A cable circuit of a substation in the United Kingdom showed high level of PD activities during a survey using hand hold PD testing equipment. The authors were invited to carry out on-site PD testing experiment to fur...A cable circuit of a substation in the United Kingdom showed high level of PD activities during a survey using hand hold PD testing equipment. The authors were invited to carry out on-site PD testing experiment to further diagnose and locate the potential problem of the cable system. This paper presents the experience of the present authors carrying out the cable test. Following a brief introduction to the experiment equipments and physical connections, the paper analyses the data collected from the testing, including PD pulse shape analysis, frequency spectrum analysis and phase resolved PD pattern analysis. Associated with PD propagation direction identification, PD source diagnosis and localisation was made. Four different types of sensors, which were adapted during the testing, are shown to have different frequency bandwidths and performed differently. Aider comparing the parameters of the sensor and the PD signals detected by individual sensor, optimal PD monitoring bandwidth for cable system is suggested.展开更多
Mn-CeOff-l＇i-pillared clay （PILC） is an attrac- tive catalyst for selective catalytic reduction of NOx at low temperature because of its low cost. The poisoning of K and Ca on the catalyst of Mn-CeOx/Ti-PILC is an ...Mn-CeOff-l＇i-pillared clay （PILC） is an attrac- tive catalyst for selective catalytic reduction of NOx at low temperature because of its low cost. The poisoning of K and Ca on the catalyst of Mn-CeOx/Ti-PILC is an important problem because K and Ca are always in presence in flue gas. To investigate the effect of K and Ca on the physicochemical characters of the catalysts, the techniques of NH3-temperature programmed desorption （TPD）, H2-temperature programmed reduction （TPR）, and X-ray photoelectron spectroscopy （XPS） were used to analyze the fresh and deactivated catalysts of Mn-CeOJTi- PILC. （Ca）Mn-CeOx/Ti-PILC and （K）Mn-CeOx/Ti-PILC are denoted for the dopes of the catalyst of Mn-CeOJTi- PILC with Ca and K, respectively. The activities of Mn- CeOx/Ti-PILC, （Ca）Mn-CeOx/Ti-PILC and （K）Mn-CeOx/ Ti-PILC for NH3-selective catalytic reduction （SCR） reaction at low temperature were investigated. The results showed that with the dopes of K and Ca on the catalysts, the SCR activities of the catalysts decreased greatly, and K exhibited more poisoning effect than Ca. With the dopes of K and Ca, the acidity, the redox property and chemisorbed oxygen on the surfaces of the catalysts were decreased, which resulted in a decreasing in SCR activity.展开更多
文摘A cable circuit of a substation in the United Kingdom showed high level of PD activities during a survey using hand hold PD testing equipment. The authors were invited to carry out on-site PD testing experiment to further diagnose and locate the potential problem of the cable system. This paper presents the experience of the present authors carrying out the cable test. Following a brief introduction to the experiment equipments and physical connections, the paper analyses the data collected from the testing, including PD pulse shape analysis, frequency spectrum analysis and phase resolved PD pattern analysis. Associated with PD propagation direction identification, PD source diagnosis and localisation was made. Four different types of sensors, which were adapted during the testing, are shown to have different frequency bandwidths and performed differently. Aider comparing the parameters of the sensor and the PD signals detected by individual sensor, optimal PD monitoring bandwidth for cable system is suggested.
文摘Mn-CeOff-l＇i-pillared clay （PILC） is an attrac- tive catalyst for selective catalytic reduction of NOx at low temperature because of its low cost. The poisoning of K and Ca on the catalyst of Mn-CeOx/Ti-PILC is an important problem because K and Ca are always in presence in flue gas. To investigate the effect of K and Ca on the physicochemical characters of the catalysts, the techniques of NH3-temperature programmed desorption （TPD）, H2-temperature programmed reduction （TPR）, and X-ray photoelectron spectroscopy （XPS） were used to analyze the fresh and deactivated catalysts of Mn-CeOJTi- PILC. （Ca）Mn-CeOx/Ti-PILC and （K）Mn-CeOx/Ti-PILC are denoted for the dopes of the catalyst of Mn-CeOJTi- PILC with Ca and K, respectively. The activities of Mn- CeOx/Ti-PILC, （Ca）Mn-CeOx/Ti-PILC and （K）Mn-CeOx/ Ti-PILC for NH3-selective catalytic reduction （SCR） reaction at low temperature were investigated. The results showed that with the dopes of K and Ca on the catalysts, the SCR activities of the catalysts decreased greatly, and K exhibited more poisoning effect than Ca. With the dopes of K and Ca, the acidity, the redox property and chemisorbed oxygen on the surfaces of the catalysts were decreased, which resulted in a decreasing in SCR activity.
