About the editor |
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xi | |
Preface |
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xiii | |
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xv | |
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1 Dissolved gas analysis, measurements and interpretations |
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1 | (38) |
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1 | (1) |
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2 | (1) |
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3 | (1) |
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1.3 The transformer as a chemical reactor |
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3 | (4) |
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1.3.1 Gas production mechanisms |
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5 | (2) |
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7 | (2) |
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8 | (1) |
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9 | (5) |
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12 | (1) |
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13 | (1) |
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1.6 Interpretation techniques |
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14 | (19) |
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16 | (1) |
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1.6.2 Techniques that rely on the gas profile |
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17 | (6) |
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1.6.3 Techniques that rely on ratios |
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23 | (5) |
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1.6.4 Techniques that rely on rates of change |
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28 | (1) |
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1.6.5 Putting it all together |
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29 | (4) |
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1.7 Future of oil analysis |
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33 | (6) |
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33 | (1) |
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34 | (1) |
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1.7.3 Analysis automation |
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34 | (1) |
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35 | (4) |
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2 Partial discharges: keys for condition monitoring and diagnosis of power transformers |
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39 | (48) |
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39 | (1) |
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39 | (1) |
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2.2 Dielectric materials used in power transformers |
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40 | (3) |
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2.3 Effects of ageing in insulation systems of power transformers |
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43 | (6) |
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43 | (2) |
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45 | (1) |
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46 | (2) |
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48 | (1) |
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2.4 Condition monitoring techniques in power transformers |
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49 | (28) |
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2.4.1 Electrical measurements |
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49 | (2) |
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2.4.2 Apparent charge estimation: quasi-integration and calibration |
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51 | (3) |
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2.4.3 PD detection in transformers |
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54 | (4) |
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2.4.4 Unconventional methods of partial discharge measurements in power transformers |
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58 | (5) |
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2.4.5 Methods of partial discharge analysis |
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63 | (14) |
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77 | (10) |
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78 | (1) |
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79 | (8) |
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3 Moisture analysis for power transformers |
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87 | (38) |
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87 | (1) |
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3.2 Moisture in transformer insulation |
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88 | (2) |
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3.2.1 Risks associated to the presence of high levels of moisture in transformers |
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88 | (1) |
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3.2.2 Sources of moisture contamination in transformers |
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89 | (1) |
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3.3 Moisture dynamics in transformers |
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90 | (11) |
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3.3.1 Adsorption and desorption of moisture in cellulosic insulation |
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92 | (2) |
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3.3.2 Moisture distribution within transformer solid insulation |
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94 | (1) |
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3.3.3 Solubility of water in oil |
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95 | (1) |
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3.3.4 Moisture equilibrium between paper and oil |
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96 | (2) |
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3.3.5 Moisture equilibrium in alternative fluids |
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98 | (2) |
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3.3.6 Moisture dynamics in a transformer under operation |
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100 | (1) |
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3.4 Monitoring of moisture content in oil |
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101 | (5) |
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3.4.1 Periodical sampling of oil |
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101 | (1) |
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3.4.2 On-line measure of oil moisture with capacitive sensors |
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102 | (2) |
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3.4.3 Interpretation of the moisture content of oil |
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104 | (2) |
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3.5 Estimation of the moisture content of solid insulation from moisture in oil measures |
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106 | (2) |
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3.5.1 Determination of moisture content of paper using the equilibrium charts |
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106 | (1) |
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3.5.2 Improved methodologies to estimate the moisture content of paper from the measures of moisture content of oil |
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107 | (1) |
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3.6 Dielectric response methods for the estimation of moisture in solid insulation |
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108 | (11) |
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3.6.1 Theoretical principles |
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108 | (2) |
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3.6.2 Frequency dielectric spectroscopy |
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110 | (5) |
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3.6.3 Recovery voltage method |
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115 | (2) |
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3.6.4 Polarisation and depolarisation currents |
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117 | (2) |
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3.7 Conclusions, future trends and challenges |
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119 | (6) |
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120 | (5) |
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4 Assessing DP value of a power transformer considering thermal ageing and paper moisture |
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125 | (18) |
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Ricardo David Medina Velecela |
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Andres Arturo Romero Quete |
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Diego Xavier Morales Jadan |
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125 | (1) |
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4.1 Introduction and preliminary issues |
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126 | (1) |
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126 | (1) |
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4.3 Theoretical framework |
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127 | (6) |
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4.3.1 Paper as power transformer solid insulation system |
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127 | (1) |
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4.3.2 Paper degradation process |
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127 | (2) |
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4.3.3 Degradation accelerators |
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129 | (1) |
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129 | (2) |
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4.3.5 Assessing of depolymerization process |
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131 | (2) |
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133 | (2) |
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4.4.1 Problem description |
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133 | (1) |
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4.4.2 Oil moisture estimation |
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133 | (1) |
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4.4.3 New approach for degree or polymerization assessing |
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134 | (1) |
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135 | (4) |
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136 | (3) |
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139 | (4) |
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140 | (3) |
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5 Frequency response analysis |
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143 | (68) |
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143 | (1) |
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143 | (1) |
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5.2 Transformer winding deformation |
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144 | (4) |
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5.2.1 Deformation types and short-circuit current |
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144 | (2) |
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5.2.2 Transformer transportation causing active part displacement |
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146 | (2) |
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5.3 Methods to recognize winding deformation |
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148 | (4) |
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5.3.1 Short-circuit impedance |
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148 | (3) |
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151 | (1) |
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5.4 Sweep frequency response analysis |
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152 | (1) |
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5.5 Standard connection methods |
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153 | (2) |
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5.5.1 End-to-end measurement |
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153 | (1) |
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5.5.2 Inductive intevwinding measurements |
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153 | (1) |
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5.5.3 Capacitive interwinding measurements |
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153 | (1) |
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5.5.4 End-to-end short-circuit measurements |
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153 | (2) |
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5.6 FRA signature assessment |
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155 | (11) |
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5.6.1 Visual assessment of FRA signature |
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155 | (7) |
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5.6.2 Statistical assessment of FRA signature |
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162 | (4) |
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5.7 Factors affecting frequency response signature |
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166 | (33) |
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5.7.1 Winding inductance, capacitance |
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166 | (12) |
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5.7.2 Series capacitance under buckling |
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178 | (1) |
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5.7.3 Shunt capacitance under buckling |
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178 | (1) |
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178 | (5) |
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5.7.5 Paper insulation deterioration |
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183 | (4) |
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5.7.6 Temperature and moisture content |
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187 | (12) |
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5.8 Online transformer winding deformation diagnosis |
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199 | (12) |
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5.8.1 Methods for online transformer active part assessment |
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199 | (4) |
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203 | (2) |
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5.8.3 Online FRA (OFRA) progress and influence of bushing tap |
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205 | (2) |
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207 | (4) |
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6 Monitoring of power transformers by mechanical oscillations |
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211 | (28) |
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211 | (1) |
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6.2 Physics of mechanical oscillations |
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212 | (2) |
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6.2.1 Oscillations of the core |
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212 | (1) |
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6.2.2 Oscillations of the windings |
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213 | (1) |
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6.3 Measurement of vibrations |
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214 | (3) |
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6.3.1 Comparison of tank wall and in-oil measurement |
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216 | (1) |
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6.4 Sensitivity of surface tank measurements |
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217 | (3) |
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217 | (2) |
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6.4.2 Field test: sensor positions |
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219 | (1) |
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6.5 Superimposing effects on tank wall measurements |
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220 | (3) |
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6.5.1 Effects of on-load tap-changer position |
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220 | (1) |
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6.5.2 Effects of transformer load and operating temperature |
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221 | (2) |
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6.6 Practical case studies |
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223 | (2) |
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6.6.1 Mechanical oscillations over time |
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223 | (2) |
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6.7 Behaviour of mechanical oscillations at DC superimposition |
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225 | (9) |
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6.7.1 DC-coupling path into power transformers |
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225 | (1) |
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6.7.2 Saturation and its effect on magnetostriction |
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226 | (1) |
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6.7.3 Test setup for DC superimposed effects |
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227 | (2) |
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6.7.4 DC-detection using vibration measurement |
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229 | (2) |
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6.7.5 Dependency of DC-driven vibration and transformer noise |
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231 | (2) |
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6.7.6 Case study on transformers impacted by DC |
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233 | (1) |
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234 | (5) |
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235 | (4) |
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7 Lifecycle management of power transformers in a new energy era |
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239 | (20) |
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239 | (1) |
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240 | (6) |
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7.2.1 Renewable energy sources |
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243 | (3) |
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246 | (1) |
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7.3 Impact on asset management strategies |
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246 | (2) |
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7.3.1 Operation, maintenance and replacement of ageing assets |
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247 | (1) |
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7.4 The advent of artificial intelligence |
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248 | (3) |
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7.5 Analysis automation as an aid to lifecycle management |
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251 | (3) |
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7.5.1 Condition attributes |
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252 | (1) |
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253 | (1) |
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253 | (1) |
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7.5.4 Implementation tool |
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254 | (1) |
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7.6 The digital substation |
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254 | (2) |
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254 | (1) |
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7.6.2 Technical standards |
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255 | (1) |
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7.6.3 Hardware and software technologies |
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255 | (1) |
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256 | (1) |
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256 | (3) |
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257 | (2) |
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8 Power transformer asset management and remnant life |
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259 | (36) |
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259 | (1) |
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259 | (2) |
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8.2 Transformer health condition |
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261 | (2) |
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263 | (1) |
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8.4 Fuzzy-logic model development |
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264 | (20) |
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265 | (2) |
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8.4.2 CO ratio criticality |
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267 | (3) |
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8.4.3 Paper ageing criticality |
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270 | (1) |
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8.4.4 Relative accelerating ageing criticality |
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271 | (3) |
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8.4.5 Thermal fault criticality |
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274 | (1) |
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8.4.6 Electrical fault criticality |
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275 | (1) |
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8.4.7 Overall thermal-electrical fault criticality |
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276 | (1) |
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277 | (4) |
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8.4.9 Remnant life estimation |
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281 | (1) |
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8.4.10 Asset management model |
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282 | (2) |
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8.5 Case study on pre-known condition of power transformer |
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284 | (5) |
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289 | (6) |
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291 | (1) |
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291 | (4) |
Index |
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