Electrical Safety of Island Operated Low Voltage DC Network

Today, renewable energy technologies and modern power electronics have made it feasible to implement low voltage direct current (LVDC) microgrids (MGs) ca-pable to island operation. Such LVDC networks are particularly useful in remote areas. However, there are still pending issues in island operated LVDC MGs like electrical safety and controlled operation, which should be addressed before wide-scale implementation. This thesis is focused on the overall protection of an island operated LVDC network concept, including protection against electrical shocks, mains equipment protection and protection of photovoltaic (PV) power sources and battery energy storage systems (BESSs). The topic is approached through ex-amination of the safety hazards and the appropriate methods to protect against them, comprising considerations for earthing system selection and realisation of the protection system.

Automated system of seedling image analysis (SVIS) and electrical conductivity to assess sun hemp seed vigor

The development of new procedures for quickly obtaining accurate information on the physiological potential of seed lots is essential for developing quality control programs for the seed industry. In this study, the effectiveness of an automated system of seedling image analysis (Seed Vigor Imaging System - SVIS) in determining the physiological potential of sun hemp seeds and its relationship with electrical conductivity tests, were evaluated. SVIS evaluations were performed three and four days after sowing and data on the vigor index and the length and uniformity of seedling growth were collected. The electrical conductivity test was made on 50 seed replicates placed in containers with 75 mL of deionised water at 25 ºC and readings were taken after 1, 2, 4, 8 and 16 hours of imbibition. Electrical conductivity measurements at 4 or 8 hours and the use of the SVIS on 3-day old seedlings can effectively detect differences in vigor between different sun hemp seed lots.

802.11-standardiperhe

Langattomien verkkojen kehitys juontaa juurensa 1980-luvulle, jolloin eri valmistajat julkaisivat omia valmistajakohtaisia tuotteitaan. Kuluttajalle tämä tarkoitti sitoutumista yhteen valmistajaan ja yhteensopivuusongelmia eri laitteiden kesken. Ensimmäinen ajatus oli luoda vain uusi fyysinen taso langallisen lähiverkon 802.3-standardiin, mutta pian ymmärrettiin, että tarvitaan kokonaan uusi MAC-taso, sillä tiedonsiirto radioteitse on huomattavan erilaista kuin kaapelia pitkin tehtävä tiedonsiirto. Esimerkiksi langallisen lähiverkon 802.3-standardista tuttua CSMA/CD (Carrier Sense Multiple Access with Collision Detect) siirtotien varausmenetelmää ei voida käyttää, vaan se on korvattu langattomassa lähiverkossa CSMA/CA:lla (Carrier Sense Multiple Access with Collision Avoidance) IEEE:n (Institute of Electrical and Electronics Engineers) 802.11-standardi sai alkunsa 21.3.1991 ja ensimmäinen 802.11-standardi, 802.11-1997, julkaistiin vuonna 1997. 802.11-standardia kehitetään edelleen, ja tällä hetkellä uusin julkaistu laajennos on vuonna 2014 julkaistu 802.11ac. Tässä tutkielmassa perehdytään erilaisiin langattoman lähiverkon tekniikoihin pääpainon ollessa IEEE:n 802.11-standardissa ja sen tietoturvassa.

Ventricular rate during acute atrial fibrillation and outcome of electrical cardioversion: The FinCV Study

The impact of ventricular rate (VR) on the outcome of electrical cardioversion (ECV) of acute atrial fibrillation (AF) is currently unknown. We aimed to determine the effect of VR during acute AF on the success of ECV, recurrence of AF and occurrence of post-cardioversion complications in 30 days follow-up. All ECVs performed in patients with acute atrial fibrillation lasting <48 hours in 2 Finnish university hospitals during 2003-2010 and 1 central hospital during 2010 were retrospectively identified. A total of 6,624 ECVs were performed in 2,821 consecutive patients. VR≤60 BPM was defined low and VR≥160 BPM high. The median VR before ECV was 109 BPM. The success rate of ECV was 94.2%. Bradycardia occurred in 62 (0.9%) and thromboembolic complications in 39 (0.6%) ECVs. Low VR was observed before 75 (1.1%) ECVs and male sex was its only independent predictor. High VR was observed in 165 (2.5%) ECVs. The independent predictors of high VR were younger age, <12 h episode duration, no previous history of AF and alcohol abuse. Low or high VR were not related to the success of ECV, incidence of thromboembolic or bradycardic complications, or recurrence of AF, although VR was significantly (p<0.001) lower in the patients in whom AF recurred. In conclusion, ECV of acute AF is an effective procedure and VR during AF does not affect its efficacy, the maintenance of sinus rhythm or the incidence of bradycardic, thromboembolic or other complications during 30 days follow-up after ECV. Low VR is predominately observed in male patients, while high VR was a feature related to a shorter history of AF and high alcohol-intake.

Energy Efficiency in Electrical Drive Systems: Technical potentials, barriers and policy approaches for small and medium industries in Ghana

Today industries and commerce in Ghana are facing enormous energy challenge. The pressure is on for industries to reduce energy consumption, lower carbon emissions and provide se-cured power supply. Industrial electric motor energy efficiency improvement is one of the most important tools to reduce global warming threat and reduce electricity bills. In order to develop a strategic industrial energy efficiency policy, it is therefore necessary to study the barriers that inhibit the implementation of cost – effective energy efficiency measures and the driving forces that promote the implementation. The aim of this thesis is to analyse the energy consumption pattern of electric motors, study factors that promote or inhibit energy efficiency improvements in EMDS and provide cost – effective solutions that improve energy efficiency to bridge the existing energy efficiency gap in the surveyed industries. The results from this thesis has revealed that, the existence of low energy efficiency in motor-driven systems in the surveyed industries were due to poor maintenance practices, absence of standards, power quality issues, lack of access to capital and limited awareness to the im-portance of energy efficiency improvements in EMDS. However, based on the results pre-sented in this thesis, a policy approach towards industrial SMEs should primarily include dis-counted or free energy audit in providing the industries with the necessary information on potential energy efficiency measures, practice best motor management programmes and estab-lish a minimum energy performance standard (MEPS) for motors imported into the country. The thesis has also shown that education and capacity development programmes, financial incentives and system optimization are effective means to promote energy efficiency in elec-tric motor – driven systems in industrial SMEs in Ghana

Standardized electrical tests for electrical equipment in road vehicles Case: Visedo Oy PowerMASTER M-frame

Electrical road vehicles were common at the begin of the 20th century but internal combustion engines took a victory from electrical motors in road vehicles. The acknowledgement of the environment, and the price and the availability of the crude oil are reasons for the comeback of the electrical vehicles. Advancement in industrial technology and political atmosphere in EU as the directive 20--20--20, which consists of reducing fossil emission, increasing renewable energy and increasing the energy efficiency, have made the electrification popular again. In this thesis tests based on standard ISO 16750--2 electrical loads for electrical equipment in road vehicles are made for Visedo Oy's PowerMASTER M-frame power electronics device. This device is designed for mainly drive trains in mobile work machines and marine vessels but can be used in other application in its power range which also includes road vehicles. The functionality of the device is tested with preliminary tests which act as a framework for the tests based on standards.

Design and Material Selection of High-Speed Rotating Electrical Machines

The increasing emphasis on energy efficiency is starting to yield results in the reduction in greenhouse gas emissions; however, the effort is still far from sufficient. Therefore, new technical solutions that will enhance the efficiency of power generation systems are required to maintain the sustainable growth rate, without spoiling the environment. A reduction in greenhouse gas emissions is only possible with new low-carbon technologies, which enable high efficiencies. The role of the rotating electrical machine development is significant in the reduction of global emissions. A high proportion of the produced and consumed electrical energy is related to electrical machines. One of the technical solutions that enables high system efficiency on both the energy production and consumption sides is high-speed electrical machines. This type of electrical machines has a high system overall efficiency, a small footprint, and a high power density compared with conventional machines. Therefore, high-speed electrical machines are favoured by the manufacturers producing, for example, microturbines, compressors, gas compression applications, and air blowers. High-speed machine technology is challenging from the design point of view, and a lot of research is in progress both in academia and industry regarding the solution development. The solid technical basis is of importance in order to make an impact in the industry considering the climate change. This work describes the multidisciplinary design principles and material development in high-speed electrical machines. First, high-speed permanent magnet synchronous machines with six slots, two poles, and tooth-coil windings are discussed in this doctoral dissertation. These machines have unique features, which help in solving rotordynamic problems and reducing the manufacturing costs. Second, the materials for the high-speed machines are discussed in this work. The materials are among the key limiting factors in electrical machines, and to overcome this limit, an in-depth analysis of the material properties and behavior is required. Moreover, high-speed machines are sometimes operating in a harsh environment because they need to be as close as possible to the rotating tool and fully exploit their advantages. This sets extra requirements for the materials applied.

Electrical properties of some single crystal dodecaborides /|nby Jyoti Burte. -- 260 St. Catharines [Ont. : s. n.],

PreVi011.3 ':i or~ : indicat e('. tk~t ho t~)rE's sed ~-Al B 12 1i~2, ~' a semiconductor. r:Toreove r , the s i mpl.(~ electronic t heory also indi cates that ~ -AIB1 2 should be a semico nductor, since thf're is one nonbonding e 'Le ctrofl per AlB12- uni t. JPor these reasons, we decided to measure t he electrical n ropert i ~ s of ~ -AlB1 2 single crystal s . Singl e crystal s of¥- AIB 12 ab ou t 1 x 1 r1n1 . size were grown from a copper mel t at 12500 C. The melt technique coupled. 1,vi th slow cooling vilas used because of i ts advantages such as : siTYInle set- up of the expe rimon t ; only e ;l.sil y available c hemi cals are required and it i s a c omparatively strair::bt forvvard y,le t hod still yielding crystal s big enouGh for OtU' purpose . Copper rms used as a solvent , i nst8ad of previOl.wly used aluminum , because it allows c.l.'ystal growth at hig he r t emneratures. HovlGver, the cry s tals of ] -AlB12 shm'red very hi gh res i s t ance a t r oom temperature . From our neasureJ'lents we conclude that the r esistivity of j3- Al B12 is, at least, given as ~ = 4. x 107 oblD .em •• Those results are inc ons i s t ent wi 'uh the ones .. reported by IIiss Khin fo r bot- pressed j3-AlB12 g i ven a s = 7600 ohm . em . or I e s s . ' Since tbe hot pressing was done at about 800 - ' 9000C i n ~ rap hi te moul ds 1,7i th 97% AlB12- p oVJder, vie thi nk there is pas s ib i 1 i ty th a.t lower borides or borot] carbide are , being formed, ':.Jhich are k11 own to be good semiconductors . v7e tried to ro-pe r-AlB12 by addi'J,'?: agents s uch as l:Ig , IG.-InO 4. ' HgS04 , KI12PO 4·' etc. to t he melt .. However , all these re age 11 t eel either reduced the yield and size of t lJe crystals or r;ave crystals of high r esis'can ce again. We think tba t molten copper keeps t he i mpurities off . There is also a pos s i bil i ty t hc:!,t these doping agents get oxidi~::;ed at '1 250°C • Hence, we co ~ clud e that J -AIB12 has v~ ry high r es i stance at r oom temperature . This was a l s o C011 - fi rmed by checki ng the siYlgle and. polycrystals of .~-AIB12 from Norton Co., Ontario and Cooper Nletallurgical Association. Boron carbide has been reported to be a semiconductor with ~ - 0.3 to 0.8 ohm . cm. for hotpres sed s araples. Boron carbide b e inq: struct urally related to ¥-AIB12 , we de cided to study the electrical prone rties of it~ Single crystals. These crystals were cut from a Single melt grovvn crystal a t Norton Co., Ontario. The resistivity of th," se crystal s was measured by the Van der Pam-v' s ~ nethod, which \vas very c onvenient fo r our crystal sha-pp.s. Some of the crystals showed resistivity ~ == 0.50 ob,Tn.cr] . i n agreement with the previously reported results . However , a few crystals showed lower resistivity e.g . 0 .13 and 0.20 ohm.cra • • The Hall mobility could .not be measured and th8reiore i s lower than 0 .16 em 2 v - 1 sec -1 • This is in agreement \vith t he re1)orted Hall mobility for pyrolytic boron . _ 2 -1 -1 carbide as 0.13 cm v sec • We also studied the orientation of the boron carbide crystals by the Jjaue-method. The inclination of c-axis with res pect to x-ray be81Il was det ermined . This was found to be 100 t o 20° f or normal resistivity sarnples (0.5 ohm . cm.) and 27 - 30° for t he lower r esistivity samples (0.1 ~5 to 0.20 ohm.cm .). This indica tes the possibility that th.e r es if.1tivity of B13C3 i s orientation dependent.

Engineers and technicians : the effect of cognitive style and gender on visual information processing

The purpose of this project was to identify in a subject group of engineers and technicians (N = 62) a preferred mode of representation for facilitating correct recall of information from complex graphics. The modes of representation were black and white (b&w) block, b&w icon, color block, and color icon. The researcher's test instrument included twelve complex graphics (six b&w and six color - three per mode). Each graphics presentation was followed by two multiple-choice questions. Recall performance was better using b&w block mode graphics and color icon mode graphics. A standardized test, the Group Embedded Figures Test (GEFT) was used to identify a cognitive style preference (field dependence). Although engineers and technicians in the sample were strongly field-independent, they were not significantly more field-independent than the normative group in the Witkin, Oltman, Raskin, and Karp study (1971). Tests were also employed to look for any significant difference in cognitive style preference due to gender. None was found. Implications from the project results for the design of visuals and their use in technical training are discussed.

Some electrical properties of semi-conductor crystals / |nPhyu Phyu Khin. -- 260 St. Catharines, Ont. : [s. n.],

SiC and AtB 12 have been prepared and their resistivities and Hall voltages measured. The resistivities and Hall voltages were measured by the Van der Pauw's method, using spring loaded tungsten contacts. In this method, the major requirement is to have samples of plane parallel surfaces of arbitrary shape with four small contacts at the circumference. Similar measurements were made with a number of SiC crystals obtained from the Norton Research Corporation (Canada)-Ltd., Carolina Aluminum Co., Exolon Co. and Carborundum Co. It was found that resistivity, carrier concentration and mobility of ions depend on the type of impurity. AtB 12 was prepared from the melt containing At and B in the ratio of 4:1. They formed amber-colour pseudo tetragonal crystals. As the crystals obtained were small for electrical measurements, hot pressed lumps have been used to measure their resistivity.

The effects of moisture, cation concentration, temperature, density and composition of soils on their electrical resistivity

The effects. of moisture, cation concentration, dens ity , temper~ t ure and grai n si ze on the electrical resistivity of so il s are examined using laboratory prepared soils. An i nexpen si ve method for preparing soils of different compositions was developed by mixing various size fractions i n the laboratory. Moisture and cation c oncentration are related to soil resistivity by powe r functions, whereas soil resistiv ity and temperature, density, Yo gravel, sand , sil t, and clay are related by exponential functions . A total of 1066 cases (8528 data) from all the experiments were used in a step-wise multiple linear r egression to determine the effect of each variable on soil resistivity. Six variables out of the eight variables studied account for 92.57/. of the total variance in so il resistivity with a correlation coefficient of 0.96. The other two variables (silt and gravel) did not increase the · variance. Moisture content was found to be - the most important Yo clay. variable- affecting s oil res istivi ty followed by These two variables account for 90.81Yo of the total variance in soil resistivity with a correlation ~oefficient ·.of 0 . 95. Based on these results an equation to ' ~~ed{ ct soil r esist ivi ty using moisture and Yo clay is developed . To t est the predicted equation, resistivity measurements were made on natural soils both in s i tu a nd i n the laboratory. The data show that field and laboratory measurements are comparable. The predicted regression line c losely coinciqes with resistivity data from area A and area B soils ~clayey and silty~clayey sands). Resistivity data and the predicted regression line in the case of c layey soils (clays> 40%) do not coincide, especially a t l ess than 15% moisture. The regression equation overestimates the resistivity of so i l s from area C and underestimates for area D soils. Laboratory prepared high clay soils give similar trends. The deviations are probably caused by heterogeneous distribution of mo i sture and difference in the type o f cl ays present in these soils.

Collective Labour Agreement between the Public Utilities Commission of the City of St. Catharines and Local 556, The International Brotherhood of Electrical Workers, 1952

In 1952, Local 556 of The International Brotherhood of Electrical Workers negotiated a contract with The Public Utilities Commission of the City of St. Catharines. The contract was to be in effect from July 1952 to September 1953. The document is unsigned.

Electrical Development Company of Ontario certificate of stock ownership, ca. 1910.

The Electrical Development Company of Ontario was created in 1903. It was one of three private power companies that had water power leases with the Niagara Parks Commission, but was the only one that was financed with Canadian capital. The company built the Toronto Power Generating Station at Niagara Falls beginning in 1906, and the power house was completed in 1913. During the construction, there was much debate about whether the utility should remain privately operated or become a public utility. In 1920, the company became part of the public utility.

Crystallinity, Magnetic and Electrical Properties of Bi doped LaVO3

We report the results of crystal structure, magnetization and resistivity measurements of Bi doped LaVO3. X-ray diffraction (XRD) shows that if doping Bi in the La site is less than ten percent, the crystal structure of La1-xBixVO3 remains unchanged and its symmetry is orthorhombic. However, for higher Bi doping (>10%) composite compounds are found where the XRD patterns are characterized by two phases: LaVO3+V2O3. Energy-dispersive analysis of the x-ray spectroscopy (EDAX) results are used to find a proper atomic percentage of all samples. The temperature dependence of the mass magnetization of pure and single phase doped samples have transition temperatures from paramagnetic to antiferromagnetic region at TN=140 K. This measurement for bi-phasic samples indicates two transition temperatures, at TN=140 K (LaVO3) and TN=170 K (V2O3). The temperature dependence of resistivity reveals semiconducting behavior for all samples. Activation energy values for pure and doped samples are extracted by fitting resistivity versus temperature data in the framework of thermal activation process.