A digital sampling rate synchronization scheme for fully digital relay protection

2010 ◽  
Author(s):  
Chao Cai ◽  
Yuping Lu
Keyword(s):  
Sampling Rate ◽  
Relay Protection ◽  
Digital Sampling ◽  
Synchronization Scheme

scholarly journals Application of unified microprocessor relay protection units in electrical machine diagnostics

2020 ◽  
Vol 21 (6) ◽  
pp. 93-100
Author(s):  
V. I. Polishchuk ◽  
M. V. Kritsky ◽  
D. M. Bannov ◽  
S. V. Malyshev
Keyword(s):  
Short Circuit ◽  
Asynchronous Motor ◽  
Sampling Rate ◽  
Relay Protection ◽  
Synchronous Generator ◽  
Digital Processing ◽  
Electrical Machine ◽  
Selective Determination ◽  
Rotor Winding

The article concentrates on the topical issue connected with the detection of defects in the rotor winding of electric machines. The experimental sampling and digital processing of electrical signals from controlled windings is in the basis. The authors conducted the research using two experimental units for asynchronous motor and synchronous generator, respectively. A distinctive feature of the proposed research stands is in solving the problems of digital processing and data analysis on the basis of the application of microprocessor relay protection unit BMRZ developed in Russia. The authors applied method of wavelet decomposition to select the detailing component. They also presented the results of experiments for the breakage in the short-circuit rotor of an asynchronous motor and proved that the microprocessor-based BMRZ device is capable of digitizing at a sampling rate that meets the requirements, and in conjunction with the data processing algorithms that carry out the selective determination of hard-to-detect defects, is applicable in the diagnosis of electrical machines.

Method for Determining the Estimated Timing Uncertainty for Digital Sampling Instruments

2021 ◽  
Author(s):  
Sara DiGregorio ◽  
Keyword(s):  
Rise Time ◽  
Measurement Errors ◽  
Interpolation Method ◽  
Sampling Error ◽  
Sampling Rate ◽  
Department Of Energy ◽  
Time Base ◽  
Percentage Error ◽  
Digital Sampling ◽  
Timing Uncertainty

The overall uncertainty in digital captured data points is often misunderstood in our organization and is typically accepted as only the manufacturer uncertainty specification of the time base clock typically on the order of 10-100 parts per million. The time base clock of digital sampling technologies is critically important to maintain timing control of the internal electronics and to achieve the specified sampling rate of the instrument. The time base clock must remain within the manufacturer specification tolerance throughout the calibration interval to assure accurate performance. However, the time base uncertainty does not adequately account for the additional measurement errors accompanying the capture and evaluation of the time values for any cardinal points of interest when periodically sampling analog waveforms generated by other instruments or Units Under Test (UUTs). The proposed methodology described here details a general approach used to estimate the magnitude of the digital instrument sampling error when capturing analog waveforms based upon the instrument sampling rate, the frequency of a nominally equivalent sinusoidal waveform, as well as, whether the time value of any cardinal points is selected by a ‘Next Point After’ or Interpolation method for our purposes. Finally, the overall estimated timing uncertainty is quantified by arithmetically combining the error contributions for the sampling rate, the cardinal point selection method, and the instrument time base specification. The results of this method aid in selecting the appropriate digital sampling technology based upon waveform rise time requirements and provide general engineering guidance. Since the estimated error is a portion of the sampling timestep interval, the percentage error could be significant based upon the measured rise time. Sandia National Laboratories is a multi-mission laboratory managed and operated by National Technology & Engineering Solutions of Sandia, LLC, a wholly owned subsidiary of Honeywell International Inc., for the U.S. Department of Energy National Nuclear Security Administration under contract DE-NA0003525.

Digital sampling rate and ECG analysis

1985 ◽  
Vol 7 (3) ◽  
pp. 247-250 ◽  
Author(s):  
G.P. Pizzuti ◽  
S. Cifaldi ◽  
G. Nolfe
Keyword(s):  
Sampling Rate ◽  
Ecg Analysis ◽  
Digital Sampling

The extended Fourier algorithm: Application in discrete optics and electron holography

1994 ◽  
Vol 52 ◽  
pp. 918-919
Author(s):  
E. Voelkl ◽  
L. F. Allard
Keyword(s):  
Fourier Transform ◽  
Fourier Transforms ◽  
Sampling Rate ◽  
Electron Holography ◽  
Optical Bench ◽  
Fourier Space ◽  
Ccd Cameras ◽  
Simulated Image ◽  
Initial Sampling ◽  
Fourier Algorithm

The conventional discrete Fourier transform can be extended to a discrete Extended Fourier transform (EFT). The EFT allows to work with discrete data in close analogy to the optical bench, where continuous data are processed. The EFT includes a capability to increase or decrease the resolution in Fourier space (thus the argument that CCD cameras with a higher number of pixels to increase the resolution in Fourier space is no longer valid). Fourier transforms may also be shifted with arbitrary increments, which is important in electron holography. Still, the analogy between the optical bench and discrete optics on a computer is limited by the Nyquist limit. In this abstract we discuss the capability with the EFT to change the initial sampling rate si of a recorded or simulated image to any other(final) sampling rate sf.

The Attenuation of Very Low Frequency Brain Oscillations in Transitions from a Rest State to Active Attention

2009 ◽  
Vol 23 (4) ◽  
pp. 191-198 ◽  
Author(s):  
Suzannah K. Helps ◽  
Samantha J. Broyd ◽  
Christopher J. James ◽  
Anke Karl ◽  
Edmund J. S. Sonuga-Barke
Keyword(s):  
Brain Activity ◽  
Sampling Rate ◽  
Low Frequency ◽  
Future Research ◽  
Adhd Symptoms ◽  
Default Mode ◽  
Very Low Frequency ◽  
Wide Range ◽  
Interference Hypothesis ◽  
Mode Interference

Background: The default mode interference hypothesis ( Sonuga-Barke & Castellanos, 2007 ) predicts (1) the attenuation of very low frequency oscillations (VLFO; e.g., .05 Hz) in brain activity within the default mode network during the transition from rest to task, and (2) that failures to attenuate in this way will lead to an increased likelihood of periodic attention lapses that are synchronized to the VLFO pattern. Here, we tested these predictions using DC-EEG recordings within and outside of a previously identified network of electrode locations hypothesized to reflect DMN activity (i.e., S3 network; Helps et al., 2008 ). Method: 24 young adults (mean age 22.3 years; 8 male), sampled to include a wide range of ADHD symptoms, took part in a study of rest to task transitions. Two conditions were compared: 5 min of rest (eyes open) and a 10-min simple 2-choice RT task with a relatively high sampling rate (ISI 1 s). DC-EEG was recorded during both conditions, and the low-frequency spectrum was decomposed and measures of the power within specific bands extracted. Results: Shift from rest to task led to an attenuation of VLFO activity within the S3 network which was inversely associated with ADHD symptoms. RT during task also showed a VLFO signature. During task there was a small but significant degree of synchronization between EEG and RT in the VLFO band. Attenuators showed a lower degree of synchrony than nonattenuators. Discussion: The results provide some initial EEG-based support for the default mode interference hypothesis and suggest that failure to attenuate VLFO in the S3 network is associated with higher synchrony between low-frequency brain activity and RT fluctuations during a simple RT task. Although significant, the effects were small and future research should employ tasks with a higher sampling rate to increase the possibility of extracting robust and stable signals.

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