1,720,964 research outputs found
A confirmation algorithm for predictive maintenance using the Rough Set Theory
No full textThis paper presents a technique to improve the accuracy of the predictions obtained using the Rough Set
Theory (RST) in non-deterministic cases (rough cases). The RST is here applied to the data collected by the
Intelligent Field Devices for identifying predictive diagnostic algorithms for machinery, plants, subsystems,
or components. The data analysis starts from a historical data set recorded from the field instruments,
and its final result is a set of ‘‘if–then” rules identifying predictive maintenance functions.
These functions may be used to predict if a component is going to fail or not in the next future. The prediction
is obtained by applying the rules extracted with the RST algorithm on the real-time values transmitted
by the field device. It may happen that some diagnoses are uncertain, in the sense that it is not
possible to take a certain decision (device sound or close to fail) with a given set of data. In this paper,
a new algorithm for increasing the confidence in these uncertain cases is presented. To show an example,
the proposed confirmation algorithm is applied to the predictive algorithms obtained for an intelligent
pressure transmitter
Validation of ZnO surge arresters model for overvoltage studies
No full textAbstract—This paper presents an improvement of the procedure
to determine the parameters of the simplified model for
metal-oxide surge arresters, derived from the IEEE standard
model. The main innovation introduced by the paper lays in the
possibility to define an approximate dynamic model even if data
about residual voltages for steep current pulse are not defined in
the manufacturer’s data sheets. This model has a wide rangeability
and its effectiveness is good for both medium- and high-voltage
arresters. The effectiveness of the model was tested for several arresters
of different manufacturers. The residual voltages reported
in the datasheets and obtained by the manufacturers through a
discharge test are compared with the simulations performed with
Matlab. The possibility of defining a dynamic model for surge
arresters even with missing data makes the proposed model a
useful tool for insulation coordination studies involving steep front
transients
Definition of Power Quality Indices for DC Low Voltage Distribution Networks
No full textThe problem of definition of Power Quality assessment for Low Voltage dc distribution networks is addressed, with focus on: definition of meaningful electromagnetic phenomena; power quality indices and measurement methods; simulation and experimental results
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