Page 13 - Electrical Safety of Low Voltage Systems

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Dr. Massimo A. G. Mitolo

11.6 The PEN Conductor 197
FAQs 198

Endnotes 199
12 Safety Against Overvoltages 201

12.1 Introduction 201
12.2 Temporary Overvoltages and Safety 202

12.2.1 High-Voltage Ground Faults in TN Systems 202
12.2.2 High-Voltage Ground Faults in TT Systems 204

12.2.3 High-Voltage Ground Faults in IT Systems 206
12.3 External Overvoltages 208

12.3.1 Characterization of Earthing Systems Under Impulse Conditions 209
12.3.2 Induced Overvoltages 210

Endnotes 212
13 Safety Against Static Electricity 213

13.1 Introduction 213
13.2 Generation of Static Electricity 215
13.3 Static Charge Energy 216

13.4 Mitigation Strategies 218

13.5 Residual Voltages 219
Endnotes 222

14 Testing the Electrical Safety 223
14.1 Introduction 223

14.2 Soil Resistivity Measurement 223
14.3 Earth Resistance Measurement 226
14.4 Earth Resistance Measurements in Industrial Facilities 228

14.5 Earth Resistance Measurement in TT Systems 230

14.6 Measurement of the Fault-Loop Impedance in TN Systems 232
14.7 Touch Voltage Measurement in TN Systems (Low-Voltage Earth Faults) 234
14.8 Step and Touch Voltage Measurements in TN Systems 235

14.9 Fundamental Measurements in IT Systems 238

14.10 Protective Conductor Continuity Test 239
14.11 Insulation Resistance Test 240
Endnotes 242