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"Lightning current waves are resulted by electric discharge from the clouds to the ground These waves are stated as a wave-front time and wave-tail time. The comparation between the wave-tail time and the wave front time defined as a constant "k". A mathematical approach to determine the impulse wave which base on the constant "k" has been published however these were limited by the big constant "h" or the wave which has a long tail. This paper will explain how to determine the constant "lc" of impulse wave which has a short and long tail. The constant "k" resulted from the experiment will be applied to determine the impulse wave. The comparation from the experiment and mathematical approach resulting very satisfactory outcome."

"Penghijauan bukan merupakan kegiatanyangpositifbagi saluran udara tegangan menengah (SUTM), karena sering menimbulkan gangguan sesaat akibat sentuhan ranting pohon yang tertiup angin dengan konduktor SUTM. Untuk mengatasi gangguan sesaat tersebut, maka digunakan kabel udara.Performance terhadap petir pada SUTM dengan kabel udara (OHC) juga akan mengalami perubahan, karena kekuatan isolasi OHC akan mempengaruhi jarak sambaran petir pada konduktor SUTM. Percobaan dengan menggunakan skala model telah dilakukan untuk mendapatkan hubungan jarak sambaran petir langsung ke SUTM yang menggunakan konduktor telanjang dan OHC. Dari hasil percobaan menunjukan bahwa kekuatan isolasi OHC akan memperkecil jarak sambaran petir langsung.

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Forestation is not always a positive activity for medium voltage overhead lines (MVOL), because it is often causing a temporary fault to MVOL when branches of adjacent trees is blown by the wind and to avoid that fault, then overhead cable (OHC) is used.

Lightning performance of MVOL using OHC have been improved since the dielectric strength of the insulation of OHC will affect and improve the striking distance to conductor of MVOL. The experiment results using scaled model shows the correlation between the striking distance of MVOL bare conductors to OHC, and the strength of OHC insulation will reduce the striking distance."

"ABSTRAKTorsi cogging adalah torsi yang ada pada setiap generator magnet permanen, muncul karena adanya interaksi antara slot pada stator dengan medan elektromagnetik yang dihasilkan oleh magnet permanen pada rotor. Torsi ini menghambat kerja generator untuk menghasilkan daya listrik Penelitian ini memfokuskan pada reduksi torsi cogging pada generator magnet permanen dengan metode anti notch. Akibat adanya anti notch, maka dilakukan penurunan model matematik dari kerapatan fluks magnetik normal Bn = Bar dan kerapatan fluks magnetik tangensial Bt = Ba? . Persamaan torsi cogging yang baru berdasarkan perbedaan radius tepi dalam stator pada posisi-posisi tertentu. Validasi persamaan matematik melalui perhitungan dengan MATLAB dan FEMM. Metode anti notch efektif untuk menurunkan torsi cogging namun perubahan energi yang berhubungan dengan efisiensi tidak banyak berubah. Dengan penambahan anti notch maka nilai Bt turun sehingga torsi cogging minimal. Hasil torsi cogging yang didapatkan antara keduanya tidak persis sama nilainya, namun pola dan kecenderungannya sama, yaitu cenderung mendekati nol dan lebih stabil dibandingkan dengan model referensi. Persentase reduksi torsi cogging untuk model sederhana anti notch adalah 92,9 dan 97,03 . Eksentrisitas rotor yang diijinkan antara 0,5 sampai 1 derajat. Torsi cogging minimal akan memperhalus jalannya rotor, sehingga pada kecepatan angin rendah, rotor akan berputar untuk menghasilkan daya listrik

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ABSTRACTCogging torque is the remaining torque of any permanent magnet generator, arising from the interaction between the stator slot and the electromagnetic field brought about by the permanent magnet on the rotor. This torque discourages the performance of the generator to generate electrical power. This research concentrates on reducing cogging torque on the permanent magnet generator by anti notch method. As a following of the anti notch, the mathematical model is derived from normal magnetic flux density Bn Bar and tangential magnetic flux density Bt Ba . The new cogging torque equation is based on the diversity in the edge radius in the stator at particular positions. Validate mathematical equations through computations with MATLAB and FEMM. An adequate anti notch method for reducing cogging torque but energy related changes in efficiency has not varied considerably. With the extension of anti notch thus the value of Bt down so that the minimum cogging torque. The result of the cogging torque achieved between the two is not precisely the same value, but the pattern and trend are the same, which tends to be near zero and further steady than the reference model. The percentage of cogging torque reduction for simple anti notch models is 92.9 and 97.03 . The permissible rotor permeability is between 0.5 to 1 degree. Minimum cogging torque will lighten the rotor course, so at moderate wind speeds, the rotor will rotate to generate electrical power."