Identifying Power Equipment Partial Discharge Signals via Pulse Appearance Frequency, Duration, and Pulse Polarity

2011 ◽  
Vol 354-355 ◽  
pp. 1228-1234 ◽  
Author(s):  
Ju Chu Hsieh ◽  
Yu Hsun Lin
Keyword(s):  
Pulse Duration ◽  
Laboratory Experiments ◽  
Noise Suppression ◽  
Partial Discharge ◽  
Power Equipment ◽  
Shape Features ◽  
Duration Time ◽  
Field Noise ◽  
Pulse Polarity ◽  
Appearance Frequency

At present, the contribution of partial discharge (PD) to power equipment insulation diagnosis is highly valued globally. However, most PD measurements are still performed in the laboratory, the main reason being that the effects of on-field noise suppression are still limited and unsatisfactory. To date, among noise suppression methods, wavelet de-noising is the most common. This study focuses on improving the effects of on-field noise suppression. The shape features (pulse equivalent bandwidth and pulse duration time) can be analyzed, and PD signals can consequently be discovered. This study applied the proposed method to on-field and laboratory experiments, and presents a discussion of the outcomes regarding the effects on noise suppression. This method can improve the effects of noise suppression.

Matched field noise suppression: Principle with application to towed hydrophone line array

2003 ◽  
Vol 48 (12) ◽  
pp. 1207-1211 ◽  
Author(s):  
Yuanliang Ma ◽  
Shefeng Yan ◽  
Kunde Yang
Keyword(s):  
Noise Suppression ◽  
Line Array ◽  
Field Noise

Acoustic and flow fields of an excited high Reynolds number axisymmetric supersonic jet

2010 ◽  
Vol 656 ◽  
pp. 507-529 ◽  
Author(s):  
M. SAMIMY ◽  
J.-H. KIM ◽  
M. KEARNEY-FISCHER ◽  
A. SINHA
Keyword(s):  
Reynolds Number ◽  
Nozzle Exit ◽  
Noise Suppression ◽  
Polar Angle ◽  
Broadband Noise ◽  
Far Field ◽  
Initial Growth ◽  
Wide Range ◽  
Field Noise ◽  
Noise Amplification

An axisymmetric perfectly expanded Mach 1.3 jet, with a Reynolds number based on the nozzle exit diameter (ReD) of 1.1 × 106 and turbulent boundary layer at the nozzle exit, was excited using localized arc filament plasma actuators over a wide range of forcing Strouhal numbers (StDF). Eight actuators distributed azimuthally were used to excite azimuthal modes m = 0–3. Far-field acoustic, flow velocity and irrotational near-field pressure were probed with a three-fold objective: (i) to investigate the broadband far-field noise amplification reported in the literature at lower speeds and ReD using excitation of m = 0 at low StDF; (ii) to explore broadband far-field noise suppression using excitation of m = 3 at higher StDF; and (iii) to shed some light on the connection between the flow field and the far-field noise. The broadband far-field noise amplification observed is not as extensive in amplitude or frequency range, but still sufficiently large to be of concern in practical applications. Broadband far-field noise suppression of 4–5 dB at 30° polar angle peak frequency, resulting in approximately 2 dB attenuation in the overall sound pressure level, is achieved with excitation of m = 3 at StDF ~ 0.9. Some of the noteworthy observations and inferences are (a) there is a strong correlation between the far-field broadband noise amplification and the turbulence amplification; (b) far-field noise suppression is achieved when the jet is forced with the maximum jet initial growth rate frequency thus limiting significant dynamics of structures to a shorter region close to the nozzle exit; (c) structure breakdown and dynamic interaction seem to be the dominant source of noise; and (d) coherent structures dominate the forced jet over a wide range of StDF (up to ~ 1.31) with the largest and most organized structures observed around the jet preferred mode StDF.

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