Applied Mechanics and Materials Vols. 325-326

Abstract: In actual operation the centralized solar hot water system whether can more energy saving, influenced by the collector area design, system operation and control mode , installation accuracy and various factors so on. The analysis in this paper is mainly based on the measured data of the collector area key design parameters such as average daily water use, water temperature, the thermal collection efficiency, water tank and pipeline heat loss and other parameters, as well as the problem found in the test of the construction and operation control , put forward reasonable suggestions for energy saving potential, provide reference for the centralized solar hot water system design and operation in future.

Abstract: The electric field and absolute radiance of 13 strong lines in the positive column of narrow bore T2 (outer diameter 7 mm) low-pressure Ar-Hg discharges were measured experimentally, which includes 11 Hg lines ranging from 185 to 579 nm and 2 Ar lines of 811, 842 nm. The discharges were operated with different argon filling pressure ranging from 2 to 10 Torr (corresponding to 266 to 1333 Pa), for discharge currents 20-200 mA and cold spot temperature 20-80 °C (0.16-11.8 Pa Hg vapour pressure). The Koedam factors of important emission lines were also measured for various discharge parameters, in order to convert radiance to exitance, whereafter the radiant power of all the lines except 185 nm, could be calculated and their radiant efficiency could be compared as well. Considering the absorption of 185 nm radiation in air, the ratio of the radiance at 185 nm to that at 254 nm was measured instead of its Koedam factor for current 80-200 mA and cold spot temperature 20-60 °C. Therefore, 185 nm radiant power was derived indirectly from that of 254 nm in corresponding discharge conditions. According to our measured results, the argon pressure for the maximum production of 254 nm radiation is around 5 Torr. It is showed that the optimum cold spot temperature for 254 nm radiant efficiency is higher than 50 °C, which is consistent with the temperature dependence on the tube diameter. With increasing discharge current and cold spot temperature, 185 nm radiant power has the similar tendency to that of 254 nm, while the fraction of electrical power converted to 185 nm radiation increases slightly with these parameters. Generally, the ratio of radiant power at 185 nm to that at 254 nm is higher than 0.2. For evaluating the energy balance of the positive column as well as the luminous efficacy of the fluorescent lamp product, the radiant powers of other strong lines also has significantly effect though they are considerably smaller than that of 254 nm and 185 nm. Besides, it must be taken in consideration that mercury depletion on the axis of positive column is serious for T2 narrow tube discharge especially at low Hg vapour pressure and high current.

Abstract: High output low pressure mercury (LPM) discharge UV lamps have been briefly introduced. In order to measure the 254 nm radiant efficiency simply and preciously, Keitz formula was used and its advantage was illustrated. The LPM lamps had outer diameter of 19 mm (T6). The buffer gases are neon (65%) and argon (35%) with total pressure 1-10 Torr (133-1333 Pa). The lamps were operated with cold spot temperatures from 20°C to 80°C and discharge current from 0.8 A to 2.0 A. The electric field, input power, 254 nm UV irradiance and irradiance of other Hg lines from 265 to 579 nm in positive column were measured. The radiant power of each wavelength can be calibrated according to the 254 nm output and the Keitz formula. It was shown that the radiant efficiency of 254 nm can reach a maximum of above 40% at cold spot temperature 45-47 °C and current 1.6 A for filling pressure less than 3 Torr. The optimal mercury vapor pressure was 1.2 to 1.4 Pa. The output percentage of other Hg lines was below 5%. With the decrease of buffer gas pressure, the 254 nm radiant efficiency increased obviously.

Abstract: The voltage, current and power are measured for short arc ultra-high pressure mercury lamps (UHP) with rating power 250 W driven by 50 Hz square waveform power supply. It is found that the curve slope of voltage-current characteristics is positive in most of the power range, and negative around 170 W. The photometric, colorimetric and electric parameters are measured with an integrating sphere system couple with a spectrometer in UHP dimming experiments. The results show luminous flux increases with power linearly. The luminous efficacy and color rendering index (CRI) reduce with power reduction because of the decrease of spectral continuum. The mercury pressure are calculated with the full width at the half maximum (FWHM) of 546 nm spectral band, which is 6.2-11.0 nm according to the mercury pressure 15.3-25.8 MPa for UHP power 43-258 W.

Abstract: The working principle of on-load automatic capacity regulating distribution transformer is elaborated in this study, a layout scheme with anti-parallel thyristor valve assembly as capacity regulating switch is designed. The thyristor valve assembly is selected. The respective character in the system of electromagnetism trigger and online monitoring as well as photoelectricity trigger and online monitoring is described. With the comparison, it takes the system of electromagnetism trigger and online monitoring at last.

Abstract: Bidirectional Associative Memory (BAM) network is presented to analysis the fault of power transformer. In order to improve the classification accuracy, the conception of combination is introduced. The fault diagnosis of power transformer is consisted of 4 BAM networks. The first BAM network is used to classify the normal and fault. The second BAM network is used to classify the heat fault and partial discharge (PD) fault. The third BAM network is used to classify MC-overheating faults in magnetic circuit and EC-overheating faults in electrical circuit. The fourth BAM network is used to classify RSI-discharge faults related to solid insulation, USI-discharge faults unrelated to solid insulation. By comparing with the RBF neural network algorithm for the same 90 input set, we conclude that the BAM network a good classifier for the fault diagnosis of power transformer.

Abstract: In this paper, we demonstrated a lightweight compact motor operating at 70 ~ 100 kHz. The motor is simpler than an electric motor in structure and lower power consumption but higher speed than that of conventional peizoelectric motors. Driver for the PMM is impressively simple. A wave generator and amplifier are all that it takes to supply the piezoelectric ceramic with voltage. Finite element model was developed using ANSYS for the purpose of prediction of the resonance frequency of the vibration mode for the motor driving stator. The periodic plate modal deformation is passed on to a driving bolt, which causes it to oscillate with a movement resembling that of a turning vibrator. The rotor attached to the motor presses its tip on to driving bolt to be driven. The motor is continually being modified to enhance the performance and efficiency. It has a lot of merits such as slim shape, easy holding for motor structure and low manufacturing cost.

Abstract: The water friction which is produced in the high-voltage wet submersible motor is much more than that of General motor, and it plays an important role in total consumption of motor. It is difficult to calculate the consumption of water friction. In order to study the high-voltage wet submersible motor water friction loss and temperature field distribution more accurately, this paper take the 6kV-3150kW motor as an example. Based on the Fluid Theory and the Heat Transfer Theory, it establishes the model of the loss of water friction and rotor temperature field. At last, the finite element software is used to analyze the water friction loss of motor and calculate the rotor temperature field .The rationality of the model and the validity of the calculated value are verified by the experimental results, which lay a theoretical foundation for the optimum design of high-voltage wet submersible motor for future application.

Abstract: As a nonlinear load, a large number of electric vehicle chargers inserted into power might bring many challenges, cause harmonic pollution to power grid. In this paper, a high-frequency charger is regarded as a researching object, the power characteristics of charger, harmonic current and impactive parameters are analyzed, and the harmonic analysis model of the charger accessed to power grid is built. Applying the Simulink and SimPowerSystems toolbox in Matlab and the simulation method facing the systems structure of electrical principle, the model is simulated. The harmonic generative rules and characteristics for a single high-frequency charger are present. The results might forecast the harmonic pollution of charge station, and provide the theory base for choosing harmonic control device and methods.

Abstract: Aiming at the misoperation of the conventional phase selector by phase current-difference during some cross country faults, a fault phase selector is developed. Based on the fault lines of the corresponding fault phase are selected, a novel synthesis fault phase selector using voltages and currents in single circuit at single side is proposed, which is based on comparing the difference of fault voltages to make sure all the fault phase in the lines and judging the phase degree and amplitude condition of the fault currents. Used this scheme and the phase current difference, the fault phase may be picked up correctly in double circuit lines on the same tower, especially in cross country faults.