Inhibition of Mild Steel Corrosion in 0.25 M Sulphuric Acid Solution by Imatinib Mesylate

Mohana, K.N.,Shivakumar, S.S.,Badiea, A.M. Korean Chemical Society 2011 대한화학회지 Vol.55 No.3

The corrosion inhibition of imatinib mesylate (IMT) on mild steel in 0.25 M sulphuric acid has been studied using gravimetric and potentiodynamic polarization techniques at various concentrations of inhibitor, temperature and fluid velocities. The results obtained showed that, inhibition efficiency (% IE) increases with increasing concentration of the inhibitor. The adsorption process on mild steel surface follows Langmuir adsorption isotherm. The values of Gibbs free energies of adsorption obtained suggest that, the adsorption process of IMT on mild steel is chemisorption. Thermodynamic parameters were evaluated and discussed. The electron orbital density distribution of HOMO and LUMO of IMT was used to discuss the inhibition mechanism. FT-IR spectroscopy and SEM images were used to analyze the surface adsorbed film. 다양한 억제제의 농도, 온도, 유속에서 중량 분석과 변전위 분극법을 이용하여 0.25 M 황산 용액상에 있는 연강철에 대한 imatinib mesylate (IMT)의 부식 억제를 연구하였다. 억제제의 농도가 증가함에 따라 억제 효과가 증가한다는 결과를 얻었다. 연강철 표면 위의 흡착 과정은 Langmuir 흡착 등온선을 따른다. 얻어진 흡착 깁스 자유 에너지의 값은 연강철 위의 IMT의 흡착 과정이 화학흡착이라는 것을 보여준다. 열역학 변수들이 계산되고, 논의되었다. IMT의 HOMO와 LUMO의 전자궤도 밀도 분포는 억제 메커니즘을 논의하는데 이용되었다. FT-IR 분광학과 SEM 이미지는 필름에 흡착된 표면을 분석하기 위해 사용되었다.

Measurement of Transient Electric Field Emission from a 245 ㎸ Gas Insulated Substation Model during Switching

M. Mohana Rao,M. Joy Thomas,B. P. Singh 대한전기학회 2007 Journal of Electrical Engineering & Technology Vol.2 No.3

The transient fields generated during switching operations in a Gas Insulated Substation (GIS) are associated with high frequency components in the order of few tens of ㎒. These transient fields leak into the external environment of the gas-insulated equipment and can interfere with the nearby electronics. Measurements of the transient fields are thus required to characterise the interference caused by switching phenomena in such substations. In view of the above, E-field emission measurement during a switching operation bas been carried out for a 245 ㎸ GIS model, using a resonant dipole antenna and D-dot sensor. The characteristics of the E-fields i.e., frequency spectra and their levels have been analysed and are reported in the paper. Suitability of the measurements has been confirmed by comparing frequency spectra of the measured and computed transient fields.

Computer Aided Identification of Inter-Layer Faults in Gas Insulated Capacitively Graded Bushing during Switching

M. Mohana Rao,P.Dharani,T. Prasad Rao 대한전기학회 2009 Journal of Electrical Engineering & Technology Vol.4 No.1

In a Gas Insulated Substation (GIS), Very Fast Transients (VFTs) are generated mainly due to switching operations. These transients may cause internal faults, i.e., layer-to-layer faults in a capacitively graded bushing as it is one of the most important terminal equipment for GIS. The healthiness of the bushing is generally verified by measuring its leakage current. However, the change in current magnitude / pattern is only marginal for different types of fault conditions. Leakage current monitoring (LCM) systems generate large amounts of data and computer aided interpretation of defects may be of great assistance when analyzing this data. In view of the above, ANN techniques have been used in this study for identification of these minor faults. A single layer perceptron network, a two layer feed-forward back propagation network and cascade correlation (CC) network models are used to identify interlayer faults in the bushing. The effectiveness of the CC network over perceptron and back propagation networks in identification of a fault has been analysed as part of the paper.

Simulation of Capacitively Graded Bushing for Very Fast Transients Generated in a GIS during Switching Operations

M. Mohana Rao,T. Prasad Rao,S.S. Tulasi Ram,B. P. Singh 대한전기학회 2008 Journal of Electrical Engineering & Technology Vol.3 No.1

In a gas insulated substation (GIS), Very Fast Transient Over-voltages (VFTOs) are generated due to switching operations and ground faults. These fast transients are associated with high frequency components of the order of a few hundreds of ㎒. These transients may cause internal faults i.e., layer-to-layer faults or minor faults in a capacitively graded bushing, which is one of the important pieces of terminal equipment for GIS. In the present study, the PSPICE model has been developed to calculate the voltage distribution across the layers of 420 ㎸ graded bushing for high frequency pulses of rise time I to 50 ㎱, which simulate the VFTO. For this simulation, an equivalent electrical network of bushing with different equivalent layers has been considered. The effect of different equivalent layers modeling circuits on the non-uniform voltage factor has been analysed. The influence of copper strip inductance on voltage distribution across layers has also been analysed for various rise times of high frequency transients. Finally, the leakage current of the bushing is calculated for evaluating the bushing condition under these transients.

Effect of Metallic Particles on E-field Enhancement in Extra High Voltage Gas-insulated Transmission Lines

M. Mohana Rao,S. Satyanarayana,S. Vinay Kumar,H.S. Jain 대한전기학회 2010 Journal of Electrical Engineering & Technology Vol.5 No.4

Gas-insulated transmission lines (GITL) are valued as technological solutions in hydropower stations due to their enormous power handling capabilities. The performance of GITL is a function of the size of metallic particles inside the gas-insulated chamber. Electrostatic field (E-field) enhancement is a common phenomenon in gas-insulated lines due to these metallic particles. In this study, the E-field enhancement factor is calculated by considering metallic particles at various locations in the gas-insulated line/bus section, such as high-tension (HT) conductor, high-voltage shields, support insulator, and inner surface of grounded enclosure. For this purpose, a two-dimensional model based on finite element (FE) method is developed. The length of the metallic particle is in the range of 1 to 10 ㎜ while the diameter is between 1 to 3 ㎜. E-field enhancement is also computed for various particle configurations of the gas-insulated system, with focus on dielectric coating made of epoxy on HT conductor and inner surface of grounded enclosure.

Simulation of Capacitively Graded Bushing for Very Fast Transients Generated in a GIS during Switching Operations

Rao, M.Mohana,Rao, T. Prasad,Ram, S.S. Tulasi,Singh, B.P. The Korean Institute of Electrical Engineers 2008 Journal of Electrical Engineering & Technology Vol.3 No.1

In a gas insulated substation (GIS), Very Fast Transient Over-voltages (VFTOs) are generated due to switching operations and ground faults. These fast transients are associated with high frequency components of the order of a few hundreds of MHz. These transients may cause internal faults i.e., layer-to-layer faults or minor faults in a capacitively graded bushing, which is one of the important pieces of terminal equipment for GIS. In the present study, the PSPICE model has been developed to calculate the voltage distribution across the layers of 420kV graded bushing for high frequency pulses of rise time 1 to 50ns, which simulate the VFTO. For this simulation, an equivalent electrical network of bushing with different equivalent layers has been considered. The effect of different equivalent layers modeling circuits on the non-uniform voltage factor has been analysed. The influence of copper strip inductance on voltage distribution across layers has also been analysed for various rise times of high frequency transients. Finally, the leakage current of the bushing is calculated for evaluating the bushing condition under these transients.

Computer Aided Identification of Inter-Layer Faults in Gas Insulated Capacitively Graded Bushing during Switching

Rao, M.Mohana,Dharani, P.,Rao, T. Prasad The Korean Institute of Electrical Engineers 2009 Journal of Electrical Engineering & Technology Vol.4 No.1

In a Gas Insulated Substation (GIS), Very Fast Transients (VFTs) are generated mainly due to switching operations. These transients may cause internal faults, i.e., layer-to-layer faults in a capacitively graded bushing as it is one of the most important terminal equipment for GIS. The healthiness of the bushing is generally verified by measuring its leakage current. However, the change in current magnitude/pattern is only marginal for different types of fault conditions. Leakage current monitoring (LCM) systems generate large amounts of data and computer aided interpretation of defects may be of great assistance when analyzing this data. In view of the above, ANN techniques have been used in this study for identification of these minor faults. A single layer perceptron network, a two layer feed-forward back propagation network and cascade correlation (CC) network models are used to identify interlayer faults in the bushing. The effectiveness of the CC network over perceptron and back propagation networks in identification of a fault has been analysed as part of the paper.

Measurement of Transient Electric Field Emission from a 245 kV Gas Insulated Substation Model during Switching

Rao, M. Mohana,Thomas, M. Joy,Singh, B.P. The Korean Institute of Electrical Engineers 2007 Journal of Electrical Engineering & Technology Vol.2 No.3

The transient fields generated during switching operations in a Gas Insulated Substation (GIS) are associated with high frequency components in the order of few tens of MHz. These transient fields leak into the external environment of the gas-insulated equipment and can interfere with the nearby electronics. Measurements of the transient fields are thus required to characterise the interference caused by switching phenomena in such substations. In view of the above, E-field emission measurement during a switching operation has been carried out for a 245 kV GIS model, using a resonant dipole antenna and D-dot sensor. The characteristics of the E-fields i.e., frequency spectra and their levels have been analysed and are reported in the paper. Suitability of the measurements has been confirmed by comparing frequency spectra of the measured and computed transient fields.

Effect of Metallic Particles on E-field Enhancement in Extra High Voltage Gas-insulated Transmission Lines

Rao, M. Mohana,Satyanarayana, S.,Kumar, S. Vinay,Jain, H.S. The Korean Institute of Electrical Engineers 2010 Journal of Electrical Engineering & Technology Vol.5 No.4

Gas-insulated transmission lines (GITL) are valued as technological solutions in hydro-power stations due to their enormous power handling capabilities. The performance of GITL is a function of the size of metallic particles inside the gas-insulated chamber. Electrostatic field (E-field) enhancement is a common phenomenon in gas-insulated lines due to these metallic particles. In this study, the E-field enhancement factor is calculated by considering metallic particles at various locations in the gas-insulated line/bus section, such as high-tension (HT) conductor, high-voltage shields, support insulator, and inner surface of grounded enclosure. For this purpose, a two-dimensional model based on finite element (FE) method is developed. The length of the metallic particle is in the range of 1 to 10 mm while the diameter is between 1 to 3 mm. E-field enhancement is also computed for various particle configurations of the gas-insulated system, with focus on dielectric coating made of epoxy on HT conductor and inner surface of grounded enclosure.

Measurement of Transient Electric Field Emission from a 245 kV Gas Insulated Substation Model during Switching

Mandava Mohana Rao,M Joy Thomas,B.P. Singh 대한전기학회 2007 Journal of Electrical Engineering & Technology Vol.2 No.3

The transient fields generated during switching operations in a Gas Insulated Substation(GIS) are associated with high frequency components in the order of few tens of MHz. These transient fields leak into the external ennearby electronics. Measurements of the transient fields are thus required to characterise the interference caused by switching phenomena in such substations. In view of the above, E-field emission measurement during a switching operation has been carried out for a 245 kV GIS model, using a resonant dipole antenna and D-dot sensor. The characteristics of the E-fields i.e., frequency spectra and their levels have been analysed and are reported in the paper. Suitability of the measurements has been confirmed by comparing frequency spectra of the measured and computed transient fields.