Ching-Chau Su

Partial discharge detection using acoustic emission method for a waveguide functional high-voltage cast-resin dry-type transformer

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 method for electrical equipments measurement. Finally, a waveguide is practically installed on a cast-resin dry-type transformer; the measurements and the locating of PDspsila AE signals for transformer are carried out. This study demonstrates a feasible new simple, safe and economical solution for diagnosing and locating PDs in the transformer.

Simple partial discharge detector for power equipment using acoustic emission technique

The present invention relates to a simple detector for partial discharge with the acoustic emission technique, which provides essentially with an acoustic emission sensor being set on a power equipment. Still, the output of the acoustic emission sensor is connected with a preamplifier and a bandpass filter in turn and the output of the bandpass fitted up with a comparator. The signals of square waves generated by the comparator can be transmitted to a microprocessor as concurrently as a counter in the microprocessor can be used to count up times for partial discharge by seconds; then, the resulted times can be displayed. Consequently, it is convenient to determine whether the power equipment is necessarily maintained by means of counting up times for partial discharge.

Partial discharge signal analysis using HHT for cast-resin dry-type transformer

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 for collecting information on PD signals both with regards to the time and frequency domains simultaneously. It has been verified that the HHT can provide more information when compared with FT method. In this work, the marginal spectrum simplifies the results of HHT method fatherly. From the marginal spectrum, the abiding and weak noise source can be properly estimated, and the instantaneous variation can be emphasized. The results reported here show that the HHT method has great promise for cast-resin dry-type transformer PD signals analysis.

GIS partial discharge examination and classification from the on-line measurements

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 and tell what chambers are possible related to the events. By AE sensors, we can further confirm that whether it is the chamber of PD or particle impact occurred. If there is no discharge events measured from the CC sensors, the AE sensors would be stuck on the chamber to further determine whether particle impact occur in the chambers or not. The signals of particle impact received from the online measurement of GIS are verified through the inspection results of opening.

The transmission characteristics of sound wave in power cable

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 have paid more and more attention on the maintenance of high voltage cables and diagnosis techniques of fault prediction. The acoustic emission method mentioned in this article is mainly on the characteristics analysis of basic measurement of sound delivery characteristics during the electric cable connection, the research on the original location of sound wave, and distribution attenuation.

Data Analysis Using Hilbert-Huang Transform for Partial Discharge in Low Voltage Motors

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 the PD signal analysis application.

The application of partial discharge detector and electro-acoustic signals analysis methods for power cables monitoring

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 to measure the discharge signal. However, when measuring on site, the signals are influenced by noise. Our solution for this problem is from two perspectives. First, we designed a low-cost simple PD detector and use multiple detectors to measure PD in power cables. Second, empirical mode decomposition (EMD) and fast Fourier transform (FFT) signal processing methods were used to analyze and compare the collected data.