Electrical Safety Engineering of Renewable Energy Systems

Rodolfo Araneo, Massimo Mitolo

• Publisher: Wiley-IEEE Press
• Year: 2021
• ISBN:
  9781119625018
• Edition: 1
• Topic: Ciencias físicas
• Subtopic: Energía

Electrical Safety Engineering of Renewable Energy Systems

A reference to designing and developing electrical systems connected to renewable energies

Electrical Safety Engineering of Renewable Energy Systems is an authoritative text that offers an in-depth exploration to the safety challenges of renewable systems. The authors—noted experts on the topic—cover a wide-range of renewable systems including photovoltaic, wind, and cogeneration and propose a safety-by-design approach. The book clearly illustrates safe behavior in complex real-world renewable energy systems using practical approaches.

The book contains a review of the foundational electrical engineering topics and highlights how safety engineering links to the renewable energies. Designed as an accessible resource, the text discusses the most relevant and current topics supported by rigorous analytical, theoretical and numerical analyses. The authors also provide guidelines for readers interested in practical applications. This important book:

• Reviews of the major electrical engineering topics
• Shows how safety engineering links to the renewable energies
• Discusses the most relevant current topics in the field
• Provides solid theoretical and numerical explanations

Written for students and professional electrical engineers, Electrical Safety Engineering of Renewable Energy Systems explores the safety challenges of renewable systems and proposes a safety-by-design approach, which is currently missing in current literature.

1
Fundamental Concepts of Electrical Safety Engineering

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CONTENTS

1.1 Introduction

1.2 Electric Shock

1.2.1 Ventricular Fibrillation

1.2.2 The Heart-current Factor

1.3 The Electrical Impedance of the Human Body

1.3.1 The Internal Resistance of the Human Body

1.4 Thermal Shock

1.5 Heated Surfaces of Electrical Equipment and Contact Burn Injuries

1.6 Ground-Potential and Ground-Resistance

1.6.1 Area of Influence of a Ground-electrode

1.7 Hemispherical Electrodes in Parallel

1.8 Hemispherical Electrodes in Series

1.9 Person’s Body Resistance-to-ground and Touch Voltages

Example 1.1

1.10 Identification of Extraneous-Conductive-Parts

1.11 Measuring Touch Voltages

References

I shall be telling this with a sigh
Somewhere ages and ages hence:
Two roads diverged in a wood, and I-
I took the one less traveled by,
And that has made all the difference.

Robert Frost

1.1 Introduction

The renewable energy sector has been rapidly growing in the past decade [1–3], and so has been the number of accidents involving workers in “green” projects. Statistics in the United States reveal that injuries and death are caused by lack of safety training and safety procedures [4]. The Electric hazard, but also Falls, Struck by and Caught in between hazards, are always present during all photovoltaic, solar thermal, and wind tower construction projects, regardless of the magnitude of the job.

The culture of the safety-by-design [5, 6] seems to be the appropriate response to the increased risk offered by renewable energy systems (RES). RES may challenge the safety of workers because they are generally always live, and the system voltage may exceed 500 V d.c.¹

In addition to safety training and procedures, electrical safety may be conveyed through engineering measures that reduce the risk of electric shock below a threshold that is conventionally deemed acceptable by applicable standards. In fault-free conditions, the basic protection ensures that persons cannot come into contact with parts normally live (i.e., proper insulation of electrical components). In the case of failure of the basic insulation of components, the fault protection ensures defense against electric shock by automatic interruption of the fault current. In some scenarios, the fault protection may be obtained with alternative methods to the fault current interruption.

In general, the safety-by-design of RES [7] is achieved if hazardous energized parts are never accessible, and that equipment/appliances, also referred to as exposed-conductive-parts (ECPs), are never hazardous either under normal operations or in the event of single-faults. In essence, touch voltages and contact durations must be within the magnitudes deemed safe by applicable technical standards and codes.

1.2 Electric Shock

External electrical stimuli applied to the human body can prevent operational skeletal and cardiac muscles from properly operating, as well as destroy bodily tissues by thermal shock.[8]

External a.c. currents with frequency ranging from 50 to 100 Hz of magnitude around 10 mA for adult males and 15 mA for adult females, can override the internal electrical signals from ...