Rancang Bangun Prototipe Superconducting Fault Current Limiter Modelinduktif

RANCANG BANGUN PROTOTIPE SUPERCONDUCTING FAULT CURRENT LIMITER MODELINDUKTIF. Rancang bangun prototipe Superconducting Fault Current Limiter (SFCL) model induktif telah dilakukan. Prototipe SFCL model induktif dirancang dengan topologi transformator, memiliki lilitan primer dari kawat tembaga dan lilitan sekunder berupa tabung superkonduktor yang dibuat dari bahan YBCO. Simulasi SFCL dilakukan pada tegangan Vs = 3.000 volt, frekuensi arus bolak-Balik = 50 Hz dan beban jaringan RL = 1.250 . Jika SFCL dipasang pada rangkaian tanpa beban dan SFCL dalam keadaan tidak resistif, maka arus yang mengalir bisa mencapai Is = (9,6-11,6)×106 A. Pada keadaan resistif, arus tersebut dapat direduksi oleh SFCL hingga Is = (3,3-9,1)×10-1 A. Jadi arus disusutkan (2,9-1,3)×107 kali. Jika SFCL dipasang pada rangkaian berbeban RL = 1250 dan SFCL dalam keadaan tidak resistif, maka arus yang mengalir adalah Is = 2,4 A. Tetapi pada keadaan resistif, SFCL dapat mereduksi Is menjadi (2,9-6,6)×10-1 A. Jadi arus Is disusutkan 3,6 hingga 8,3 kali. Prototipe SFCL dapat difungsikan sebagai pengaman jaringan terhadap arus gagal akibat hubungan singkat

RANCANG BANGUN PROTOTIPE SUPERCONDUCTING FAULT CURRENT LIMITER MODELINDUKTIF

RANCANG BANGUN PROTOTIPE SUPERCONDUCTING FAULT CURRENT LIMITER MODELINDUKTIF. Rancang bangun prototipe Superconducting Fault Current Limiter (SFCL) model induktif telah dilakukan. Prototipe SFCL model induktif dirancang dengan topologi transformator, memiliki lilitan primer dari kawat tembaga dan lilitan sekunder berupa tabung superkonduktor yang dibuat dari bahan YBCO. Simulasi SFCL dilakukan pada tegangan Vs = 3.000 volt, frekuensi arus bolak-balik = 50 Hz dan beban jaringan RL = 1.250 . Jika SFCL dipasang pada rangkaian tanpa beban dan SFCL dalam keadaan tidak resistif, maka arus yang mengalir bisa mencapai Is = (9,6-11,6)×106 A. Pada keadaan resistif, arus tersebut dapat direduksi oleh SFCL hingga Is = (3,3-9,1)×10-1 A. Jadi arus disusutkan (2,9-1,3)×107 kali. Jika SFCL dipasang pada rangkaian berbeban RL = 1250 dan SFCL dalam keadaan tidak resistif, maka arus yang mengalir adalah Is = 2,4 A. Tetapi pada keadaan resistif, SFCL dapat mereduksi Is menjadi (2,9-6,6)×10-1 A. Jadi arus Is disusutkan 3,6 hingga 8,3 kali. Prototipe SFCL dapat difungsikan sebagai pengaman jaringan terhadap arus gagal akibat hubungan singkat

THE STRUCTURAL AND MICROSTRUCTURAL characteristics IN THE MILLED Fe50C50 MAGNETIC COMPOSITES

THE STRUCTURAL AND MICROSTRUCTURAL characteristics IN THE MILLED Fe50C50 MAGNETIC COMPOSITES. The structural and microstructural characteristics in the milled Fe50C50 magnetic composites have been investigated by the x-ray diffraction technique using Rietveld analysis method. The starting materials of composite were the pure iron (Fe) and carbon (C) powders (weight ratio Fe:C = 50:50). The composites were prepared by mixing Fe and C powders by high energy milling (HEM) at various milling time start from 1.5 to 4.5 h. The x-rays diffraction measurements were performed by using a Philips X-Ray Diffractometer, PW170 type at room temperature with CuKα radiation, 2θ range = 10°-100°, preset time = 1 sec, and step size = 0.020°. With a mechanical milling of 4.5 hours, the elemental powders undergo a better crystallization. It means that the amorphization. Of its components do not happen yet. The carbon elements in composites get a homogeneous strain field, while the iron elements get an inhomogeneous strain field. The crystallite size of C particles almost do not change yet until the milling time of 4.5 hours. This is presumably due to the C particles are trapped at the weld interfaces between the Fe particles. While, the Fe particles fracture into smaller segments on the milling time of 1.5 hours. On the further milling, the Fe particles undergo welding processes to be bigger crystallites. Magnetic parameter such as Hc, Ms and Ku were confirmed this suggestion

Characterization of (Cuo-fe2o3) Ceramics with Three Different Compositions Sintered at 1100 Oc for Ntc Thermistor

CHARACTERIZATION OF (CuO-Fe2O3) CERAMICS WITH THREE DIFFERENT COMPOSITIONS SINTERED AT 1100 oC FOR NTC THERMISTOR. The formation of (CuO-Fe2O3) ceramics for NTC thermistors based on CuO-Fe2O3 phase diagram has been studied. The ceramics were produced by pressing an homogeneous mixture of powder of (50 mole % CuO and 50 mole % Fe2O3 as composition 1), (40 mole % CuO and 60 mole % Fe2O3 as composition 2) and (34 mole % CuO and 66 mole % Fe2O3 as composition 3) and sintering the pressed powder at 1100 oC for 2 hours in air with cooling rate of 10 oC/minutes. Electrical characterization was performed by measuring electrical resistivity of the ceramics at various temperatures (25 oC - 100 oC). Analyses of microstructure and crystal structure were carried out by using optical microscope and x-ray diffractometer (XRD), respectively. The x-ray diffraction (XRD) analyses showed that the ceramics of composition 1 and 3 were composed of tetragonal spinel and that of composition 2 was composed of cubic spinel. Hematite second phase was found in the ceramic of composition 3. According to the optical microscopy data, it was known that the ceramics having three different microstructures have been produced. Very large rounded grains were observed in the ceramic of composition 1, polygonal grains were observed in that of composition 2 and very small grains were seen in that of composition 3. According to the electrical data, it was known that the ceramics having thermistor constant (B) between 2000 K and 5000 K have been produced. It was known also that the room temperature resistivity (ρRT) and thermistor constant (B) increased with the increase of Fe2O3 content. The value of B and ρRT of the produced (CuO-Fe2O3) ceramics fits the market requirement

Konfigurasi Fasa Kobalt (Co) Dan Karakteristik Magnetoresistance Pada Paduan Granular Co-c Pasca Milling Energi Tinggi

CONFIGURATION OF Co PHASE AND MAGNETORESISTANCE PROPERTIES IN HIGH ENERGY MILLED Co-CGRANULAR COMPOUNDS. The Co-C granular compounds which composition of Co: C was 36:34 prepared using high energymilling (HEM) process for 4.5, 12 and 20 h. The samples were characterized using X-RayDiffraction with CuKα radiation. Subsequently, the magnetic hysteresis loop of the sampleswasmeasured by aVibrating SampleMagnetometer (VSM). Themagnetoresistance (MR)wasmeasured by standar Four Point Probe (FPP). The of XRD analyses show that a-Carbon, Co-HCP and C-FCC phases existed for the samples of 4.5 and 12 hours milling. Furthermore, the magnoresistance curves show positive trend for the sampples. On the other hand, Co3O4 phase beside of C, Co-HCP, Co-FCC phases existed with negative trend for magnoresistance curve for the samples of 20 hours milling

X-rays Diffraction Study On The Iron Nano Particles Prepared By Two Steps Milling Method

X-RAYS DIFFRACTION STUDY ON THE IRON NANO PARTICLES PREPARED BY TWO STEPS MILLING METHOD. X-rays diffraction study on the iron nanoparticles prepared by two-step milling method has been carried out. First, the raw material of micro-sized Fe was crushed by High Energy Milling (HEM) in the presence of isopropyl alcohol, here in after referred to as FI precursor. FI precursor then was crushed again with planetary balls mill in Cetyl-Trimethyl- Ammonium Bromide (CTAB)media, here in after referred to as FC sample. The phases analysis in the two samples were carried out by X-rays diffraction technique using the Rietveld method. Crystallites size were calculated with the Debye-Scherrer formula and the size of particles were measured by means of Particles Size Analyzer (PSA). The magnetic properties of the two samples were characterized with Vibration Sample Magnetometer (VSM). The analysis result showed that each of FI and FC samples consist of Fe, γ-Fe2O3 and Fe3O4 phases in the formof the nano-sized powder ranging fromaround 7 to 10 nm. PSA data indicate that the particle size of FI and FC are the same, i.e., 7.5 nm with narrow size distribution. The VSM data revealed that both FI and FC samples display super paramagnetic behavior at room temperature. The magnetization value in FC sample has been reduced due to more of the mass fraction of Fe transforms into iron oxide phases. The particle size is generally not the same as the size of the crystallites and in particular for the nano-sized particles, the size of crystallites could be equal to or greater than the particle size due to the presence of polycrystalline aggregates

ANALISIS FASA MINOR DENGAN TEKNIK DIFRAKSI NEUTRON

ABSTRAKANALISIS FASA MINOR DENGAN TEKNIK DIFRAKSI NEUTRON. Keberadaan fasa minor dalam suatu cuplikan telah dianalisis dengan teknik difraksi neutron. Dalam penelitian ini dipilih cuplikan partikel nano Fe (PNF) sebagai objek studi kasus. Langkah pertama adalah menyiapkan cuplikan PNF dengan teknik ball milling. Cuplikan hasil milling selanjutnya disebut FIC2. Keberadaan fasa-fasa yang terbentuk di dalam cuplikan FIC2 dianalisis secara kualitatif dan kuantitatif dengan teknik difraksi neutron resolusi tinggi (HRPD) dan difraksi sinar-X (XRD). Data difraksi dianalisis dengan metode Rietveld memanfaatkan program FullProf dan dilakukan dengan mengacu pada data dukung, yakni ukuran partikel dan sifat magnetik bahan. Kedua jenis data dukung tersebut diperoleh berturut-turut dengan PSA (Particles Size Analyzer) dan VSM (Vibrating Samples Magnetometer). Hasil analisis menunjukkan bahwa kualitas fitting pola difraksi neutron lebih baik dari kualitas fitting pola difraksi sinar-X. Dari data difraksi neutron diperoleh bahwa FIC2 terdiri dari fasa Fe, gFe2O3, dan Fe3O4 berturut-turut sebanyak 78,62; 21,37 dan0,01%. Dari data difraksi sinar-X didapat bahwa FIC2 terdiri dari fasa Fe dan gFe2O3 berturut-turut sebanyak 99,96 dan 0,04%; sedangkan keberadaan fasa Fe3O4 tidak teramati.Dengan teknik difraksi neutron, keberadaan fasa minor dapat ditentukan secara akurat. Kata kunci: difraksi neutron, difraksi sinar-X, fasa minor. ABSTRACT ANALYSIS OF MINOR PHASE WITH NEUTRON DIFFRACTION TECHNIQUE. The presence of minor phases in a sample have been analyzed with the neutron diffraction technique. In this research, the sample of Fe nanoparticles (FNP) has been selected as the object of case study. The first step was to prepare the FNP sample with the ball milling technique. Hereinafter, the sample of milling result was referred FIC2. The presence of phases formed in FIC2 were analyzed qualitatively and quantitatively using the high resolution neutron diffraction (HRPD ) and X-Ray Diffraction (XRD) techniques. The diffraction data were analyzed by means of the Rietveld method utilizing a computer code, namely FullProf and performed by referring to the supporting data, namely particle size and magnetic properties of materials. The two kinds of supporting data were obtained from the PSA (Particles Size Analyzer) and VSM (Vibrating Samples Magnetometer), respectivelly.The analysis result shows that quality of fitting for neutron diffraction pattern is better than the fitting quality for x-ray diffraction pattern. Of the HRPD data were revealed that FIC2 consists of Fe, gFe2O3 and Fe3O4 phases as much as 78.62; 21.37 and 0.01%, respectively. Of the XRD data were obtained that FIC2 consits of Fe and gFe2O3 phases with amount of 99.96 and 0.04%, respectively; the presence of Fe3O4 phase was not observed. With the neutron diffraction technique, the presence of minor phase can be determined accurately. Keywords: neutron diffraction, X-ray diffraction, minor phase

ANALISIS KUALITATIF DAN KUANTITATIF FASA (Na0,5Bi0,5)TiO3 DENGAN TEKNIK DIFRAKSI SINAR-X MENGGUNAKAN METODE RIETVELD

ANALISIS KUALITATIF DAN KUANTITATIF FASA (Na0,5Bi0,5)TiO3 DENGAN TEKNIK DIFRAKSI SINAR-X MENGGUNAKAN METODE RIETVELD. Telah dilakukan analisis kualitatif dan kuantitatif fasa (Na0,5Bi0,5)TiO3 (NBT) dengan teknik difraksi sinar-X, metode Rietveld. Cuplikan NBT disintesis dengan metode reaksi padatan. Struktur mikro cuplikan diteliti dengan bantuan mikroskop elektron. Dalam penelitian ini ada enammodel masukan parameter least square, yakni model NBT1, NBT2, NBT3, NBT4, NBT5 dan NBT6. Hasil analisis menunjukkan bahwa model struktur yang paling cocok adalah model NBT3, yakni suatu model struktur dengan NBT terdiri dari dua fasa, yakni fasa tetragonal, grup ruang I4/mcm, No. 140, parameter kisi a = b = 5,485(1)Å, c = 7,772(2)Å, α=β=γ= 90°, fraksi berat 93,44 % dan fasa rombohedral, grup ruang R3c, No. 161-1, parameter kisi a = b = c = 3,908(1)Å, α=β=γ= 90,08(4), fraksi berat 6,56 %. Indeks reliabilitas Rwp =15,91 dan Rp = 11,86. Regangan kisi (ηT ) dan ukuran kristalit (DR) untuk sistem kristal tetragonal, sebesar 0,015 dan 150,00 Å. Sedangkan regangan kisi (ηT) dan ukuran kristalit (DR) untuk sistem kristal rombohedral, sebesar 0,016 dan 142,857 Å. Keberadaan unsur penyusun senyawa NBT di dalam cuplikan, yakni Bi, Na, Ti dan O, dibuktikan dari kurva cacahan hamburan sinar-X karakteristik terhadap energi dispersif. Secara dominan cuplikan NBT berfasa tetragonal ( > 90 %). Terbentuknya fasa rombohedral ( < 7 %) di dalam cuplikan NBT mungkin akibat ukuran butir dan distribusi tekanan di dalam prekursor pada saat pembuatan pelet tidak merata. Sehingga difusi atom-atom Bi, Na dan Ti pada saat proses sinter tidak merata di seluruh cuplikan

CHARACTERIZATION OF (CuO-Fe2O3) CERAMICS WITH THREE DIFFERENT COMPOSITIONS SINTERED AT 1100 oC FOR NTC THERMISTOR

CHARACTERIZATION OF (CuO-Fe2O3) CERAMICS WITH THREE DIFFERENT COMPOSITIONS SINTERED AT 1100 oC FOR NTC THERMISTOR. The formation of (CuO-Fe2O3) ceramics for NTC thermistors based on CuO-Fe2O3 phase diagram has been studied. The ceramics were produced by pressing an homogeneous mixture of powder of (50 mole % CuO and 50 mole % Fe2O3 as composition 1), (40 mole % CuO and 60 mole % Fe2O3 as composition 2) and (34 mole % CuO and 66 mole % Fe2O3 as composition 3) and sintering the pressed powder at 1100 oC for 2 hours in air with cooling rate of 10 oC/minutes. Electrical characterization was performed by measuring electrical resistivity of the ceramics at various temperatures (25 oC - 100 oC). Analyses of microstructure and crystal structure were carried out by using optical microscope and x-ray diffractometer (XRD), respectively. The x-ray diffraction (XRD) analyses showed that the ceramics of composition 1 and 3 were composed of tetragonal spinel and that of composition 2 was composed of cubic spinel. Hematite second phase was found in the ceramic of composition 3. According to the optical microscopy data, it was known that the ceramics having three different microstructures have been produced. Very large rounded grains were observed in the ceramic of composition 1, polygonal grains were observed in that of composition 2 and very small grains were seen in that of composition 3. According to the electrical data, it was known that the ceramics having thermistor constant (B) between 2000 K and 5000 K have been produced. It was known also that the room temperature resistivity (ρRT) and thermistor constant (B) increased with the increase of Fe2O3 content. The value of B and ρRT of the produced (CuO-Fe2O3) ceramics fits the market requirement