Bicol University Civil Engineering Department Course Project - PDF

BICOL UNIVERSITY Legazpi East Campus College of Engineering CIVIL ENGINEERING DEPARTMENT COURSE PROJECT IN ENGINEERING UTILITIES 1 Building Electrical Service Equipment and Overcurrent Protection Devices: Fuses and Breakers...

BICOL UNIVERSITY Legazpi East Campus College of Engineering CIVIL ENGINEERING DEPARTMENT COURSE PROJECT IN ENGINEERING UTILITIES 1 Building Electrical Service Equipment and Overcurrent Protection Devices: Fuses and Breakers PALACIO, ANTHONY JR. P. SY, KISSY JEIREL D. BSCE-3C ENGR. HANA MYKA GATON-DULAY COURSE INSTRUCTOR  BICOL UNIVERSITY Legazpi East Campus College of Engineering CIVIL ENGINEERING DEPARTMENT CHAPTER 2: BUILDING ELECTRICAL SERVICE EQUIPMENT AND OVERCURRENT PROTECTION: FUSES AND CIRCUIT BREAKERS OVERVIEW: This module will provide an understanding about the concept and components of building service equipment that are utilized in the electrical system of a building, and the crucial role of overcurrent protection, such as fuses and breakers, in ensuring the safety and efficiency of power distribution in the building. LEARNING OBJECTIVES: By the end of this module, the students should be able to: Know the components of building electrical service equipment Understand the concept of overcurrent protection and its potential hazards Differentiate the types of fuses and circuit breakers Apply the knowledge in real-life application such as selecting appropriate overcurrent protection devices based on electrical requirements INTRODUCTION: Electrical service equipment and overcurrent protection are essential components in any building’s electrical system. Electrical service equipment serves as the nervous system of a building, distributing electrical energy across different parts of the building. These are the components installed in the building to manage distribution, control and protection of electricity from the utility supply to the various circuits within the building. A crucial part of this system is the overcurrent protection. It refers to the methods and devices used to protect electrical circuits and equipment from damage caused by excessive current flow. Additionally, this protects the building from any potential hazards caused by overcurrent such as fire and electric shock.  BICOL UNIVERSITY Legazpi East Campus College of Engineering CIVIL ENGINEERING DEPARTMENT BUILDING ELECTRICAL SERVICE EQUIPMENT: Electrical Service Equipment -is considered as the nervous system of a building. It refers to the conductors and equipment responsible for the distribution of electric energy from the serving utility to the wiring system of the premises served. Building electrical service equipment includes: 1. Service Entrance Conductor- refers to the conductors that carry power from the transformer through a metering device to the building’s service disconnects. Types of Service Entrance Conductors: a. Overhead Service Entrance Conductors (Service Drop): The overhead wires that bring electricity from the utility pole to a building. These wires run from the pole to a point on the building, usually above the roof, where they connect to the building's electrical system. b. Underground Service Entrance Conductors (Service Lateral): The underground cables that bring electricity from the utility’s underground system to a building. These cables are buried in the ground and connect to the building's electrical system, usually at a meter or service panel. Photo from: https://energyknowledgebase.com/  BICOL UNIVERSITY Legazpi East Campus College of Engineering CIVIL ENGINEERING DEPARTMENT 2. Service Entrance- This refers to the location where the service entrance conductors connect to the building’s electrical system. It is the starting point for all electrical power that comes into a building. Additionally, it includes the components that connect the utility- supplied wiring (the service lateral or service drop) to the service disconnect, excluding the utility’s metering equipment. Photo from: https://home.howstuffworks.com/ ▪ Service Entrance Equipment- receives the service entrance conductors. ▪ Service Disconnect- part of service entrance equipment that allows electrical service from the utility company to be switched off so that power is disconnected to the building installation. It is a set of fuses or a circuit breaker that protects the service entrance conductors. 3. Switchboard- is considered as the nerve centers of electrical systems, acting as the primary distribution point for electrical power. It is responsible for receiving electricity from the main power source and distributing it to various circuits and devices throughout a building or facility. Photo From: https://jaricgroup.com.au/  BICOL UNIVERSITY Legazpi East Campus College of Engineering CIVIL ENGINEERING DEPARTMENT 4. Panelboard- also known as distribution board or breaker panel, serves as secondary distribution points within electrical systems. It receives power from the switchboard and further distributes it to individual circuits, accommodating the specific electrical requirements of different areas or equipment. Panelboards feature circuit breakers or fuses that protect circuits from overloads and Photo From: https://ultrasteel.com.ph/ short circuits, safeguarding both electrical equipment and human life. 5. Building Transformer - is a device used in transmitting and distributing power from the power plant to a substation. It is responsible for increasing or decreasing the incoming voltage from the utility provider to the levels required for the building’s electrical system. Photo From: https://daelim- electric.com/ OVERCURRENT PROTECTION: Overcurrent - occurs when the current in an electrical circuit exceeds the circuit’s capacity, leading to potential hazards like overheating, fires, or equipment damage. Common causes of overcurrent: 1. Short circuit- occurs when electrical conductors accidentally touch, creating a path of very low resistance, leading to a surge of current. 2. Overload- happens when a circuit carries more current than it’s designed for, typically due to too many devices or appliances operating simultaneously.  BICOL UNIVERSITY Legazpi East Campus College of Engineering CIVIL ENGINEERING DEPARTMENT Overcurrent Protection is crucial for electrical safety as it prevents excessive current from flowing through electrical circuits, which could otherwise cause overheating, fires, or damage to equipment. By detecting conditions short circuits and overloads, overcurrent protection devices automatically interrupt the flow of electricity, mitigating risks and ensuring the safety operation of electrical systems. Tripping- refers to the automatic operation of an OCP device that interrupts the flow of electrical current in a circuit when an abnormal condition occurs. OVERCURRENT PROTECTIVE DEVICES: Overcurrent protective devices are designed to safeguard circuits from excessive currents that can lead to overheating, fires, or equipment damage. These devices detect abnormal conditions, such as short circuits and/or overloads, that automatically interrupt the flow of electricity to prevent potential hazards. Fuses and circuit breakers serve as automatic overcurrent protection devices. They are designed to open a circuit if the amount of current, in amps, that flows through the circuit exceeds the OCP device rating. 1. Fuse- a protective device designed to prevent overcurrent in electrical circuits. It consists of metal wire or strip that melts when the current exceeds a specific threshold, breaking the circuit and interrupting the flow of electricity. This process, known as blowing. Types of Fuses: a. Plug Fuse- is a round fuse which screw into a base in the fuse holder to complete the circuit. It is used primarily in residential and light commercial electrical systems with low-voltage, low-current circuits. The operating range is usually up to 150 volts and from 0.5 ampere to 30 amperes.  BICOL UNIVERSITY Legazpi East Campus College of Engineering CIVIL ENGINEERING DEPARTMENT b. Cartridge Fuse- operates exactly like the plug-type fuse. In the cartridge fuse, the fuse link is enclosed in a tube of insulating material with metal ferrules at each end (for contact with the fuse holder). c. Fast-acting fuse (quick-blow fuse)- is a type of fuse designed to interrupt the electrical circuit almost immediately when the current exceeds its rated capacity. It provides rapid protection for sensitive electronic components and circuits that cannot tolerate even short-duration overcurrent conditions. d. Time-Delay Fuse (Slow-Blow Fuse) - is designed to tolerate short bursts of overcurrent, such as inrush currents, without blowing immediately. This feature makes time-delay fuses suitable for circuits where temporary current spikes are normal, such as those with inductive loads. e. Resettable Fuses/ Positive Temperature Coefficient (PTC) Fuses - are designed to protect electrical circuits by automatically resetting after an overcurrent condition has cleared, offering a reusable option compared to traditional single-use fuses. 2. Circuit Breaker- is an electrical device that automatically interrupts the flow of current in a circuit when an abnormal condition, such as an overload or short circuit, is detected. They operate using an internal mechanism that senses the fault and trips the breaker, cutting off the electrical supply to prevent damage to the circuit and connected devices. Unlike fuses, circuit breakers can be reset manually after tripping, allowing the circuit to return to normal operation.  BICOL UNIVERSITY Legazpi East Campus College of Engineering CIVIL ENGINEERING DEPARTMENT Common Types of Circuit Breakers: a. Miniature Circuit Breaker (MCB) - designed for low voltage applications, MCBs protect against overloads and short circuits in residential and light commercial settings. They have a fixed trip setting, making them suitable for consistent load conditions. b. Molded Case Circuit Breaker (MCC)- used in higher current applications than MCBs. MCCBs offer adjustable trip settings and are common in industrial environments. They provide protection against overloads, short circuits and in some cases ground faults. c. Residual Current Device (RCD) / Residual Current Circuit Breaker (RCCB) - This device detects and disconnects circuits when it senses a leakage current (earth fault), preventing electric shocks. RCDs are essential in applications when direct human contact with electrical components is a risk. d. Air Circuit Breaker (ACB)- Used primarily in high- current industrial applications, ACBs operate by interrupting the circuit using air as the arc extinguishing medium. They are typically employed in the main power distribution of large buildings and industrial plants.  BICOL UNIVERSITY Legazpi East Campus College of Engineering CIVIL ENGINEERING DEPARTMENT e. it protects electrical power stations and distribution systems by interrupting electric currents, when tripped by a protective relay. SF6 (sulfur hexafluoride) gas is commonly used as an insulating medium in high- voltage circuit breakers and other electrical equipment. FACTORS TO CONSIDER WHEN SELECTING FUSE AND CIRCUIT BREAKER: 1. Current Rating- also known as ampacity or ampere rating, determines the maximum current the fuse can handle without blowing, providing protection for electrical components from overcurrent conditions. Overrating or underrating the fuse or breaker can lead to either tripping or failure to protect the circuit. 2. Voltage Rating- it indicates the maximum voltage the fuse can safely interrupt without breaking down. A fuse or circuit breaker with a voltage rating lower than the circuit voltage may fail to open properly during a fault. The voltage rating should be equal to or greater than the maximum voltage present in the circuit. 3. Interrupting Capacity- also known as breaking capacity is the maximum current which the fuse can safely break or interrupt at rated voltage. It is essential to ensure that the fuse's breaking capacity is higher than the potential short-circuit current of the circuit. 4. Operating Environment- when selecting an OCP device, it is important to consider the operating environment, such as temperature, humidity, corrosive atmospheres, and potential exposure to chemicals or dust. Certain fuses and breakers are designed for specific environmental conditions. 5. Response Time- is the time it takes to blow and interrupt the current once an overcurrent condition occurs. Fuses come in various types, such as fast-acting (quick-blow) and time-delay (slow-blow). The selection depends on the sensitivity of the circuit and the nature of the load. Fast-acting fuses protect  BICOL UNIVERSITY Legazpi East Campus College of Engineering CIVIL ENGINEERING DEPARTMENT 6. sensitive components, while time-delay fuses handle inrush currents without blowing. 7. Standards and Approvals- The fuse should meet the required safety standards and approvals (e.g. Philippine Electrical Code (PEC) and International Electrical Code (IEC) for the application and region in which it will be used. 8. Types of Loads- different types of electrical loads have unique characteristics that affect how current flows through a circuit. Understanding the type of load helps in choosing the appropriate protective devices that provide effective protection. Resistive Loads: These loads, such as incandescent lighting and heating elements, have a consistent current draw without significant inrush. For these loads, standard fuses or circuit breakers with appropriate current ratings can be used. Inductive Loads: Loads like motors, transformers, and inductors draw higher currents when first energized, known as inrush current, which can be 5 to 10 times the normal operating current. Time-delay fuses or breakers are often required to handle the inrush without tripping unnecessarily. Capacitive Loads: These loads, such as power factor correction capacitors and certain electronic devices, may also exhibit inrush currents, though their characteristics differ from inductive loads.  BICOL UNIVERSITY Legazpi East Campus College of Engineering CIVIL ENGINEERING DEPARTMENT References: What are Overcurrent Protection Devices? (2021, February 10). Retrieved September 3, 2024, from https://eepower.com/technical-articles/what-are-overcurrent-protection- devices/ Service conductor · Energy KnowledgeBase. (n.d.). https://energyknowledgebase.com/topics/service-conductor.asp Different Types of Fuses and their Applications. (n.d.). Components101. https://components101.com/articles/different-types-of-fuses-and-their-applications AllumiaX LLC. (2020b, October 2). How to select the right fuse for power systems protection. https://www.allumiax.com/blog/how-to-select-the-right-fuse-for-power- systems-protection Limited, C. E. (2023, September 20). Circuit Breaker Types and Applications - C&S Electric. C&S Electric Blog. https://cselectric.co.in/blog/everything-need-know-circuit- breakers-introduction-applications-types/ PLUG-TYPE FUSE. (n.d.). https://electriciantraining.tpub.com/14175/css/Plug-Type- Fuse-92.htm