Experimental Research on Power Transformer Vibration Distribution under Different Winding Defect Conditions

Vibration analysis is one of the important tools for the transformer winding faults diagnosis. Previous researchers have proved that the vibration spatial distribution of the winding is significantly influenced by the winding defects for the open circuit condition. In order to study the effects of the loading current on the winding vibrations under different mechanical conditions, experiments were designed and operated on a three-phase transformer winding to analyze the winding vibration distribution under different winding defect cases. Further, to study to what extent the mechanical defects and the loading current influence characteristics of the vibration distribution on the tank, the tank vibration distribution under various winding defects and different loading currents were also measured and discussed. In addition, the possibility of detection of transformer winding faults based on tank vibration spatial distribution characteristics was also discussed.

Accelerated ageing of organic LED panels using ultraviolet exposure

Two different types of commercial organic LED panels were aged with ultraviolet light. One type was aged in an over-filled and open circuit condition with broadband ultraviolet radiation, and the other in an under-filled and closed circuit condition with spectrally dispersed light. Both the luminance values and the spectral power distributions of the panels were measured for both types. The results show that the light output and the spectrum of the panel decay faster when the panels are exposed to ultraviolet radiation when compared to natural ageing. For the panels aged using the under-filled method, the wavelength that reduces the output most is between 320 nm and 340 nm, and the ultraviolet exposure with wavelengths longer than 350 nm did not accelerate the ageing. The ultraviolet radiation exposure increased the ageing by a factor of eight as compared to natural ageing, when the used ultraviolet levels corresponded to one year of exposure on a clear summer day condition. Based on the results, the under-filled method is a valid option for accelerated ageing, especially for studying simultaneously accelerated and natural ageing.

SrCe0.9Sm0.1O3-α Compounded with NaCl-KCl as a Composite Electrolyte for Intermediate Temperature Fuel Cell

SrCeO3 and SrCe0.9Sm0.1O3-α were synthesized using a high-temperature solid-state reaction method using Sm2O3, SrCO3, CeO2 as precursors, then the SrCe0.9Sm0.1O3-α-NaCl-KCl composite electrolyte was fabricated by compounding SrCe0.9Sm0.1O3-α with NaCl-KCl and sintering it at a lower temperature (750 °C) than that of a single SrCeO3 material (1540 °C). The phase and microstructure of the samples were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The conductivities of the samples were measured in dry nitrogen atmosphere using electrochemical analyzer. The conductivities of the SrCeO3, SrCe0.9Sm0.1O3-α and SrCe0.9Sm0.1O3-α-NaCl-KCl at 700 °C were 2.09 × 10−5 S·cm−1, 1.82 × 10−3 S·cm−1 and 1.43 × 10−1 S·cm−1 respectively. The conductivities of SrCe0.9Sm0.1O3-α-NaCl-KCl composite electrolyte are four orders of magnitude higher than those of SrCeO3 and two orders of magnitude higher than those of SrCe0.9Sm0.1O3-α. The result of logσ ~ logpO2 plot indicates that SrCe0.9Sm0.1O3-α-NaCl-KCl is almost a pure ionic conductor. The electrolyte resistance and the polarization resistance of the H2/O2 fuel cell based on SrCe0.9Sm0.1O3-α-NaCl-KCl composite electrolyte under open-circuit condition were 1.0 Ω·cm2 and 0.2 Ω·cm2 respectively. Further, the obtained maximum power density at 700 °C was 182 mW·cm−2.

Performance Analysis of 12Slot with Various Rotor Pole Numbers HE-FSM for HEV Application

This paper presents performance analysis of 12Slot with various rotor pole numbers Hybrid Excitation Flux Switching Machine (HEFSM) for Hybrid Electric Vehicles (HEVs) application. HEFSM has carried out by combining the advantage of Permanent Magnet (PM) machines and DC Field Excitation Coil (FEC) synchronous machines. Previously, most of HEFSM structure having FEC windings in theta direction that create a problem of flux cancellation that will affect the performances of the machine. Thus, a design of 12Slot HEFSM with FEC wounded in radial direction is proposed to eliminate the flux cancellation effect. At first, armature coil arrangement test at no-load condition is conducted to analyze PM flux. Furthermore, induced voltage and cogging torque at open circuit condition are investigated based on 2D finite element analysis (FEA). Finally, torque and power performances are also examined at maximum FEC and armature current densities. The outcomes demonstrate that 12S-14P configuration has the highest PM flux linkage, torque, power and less distortion of back-emf waveform which are required to be used as a motor in HEVs. The highest torque and power achieved are 220.15Nm and 92.45kW, respectively.