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The classical multiple signal classification (MUSIC) method has been widely used in induction machine fault detection and diagnosis. This method can extract meaningful frequencies but cannot give accurate amplitude information of fault harmonics. In this paper, we propose a new frequency analysis of stator current to estimate fault-sensitive frequencies and(More)
This paper proposes a new diagnosis algorithm to detect broken rotor bars (BRBs) faults in induction motors. The proposed algorithm is composed of a frequency signal dimension order (FSDO) estimator and a fault decision module. The FSDO estimator finds a number of fault-related frequencies in the stator current signature. In the fault decision module, the(More)
A newly developed diagnosis system using DGA (dissolved gas analysis) was studied for the effective management of oil-immersed transformers. It consists of the measurement system of dissolved hydrogen gas in oil and DGA software based on dissolved gases such as acetylene (C<sub>2</sub>H<sub>2</sub>), hydrogen (H<sub>2</sub>), ethylene(More)
Since partial discharges weaken the insulation performance of power transformers, the detection of PD is very important for prevention of fatal incidents. This study describes the use of electromagnetic coupler for the partial discharge measurement of transformers. Folded dipole antennas were used as sensors and installed in test chamber for experiments.(More)
A time-domain transmission measurement technique for extracting the complex propagation constant of a cross-linked polyethylene cable is proposed. For this extraction, a pulse transmitted through the cable is measured in the time domain and analyzed in the frequency domain. The proposed technique does not use an open termination for reflection, and(More)
This paper described the differences of partial discharge spectra which were measured according to types of defects and couplers. The partial discharge spectra which were occurred in three type defects were measured in the GIS chamber with a log periodic coupler and partial discharge spectra which were occurred in surface discharge defects were measured in(More)
This paper describes applicability of semiconductor gas sensor for measurement of dissolved hydrogen gas in oil. On line gas measurement is useful for continuous monitoring of power transformer. Recently many studies on application of hydrogen gas sensors, due to their simplicity and low price, have been done for that purpose. In general responses of(More)
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