Frequencies Dominations for Different Rating of Distribution Transformer under Transients

Power transients faults on high voltage lines are prominently due to high frequency transients. These transients affect the predicted life and efficiency of equipment. The Fast Fourier Transform (FFT) is helpful in analysing the effect of high frequencies and Frequency Response Analysis (FRA) provide support in diagnosis and detection of deformation in a transformers. The major aim of this study is to analyse the incorporation of frequencies based on resonating core of a particular transformer. Using transfer function method an impedance change in transformer has been observed when equipment is subjected to high voltage transients. The effect of change in impedance is that it degrade the life of a core with respect to time. In this paper, research that has been done already on Transformers of different ratings i.e. 100, 50 and 30 kVA are studied and then an experiment is performed on 50-kVA transformer. It was concluded that the core of a transformer having rating equal or less than 50 kVA practically shows single resonance behavior while above 50 kVA for instance 100-kVA transformer core resonates twice. In actual, result defines the core deviating frequency with respect to the rating of a transformer

Analisis Hasil Pengukuran Kualitas Daya Energi Listrik Pada Industri Tekstil

Primary energy used in the production process of PT. Textile Industries is the electric energy and thermal energy. The electrical energy supplied by PT. PLN (Persero) with contractual power of 5540 kVA, and has 5 units with a capacity of 2500 kVA transformer (1 unit), 2,000 kVA (2 units), and 1,250 kVA (2 units). From the analysis of several potential energy saving electrical system supply side can be recorded as follows: An unbalanced load can result in decreased system efficiency by 2%. Optimizing the performance of the capacitor bank regulators so that the work factor to achieve an optimum value (0.9). Losses incurred due to the low power factor can be calculated based on the following approaches: Losses = [1 -{pflow/pfhigh}2] x 100%. Losses in the transformer-1 (2000 kVA) is 479.8 kW, transformer-3 (2000 kVA) is 834.2 kW, transformer-4 (1250 kVA) is 521.4 kW, and transformer-5 (1250 kVA) is 125 kW. Current THD (total harmonic distortion) reduction to < 5%. Replacement tranformator so in accordance with the optimum loading and maximum efficiency from 9000 kVA to 6660 kVA. This replacement will reduce losses as high as zero load is usually equal to 3%

Lightweight, high-frequency transformers

The 25-kVA space transformer was developed under contract by Thermal Technology Laboratory, Buffalo, N. Y. The NASA Lewis transformer technology program attempted to develop the baseline technology. For the 25-kVA transformer the input voltage was chosen as 200 V, the output voltage as 1500 V, the input voltage waveform as square wave, the duty cycle as continuous, the frequency range (within certain constraints) as 10 to 40 kHz, the operating temperatures as 85 deg. and 130 C, the baseplate temperature as 50 C, the equivalent leakage inductance as less than 10 micro-h, the operating environment as space, and the life expectancy as 10 years. Such a transformer can also be used for aircraft, ship and terrestrial applications

New meter probes provide protection from high current power sources at potentials up to 600 volts

Meter probes incorporating integral fuse holder which contains limitation fuse of 600 V, 5A, with interruption rating of 50,000 KVA. provide required protection and minimize danger incurred by defective or improperly operated meter

Pollen, women, war and other things : reflections on the history of palynology

I am grateful to the Royal Swedish Academy of Sciences (Kungliga Vetenskapsakademien; KVA), Stockholm, for hosting the conference at which the themes in this paper were presented. For archival material, I appreciate access to (and the assistance of): Gunnar Erdtman papers, Center for History of Science, KVA (Maria Asp); Thomas Woodhead papers, Kirklees Museums and Galleries (Tolson Memorial Museum, Huddersfield; Chris Yates); Harold Hyde papers, Botany Section Correspondence, Amgueddfa Cymru National Museum Wales (Heather Pardoe); Kathleen Blackburn papers, Natural History Society of Northumbria Archive, Great North Museum (Hancock), Newcastle upon Tyne (Alan Hart); material concerning Florence Campbell James, Aberystwyth University (Julie Archer). Richard Bradshaw, Paul Buckland, Andrew Cameron, Peter Coxon, Egill Erlendsson, Michael Grant, Alan Hart, Angus Lunn, Limi Mao, Heather Pardoe, Ed Schofield and Richard West are thanked for advice and assistance. I appreciate the constructive comments on a draft of this paper by John Birks. Jenny Johnston assisted with artwork.Peer reviewedPublisher PD

Parameter estimation of electric power transformers using Coyote Optimization Algorithm with experimental verification

In this work, the Coyote Optimization Algorithm (COA) is implemented for estimating the parameters of single and three-phase power transformers. The estimation process is employed on the basis of the manufacturer's operation reports. The COA is assessed with the aid of the deviation between the actual and the estimated parameters as the main objective function. Further, the COA is compared with well-known optimization algorithms i.e. particle swarm and Jaya optimization algorithms. Moreover, experimental verifications are carried out on 4 kVA, 380/380 V, three-phase transformer and 1 kVA, 230/230 V, single-phase transformer. The obtained results prove the effectiveness and capability of the proposed COA. According to the obtained results, COA has the ability and stability to identify the accurate optimal parameters in case of both single phase and three phase transformers; thus accurate performance of the transformers is achieved. The estimated parameters using COA lead to the highest closeness to the experimental measured parameters that realizes the best agreements between the estimated parameters and the actual parameters compared with other optimization algorithms

Masalah Kurang Vitamin A (Kva) dan Prospek Penanggulangannya

Indonesia pernah tercatat karena keberhasilannya mengatasi masalah xerophtalmia sehingga tidak lagi menjadi masalah kesehatan masyarakat, meskipun masalah kurang vitamin A tingkat sub klinis (serum vitamin A &lt; 20 µg/dl) pada anak Balita masih 50%. Sejak krisis ekonomi tahun 1997, diperkirakan masalah KVA meningkat lagi, ditandai dengan diketemukannya kasus-kasus xerophtalmia di beberapa daerah dan bahkan xerophtalmia pada wanita usia subur (WUS). Apakah pada era otonomi dan desentralisasi, masalah KVA akan semakin cepat dapat diatasi sesuai dengan kemampuan daerah? Makalah ini mengkaji masalah KVA dan prospek penanggulangannya

ANALISA TEKNIS DAN PERENCANAAN PADA PANEL UTAMA TEGANGAN RENDAH DI HARCO MANGGA BESAR

Harco Mangga Besar adalah salah satu projek pembangunan mall, apartemen dan hotel. Untuk mendukung daya yang dibutuhkan dalam pembangunan tersebut digunakan sebuah trafo. Namun pada prakteknya, pemakaian beban dalam diagram satu garis tidak sesuai dengan beban yang direncanakan. Maka perlu adanya analisa dan kajian teknis maupun perencanaan sistem kelistrikan dalam pembuatan panel di Harco Mangga Besar, meliputi pengumpulan data transformer distribusi, sistem jaringan distribusi, penggunaan kawat penghantar jaringan distribusi, pembatas beban tiap titik jaringan dalam rangka menguji hipotesis. Berdasarkan data dari gambar perencana jumlah beban pada PUTRM1 sebesar 1.151.926 Watt kapasitas trafo 1600 kVA dan PUTR-M2 sebesar 1.172.286 Watt kapasitas trafo 1250 kVA. Setelah dilakukan perhitungan ulang, jumlah beban sebenarnya pada PUTR-M1 sebesar 821.835 Watt kapasitas trafo 1000 kVA dan PUTR-M2 sebesar 802.489 Watt kapasitas trafo 1000 kVA. Dari analisa data dan hasil pembahasan presentase penurunannya 30% dari total jumlah beban 1.624.324 watt kapasitas trafo 2000 kVA mampu mengatasi pertumbuhan beban selama 10 tahun kedepan sebesar 1.905.910 watt dengan mempertimbangkan karakteristik beban. Kata Kunci: Diagram Satu Garis, Trafo Distribusi, Karakteristik Beban. Harco Mangga Besar is one of the projects development of mall, apartment and hotel. To support the required power, one transformator is used. However in practice, the loads usage in a single line diagram does not match with the planned load. Thus it is necessary to do analysis, technical study and planning in electrical system in making the panel of Harco Mangga Besar, including collecting distributed data transformer, distribution network system, distribution network usage wire, limiting the burden of each network point in order to test hypothesis. Based on the data from the planner drawing, the total load on PUTR-M1 is 1,151,926 Watt with transformer capacity of 1600 kVA and PUTR-M2 is 1,172,286 Watt with transformer capacity of 1250 kVA. After re-calculation, the real load amount on PUTR-M1 is 821,835 Watt with transformer capacity of 1000 kVA and PUTR-M2 is 802.489 Watt with transformer capacity of 1000 kVA transformer. From the data analysis and discussion result, 30% reduction of the total load number of 1,624,324 watts capacity of 2000 kVA transformer is able to overcome the load growth for 10 years ahead of 1.905.910 watt by considering load characteristics. Keywords: Single Line Diagram, Distribution Transformator, Load characteristi