I Gusti Ngurah Satriyadi Hernanda
Institut Teknologi Sepuluh Nopember

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Analisis Karakteristik Arus dan Tegangan pada Inisiasi Feroresonansi Transformator Tegangan Rendah Hernanda, I Gusti Ngurah Satriyadi; Negara, I Made Yulistya; Soeprijanto, Adi; Asfani, Dimas Anton; Wahyudi, Mochammad; Fahmi, Daniar
Jurnal Nasional Teknik Elektro dan Teknologi Informasi (JNTETI) Vol 7, No 2 (2018)
Publisher : Jurusan Teknik Elektro dan Teknologi Informasi, Fakultas Teknik, Universitas Gadjah Mada

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (1195.58 KB) | DOI: 10.22146/jnteti.v7i2.429

Abstract

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.
Evaluasi Degradasi Isolasi Motor akibat Multi-factor Aging berdasarkan Indeks Polarisasi dan SEM-EDX Wahyudi, Mochammad; Asfani, Dimas Anton; Negara, I Made Yulistya; Fahmi, Daniar; Hernanda, I Gusti Ngurah Satriyadi
Jurnal Nasional Teknik Elektro dan Teknologi Informasi Vol 8, No 1 (2019)
Publisher : Jurusan Teknik Elektro dan Teknologi Informasi, Fakultas Teknik, Universitas Gadjah Mada

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (1189.562 KB) | DOI: 10.22146/jnteti.v8i1.495

Abstract

The operation of induction motor affected by stress factor causes insulation degradation. This degradation can be observed from changes in insulation characteristics, including electrical, physical, and chemical. This study aimed to evaluate the insulation resistance (IR) and polarization index (PI) since the induction motor condition was good until burned out. Scanning Electron Microscopy with Energy Dispersive X-ray Spectroscopy (SEM-EDX) testing was also carried out to analyze changes in microstructure, morphological characteristics, and chemical composition in stator windings. In addition, X-ray powder diffraction (XRD) testing was presented to validate that the damaged insulation was caused by the given stress. To accelerate degradation of insulation, induction motor in service condition was subjected by a lot of pressure simultaneously, including thermal, moisture, and salt contamination. The accelerated aging testing was gradually conducted according to three schemes with different pressure levels. The results showed that the applied stresses could accelerate the insulation aging. A significant decrease of IR and PI values was found in the third scheme, as the IR value was less than 5 MΩ and the PI value was 0.6 (danger category). The insulation failure was achieved at a total duration of testing for 222 hours. The results of SEM-EDX and XRD testing showed the presence of mineral deposits from water vapor, salt contaminants, cracks, and fracture on the insulation surface.