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Electrical Principles Chapter 2. Energy, Voltage, Voltage Types, AC/DC, Current, Power, Restrictive Circuits, Inductive Circuits, Resistance, Heat, and Light. Energy. Energy. Energy – Is the capacity to do work. There are two types of Energy – Potential and Kinetic .
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Electrical PrinciplesChapter 2 Energy, Voltage, Voltage Types, AC/DC, Current, Power, Restrictive Circuits, Inductive Circuits, Resistance, Heat, and Light
Energy • Energy – Is the capacity to do work. There are two types of Energy – Potential and Kinetic. • Potential Energy – Stored Energy. Example: Battery. • Kinetic Energy – Energy in motion. Kinetic Energy is released Potential Energy. Example: Battery operated electric motor.
Energy • Consumed Energy : Sources of Energy that once used can not be replaced. Example: Coal, Oil, Fossil Fuels. • Renewable Energy : Solar, Wind, Water, Thermal Sources, Wood.
Voltage • Voltage: Is the amount of electrical pressure in a circuit. • Voltage is measured in Volts (V). • Voltage is also known as ElectroMotive Force (EMF) or Potential Difference. Pressure
Voltage • Voltage is produced any time there is an excess of electrons at one terminal of a Voltage source and a deficiency of electrons at the other terminal. • Voltage may be produced by electromagnetism (generators), chemicals (batteries), light (photocells or solar cells), heat (thermocouples – Nuclear power), pressure (pizioelectricity – electronic drum pads), or friction (static electricity).
Voltage • Amount of Voltage in a circuit depends on the application. Example: IPODs require one or two batteries. • Two types of Voltage – Alternating Current (AC) and Direct Current (DC). • Alternating Current (AC) – Voltage that reverses its direction of flow at regular intervals (Two steps forward – One step back). Most common type of voltage.
Voltage • Direct Current (DC) – Flows in one direction depending upon Polarity of circuit. All points in a DC circuit has Polarity. • Polarity – Is the positive (+) or negative (-) state of an object. • Rectifier : AC current can be changed to DC current by passing the AC current through a Rectifier. Example: Power Chargers for Cell Phones are AC/DC Rectifiers.
Current • Current (I) flows through a circuit when a source of power is connected to a device that uses electricity. • Current (I) is the amount of electrons flowing through an electrical circuit. • Current (I) is measured in Amperes (A). Current
Current • An Ampere is the number of electrons passing a given point in one second. • The more power a load requires, the larger the amount of Current flow. • Current may be direct (DC) or alternating (AC). • Two types of Current Flow – Conventional Current Flow and Electron Current Flow.
Current • Conventional Current Flow is current flow from the positive (+) to negative (-). • Electron Current Flow is current flow from the negative (-) to positive (+).
Power • Power (P) is the rate of doing work or using energy. • Power may be expressed as True Power (PT ) or Apparent Power (PA). • True Power (PT ) is the actual power used in an electrical circuit. • Apparent Power (PA) is the product of the voltage and current in a circuit calculated without considering the phase shift that may be present between the voltage and the current in the circuit.
Power • True Power is expressed in Watts (W). PT = W • Apparent Power is expressed in Volt Amps (VA). PA=VA. • PT is always less than PAin any circuit in which there is a phase shift between voltage and current.
Power • Phase Shift is the state when voltage and current in a circuit do not reach their maximum amplitude and zero level at the same time.
Power • Restrictive Circuit is a circuit that contains only resistance. • In-phase is the state when voltage and current reach their maximum amplitude and zero level at the same time.
Power • Inductance is the property of an electric device that opposes a change in current due to its inability to store energy in a magnetic field. • Inductive Circuit is a circuit in which current lags voltage. • Capacitance is the ability to store energy in the form of an electrical charge.
Power • Capacitive Circuit is a circuit in which current leads voltage. The greater the Capacitance in a circuit, the larger the phase shift. • Power Factor is the ratio of true power used in an AC circuit to apparent power delivered to the circuit.
Power • Resistance (R) is the opposition to current flow. Resistance is measured in Ohms (Ώ). Resistance limits the flow of current in an electrical circuit. • Conductors are made of materials that have very little resistance and permits electrons to move through it easily.
Power • Insulators are made of a material that has a very high resistance and resists the flow of electrons. • Heat is thermal energy. Electrical energy may be converted to heat. • British Thermal Units (BTU) or Calories are used to measure heat.
Power • One BTU is the amount of heat required to raise the temperature of 1 lb of water 1 degree Fahrenheit. • One Calorie is the amount of heat required to raise 1gram of water 1 degree celcius.
Power • Thermal Conductivity is the property of a material to conduct heat in the form of thermal energy. • Heat Sink is a device that conducts and dissipates heat away from a component. • HEAT kills electronics. • Light is that portion of the electromagnetic spectrum which produces radian energy. Lumen (lm) is the unit used to measure the total amount of light produced by a light source.
