Basic Electricity With Safety PDF

BASIC ELECTRICITY WITH SAFETY and down quickly. This movement of air is just what is needed to cause a charge OBJECTIVES separation in the clouds and on the ground....

BASIC ELECTRICITY WITH SAFETY and down quickly. This movement of air is just what is needed to cause a charge OBJECTIVES separation in the clouds and on the ground. The top of the cloud becomes positively At the end of the session, participants will be charged, as does the ground. The bottom of able to: the cloud becomes negatively charged. The figure below depicts the charging that occurs  discuss the basic elements of electricity during a storm.  describe typical cases of electric shock accidents  articulate effects of electric current to the human body  explain means of preventing electric shock INTRODUCTION OSH (Occupation Safety and Health) DYNAMIC ELECTRICITY PRINCIPLES Standards has devoted an entire section The (Rule 1210) which specifies standards on ELECTRICAL SAFETY.  Current is defined as the movement of free electrons. The employer must train employees in safe work practices in working with electrical equipment.  The training rules distinguish between workers who work on or near exposed energized parts and those who do not.  Even if you are not qualified to work on electrically energized equipment, you must know the specific safety practices which apply to your job. COPPER ATOM To handle electricity safely, including working with electrical equipment, you need to understand how electricity acts, how it can be approached, the hazards it presents, and how those hazards can be controlled. Basically, there are two (2) kinds of electricity: 1. STATIC (stationary) CONDUCTORS AND INSULATORS 2. DYNAMIC (moving) WHAT IS AN ELECTRICAL INSULATOR? Lightning is one of the most dramatic examples of static electricity. During a storm, A material having few free electrons that the wind turbulence causes air to move up cannot move easily.  SOURCES OF ELECTRICITY  Rubber, dry wood, porcelain, and Chemical means movement of electrons clay are good insulators. from one electrode to the other placed in a  Insulators prevent the flow of current solution known as an electrolyte. in an electric circuit.  Ex. Batteries WHAT IS AN ELECTRICAL CONDUCTOR? A material having many free electrons that can move easily. Metals (especially copper) are good conductors. A copper wire will allow billions of electrons Thermal means two dissimilar metals when to flow in the same direction to create a great heated will produce electricity. source of electrical current.  Ex.: Thermocouple Sources of Dynamic Electricity  Mechanical means Conductors cutting magnetic field  Ex. Generator driven by various prime movers such as: diesel, steam or water turbine, etc. Faraday's Discovery Solar means energy from the sun "Moving a conductor across magnetic  Ex.: Solar panels lines of force will produce voltage at the ends of the conductor.” GENERATOR An electric generator is a device used to convert mechanical energy into electrical energy. Piezoelectric means applying pressure to SUMMARY some materials such as Rochelle salts or quartz crystals will produce electricity  By understanding the basic elements of electricity, one will be able to  Ex.: Quartz watches practice electrical safety. CHARACTERISTICS OF ELECTRICITY Engineering-Utilities.-INTRODUCTION Electricity flowing through a circuit can be INTRODUCTION likened to the flow of water through a pipe, and if this analogy is kept in mind, the IMAGINE YOURSELF IN THE MOST following terms shall be understood. FABULOUS BUILDING IN THE WORLD. Now take away the lighting, heating and  CURRENT (I) ventilation, the lifts and escalators, acoustics,  VOLTAGE (V or E) plumbing, power supply and energy  RESISTANCE (R) management systems, the security and safety systems.... and you are left with a cold, CURRENT may be thought of as the TOTAL dark, uninhabitable shell. VOLUME OF WATER flowing past a certain point in a given length of time. Electric Everything inside a building which makes it current is measured in amperes, which is a safe and comfortable to be in comes under very large quantity; therefore, in relation to the title Building Utilities. the effect of shock on the human body, the measurement used is the milliampere (0.001 A building must do-not just provide shelter ampere). but also be an environment where people can live, work and achieve. VOLTAGE may be thought of as the PRESSURE in a pipeline: it is measured in BUILDING UTILITIES volts. Building Utilities means "covered equipment" RESISTANCE is any condition which permanently mounted on or in a building and RETARDS FLOW; it is measured in ohms. used to provide any of the following services within the building: heating, ventilating, air conditioning, electrical power, hot water, elevator or escalator services, central vacuum, natural gas service or communication. DIFFERENCE BETWEEN BUILDING THE DEMAND FOR UTILITIES WILL MAKE SERVICES AND UTILITIES THE PROCESS OF CONSTRUCTION MORE COMPLICATED DUE TO THE Building services refer to the systems and SIMULTANEOUS ACTIVITIES IN THE equipment within a building that provide JOBSITE heating, ventilation, air conditioning, lighting, power, and other services necessary for the Why is there a need for Civil Engineers to building's occupants. This can include things study Basic Electricity? like elevators, escalators, and fire safety systems. Utilities, on the other hand, refer to I have worked for over 30 years as an the external services and infrastructure that architectural designer. a building relies on, such as electricity, gas, water, and sewer. These utilities are typically Why is there a need for basic electrical provided by public or private companies and knowledge in civil engineering? are essential for the functioning of a building. In summary, building services are the I can identify at least one reason why a civil internal systems and equipment within a engineer would need to have basic electrical building that provide comfort and safety for knowledge and identify electrical symbols the occupants, while utilities are the external and that is when they select structural services that the building relies on for its framing that need to be solid he makes sure basic functioning. that the electrical devices and components are not installed in a manner that will  In a REFINERY - for example compromise the integrity of the structural members, systems or subsystems. Also that Utilities would be: the structural framing has adequate backing for mounting such electrical components. 1. Electricity 2. Compressed air  Civil engineers often work on projects 3. Steam that involve the design, construction, 4. Potable water and maintenance of infrastructure 5. Wastewater such as buildings, roads, bridges, 6. Vacuum and other structures. o and others - depending on the site  These projects often require electrical systems such as lighting,  In a SHOPPING MALL power distribution and control systems. Utilities would be: By studying the fundamentals of electrical 1. Electricity engineering, civil engineers gain a deeper 2. Water understanding of how these systems work 3. Wastewater removal and how to design and integrate them into 4. Telecommunications their projects. 5. They could ALSO include: Additionally, an understanding of electrical  Piped music engineering can enhance the energy  Internet (fibre or wifi) efficiency and sustainability of civil  Security engineering projects. ENGINEERING UTILITIES Copper Atom BASIC ELECTRICITY ELECTRICITY Electricity has a very large influence on our lives, but it is not well understood by many people. Electricity is used to power many of Conductors and Insulators the things that we use every day.  Conductors are the materials or substances which allow electricity to flow through them. Conductors and Insulators Electric Charges  Conductors are the materials or substances which allow electricity to Three particles that make up an atom: flow through them.  Protons (positive)  Insulators are the materials or  Neutrons (neutral) substances which resist or don’t allow  Electrons (negative) the current to flow through them.  Semi-conductors are materials that possess the properties of both the conductor and the insulator. (examples: silicon and germanium.) Electric Circuit figure below depicts the charging that occurs during a storm. SOURCES OF DYNAMIC ELECTRICITY 1. Mechanical Voltage 2. Chemical 3. Photovoltaic  It is the force that makes electrons 4. Thermoelectric move in a certain direction within a 5. Piezoelectric conductor.  Also known as the Electromotive MECHANICAL MEANS Force (EMF)  Can be DC or AC  Symbol is E or V Conversion of mechanical energy to  Unit is volts(V) electrical energy  ICE (Internal Combustion Engines) EXAMPLES OF VOLTAGE SOURCES ENGINES (Diesel, gasoline, bunker, etc.)  Coal plants  Nuclear  Geothermal  Hydro Example: Generator Open Type: STATIC ELECTRICITY Lightning is one of the most dramatic example of static electricity. During a storm, Closed Type: the wind turbulence causes air to move up and down quickly. This movement of air is just what is needed to cause a charge separation in the clouds and on the ground. The top of the cloud becomes positively charged, as does the ground. The bottom of the cloud becomes negatively charged. The Faraday’s Discovery  So the generalized equation for generated EMF of DC generator is: “Moving a conductor across magnetic lines Eg = kΦω of force will produce voltage at the ends of the conductor.” Where: o K = ZP/2πA = constant of the DC machine o ω = 2πN/60 = angular speed in rads per second CHEMICAL MEANS movement of electrons from one electrode to the other placed in a solution known as an electrolyte. Ex. Batteries  Voltage generated is directly proportional to the speed of rotation. V increases as Chemical means conversion of chemical speed (RPM) is increased. energy to electrical energy.  Voltage generated will also increase as the number of turns is increased. V increases as N is increased. EMF Equation for DC Generator:  The EMF generated per conductor in a DC generator is:  EMF equation for DC generator o Z = number of conductors o P = number of Poles o N = Speed of rotor in RPM Electricity from Solar Panels o A = number of parallel paths  The EMF generated per path for a wave winding & lap-winding;  The instrument used to measure resistance is the ohmmeter. The ohmmeter function is available in a Multi- Tester or VOM (Volt-Ohm-Milliammeter) THERMAL MEANS Conversion of heat energy to electrical energy.  In 1926, George Simon Ohm described the relationship between Common applications in instrumentation and current, voltage and resistance with controls. his popular Ohm’s Law. Devices are responsible in automation of systems. Thermal Means Ohm’s Law states that “Current (I) is directly proportional to the Two dissimilar metals when heated will amount of Voltage (V) and inversely produce electricity. proportional to the value of Resistance (R).” Ex.: Thermocouple VI = R Resistance The opposition to the flow of electrical current. Measured in ohms is a term that describes the forces that oppose the flow of electrical current in a conductor. OHM’S LAW TRIANGLE  Unit is ohms  Symbol 1K = 1000 1M =1,000,000  ENERGY Energy = Power x Time Units: Energy = KW x HOURS 1 KW-HOUR = 1000 WATT-HOURS 1. An electric bulb draws a current of 2 amperes when connected to a We are buying energy from CENECO since 12volts DC source. What is the they sell their services in KW-Hrs. resistance of the electric bulb? 2. The electrician measured the resistance of a water heater to be 10 7. How much will CENECO charge if I ohms. If connected to a 220 volt operate a1000 watt pressure cooker source, how much current will flow in for 2 hours? Assume CENECO will the circuit? charge P12.00 per KW-HR 3. What will be the appropriate fuse for 8. What would be your electric bill in one a rice cooker with a resistance of 75 month for using the ohms if connected to a 220V source? following appliances? Assume a A. 2 amperes 30 day month. B. 3 amperes 1. Refrigerator, 400 watts with an C. 4 amperes average operating hours of 16 hours per day POWER 2. 4 Incandescent bulbs with 50Watts power rating operating at The amount of energy transferred or 12 hours per day. converted per unit time. In the International 3. 1- 5 horsepower Aircon unit System of Units, the unit of power is the watt. operating at 4 amperes current operating at 10 hours per day. 1 HORSEPOWER = 746 WATTS 4. How much current will a 50 watts 1 KILOWATT= 1000 WATTS incandescent bulb draws if connected to a 220 V source? 4. How much current will a 50 watts 5. A 5 horsepower DC motor is incandescent bulb draws if connected to a 110 volts source. connected to a 220 V source? What is the resistance of this 5. A 5 horsepower DC motor is motor? connected to a 110 volts source. 6. A certain resistor has a resistance What is the resistance of this motor? of 1.5 kilohms. How much current 6. A certain resistor has a resistance of in milliamperes it will draw if 1.5 kilohms. How much current in supplied from a 6 volts battery? milliamperes it will draw if supplied What should be its power rating? from a 6 volts battery? What should be its power rating?