Generatori za pretvaranje energije vetra u električnu energiju

This paper presents the characteristes of an electrical generators which are being used for conversion of wind energy to electrical energy. There has been performed analysis of the work of induction generators whith the squirrel-cage rotor, as well as analysis of synchronous generator and double-fed induction generator in the systems where electric energy is generated from wind energy, upon which is concluded what kind of generators is optimal for specific cases.U radu su date karakteristike električnih generatora koji se koriste u vetroelektranama, za pretvaranje energije vetra u električnu energiju. Izvršena je analiza rada asinhronih generatora sa kaveznim rotorom, sinhronih generatora i asinhronih generatora sa dvostranim napajanjem u uslovima koji se imaju prilikom rada u vetrogeneratorskim postrojenjima i izvedeni zaključci u pogledu izbora optimalne vrste generatora za konkretne uslove

Uticaj primjene kultivator sijačice na efekte rekultivacije degradiranih zemljišta

Damaged and degraded terrain categories represent a present time problem, with tendency of further growth on account of fertile and cultivable terrain. Recultivation of degraded terrain, depots, is multiply significant from the aspect of technology and machines choice, economic validity and environment protection. The depot on which the research in mechanical structure was made, represents a heterogenous material, made mostly of cement rock with CaCO3 content of (43,87 to 65,60%). Research in cultivator seeder application in recultivation was made at the Pljevlja coal mine depot, in the period from year 1995. to 1997. Recultivation was made with John Deree cultivator seeder, model 1550. In serial agregate seeding, average technical productivity of (1,12 ha/h) was made with average speed of (8,7 km/h). Average returns of formed sod green mass in serial seeding was around (13,3 t/ha).Kategorije oštećenih i degradiranih zemljišta predstavljaju problem današnjice sa tendencijom daljeg rasta, a na štetu obradivih površina. Rekultivacija degradiranih zemljišta i odlagališta višestruko je značajna sa stanovišta izbora tehnologija, mašina, ekonomske opravdanosti i zaštite životne sredine. Odlagalište na kome su obavljena istraživanja u mehaničkom sastavu predstavlja heterogen materijal koga čine u većoj mjeri laporac sa sadržajem CaCO3 od 43,87 do 65,60%. Istraživanja primjene kultivator sijačice u rekultivaciji obavljena su na odlagalištu Rudnika uglja Pljevlja u periodu od 1995 – 1997. godine. Rekultivacija je obavljena sa kultivator sijačicom JOHN DEREE, model 1550, u agregatu vučnopogonske mašine od 88 kW

Tehnički sistemi za kontrolu mikroklime u plastenicima

Plant production within a protected area presents the most intense way of agricultural production. Plant growing is intense year-round, with high yields and high quality products. The point of microclimate regulation in green house is to increase agriculture production within limited (protected) areas (spaces) with the least amount of production costs, by arranging a balanced ratio of many factors, first of all the climate, which influences the yields of the cultivated crops. Microclimate control in green houses presents an accountable, precise and complicated process, with respect to a number of factors that affect the climate within a protected space, which are interdependent, so the control could be successfully achieved only by applying the right technical systems and devices controlled by computers. The work shows new generations of control systems and devices with characteristics that are used to control microclimate of a green house.Biljna proizvodnja u zaštićenom prostoru predstavlja najintenzivniji oblik proizvodnje u poljoprivredi. Rast biljaka je intenzivan tokom cele godine, sa ostvarivanjem visokog prinosa i kvaliteta proizvoda . Svrha regulacije mikroklime u plastenicima je povećanje obima poljoprivredne proizvodnje na ograničenim (zaštićenim) površinama (prostorima) pri najmanjim proizvodnim troškovima, dovođenjem u skladan odnos mnogobrojnih faktora pre svega klime od kojih zavisi prinos gajenih kultura. Kontrola mikroklime u plastenicima predstavlja odgovoran, precizan i komplikovan proces, obzirom da ima više faktora koji utiču na klimu u zaštićenom prostoru, koji su uzajamno zavisni, pa se kontrola može uspešno postići jedino primenom odgovarajućih tehničkih sistema i uređaja kontrolisanih PC računarima. U radu su prikazane novije generacije kontrolnih sistema i uređaja sa karakteristikama koje se koriste u kontroli mikroklime plastenika

Merenje momenta asinhronog motora

Review of methods for induction electrical motor torque measurement is presented in this paper. Standard load methods were treated, also as modern methods that accomplished owing to the very intensive development of power electronics, microcontroller systems and various types of sensors and transducers. Appliance of novel torque measurement methods enabled, by the static characteristic, also obtainment of dynamic torque-speed characteristic of induction motors, also as planty of other data important for service and optimization of analysed electric drive.U radu je prikazan pregled metoda za merenje momenta asinhronog elektromotora. Obrađene su klasične metode opterećenja i savremene metode koje su se razvile zahvaljujući veoma intenzivnom razvoju energetske elektronike, mikrokompjuterskih sistema i raznih vrsta senzora i pretvarača. Primenom savremenih metoda merenja momenta moguće je pored statičke dobiti i dinamičku karakteristiku momenta asinhronih motora i niz drugih podataka značajnih za eksploataciju i optimizaciju električnog pogona

Hidraulički sistemi prenosa snage u poljoprivrednoj tehnici

Current development of agriculture is being determined with research and implementation of new technologies and modern technical appliances which will be able to provide quality and economically approved application for all technological operations all mentioned, with the least possible consumption of energy and human resource and engagement, as well as to achieve environment preservation, and provide healthy working conditions. One of the most important matters, from the aspect of usage and market value of agricultural machinery and the others working machines, is the choice of propulsion. Mechanical power transmission does not satisfy newly established conditions for changes in output parameters, or these solutions are becoming too complex and expansive. Therefore, power transmission in agricultural technics is often based on hydraulic transmission systems. In this work will be presented new solutions for hydrostatical and hydrodynamical power transmission, and applycability analysses of connection between electric motor and internal combustion engine with turbojoints and turbotransmiters.Današnji razvoj poljoprivrede karakteriše osvajanje i primena novih tehnologija i savremenih tehničkih sredstava koja će obezbediti kvalitetno i ekonomski opravdano obavljanje predviđenih tehnoloških operacija, uz što manji utrošak energije, ljudskog rada i vremena, očuvanje okoline i obezbeđenje humanih uslova za rukovaoce. Izbor vrste pogona poljoprivrednih mašina predstavlja značajno pitanje koje utiče na upotrebnu i tržišnu vrednost mašina. Mehanički prenosnici snage ne zadovoljavaju sve strožije zahteve za promenom izlaznih parametara ili ova rešenja postaju komplikovana i skupa. Zbog toga se savremeni razvoj prenosa snage u poljoprivrednoj tehnici sve više bazira na hidrauličkom prenosu snage. U radu će biti prikazane varijante hidrostatičkog i hidrodinamičkog prenosa snage i analiza pogodnosti povezivanja elektromotora i motora SUS sa turbospojnicama i turbomenjačima

Preventivne mere u sprečavanju udesa sa traktorima u poljoprivredi Republike Makedonije

In this paper are presented prevention measures for decreasing the number of tractor accidents in agriculture in Republic of Macedonia. According from the results of the investigation from 1999 to 2003 in agriculture production was reported 398 tractor accidents. As the results of disrespect of traffic signs and regulations happened 203 (51, 00%) accidents, psycho-physical condition and poorly experience was cause of 87 (21,86%) accidents and 42 (10,55%) accidents are results of mistakes of pedestrians, riders and technical malfunction of vehicles. In agricultural condition on the field happened 66 (16,58%) tractor accidents. For decreasing the number of tractor related accidents and injuries in the agriculture production in Republic of Macedonia, we have to implement recommendations which are described in: Regulations for tractor safety, Technical solution for increasing of tractor safety, and The organization measures for safety tractor exploitation.U radu su prikazane preventivne mere u cilju sprečavanja udesa sa traktorima u poljoprivredi Republike Makedonije. Prema rezultatima istraživanja u vremenskom periodu od 1999 do 2003 godine, dogodilo se ukupno 398 nesreća u kojima su učestvovali traktori. Kao rezultat nepoštovanja saobraćajnih znakova i propisa dogodilo se 203 (51,00 %) nesreća, psiho-fizičko stanje i nedovoljno iskustva rukovaoca traktora uzrok je 87 (21,86%) nesreća, a greške pešaka, putnika i tehnička neispravnost vozila 42 (10,55%) nesreća. Pri radu sa traktorima u poljoprivrednim uslovima dogodilo se ukupno 66 ( ili 16,58%) nesreća. Kao posledice u ovim nesrećama nastradalo je ukupno 610 osoba. Sa ciljem sprečavanja udesa i smanjenja broja povređenih osoba u poljoprivredi Republike Makedonije treba dosledno se pridržavati prema predloženim preventivnim merama koje su navedene u: • zakonskim regulativama sigurnosti rada TMA, • tehnička rešenja za povećanje bezbednosti i sigurnosti rada TMA, i • organizaciona rešenja rada TM

Razvoj poljoprivredne tehnike za primenu novih tehnologija u procesima eksploatacije teških zemljišta, efekti i posledice

Soil compaction is a result of degradation processes caused by human activity. Such unwanted alterations of soil structure result in decreased soil and crop productivity. Reduced tilage signifficantly influence on crop yield. This paper presents results of the research work conducted trough several years related to the rational use of agricultural machines aimed at the establishment of heavy soils.Pojava sabijanja zemljišta je jedna od posledica degradacionih procesa koji se odvijaju u zemljištu pod uticajem aktivnosti čoveka. Narušena struktura, kao nosilac plodnosti, ima za posledicu smanjenu produktivnost zemljišta i biljaka. Redukovana obrada značajno utiče na prinose poljoprivrednih useva. U radu su prikazani rezultati višegodišnjih istraživanja racionalne primene poljoprivredne tehnike za uređenje teških zemljišta

Energetski aspekti obrade teških tipova zemljišta

With the increase of the use of heavy machinery in heavy marsh soil tillage, the degradation of soil physical conditions like the formation of a hardpan is becoming a problem. To improve such conditions, the effects of different tillage systems were investigated. The soil tillage is one of the greatest energy consumers in agriculture, and that is the reason why an experiment with different tillage systems and their influence on fuel consumption was carried. The compared tillage systems were the conventional tillage and the conservation or reduced tillage. Conservation tillage systems can be an important part of a sustainable agricultural system providing benefits for the farmers in terms of labor and fuel consumption; however, yield variability may discourage and slow adoption. Effects of ploughing and subsoiling treatment on growth and yield of crops depended on the weather and soil condition. Using the right tillage system may contribute to raised the energy demand for cultivation, increase profit, crop yields, soil improvement and protection of water resources.Sa povećanjem korišćenja teških mašina u obradi teških zemljišta, degradacija fizičkih osobina zemljišta, kao što je "taban brazde", postaje sve veći problem. Da bi se ti uslovi poboljšali ispitani su efekti različitih sistema obrade. Obrada zemljišta je jedan od najvećih potrošača energije u poljoprivredi, što je razlog istraživanja različitih sistema obrade i njihovog uticaja na potrošnju goriva. Upoređeni sistemi obrade zemljišta su: konvencionalna obrada i konzervacijska ili redukovana obrada. Konzervacijski sistemi obrade mogu biti značajan deo sistema održive poljoprivrede, donoseći pogodnosti proizvođačima kroz potrošnju rada i goriva, iako varijabilnost prinosa može obeshrabriti i usporiti njihovo korišćenje. Efekti oranja i razrivanja na rast i prinos useva zavise od klimatskih i zemljišnih uslova. Korišćenje pravog sistema obrade zemljišta može doprineti smanjenju potrošnje energije za obradu, povećanju profita, prinosa i poboljšanju zemljišnih uslova i zaštiti vodenih resursa

Pogodnosti primene samohodnih nosača oruđa u mehanizaciji poljoprivrede

For a very long time, tractor development was a consequence of need for improvement. During this period, some important factors were neglected, like: energy consumption decrease, better quality of accomplishing agrotechnical quests, decrease of soil gauge, enhancement of agrotechnical characteristics, which all means creating basic drive machine with higher level of technical and economical validity. Self-propelling chassis have numerous advantages over classical tractor solution: very suitable placement of working machines and equipment, good maneuvering, improved pulling characteristics as a result of optimal distribution of weights and balasts on steering and driving wheels. In this work, a new solutions of designing a layout of self-propelling chassis have been presented, as well as comparison of characteristics of classical tractor and selfpropelling chassis. There is also shown an archetype of self-propelling chassis which is assigned in surface treatment and organisation of soil, dirt paths and passages for mobile irrigation systems.Razvoj traktora u dugom periodu je bio vezan za njegova poboljšanja. Za to vreme, neki uticajni faktori su zanemarivani: smanjenje utroška energije, kvalitetnije ispunjavanje agrotehničkih zahteva, smanjenje gaženja zemljišta, poboljšanje agrotehničkih karakteristika, odnosno osvajanje rešenja osnovne pogonske mašine sa većim stepenom tehničke i ekonomske opravdanosti. Samohodni nosači oruđa poseduju niz prednosti u odnosu na klasično rešenje traktora: pogodan izbor mesta postavljanja radnih mašna, dobra sposobnost upravljanja, poboljšanje vučnih karakteristika, što je obezbeđeno pravilnom preraspodelom težina i opterećenja na pogonske i upravljačke točkove. U radu su prikazane mogućnosti komponovanja osnove šeme samohodnih nosača oruđa i uporedne karakteristike klasičnog rešenja traktora i samohodnog nosača oruđa. Prikazano je izvedeno rešenje (prototip) samohodnog nosača oruđa koje je namenjeno uređenju zemljišta po površini, zemljanih puteva i staza za kretanje mobilnih sistema za navodnjavanje

Tragične posledice i teške telesne povrede kod dece u nesrećama sa traktorima u Republici Makedoniji

In this paper are the results from investigation of fatal consequences and hard injuries among children and young people in tractor accidents in Republic of Macedonia. According from the results of the investigation from 1999 to 2003 in Macedonia was injured 48 children and young people from 1 to 18 years old. From the total number of injured children and young people 39 or 81,25% are injured in tractor traffic accidents and 9 or 18,75% in tractor accidents on the field. From total number of injured farmers in tractor accidents with fatal injuries are 11 or 12,94%, and with hard injuries are 16 or 19,04% children and young people. Two children with fatal injuries in tractor accidents have 14 and 15 years old and died like tractor operators, and four children who drove a tractor had hard injuries.U ovom radu su prikazani rezultati istraživanja tragičnih posledica i teških telesnih povreda kod dece i mladih osoba u nesrećama sa traktorima u poljoprivredi Republike Makedonije. Prema rezultatima istraživanja od 1999 do 2003 godine u Republici Makedoniji ukupno je nastradalo 48 dece i mladih osoba do 18 godina starosti. Od ukupnog broja 39 ili 81.25% nastradali su u saobraćajnim nesrećama, a 9 ili 18,75% u nesrećama pri radu sa traktorima u poljoprivrednim uslovima. U nesrećama sa traktorima, 11 (ili 12,94%) dece i mladih osoba do 18 godina starosti je poginulo, a teško je povređeno 16 (ili 19,04%), od ukupnog broja poginulih i teško povređenih farmera. Kao rukovaoci traktora poginulo je dvoje dece koje su imali po 14 odnosno 15 godina, a još četiri su maloletni rukovaoci traktora i za posledice imali su teške telesne povrede