Damages of power transformers are caused partly by construction setting but also by operation （i. e., due to operational and degradation parameters）. A long-term operation and exceeding of the limit values of transf...Damages of power transformers are caused partly by construction setting but also by operation （i. e., due to operational and degradation parameters）. A long-term operation and exceeding of the limit values of transformer abbreviate the lifetime of this device very dramatically. A condition of insulating system oilpaper is principal diagnostic indicator that has its essential influence to failure-free operation of power transformers. The paper deals with a description of the experience with developed monitoring system, which is focused mainly on a control of oil filling of experimental transformer. Relative humidity, amount of dissolved gases and increased temperature are observed, as they have decisive influence on insulating system of transformer. Monitoring of these characteristics is completed with analysis of oil samples by infrared spectroscopy in mode of Attenuated Total Reflection technique.展开更多
Reliable and efficient power generation is a major global issue due to both political and environmental concerns.Nevertheless many critical components,particularly the blades of the low pressure(LP) side of power gene...Reliable and efficient power generation is a major global issue due to both political and environmental concerns.Nevertheless many critical components,particularly the blades of the low pressure(LP) side of power generating steam turbines,are subjected to failure due to severe erosion at the leading edges.Since taking machines off-line for maintenance and removal of damaged blade for repair is extremely expensive,increasing the service life of these critical components can offer significant economic and political benefits.Conventional techniques to increase service life include brazing of an erosion shield at the leading edge of the turbine blades,open arc hardfacing,and cladding with erosion resistant materials using gas tungsten,manual metal or plasma transferred arc welding.We have been investigating for the past eight years the potential of laser cladding to deposit a high quality and erosion resistant protection shield on the leading edge of LP blades.Laser cladding offers unique advantages over the conventional techniques.The project to-date has demonstrated the feasibility of in-situ repair of turbine blades in trials conducted at a power station using a fibre delivered Laserline diode laser and a robot.A company(Hardwear Pty.Ltd.) has been established to commercialise the technology and has delivered two commercial contracts.展开更多
Laser assisted machining(LAM) takes the advantages of local heating and softening of workpiece by laser beam in front of the cutting tool.The local softening of workpiece at the shear zone enables much easier plastic ...Laser assisted machining(LAM) takes the advantages of local heating and softening of workpiece by laser beam in front of the cutting tool.The local softening of workpiece at the shear zone enables much easier plastic deformation during machining.This paper reviews the up-to-date progress on LAM of ceramics.It covers the laser beam integration with cutting tools,analysis of temperature distribution around the cutting region,material removal mechanism,tool wear mechanism,and optimization of LAM.The benefit of LAM and its optimization are discussed in terms of material removal temperature.展开更多
文摘Damages of power transformers are caused partly by construction setting but also by operation （i. e., due to operational and degradation parameters）. A long-term operation and exceeding of the limit values of transformer abbreviate the lifetime of this device very dramatically. A condition of insulating system oilpaper is principal diagnostic indicator that has its essential influence to failure-free operation of power transformers. The paper deals with a description of the experience with developed monitoring system, which is focused mainly on a control of oil filling of experimental transformer. Relative humidity, amount of dissolved gases and increased temperature are observed, as they have decisive influence on insulating system of transformer. Monitoring of these characteristics is completed with analysis of oil samples by infrared spectroscopy in mode of Attenuated Total Reflection technique.
文摘Reliable and efficient power generation is a major global issue due to both political and environmental concerns.Nevertheless many critical components,particularly the blades of the low pressure(LP) side of power generating steam turbines,are subjected to failure due to severe erosion at the leading edges.Since taking machines off-line for maintenance and removal of damaged blade for repair is extremely expensive,increasing the service life of these critical components can offer significant economic and political benefits.Conventional techniques to increase service life include brazing of an erosion shield at the leading edge of the turbine blades,open arc hardfacing,and cladding with erosion resistant materials using gas tungsten,manual metal or plasma transferred arc welding.We have been investigating for the past eight years the potential of laser cladding to deposit a high quality and erosion resistant protection shield on the leading edge of LP blades.Laser cladding offers unique advantages over the conventional techniques.The project to-date has demonstrated the feasibility of in-situ repair of turbine blades in trials conducted at a power station using a fibre delivered Laserline diode laser and a robot.A company(Hardwear Pty.Ltd.) has been established to commercialise the technology and has delivered two commercial contracts.
文摘Laser assisted machining(LAM) takes the advantages of local heating and softening of workpiece by laser beam in front of the cutting tool.The local softening of workpiece at the shear zone enables much easier plastic deformation during machining.This paper reviews the up-to-date progress on LAM of ceramics.It covers the laser beam integration with cutting tools,analysis of temperature distribution around the cutting region,material removal mechanism,tool wear mechanism,and optimization of LAM.The benefit of LAM and its optimization are discussed in terms of material removal temperature.
