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Cast-resin dry-type transformers are widely used in high power applications. Long-term operation increases the extent of damages if no proper safeguards are taken. The major cause of transformer damages is insulation deterioration, which is correlated with partial discharge (PD) occurrence. Recent PD research studies have focused on how to locate the PD occurrence and improve the accuracy of PD detection...
In this paper, a new designed acoustic emission (AE) wideband amplifier and waveguide are used to locate the partial discharge (PD) signal in cast-resin dry-type transformer. When PD events occur in a cast-resin dry-type transformer, it is often accompanied by electromagnetic and ultrasonic signals. The AE method can be used to detect and locate ultrasonic source. However, due to the high sound attenuation...
The patterns of signal that detected by using electric and acoustic emission (AE) methods can be used for the identification of partial discharge (PD) events in power cable. Because the transmission distance of sounds in the insulation layer of power cables is limited, when discharging occurs at continuous or joint positions, a high-frequency current transformer (HFCT) and/or AE sensor can be used...
The detection and location of partial discharge (PD) in cast-resin dry-type transformers using the acoustic emission (AE) method is very difficult: the sound in filled epoxy is highly attenuated and is easily interfered with external sound sources. In addition, there is no operating procedure for the detection, identification and location of PD in cast-resin dry-type transformers up to present. In...
This paper aims to discuss the measurement and recognition of partial discharge (PD) signals in gas insulation load breaker switch (GILBS) by using high frequency current transformer (HFCT) and acoustic emission (AE) sensors. Three kinds of fault were made purposely within the GILBS that sealed up with SF 6 gas. Then we increase the voltage onto the GILBS until it produce PDs and measure the signals...
Empirical mode decomposition (EMD) has good adaptivity for non-stationary and nonlinear signal analysis. This paper uses the advantage of EMD and combines with the wavelet transform (EMD-WT) to extract partial discharge (PD) signals in noises. The wavelet transform is a common used method for PD signal denoising. However, once the signal to noise ratio (SNR) decreases seriously, the WT method will...
The acoustic emission (AE) method could be used to detect and locate partial discharges (PD) in cast-resin dry-type transformers. However, due to the high sound attenuation in the filled epoxy, the signal is prone to interference from external noises and thus, in practice, there is little possibility of detecting PD. In this study, two techniques were developed to alleviate the shortcomings of the...
The cause of power electric cable fault is often source from the cable splice and cable terminator used in the electric cable connection and the partial discharge released from the improper construction process. It makes the insulation stuff aging and damaged. When the insulation capability becomes worse, it could cause unexpected damage on the high-voltage cables, many industry and research institutes...
In this paper, we analyze and compare the partial discharge (PD) signals from acoustic emission (AE) and high-frequency current transformer (HFCT) measurements with Hilbert-Huang transform (HHT). Commonly, the Fourier transform (FT) method is used to illustrate information in frequency domain. The HHT, a time-frequency method, provides another viewpoint to interpret the PD signals. This method allows...
To detect partial discharge (PD) signal from internal defects or particles in gas insulation system (GIS), both couple capacitor (CC) and acoustic emission (AE) methods are applied in the examinations. According to the measured data, we need to distinguish whether it is PD or particle impact signal. From the CC measurement we can determine whether discharge occurs in one of the GIS chambers or not...
This study adopts the acoustic emission (AE) method to measure partial discharges (PD) in a cast-resin dry-type transformer and proposes a waveguide atop the high-voltage winding of the transformer to improve the propagation of the PD acoustic signals occurring in winding to acoustic emission sensors used. A waveguide is proposed to improve the signalspsila quick attenuation and it also is a safe...
Over the course of the past 20 years, the number of signal processing methods used to analyze the partial discharge (PD) of electrical equipments has greatly increased. In this paper, we analyze and compare the PD signals from acoustic emission (AE) and high-frequency current transformer (HFCT) measurements with Hilbert-Huang Transforms: (HHT). The HHT demonstrates several excellent advantages in...
A new, simple partial discharge (PD) detector for low-voltage rotating electrical machines using acoustical emission (AE) technique is developed in this study. Common electric components were used in the detector, which reduces the cost of inspection, comparing with the traditional PD detection methods that use expensive equipment costing from tens of thousands to several millions dollars. Experimental...
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