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"Skripsi ini dibuat dengan pengkajian dari dua prosedur pengukuran untuk diagnosis sistem isolasi pada generator tegangan tinggi. Pengukuran dapat dibagi menjadi dua bagian, yaitu pengukuran secara online dan offline. pengukuran secara offline terdiri atas resistansi isolator, faktor disipasi, dan peluahan parsial, sedangkan pengukuran secara online hanya terdiri atas peluahan parsial. IEEE and IEC telah membuat standar yang disebut praktik yang direkomendasikan atau spesifikasi teknis untuk mengukur resistansi isolator, faktor disipasi, dan peluahan parsial dengan menggunakan peralatan diagnostik elektris. Pengukuran secara offline akan dibandingkan dengan pengujian sebelumnya untuk melihat sejauh mana degradasi isolator yang terjadi. Pengukuran secara online didasarkan pada perubahan beban dan waktu kerja dari mesin tersebut. Parameter ketika mesin bekerja seperti beban, tekanan gas pendingin akan dianalisis untuk melihat bagaimana parameter tersebut mempengaruhi degradasi dari sistem isolasi. Pengujian secara offline menunjukkan bahwa fasa R memiliki kondisi isolator terburuk, fasa S memiliki penurunan kualitas isolator yang paling signifikan dan, fasa T memiliki kualitas dan stabilitas nilai isolator bila dibandingkan dengan fasa lainnya. Selain itu, pengujian peluahan parsial menunjukkan telah terjadi delaminasi tape layer pada ketiga fasa yang diakibatkan adanya perubahan nilai vibrasi yang signifikan selama pengoperasian mesin. Pengujian secara online menunjukkan bahwa fasa S memiliki perubahan arus dan daya disipasi yang paling besar dibandingkan fasa lainnya seiring bertambahnya waktu pengoperasian dan meningkatnya pembebanan.

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This work is based on the study of two different measurements procedures for the diagnosis of insulation systems of high voltage generators. The measurement can be conducted into two ways, offline or online measurement. The offline measurements consist of Insulation Resistance, Partial Discharge, and Dissipation Factor measurement, meanwhile online measurements consist only partial discharge measurement. The measurements were done in stator windings not only to check the quality but also for the investigation of changes in operating processes.

IEEE and IEC have created standards called recommended practices or technical specifications to address polarization index, dissipation factor, and offline online PD measurement using electrical diagnostic equipment. The offline measurement will be comparated with previous measurement to see how degradation takes place.

The online measurement will be based on on load variable and machine rsquo s working hour. Also, the online parameter such as load, vibration, coolers pressure, and temperature will be analysed to see how it can affect the degradation of the insulation system.

The result of offline measurements show that phase R has the worst condition, phase S has the most significant deterioration, and phase T has the best condition and stability in deterioration.

In addition, partial discharge measurement indicates that the insulation has been undergoing delamination of the tape layer due to significant changes in vibration values during the operation of the machine. The result of online measurements show phase S has the most significant changes in current and power dissipation compared to other phases due to increment of operation time and load."

"The book introduces the reader to the major components of a high voltage system and the different insulating materials applied in particular equipments.During a review of these materials, measurable properties suitable for condition assessment are identified. Analyses are included of some of the insulation fault scenarios that may occur in power equipment.The basic facilities for carrying out tests on the internal and external insulation structures at high and low voltages are described. Tests and measurements according to specifications, on-site requirements and research investigations are considered.Advances in the application of digital techniques for detection and analyses of partial discharges are discussed and methods in use, or under development, for service condition monitoring are described. These include the utilization of new sensors, the solution of online problems associated with noise rejection and the adaptation of artificial intelligence techniques for incipient fault diagnosis.The subject matter of the book is suitable for final year courses in electrical power engineering, short courses in insulation condition assessment and postgraduate programmes. Power system engineers associated with high voltage equipment should find the book of value in relation to fault investigations, maintenance requirements, insulation testing and condition monitoring."

"This paper deals with the electrical insulation of a gap bridged by a solid dielectric between a pair of electrodes in a vacuum, where the dielectric is a model of an insulating spacer holding electrodes in various vacuum devices. Such gap configuration is typical as a model for studying physical mechanisms of an electrical breakdown or a flashover in a vacuum, in which the insulation ability isconsiderably lower than a gap without any insulating spacers. Many researchers have long investigated the mechanisms of flashover, and it is believed that the charging of the insulator surface is the primary drive of such weakness. One of the effective approaches for studying mechanisms is to analyze the characteristic of charge accumulated on the insulator surface both by experiments and bynumerical analyses. This paper reviews previous works conducted by the author’s research group and demonstrates the difficulties we have encountered upon conducting the numerical analyses."

"Condition monitoring of engineering plants has increased in importance as engineering processes are automated and manpower is reduced. However, electrical machinery receives attention only at infrequent intervals when plant is shut down and the application of protective relays to machines has also reduced operator surveillance.A first edition of Condition Monitoring of Electrical Machines, written by Tavner and Penman, was published in 1987. The economics of industry have now changed, as a result of the privatisation and deregulation of the energy industry, placing emphasis on the importance of reliable operation of plant, throughout the whole life cycle, regardless of first cost. The availability of advanced electronics and software in powerful instrumentation, computers, and digital signal processors (DSP) has simplified our ability to instrument and analyse machinery. As a result condition monitoring is now being applied to a wider range of systems from fault-tolerant drives of a few hundred watts in the aerospace industry, to machinery of a few hundred megawatts in major capital plant.In this new book the original authors have been joined by Ran, an expert in power electronics and control, and Sedding, an expert in the monitoring of electrical insulation systems. Together the authors have revised and expanded the earlier book, merging their own experience with that of machine analysts to bring it up to date."

"Transformator adalah salah satu peralatan listrik yang mempunyai peran yang sangat penting dalam suatu sistem tenaga listrik. Oleh karena itu memperhatikan dan memastikan transformator agar selalu dalam keadaan baik merupakan suatu keharusan yang harus dilakukan. Salah satu faktor yang berpengaruh terhadap kondisi dari transformator adalah minyak transformator. Pengujian minyak transformator merupakan tindakan yang sering kali dilakukan guna mengetahui dan menganalisis kondisi dari transformator serta jenis kegagalan yang terjadi pada transformator. Pengujian minyak transformator meliputi pengujian terhadap parameter kualitas minyak isolasi dan pengujian analisis gas terlarut (DGA). Pada skripsi ini akan dilakukan analisis terhadap kondisi dari transformator peleburan EAF 9 pada Pabrik Baja Slab 2 PT. Krakatau Steel berdasarkan hasil pengujian terhadap minyak transformator peleburan EAF 9. Berdasarkan hasil pengujian terhadap minyak transformator peleburan EAF 9 mulai tahun 2008 hingga 2013, didapatkan beberapa hasil analisis terkait kondisi dari transformator peleburan EAF 9. Yaitu berdasarkan pengujian terhadap beberapa parameter kualitas minyak isolasi disimpulkan bahwa kondisi dari minyak isolasi dari transformator peleburan EAF 9 masih tergolong dalam keadaan baik. Sedangkan berdasarkan interpretasi terhadap hasil pengujian DGA, disimpulkan bahwa indikasi kegagalan yang terjadi pada transformator peleburan EAF 9 berupa pemanasan pada kertas isolasi dan minyak transformator.

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Power transformer is one of the most important electric equipment and vital link in a power system. Because of that, pay attention and ensure that transformer is always in good condition is a necessity which must be performed. One of the things that can affect the power transformer condition is insulating oil of transformer. Insulating oil testing is routinely used to investigate and diagnose transformer condition and the types of faults which are occurred in the power transformer. There are two types of insulating oil testing which are often performed, those are oil contamination testing and DGA (dissolved gas analysis) testing. In this paper will be performed analysis about the condition of furnace transformer of Electrical Arc Furnace 9 in Slab Steel Plant 2 PT. Krakatau Steel according the results of insulating oil testing. According the results of insulating oil testing of furnace transformer in Electrical Arc Furnace 9 since 2008 until 2013, there are some analysis that recognized about the condition of furnace transformer. According the result of oil contamination testing, can be decided that the condition and quality of insulating oil of transformer is still classified in good condition. And according interpretation from the result of DGA testing, can be decided that there are some faults that detected in the furnace transformer, those are overheating of cellulose and overheating of oil."

"Transformator daya merupakan salah satu komponen penting dalam sistem tenaga listrik yang paling banyak digunakan. Pengujian Dissolved Gas Analysis (DGA) digunakan untuk mendiagnosis kegagalan transformator sebelum terjadi kerusakan yang lebih parah dengan menganalisis indikator gas yang terlarut pada minyak transformator melalui beberapa metode salah satunya menggunakan metode konvensional. Namun, berdasarkan sebagian besar pengujian yang dilakukan oleh peneliti, tingkat akurasi pendeteksian metode konvensional tersebut masih cukup rendah, oleh karena itu, penelitian Tesis ini memiliki tujuan utama dalam mengidentifikasi kelemahan salah satu metode konvensional yaitu metode Rogers Ratio. Metode penelitian ini menggunakan modifikasi pada flow chart diagnosa gangguan yang kemudian diterapkan dalam interpretasi hasil uji DGA pada transformator daya dalam kasus di Transformator GSUT #1 20/11 kV PLTMG Manokwari. Berdasarkan hasil peneltian ini metode sebelumnya tidak dapat mendiagnosa gangguan (Undetermined) sedangkan setelah dimodifikasi dapat mendiagnosa gangguan Thermal Fault < 150-200OC. Jika dibandingkan dengan metode konvensional lain yang sudah teruji seperti dengan interpretasi metode Duval Triangle didapat hasil diagnosa gangguan Thermal Fault < 300OC artinya secara umum dapat diketahui bahwa telah terjadi gangguan thermal pada internal transformator pada temperatur dibawah 300OC. Jadi hasil interpretasi modifikasi metode Rogers Ratio lebih baik dibanding sebelumnya sehingga dapat diterapkan sebagai tambahan teknik interpretasi data hasil uji DGA.

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Power transformers are one of the most widely used important components in the electric power system. Dissolved Gas Analysis (DGA) testing is used to diagnose transformer failures before more severe damage occurs by analyzing gas indicators dissolved in transformer oil through several methods, one of which uses conventional methods. However, based on most of the tests conducted by researchers, the detection accuracy of the conventional method is still quite low, therefore, this thesis research has the main objective of identifying the weaknesses of one of the conventional methods, namely the Rogers Ratio method. This research method uses modifications to the fault diagnosis flow chart which is then applied in the interpretation of DGA test results on power transformers in the case of the GSUT #1 20/11 kV Transformer of PLTMG Manokwari. Based on the results of this research, the previous method cannot diagnose the fault (Undetermined) while after being modified it can diagnose the Thermal Fault < 150-200OC fault. When compared with other conventional methods that have been tested such as the interpretation of the Duval Triangle method, the results of diagnosing Thermal Fault < 300OC means that in general it can be known that there has been a thermal disturbance in the internal transformer at temperatures below 300OC. So the results of the modified interpretation of the Rogers Ratio method are better than before so that it can be applied as an additional technique for interpreting DGA test data."