− Methods enabling a determination of errors εI and δI for a high transformation ratio difference between a standard and tested instrument current transformers (ICT) are described in this article. A widespread method uses an automatic transformer test set for the measurement of a difference between a standard and tested ICT. A method transforming secondary currents to voltages and an indirect m...

This paper constructs a forecasting model for coal mining water inrush from the floor through the analysis and careful study of the mechanism of water inrush in coal mining and the Self-Adaptive Evolutionary Extreme Learning Machine (SaE-ELM) which obtains self-learning, generalization performance and speediness is used. In SaE-ELM, the network hidden node parameters are optimized by the self-a...

This article shows practical rules which were developed for the adjustment of Numerical Overcurrent Functions (NOCF) microprocessor-based protective relays in order to avoid their maloperation due Transformer Magnetizing Inrush Currents (TMIC). The TMIC waveforms are decaying and nonsinusoidal, effects different on instantaneous, definite-time, or inverse-time NOCF; thus, specific necessary eac...

Ensuring a stable and efficient transformer operation is very crucial task nowadays, especially with the integration of modern sensitive electrical equipment appliances down line. However, maloperation still cannot be completely avoided, particularly existence inrush current that possess similar characteristics as fault currents when occurred. Thus, this paper proposes an enhanced method for id...

Fiber optic sensors can be used to monitor deformation and/or the overall integrity of structure components. In this paper, we propose a fuzzy control theory based control principle for sensors, and design a new kind of fiber optic sensor used for Geological monitoring. In order to validate the efficiency of the designed sensor, we simulate a water inrush model in a coal mine, and observe the w...

In this paper we propose transformer-based solutions to several power quality problems. Elsewhere we have shown how to solve the acoustical noise emission problems. In this paper we introduce toroidal transformers with reduced inrush currents, transformers with reduced electromagnetic emissions, and other transformers useful to reduce the transfer of harmonics. With the low-inrush transformers ...

This paper proposes a new method to detect transformer inside incipient fault current using transformer internal parameters to determine the inside structure of transformer at good condition or bad. A transformer model was established by Jiles– Atherton theory using measured voltage and current and the initial parameters which were found using Genetic Algorithm (GA). Then, transformer internal ...