emitting insulation materials, in a process of<br />ablation.<br />This paper reviews the range of commercial breaker<br />designs that have taken advantage of ablation in the<br />interruption process from the 1930s until today. The<br />main designs and developments are outlined and some<br />important parameters are explained, such as the steady<br />state ablation-dominated arc, arc quenching and<br />dielectric recovery in the presence of ablation material.<br />The ratings of the mentioned products, as well as more<br />recent experiments, indicate that there is a design limit<br />for simple ablation-assisted breakers at around 20 kV,<br />but the reasons for the apparent limit are not thoroughly<br />studied or explained.<br />Reviving the knowledge of ablation breakers, and<br />combining this with new knowledge and new tools<br />could prove valuable to the development of SF6-free<br />MV switchgear.</p>

scholarly journals Development of Foam One-Part Geopolymers with Enhanced Thermal Insulation Performance and Low Carbon Dioxide Emissions

2015 ◽  
Vol 1129 ◽  
pp. 565-572 ◽  
Author(s):  
Z. Abdollahnejad ◽  
F. Pacheco-Torgal ◽  
José Barroso de Aguiar
Keyword(s):  
Global Warming ◽  
Thermal Insulation ◽  
Global Warming Potential ◽  
Carbon Dioxide Emissions ◽  
Cost Effective ◽  
Building Energy Efficiency ◽  
Low Carbon ◽  
Insulation Materials ◽  
Aluminium Powder ◽  
Reduce Emissions

Buildings are responsible for more than 40% of the energy consumption and greenhouse gas emissions. Thus, increasing building energy efficiency is one the most cost-effective ways to reduce emissions. The use of thermal insulation materials could constitute the most effective way of reducing heat losses in buildings by minimising heat energy needs. These materials have a thermal conductivity factor lower than 0.065 (W/m.K) while other insulation materials such as aerated concrete can go up to 0.11. Current insulation materials are associated with negative impacts in terms of toxicity. Polystyrene, for example contains anti-oxidant additives and ignition retardants. In addition, its production involves the generation of benzene and chlorofluorocarbons. Polyurethane is obtained from isocyanates, which are widely known for their tragic association with the Bhopal disaster. Besides current insulation materials releases toxic fumes when subjected to fire. This paper presents experimental results on one-part geopolymers. It also includes global warming potential assessment and cost analysis. The results show that only the use of aluminium powder allows the production mixtures with a high compressive strength however its high cost means they are commercially useless when facing the competition of commercial cellular concrete. The results also show that one-part geopolymer mixtures based on 26% Ordinary Portland Cement (OPC)+58.3% Fly Ash (FA)+8% Calcined Stuff (CS) +7.7% Calcium Hydroxide (CH) and 3.5% hydrogen peroxide constitute a promising cost efficient (67 euro/m3), thermal insulation solution for floor heating systems with low global warming potential of 443 KgCO2eq/m3.

scholarly journals Analysis of Last Development Results for High Voltage Circuit-breakers Using New G3 Gas

2017 ◽  
Vol 4 (2) ◽  
pp. 157-160 ◽  
Author(s):  
P. Robin-Jouan ◽  
K. Bousoltane ◽  
Y. Kieffel ◽  
J. Y. Trepanier ◽  
R. Camarero ◽  
...  
Keyword(s):  
Global Warming ◽  
High Voltage ◽  
Global Warming Potential ◽  
Gas Mixture ◽  
Test Results ◽  
Chemical Behavior ◽  
Circuit Breakers ◽  
Simulation Tools ◽  
Environmental Friendly

Among many alternative gases proposed to replace SF6 as insulating gas, g<sup>3</sup> (green gas for grid), fluoronitril based component officially introduced at CIGRE 2014, can be now used for insulation projects and new environmental friendly circuit breakers. This gas mixture g<sup>3</sup>, presents a reduction of the global warming potential by 98% compared to SF<sub>6</sub> gas and shows quite good dielectric withstand capability. Many new investigations about thermal and chemical behavior have been done and are precised in this paper. Last switching test campaigns will be presented for 145 kV applications. Simulation tools should be updated to be applicable to these projects. Developments and comparisons with last test results will be analyzed.

scholarly journals Variation in Soil Properties Regulate Greenhouse Gas Fluxes and Global Warming Potential in Three Land Use Types on Tropical Peat

Atmosphere ◽  
2018 ◽  
Vol 9 (12) ◽  
pp. 465 ◽  
Author(s):  
Kiwamu Ishikura ◽  
Untung Darung ◽  
Takashi Inoue ◽  
Ryusuke Hatano
Keyword(s):  
Global Warming ◽  
Soil Moisture ◽  
Groundwater Level ◽  
Global Warming Potential ◽  
C:N Ratio ◽  
Co2 Flux ◽  
Nitrate Content ◽  
N2o Flux ◽  
Ch4 Flux ◽  
In The Beginning

This study investigated spatial factors controlling CO2, CH4, and N2O fluxes and compared global warming potential (GWP) among undrained forest (UDF), drained forest (DF), and drained burned land (DBL) on tropical peatland in Central Kalimantan, Indonesia. Sampling was performed once within two weeks in the beginning of dry season. CO2 flux was significantly promoted by lowering soil moisture and pH. The result suggests that oxidative peat decomposition was enhanced in drier position, and the decomposition acidify the peat soils. CH4 flux was significantly promoted by a rise in groundwater level, suggesting that methanogenesis was enhanced under anaerobic condition. N2O flux was promoted by increasing soil nitrate content in DF, suggesting that denitrification was promoted by substrate availability. On the other hand, N2O flux was promoted by lower soil C:N ratio and higher soil pH in DBL and UDF. CO2 flux was the highest in DF (241 mg C m−2 h−1) and was the lowest in DBL (94 mg C m−2 h−1), whereas CH4 flux was the highest in DBL (0.91 mg C m−2 h−1) and was the lowest in DF (0.01 mg C m−2 h−1), respectively. N2O flux was not significantly different among land uses. CO2 flux relatively contributed to 91–100% of GWP. In conclusion, it is necessary to decrease CO2 flux to mitigate GWP through a rise in groundwater level and soil moisture in the region.

New electrical stimulation technologies for sheep carcasses New electrical stimulation technologies for sheep carcasses

2005 ◽  
Vol 45 (5) ◽  
pp. 575 ◽  
Author(s):  
F. D. Shaw ◽  
S. R. Baud ◽  
I. Richards ◽  
D. W. Pethick ◽  
P. J. Walker ◽  
...  
Keyword(s):  
Electrical Stimulation ◽  
High Voltage ◽  
Consumer Satisfaction ◽  
Electrode System ◽  
Constant Current ◽  
Eating Quality ◽  
Meat Eating ◽  
Medium Voltage ◽  
Sheep Meat ◽  
Maximum Voltage

High voltage electrical stimulation applied to the lamb carcass at the end of the dressing procedure often leads to an improvement in overall product quality by reducing the incidence of toughness. It would be advantageous if the same results could be consistently achieved with the use of lower, safer, voltages — medium voltage electrical stimulation. Experiments were conducted to determine the effect of medium voltage electrical stimulation applied to wool-on carcasses on meat quality as assessed using the Sheep Meat Eating Quality protocols. A further experiment examined the interaction of electrical stimulation and meat aging time on the consumer acceptance of lamb meat. In the first experiment, 3 treatments: control (non-stimulated), medium voltage electrical stimulation (applied to the wool-on carcass) and high voltage electrical stimulation (applied at the completion of dressing) were examined. Samples of the loin (LTL) and rump (GM) muscles were evaluated by consumers using Sheep Meat Eating Quality protocols. For both muscles, the consumers gave higher scores for tenderness, juiciness, flavour and overall acceptability to the stimulated product (P<0.001). There were no statistically significant differences between the 2 stimulation treatments. The second experiment was conducted at a commercial lamb-processing abattoir that had installed a prototype automated electrode system designed to work at chain speed. Lambs received either no stimulation (control), low current medium voltage electrical stimulation (constant current 300 mA peak, 15 Hz, maximum voltage 550 V peak) or high current medium voltage electrical stimulation (constant current 600 mA peak, 15 Hz, maximum voltage 550 V peak) immediately after sticking. Electrical stimulation improved both the objective and sensory (Sheep Meat Eating Quality) eating quality attributes of lamb loin muscle when assessed following 2 days of ageing. When expressed according to consumer satisfaction rating, 30, 37 and 70% of the loins receiving low, high or no electrical stimulation, respectively, were rated as unsatisfactory at 2 days of ageing. At 4 days of ageing no loins from carcasses in the low stimulation treatment were rated by consumers to be unsatisfactory (P<0.05) compared with either non-stimulated (40%) or high-stimulated loins (35%). With respect to the effects of aging meat, electrical stimulation improved the consumer score at 2 days post-stunning by 8.9 and 4.7 points for tenderness and overall liking, respectively. Further linear improvements due to aging were similar for both electrical stimulation and unstimulated products. Under conditions of no electrical stimulation used in this experiment, 10 days aging results in tenderness and overall liking scores greater than 60 and with ES similar scores are achieved in 5 days. Consumer scores over 60 greatly reduce the chance of meat being classified as unsatisfactory.

scholarly journals Influence of technical and electrical equipment in life cycle assessments of buildings: case of a laboratory and research building

2021 ◽  
Author(s):  
E. Hoxha ◽  
D. Maierhofer ◽  
M.R.M Saade ◽  
A. Passer
Keyword(s):  
Global Warming ◽  
Environmental Impacts ◽  
Global Warming Potential ◽  
Electrical Equipment ◽  
Primary Energy ◽  
Electronic Equipment ◽  
Detailed Result ◽  
Detailed Calculation ◽  
System Boundary ◽  
Operational Energy

Abstract Purpose A detailed assessment of the environmental impacts of the building requires a substantial amount of data that is time- and effort-consuming. However, limitation of the system boundary to certain materials and components can provide misleading impact calculation. In order to calculate the error gap between detailed and simplified assessments, the purpose of this article is to present a detailed calculation of the environmental impacts of the building by including in the system boundary, the technical, and electrical equipment. Method To that end, the environmental impacts of a laboratory and research building situated in Graz-Austria are assessed following the EN-15978 norm. Within the system boundaries of the study, the material and components of building fabric, technical, and electronic equipment for the building lifecycle stages of production, construction, replacement, operational energy and water, and end-of-life are considered. The input data regarding the quantity of materials is collected from the design and tendering documents, invoices, and from discussion with the head of the building’s construction site. Primary energy and global warming potential indicators are calculated on the basis of a functional unit of 1 m2 of energy reference area (ERA) per year, considering a reference building service life of 50 years. Results and discussion The primary energy indicator of the building is equal to 1698 MJ/m2ERA/year. The embodied impacts are found to be responsible for 28% of which 6.4% is due to technical and electronic equipment. Furthermore, the embodied impacts for the global warming potential, equal to 28.3 kg CO2e/m2ERA/year, are responsible for 73%. Together, technical and electrical equipment are the largest responsible aspects, accounting for 38% of the total impacts. Simplified and detailed result comparisons show a gap of 29% and 7.7% for global warming and primary energy indicators. These differences were from the embodied impacts and largely from the exclusion of electrical equipment from the study’s system boundary. Conclusions Technical and electrical equipment present a significant contribution to the overall environmental impacts of the building. Worthy of inclusion in the system boundary of the study, the environmental impacts of technical and electrical equipment must be calculated in detail or considered with a reliable ratio in the early design phase of the project. Further research is necessary to address the detailed impact calculation of the equipment and notably the minimization of their impacts.

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