隔离开关开合闸时,会产生高幅值陡前沿的快速暂态过电压(Very fast transient overoltage,VFTO),可能损坏GIS内部绝缘盆子及二次侧变压器等邻近设备,因此抑制VFTO极为重要。现有学者经研究分析发现铁氧体磁环具有抑制效果好、便于加工...隔离开关开合闸时,会产生高幅值陡前沿的快速暂态过电压(Very fast transient overoltage,VFTO),可能损坏GIS内部绝缘盆子及二次侧变压器等邻近设备,因此抑制VFTO极为重要。现有学者经研究分析发现铁氧体磁环具有抑制效果好、便于加工和加装的优点,但未对磁环加装位置影响抑制效果做分析。由此针对某1000k VGIS,用ATP-EMTP仿真分析出对VFTO危害最严重的三个点:断路器、BUS5端部和BUS1左端,再分析铁氧体磁环加装位置不同抑制VFTO的效果。为铁氧体磁环进一步应用到工程实际中提供参考。展开更多
Using corundum powder,SiC powder,Si3N4 powder,α-Al2O3 micropowder and metal Al powder as starting materials,PVA as binder,after ball milling,mixing,aging,moulding and drying,SiAlON bonded corundum or SiC composites w...Using corundum powder,SiC powder,Si3N4 powder,α-Al2O3 micropowder and metal Al powder as starting materials,PVA as binder,after ball milling,mixing,aging,moulding and drying,SiAlON bonded corundum or SiC composites were synthesized at 1 600 ℃ for 6 h in air,graphite embedded condition and(graphite+SiC)embedded condition,respectively.Effects of corundum or SiC powder additions(the mass percent was 7.5%-90%)and sintering atmosphere on forming amount and appearance of SiAlON phase,phase composition,microstructure and properties of the composites were studied.The results show that:(1)with corundum powder addition increasing,density and sintering property of SiAlON bonded corundum composites fired in three different conditions all improve,but the sintering property of the specimens fired in oxidation atmosphere is better than that in reduction atmosphere;(2)the main phases of SiAlON bonded corundum composites fired in two reduction atmospheres are corundum,SiAlON and SiC.The specimens fired in oxidation atmosphere have lamination phenomenon,the main phases of non-oxidation layer are SiAlON,corundum and a little mullite;(3)column-like or fiber-like SiAlON forms in SiAlON bonded corundum composites fired in two different atmospheres.Column-like SiAlON forms in oxidation atmosphere grows better than in reduction atmosphere;(4)with SiC powder addition increasing,density and sintering property of SiAlON bonded SiC composites fired in two reduction atmospheres both reduce.The specimens fired in oxidation atmosphere are oxidized and thicker glaze layer forms.展开更多
The main characteristics of high chrome refractories for coal water slurry gasifiers were introduced. The damage mechanism of the refractories was analyzed by observing the microstructure of the used high chrome refra...The main characteristics of high chrome refractories for coal water slurry gasifiers were introduced. The damage mechanism of the refractories was analyzed by observing the microstructure of the used high chrome refractories with the aid of SEM. The main influencing factors on the service life of the refractories were summarized.展开更多
文摘隔离开关开合闸时,会产生高幅值陡前沿的快速暂态过电压(Very fast transient overoltage,VFTO),可能损坏GIS内部绝缘盆子及二次侧变压器等邻近设备,因此抑制VFTO极为重要。现有学者经研究分析发现铁氧体磁环具有抑制效果好、便于加工和加装的优点,但未对磁环加装位置影响抑制效果做分析。由此针对某1000k VGIS,用ATP-EMTP仿真分析出对VFTO危害最严重的三个点:断路器、BUS5端部和BUS1左端,再分析铁氧体磁环加装位置不同抑制VFTO的效果。为铁氧体磁环进一步应用到工程实际中提供参考。
文摘Using corundum powder,SiC powder,Si3N4 powder,α-Al2O3 micropowder and metal Al powder as starting materials,PVA as binder,after ball milling,mixing,aging,moulding and drying,SiAlON bonded corundum or SiC composites were synthesized at 1 600 ℃ for 6 h in air,graphite embedded condition and(graphite+SiC)embedded condition,respectively.Effects of corundum or SiC powder additions(the mass percent was 7.5%-90%)and sintering atmosphere on forming amount and appearance of SiAlON phase,phase composition,microstructure and properties of the composites were studied.The results show that:(1)with corundum powder addition increasing,density and sintering property of SiAlON bonded corundum composites fired in three different conditions all improve,but the sintering property of the specimens fired in oxidation atmosphere is better than that in reduction atmosphere;(2)the main phases of SiAlON bonded corundum composites fired in two reduction atmospheres are corundum,SiAlON and SiC.The specimens fired in oxidation atmosphere have lamination phenomenon,the main phases of non-oxidation layer are SiAlON,corundum and a little mullite;(3)column-like or fiber-like SiAlON forms in SiAlON bonded corundum composites fired in two different atmospheres.Column-like SiAlON forms in oxidation atmosphere grows better than in reduction atmosphere;(4)with SiC powder addition increasing,density and sintering property of SiAlON bonded SiC composites fired in two reduction atmospheres both reduce.The specimens fired in oxidation atmosphere are oxidized and thicker glaze layer forms.
文摘The main characteristics of high chrome refractories for coal water slurry gasifiers were introduced. The damage mechanism of the refractories was analyzed by observing the microstructure of the used high chrome refractories with the aid of SEM. The main influencing factors on the service life of the refractories were summarized.
