Transformer fault diagnosis and repair is a complex task that includes many possible types of faults and demands special trained personnel. In this paper, Petri Nets are used for the simulation of transformer fault diagnosis process and the definition of the actions followed to repair the transformer. An oil thermometer and a Buchholz relay are used for transformer fault detection. Simulation r...

The Future Renewable Electric Energy Delivery and Management (FREEDM) project aims at providing an efficient electric power grid integrating alternative generating sources and storage with existing power systems to facilitate a green energy in a highly distributed and scalable manner. One of the central aspects of the Reliable and Secure Communication (RSC) subthrust within the FREEDM system is...

Abstract: In this paper, a Witricity-based high-power device is proposed for wireless charging of electric vehicles. According to the specific requirements of three-stage charging for electric vehicles, four compensation modes of the Witricity system are analyzed by the Loosely Coupled Theory among transformer coils and the Substitution Theorem in circuit theory. In addition, when combining vol...

This paper starts with a systematic benchmark test of the three commercialised dielectric diagnostic methods RVM (recovery voltage method), PDC (polarisation and depolarisation currents) and FDS (frequency domain spectroscopy), performed on a large transformer model. Starting from the explored strengths and weaknesses a more sophisticated instrument with corresponding software was developed. Th...

Degraded insulating property of electric equipments will lead to serious accident and great loss for the utilities and customers. Partial discharge detection is an efficient diagnosis method to prevent the failure of electric equipments arising from degrading insulation. However, universal offline partial discharge detection could be performed only during shutdown of equipments. By using the pr...

The dielectric breakdown characteristics of magnetic fluids can be influenced by the magnetic nanoparticles included because their properties should be affected by the applied electric field. Based on measuring the dielectric breakdown voltage of magnetic fluids, we found that it is higher than that of the pure transformer oil in the case of the specific volume concentrations of magnetic nanopa...

An improved mathematical model describing acoustic emission (AE) signals generated by different types of partial discharges (PD) that occur in electric power transformer insulation system is presented in the paper. AE signals are analyzed within the AE method as applied for power transformer failure detection due to occurrence of PD. There are several types of basic defects, which are character...

An instrument containing a linear variable differential transformer was constructed to obtain continuous, nondestructive measurements of both short term changes in stem diameter and long term growth. In cotton plants, stem diameter, leaf water potential, and leaf relative water content are all closely related to net radiation at the top of the canopy. Leaves from the east and west sides of a pl...

In this paper, we compare and analyze the signals of acoustic emission (AE) sensor, high-frequency current transformer (HF-CT) and capacitive coupled (CC) sensor inspection methods when they are used to detect the partial discharge (PD) in gas isolation substations (GIS). The PD location feasibility of the AE method is also studied. In general, the leakage currents are measured by using the HF-...