Daniar Fahmi

Application of health index method for transformer condition assessment

Power transformer is one of the electrical equipment that has a central and critical role in the power system. In order to avoid power transformer failure, information system that provides the transformer condition is needed. This paper is present the information system for diagnostic transformer condition based on health index. Health Index method provides a comprehensive transformer condition assessment. This method is resulting power transformer condition that divided into several categories according to the life time prediction and degradation level of transformer components. Analysis on dissolved gas, oil, and furan (insulation paper) are subjected to detect the faults types that could be occurs in transformer. The outputs of the analysis are life time prediction, types of possible faults, and recommendations for future maintenance action. For practical application, this method is applied to the transformer data test that provided by Indonesia Power Electric Company or PT PLN. Results of the analysis found that the smaller Transformer Health Index means greater number of population failure probability. This relationship is quite strong with the value of the correlation coefficient r is -0.63.

Evaluation of distribution network reliability index using Loop Restoration Scheme

In this study, to evaluate the reliability of network distribution system at Gresik area, Loop Restoration Scheme method is applied. This method is used to control the distribution system on every feeder that has a function to increase the reliability of the system. After applying this method, the information of the reliability level can be obtained and hopefully it will make a good impact. With the LRS method implementation for the PLN distribution system, it will provide a good refinement to the value of reliability index and becomes key point for further application. The reliability index values during normal conditions of PT PLN configuration with the conditions after applying the method of LRS on the distribution system is compared and analyzed. From the result of applied system, it can be informed that the distance is quiet significant and has better results.

Analisis Karakteristik Arus dan Tegangan pada Inisiasi Feroresonansi Transformator Tegangan Rendah

Ferroresonance is an interaction phenomenon between non-linear inductance and capacitance that initiates abnormal waveform of current and voltage. This phenomenon is very sensitive to system parameter and initial condition. In this paper, ferroresonance initiation involved a basic circuit of series ferroresonance with variation of source voltage magnitude on a single phase low voltage transformer. The scheme of experiment was based on the case of transformer energizing. The trends of current and voltage waveform on the primary windings were investigated and transformed by using Fast Fourier Transform (FFT). The harmonics spectrum was then employed to identify the feroresonance mode and calculate the Total Harmonics Distortion (THD) of current and voltage. The experimental results showed that the higher source voltage magnitude caused the ferroresonance responses to be seen more clearly. It was indicated by the more distorted waveform, the higher odd harmonics frequency amplitude especially for 150 Hz, and the greater THD. Based on the harmonics spectrum and wave period, the ferroresonance responses were identified as fundamental mode. The effects of initial conditions, such as residual flux of transformer and capacitor charge, were also seen on the distorted wave peak during transient condition. In addition, the difference of waveform between normal and ferroresonance condition could be more easily observed on the voltage than the current. The waveforms of current and voltage during experiment had been verified by using simulation.

Estimation of residual flux in single phase transformer using dynamic modeling of two winding single phase transformer

This study deals with estimation of residual flux in 1 kVA 1-phase transformer. Transformers used in the study have two type core cutting topology. The transformers were modeled with MATLAB software and then simulated to obtained inrush current. Experiments were also done in order to obtain its inrush current with different demagnetization time. The result showed a difference between simulated inrush current result and experimental result, which influenced by the existing residual flux and not yet disappeared during demagnetization process on the core of the single-phase transformer. The result shows that different core cutting topology affects the residual flux as well as the time of demagnetization.

Core-cutting topology effects of single phase 1-KVA transformer on inrush current

This paper deals with core-cutting method effects of single phase 1-KVA transformer on its inrush current. Different core-cutting topologies of transformer which is EI and EE were studied. Finite-element method and equivalent circuit based simulation were done to understand its effect on inrush current of transformer. Equivalent circuit is used to obtain the peak value of inrush current. Meanwhile finite-element method simulation is used to understand the distribution of flux density and magnetic field intensity. The results show that inrush current value influenced by core losses. Moreover, it is shown that EI cutting topology gives lower peak value of inrush current.

Analysis of low voltage arcing characteristic on direct short circuit through arcing thermal synchronization sensing and short circuit current

Short circuit fault cause arcing fault initiate fire accident. Fire case caused by short circuit fault in low voltage installation is occured every year. Several cases in fire accident at low voltage installation caused by short circuit fault. In this case, protection equipment failed to detect and secure the installation. This experiment investigate short circuit case at low voltage filament conductor cable 1.5 mm2. Short circuit cases variated by filament or strand that experienced contact. When short circuit occurred, arcing is recorded by thermal camera. Moreover, current and voltage arcing will be synchronized with thermal arcing image. The synchronization result is analyzed to obtain the caharacteristics of arcing that consist of value of maximum temperature arcing, sectional area arcing data, and duration of arcing. These characteristics are very useful to design arcing fault detector. The result shows that the arcing temperature, area, and duration respectively are up to 100 °C, 1300 mm2, 10 seconds.

Analysis of contaminant effect on ceramic & polymer insulator surface under artificial environmental condition

Performance of an insulating dielectric may decrease due to aging. The main cause of aging on insulator is contaminant arising on the insulator surface. In this study, effects of contaminants on the coating large leakage current on the surface of the polymer insulator are investigated. To analyze the effects, accelerated age testing module as a form of pre-conditions on polymer insulator aging is designed. Furthermore, dielectric strength testing is performed to determine the effect of contaminants on pre-breakdown voltage. The results of this study showed that the thickness level of contaminants on the surface of the layer affects insulator leakage current and pre-breakdown voltage.

Analysis of physical and electrical characteristics of transformer oil insulation during accelerated thermal aging experiment and its lifetime estimation using arrhenius law and breakdown voltage test

In this paper, the physical and electrical characteristics of accelerated thermal aged transformer oil insulation were investigated. The accelerated thermal aging of commercial transformer oil was conducted by increasing its temperature with different time. They were 100°C for 168 hours, 115°C for 96 hours, and 125°C for 48 hours. The lifetime of the tested oil was then estimated based on Arrhenius law and breakdown voltage test. The result showed that the physical characteristic of the tested oil during accelerated thermal aging could be analyzed based on its color changes, in which the higher level of thermal aging resulted in darker oils color. The electrical characteristic was associated with significant decreasing of breakdown voltage. The lifetime estimation based on Arrhenius law for the tested oil with 100°C, 115°C, and 125°C were about 25663 hours, 4300 hours, and 1408 hours, respectively. The lifetime estimation based on breakdown voltage test for the tested oil with 100°C, 115°C, and 125°C were about 20064 hours, 1526 hours, and 1106 hours, respectively.

Pemanfaatan Bentonite sebagai Media Pembumian Elektroda Batang

Sistem pentanahan merupakan suatu sistem yang bertujuan untuk mengamankan sistem tenaga listrik dari gangguan ke tanah maupun gangguan hubung singkat. Pada sistem pentanahan yang baik, resistansi pentanahan harus bernilai dibawah lima ohm. Resistansi pentanahan bergantung pada berbagai aspek antara lain yaitu struktur tanah, kelembapan tanah, dan kandungan yang ada dalam tanah itu sendiri. Dalam pengujian pada penelitian ini akan dilakukan perbaikan pada tanah dengan mencampurkan bentonite ke dalam tanah sebagai media pentanahan. Pencampuran bentonite bertujuan agar mendapatkan nilai resistansi pentanahan yang baik sesuai dengan standar sistem pentanahan. Pengujian dilakukan menggunakan elektroda batang dan alat earth resistance tester dengan metode tiga titik dimana elektroda utama atau elektroda pengukuran diberikan treatment sesuai dengan kondisi yang telah ditentukan. Diharapkan pada pengujian ini akan diketahui dampak dari bentonite terhadap penurunan nilai resistansi pentanahan. Hasil pengujian menunjukkan bahwa dengan mencampurkan bentonite pada media pentanahan, resistansi pentanahan menjadi lebih baik. Meskipun tidak terlalu signifikan, rata-rata penurunan dari setiap masing-masing treatment adalah sebesar 2 ohm.

Analisis Karakteristik Busur Api Listrik Tegangan Rendah Pada Hubung Singkat Langsung Melalui Sinkronisasi Penginderaan Termal Bunga Api Dan Arus Hubung Singkat

Salah satu bahaya yang bisa timbul akibat penggunaan listrik adalah gangguan hubung singkat yang bisa menimbulkan busur api listrik dan memicu terjadinya kebakaran. Kasus kebakaran yang disebabkan oleh hubung singkat listrik pada tegangan rendah meningkat setiap tahun. Pada beberapa kasus, kebakaran pada instalasi tegangan rendah disebabkan oleh adanya gangguan hubung singkat yang tidak menyebabkan putusnya fuse pengaman atau breaker yang diawali dengan munculnya busur api listrik. Dalam eksperimen ini akan dilakukan simulasi kejadian hubung singkat pada kabel serabut tegangan rendah ukuran 1.5mm2, dengan variasi jumlah serabut yang mengalami kontak. Ketika busur api listrik terjadi, arus dan tegangan busur api akan direkam. Selain itu, dalam waktu yang sama, proses terjadinya busur api listrik akan direkam melalui kamera termal. Data arus dan tegangan akan disinkronisasikan dengan data hasil pencitraan busur api listrik pada kamera termal. Hasil sinkronisasi ini akan dianalisa, sehingga dapat menghasilkan suhu maksimum busur api, data luas busur api, waktu peluruhan suhu busur api, arus maksimum ketika terjadi busur api, dan durasi terjadinya gangguan hubung singkat. Hasil studi ini diharapkan dapat membantu pembuatan alat proteksi busur api listrik tegangan rendah pada penelitian selanjutnya.