Desing & Management of Electrical Instalations

DESING & MANAGEMENT OF ELECTRICAL INSTALLATIONS

A guide for directors, managers, architects, engineers and students.

Elvins Aguilar G.

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Copyright © 2024 Elvins Aguilar G.

All rights reserved

The characters and events portrayed in this book are fictitious. Any similarity to real persons, living or dead, is coincidental and not intended by the author.

No part of this book may be reproduced, or stored in a retrieval system, or transmitted in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise, without express written permission of the publisher.

This guide is dedicated to all those responsible for designing, constructing, deciding, and managing electrical infrastructure in industrial plants and processes. It is also aimed at engineering students interested in the practical aspects of electrical engineering. We provide an overview of the fundamental concepts of design, as well as the most relevant considerations in the construction and management of electrical systems.

contents

Introduction

PART 1: MAIN ELECTRICAL POWER SUPPLY

CHAPTER 1. Connection to the Public Power Grid

CHAPTER 2. Independent Power Source

PART 2: ELECTRICAL SUBSTATION

CHAPTER 3. Energy Transformation

PART 3: INTERNAL ELECTRICAL DISTRIBUTION SYSTEM

CHAPTER 4. Internal Electrical Network Design

CHAPTER 5. Network Segmentation

CHAPTER 6. Feeders and Subfeeders

PART 4: ELECTRICAL PANELS

CHAPTER 7. Types of Panels and Their Applications

CHAPTER 8. Electrical Protections

PART 5: ENERGY BACKUP SYSTEMS

CHAPTER 9. UPS – Uninterruptible Power Supply

CHAPTER 10. Emergency Generators

PART 6: LIGHTING SYSTEM

CHAPTER 11. Lighting Design

PART 7: CONTROL AND AUTOMATION SYSTEMS

CHAPTER 12. Types of Control Systems

CHAPTER 13. Configuration and Programming

PART 8: ELECTRICAL NETWORK DISTURBANCES AND EFFICIENCY

CHAPTER 14. Causes and Types of Disturbances

CHAPTER 15. Detection and Mitigation of Disturbances

CHAPTER 16. Power Factor (PF)

PART 9: GROUNDING SYSTEM

CHAPTER 17. Grounding System

Introduction

¡ Welcome to the intriguing world of industrial electrical infrastructure!

Understanding the importance of electrical design is not just a technical matter but a smart business strategy. By investing in a solid electrical design from the beginning, we can protect our operations, ensure customer satisfaction, and lay the foundation for long-term sustainable growth.

As a manager, you are constantly seeking ways to improve operational efficiency, ensure facility safety, and maximize return on investment. However, there is a fundamental aspect that often goes unnoticed: the electrical design of our facilities.

Imagine for a moment your facilities operating at full capacity when suddenly an electrical failure occurs. The resulting downtime not only disrupts our production but also exposes us to significant repair costs and, more importantly, a loss of customer trust.

A good electrical design not only prevents these disastrous situations but also offers a range of tangible benefits. By ensuring proper sizing, it prolongs the lifespan of our equipment and reduces maintenance costs. Additionally, we must carefully consider the type of equipment and materials we use.

Reliability is key. A well-executed electrical design minimizes unplanned interruptions, directly translating into increased productivity and profitability for our company.

Perhaps most importantly, the potential for future growth that a proper electrical design can offer is significant. By planning our installations with flexibility in mind, we can easily adapt to changing production demands and seize new growth opportunities without compromising efficiency or safety.

In this ebook, we will explore the essential fundamentals that underpin the energy core of any industrial plant. From connecting to the power grid to managing disturbances, we will open a window into the components of each aspect, understanding the incredible importance of each network segment and strategy that ensures the optimal and safe operation of facilities. Prepare to embark on an exciting journey where you will discover how each segment of the electrical network intertwines to create a robust and efficient electrical system. Join us in this exploration of the backbone and power behind industrial production!

In my extensive career as an electrical engineer, I have dedicated over 20 years to the challenging world of industrial electricity. Throughout this time, I have gained invaluable experience in the design, development, and installation of electrical networks in various industrial process plants and institutional buildings. However, I have realized that often, the technical complexities and seemingly intangible concepts I handle daily can be inaccessible to those who lead organizations and manage production processes.

That is why I firmly believe in the importance of sharing this knowledge more widely. I believe that professionals taking their first steps in the fascinating world of industrial electrical design need a guide that goes beyond purely specific technical aspects. My goal is to offer a more holistic perspective on electrical networks, addressing not only technical aspects but also the fundamental concepts and best practices that underpin their design and operation.

Additionally, this book aims to be an essential guide for other professionals from various specialties, such as architects, civil engineers, safety engineers, process plant managers, finance managers, entrepreneurs, and project managers, who are involved in new investment projects or organizations that depend on a safe and reliable electrical network to ensure the safety and continuity of production processes. My experience has taught me that a solid understanding of electrical principles is essential for effective decision-making and success in any industrial environment. With this book, I hope to provide that necessary guidance for those seeking to better understand this vital aspect of industrial infrastructure.

WHAT WILL WE LEARN?

Let us begin by highlighting the vital importance of electrical installations in various industrial sectors. The integral functioning of an industry, the management of process plants or production lines, and IT infrastructure all depend on the electrical network as an indispensable pillar for effective business management. In data processing and storage, especially in critical sectors such as the cold chain or vital hospital devices, electrical reliability becomes crucial, as any interruption could lead to significant losses.

The costs associated with a power interruption in an industry are considerably high due to the halt in the production process. In continuous processing plants, this interruption leads to additional human resource costs and delays in production delivery deadlines. This, in turn, causes delays in the supply chain and logistics, impacting overall production. Consequently, these setbacks not only affect the company's operational efficiency but also have a direct impact on its profitability and market competitiveness.

Therefore, it is essential to manage the development of reliable and robust electrical installations from the design phase. This will minimize downtime and mitigate the costs associated with such situations. By investing in safe, high-quality electrical infrastructures and efficient backup systems from the outset, companies can reduce the likelihood of failures and optimize operational continuity. Furthermore, a careful design that considers redundancy, load capacity, and electrical safety will help maintain uninterrupted production. In summary, proactive and precise management of electrical design is crucial to ensuring reliability and energy availability and to protecting the production process from costly downtime.

We begin by exploring the crucial importance of connecting to the public power grid and analyzing the feasibility and benefits of implementing independent power sources, such as diesel generators, to ensure a reliable energy supply in case of interruptions.

In the section dedicated to electrical substations, we delve into the world of energy transformation and efficient distribution. We discuss different types of transformers and how to select the most suitable one to optimize a project. We also cover the design of distribution systems to ensure reliable energy delivery, along with safety considerations associated with the installation and operation of substations.

We continue our journey by exploring the design of the internal electrical network of the plant, from planning load distribution and cabling routes to selecting appropriate distribution equipment. We also highlight the importance of network segmentation to facilitate maintenance and fault identification, as well as implementing monitoring systems for proactive problem detection.

In the following sections, we delve into the world of distribution panels, uninterruptible power supply (UPS) systems, and emergency generators. We explore different types of UPS and generators, as well as considerations for their installation, maintenance, and operation. We also discuss industrial lighting design, control and automation systems, electrical disturbances, and strategies to mitigate these issues to ensure the efficiency and reliability of the overall electrical system. Finally, we address grounding systems for the protection of people and equipment.

PART 1

MAIN

ELECTRICAL

SUPPLY

CHAPTER 1

CONNECTION TO THE PUBLIC NETWORK

What is the best choice, high o low voltage for connecting to the distribution network?

Amanager at a plant needed to expand the process plant to meet the production goal for the next two years, which was already sold, and requested an estimate for the cost of this expansion, allocating USD$350,000 for the electrical expansion. However, when the electrical project was completed, it was discovered that the expansion of the electrical network was close to USD$900,000.

Why did the estimate fail this way?

The manager should have conducted a detailed analysis of the project scope, identifying all activities and components necessary for the electrical expansion. This would have helped avoid significant omissions that could have contributed to the increased costs.

The manager did not consider the structural limitations of the existing installation to accommodate a significant increase in the power required for the expansion. Additionally, the need to establish a new connection to the local electrical distribution network, construct a new electrical room, and the availability of outdoor space for installing the new electrical substation and backup generators was not considered. In summary, it was incorrectly assumed that the expansion was limited to the interior of the plant without accounting for additional external electrical infrastructure needs.

DIMENSIONING

The first step in designing an electrical installation is to determine the power that the new consumers will demand or if there is availability for it in the existing installations.

It is crucial to perform a detailed analysis of the current and projected electrical load, considering factors such as the power required by new equipment, the availability of electrical supply, and the structural limitations of the existing installations. This allows for designing an electrical installation that efficiently and safely meets present and future needs.

The most important question we need to ask ourselves is what power (kilowatts) we need, which will give us an initial indication of the voltage level we should connect to. And here, I should mention that the medium voltage network is sometimes not available at our physical location, and it will be necessary to construct a network extension, which you must negotiate with the distribution company.

To determine whether you should connect at medium voltage or low voltage, and the level of power in question, several factors need to be considered.

Required Power

Evaluate the total power that the new equipment or consumers to be added to the installation will demand.

It is important to inventory new equipment and consumers that will be added to the installation, including machines, HVAC (heating, ventilation, and air conditioning), lighting systems, offices, common areas, etc.

The power required by each consumer should be determined. This may involve consulting the manufacturer's technical specifications or taking direct measurements in the case of equipment similar to existing ones.

Equipment demands power in kilowatts and consumes energy in kilowatt-hours. Consequently, electrical power is the unit for which the installation is designed, and electrical energy is the consumption per unit of time at that power.

Energy (kwh)  =  Power (kw) * Time (hrs)

Some equipment has high power but consumes little energy, such as arc welders, high-power air compressors, induction heating equipment, laser cutting equipment, battery chargers or superchargers, where high power is needed for a short operating time but has a low duty cycle.

Additionally, it is necessary to know if the large consumers operate on the same cycle or are staggered, or if their operation can be sequenced, for example, refrigeration cooling systems, where the slowly varying temperature allows for sequencing consumptions to avoid simultaneous operation.

The power demanded in a plant is the sum of the powers of its consumers, multiplied by their simultaneity factor. This is known as the maximum demand.

It is essential to conduct a load analysis or electrical balance in each design, involving both the engineer in charge of the design and the plant's electrical specialist, who has in-depth knowledge of the operation cycle of processes and equipment. Only through this collaboration will an optimal design be achieved, avoiding both over-dimensioning and under-dimensioning, both of which can lead to higher investment costs.

If the required power is high (generally above a few hundred kilowatts), it may be more efficient and cost-effective to connect at medium voltage. However, there is no specific power threshold established in the NEC to determine when connection at medium voltage is mandatory. Instead of being based on power, the decision to connect at medium voltage depends on factors such as load capacity, transmission distance, and local regulations.

Transmission Distance

In many cases, users assume that the medium voltage (MV) electrical tariff is the variable to consider when choosing the supply voltage. However, it should be clarified that an MV tariff includes additional costs such as transformer losses (4%-6%), investment costs, and maintenance costs for lines and substations, and is not necessarily cheaper than the low voltage tariff. Rather, both tariffs are quite similar when considering all the before mentioned variables.

Therefore, the decision to connect at MV or LV depends on the energy loss in the low voltage conductors from the substation to the plant's consumption center. For example, the cost of energy losses for a 75-meter run, for an average power of 400 kilowatts, in an LV connection, can reach $6,000 annually, which may be a sufficient incentive to justify extending an MV line closer to the consumption center.

If the distance between the supply source and consumers is considerable, transmitting energy through medium voltage can be more efficient and cost-effective due to lower energy losses compared to low voltage transmission.

Consider why the main transmission lines in a country are built in high and very high voltage.

Capacity of Existing Infrastructure

If we are talking about a small to medium-sized installation, it is possible that the installation, whether in medium or low voltage, is designed to handle an additional load of up to 20% without the need to modify the main structure of the installation. However, the capacity of the existing electrical infrastructure to handle the additional load must always be evaluated.

A modification in a low voltage installation beyond 20% may not be advisable as it can lead to a significant increase in short-circuit power. If the electrical protections are not prepared to handle this additional load, equipment damage, power interruptions, and even safety risks may occur. Therefore, it is essential to assess the capacity of the existing infrastructure, considering whether modifications in low voltage or connecting at medium voltage would be safer and more efficient. In many cases, connecting at medium voltage can offer greater load capacity and more efficient energy transmission, thus reducing risks associated with increased consumption in low voltage installations.

Installation and Maintenance Costs

Regarding the cost of installation and maintenance, connecting at low voltage is usually more economical initially due to the lower complexity of the required equipment and materials. However, as the load and transmission distance increase, more frequent and costly upgrades may be required to meet energy demands, which can raise long-term costs.

On the other hand, connecting at medium voltage involves a higher initial investment due to the need for more robust and expensive equipment, such as transformers, switchgear, safety spaces, and additional grounding protection systems. However, these systems tend to be more efficient in transmitting energy over long distances and can handle higher loads without frequent upgrades. Additionally, maintenance costs are generally lower due to the greater durability of medium voltage equipment.

In many countries, there is the option to rent MV equipment for industrial sites from companies specializing in this service, or the same electric distribution companies may offer this option, reducing your initial investment. Furthermore, you avoid having MV specialists on your payroll, and the response time of a company specializing in MV, in the event of a failure, is often much better.

APPLICABLE REGULATIONS AND STANDARDS

Local regulations and standards related to medium and low voltage electrical connections vary by country, region, and even specific jurisdiction. Electrical regulations in different countries, both European and American, share several common characteristics. These include safety standards for electrical installations, requirements for overload and short-circuit protection, guidelines for using certified electrical materials and equipment, proper grounding guidelines, and standards for periodic inspection and maintenance of installations. Despite some specific differences, all aim to ensure the safety, reliability, and efficiency of electrical installations.

National electrical codes and standards generally establish that the connection point is the point of installation responsibility. Whether it is a medium or low voltage connection, it is common for the company to be responsible up to the metering equipment that records the customer's consumption. In the case of renting medium voltage equipment from the same electricity company, their responsibility will extend to the interconnection point with their internal network, as stipulated in the supply contract signed by the parties.

It is important to highlight that, when constructing an extension of the medium voltage network to connect to the public network, it is crucial to ensure that it complies with the design and quality standards set by