Electrical Safety of Low-Voltage Systems By Dr. Massimo A. G. Mitolo

Electrical Safety of Low-Voltage Systems By Dr. Massimo A. G. Mitolo

Contents:

1 Basic Definitions and Nomenclature

2 Fundamentals of Electrical Safety

3 Mathematical Principles of Electrical Safety

4 The Earth

5 Effects of Electric Currents Passing Through the Human Body, and Safety Requirements

6 TT Grounding System

7 TN Grounding System

8 Protective Multiple Earthing (TN-C-S Grounding System)

9 IT Grounding System

10 Extra-Low-Voltage Systems

11 Earth Electrodes, Protective Conductors, and Equipotential Bonding Conductors

12 Safety Against Overvoltages

13 Safety Against Static Electricity

14 Testing the Electrical Safety

15 Applications of Electrical Safety in Special Locations and Installations

Preface:

Electrical safety may be perceived only as a list of prudent actions to or not to undertake in the presence of energized objects, constituting the defense against direct contact with live parts. However, the safety of persons also depends on their exposure to indirect contact, that is, contact with parts normally not in tension, but likely to become energized due to faults. Thus, the attitude toward live parts is not the only key in preventing accidents. This book, prompted by this concept, is an attempt, from the academic point of view, to bridge the existing gap between life-safety electrical issues in low-voltage systems (i.e., not exceeding 1 kV) and their proper comprehension and design solution, in light of applicable IEC and IEEE standards. We assume, in fact, that we can analytically quantify the hazards caused by indirect contact, thereby promoting a proper design for the electrical system and minimizing the related risk. The book, based on my 20-year-long experience as a professor and as a professional engineer, provides an explanation of the fault-loops in different types of grounding systems (i.e., TT, TN, and IT) and of the faults occurring on both sides of the supply (i.e., the primary and secondary of substation transformers). The crucial role played by the state of the neutral is deeply examined, thereby allowing the comprehension of the reasons behind the methodologies of protection against electric shock, which are required by current standards and codes.