Electrical Engineering Reviewer CEA-1 PDF

**18.1** **[Power station ]** - is an industrial facility that houses equipment to generate electrical energy. **[Generator]** - is a mechanical device that converts mechanical energy into electrical energy. **[Armature]** - shaft with conductor windings wrapped around an iron co...

**18.1** **[Power station ]** - is an industrial facility that houses equipment to generate electrical energy. **[Generator]** - is a mechanical device that converts mechanical energy into electrical energy. **[Armature]** - shaft with conductor windings wrapped around an iron core, through a stationary magnetic field, to produce current flow. **[Turbine]** - is connected to the generator and drives the rotation of the armature shaft. **[Power substations]** - small facilities in fenced yards that contain transformers, switches, and other electrical equipment that reduce transmission voltages to safer distribution levels. **18.2** **[Service Entrance Conductors]** - carry power from the transformer through a metering device to the building's service disconnects. Overhead wires - extend from a pole-mounted distribution transformer to the building's service entrance and are generically referred to as **the service drop.** Underground (buried) service entrance conductors - are typically called the **service lateral**. **[Service Entrance]** - includes the components that connect the utility-supplied wiring the service disconnects, excluding the utility's metering equipment. **[Service Entrance Equipment]** - receives the service entrance conductors. **[Electric meter]** - an instrument that is used by the utility company to measure and record electrical energy consumed. In building services rated up to about 400 A, a feed-through meter is used. **[Service Disconnect]** - is a required part of the service entrance equipment that allows electrical service from the utility company to be switched off so that power is disconnected to the building installation. **[Switchboards]** - a large cabinet or assembly of metal cabinets in which is connected disconnecting switches, overcorrect protection devices (fuses or circuit breakers), other protective devices, and instruments designed to divide large amounts of electrical current into smaller amounts of current used by electrical equipment. **[Panelboards]** - d is one or more metal cabinets that serve as a single unit, including buses, automatic overcurrent protection devices (fuses or circuit breakers). **[Building Transformers]** - Transformers are used in transmitting and distributing power from the power plant to a substation. **[Single-Phase Transformers]** - has a single primary winding and a single secondary winding. **[Three Phase Transformers]** - three primary and three secondary windings. **18.3** **[Overcurrent Protection (OCP) device]** - safeguards the building service or an individual circuit from excessive current flows. **[Circuit Breakers]** - is an overcurrent protection device that serves two purposes: It acts as a switch that can be opened and closed manually, and most importantly, it automatically "trips off," which opens the circuit when current flowing through it exceeds the circuit rating. **[Thermal-Magnetic type]** - most popular circuit breaker. **[Fuse]** - an overcurrent protection device that consists of a strip of metal with a low melting temperature. **3 Basic types used in building electrical systems:** - **plug fuses -** screw into sockets much like a lamp. - Edison-base plug fuse **-** has threads similar to an ordinary incandescent lamp base. - **-** are interchangeable regardless of rating, allowing a 30 A fuse to improperly protect a 20 A circuit. - **Cartridge fuses --** are cylindrical in shape and available in two types. - **Time delay fuses -** can handle an overload for fraction of a second without blowing. **[OCP Device Ratings]** - OPDs have two current ratings: overcurrent and amperes interrupting current. **[Overcurrent Rating]** - The overcurrent rating of an OCP device is the highest amperage it can carry continuously without exceeding a specific temperature limit. **[Interrupting Rating]** - OCP devices must have an interrupting rating sufficient for the maximum possible fault-current (short-circuit). If the OCP is not rated to interrupt at the available fault-current, it could explode while attempting to clear the fault and/or the downstream equipment could suffer serious damage, causing possible hazards to occupants and property. **[Amperes Interruption Current (AIC)]** - rating for circuit breakers is 5000 A and 10 000 A for fuses. Circuit breakers and fuses typically have an AIC rating of 10 000 A. **18.4** **[UTILIZATION EQUIPMENT AND DEVICES]** - is a broad category of electrical or electronic machine or instrument designed to perform a specific mechanical, chemical, heating, or lighting function through the use of electrical energy. **[OUTLETS, RECEPTABLES, AND PLUGS]** - an **[outlet]** is the location in a branch circuit where electricity is used. - A **[receptacle]** is a female connecting device with slotted contacts. - A **[plug]** is a male connecting device that has two or more prongs that are inserted into a receptacle to connect to an electrical circuit. **[SWITCHES]** - A simple switch is a device placed between two or more electrical conductors in a circuit to safely and intentionally open or close the circuit or to redirect the path of current in a circuit. **[Safety switches]** - are used in building electrical systems. They are designed to reduce the possibility of contact with bare electrical conductors and have current interrupting capability. **[Heavy-duty safety switches]** - are designed for heavy industry, commercial, and institutional applications where safety, performance, and continuity of service are required. These are enclosed and may be fused or unfused. **[single-pole, double-throw (SPDT) switch]** - diverts current from one conductor path to another. A special type of SPDT switch is known as a three-way switch (S3), which allows the control of an installation from two locations. **[double-pole, single-throw (DPST) switch]** - opens or closes two conductors in a circuit. **[Switching Configurations]** - Switches provide control from one or more points in a circuit. A single-pole, single-throw switch (S) is used to provide control from one point by opening or closing the ungrounded conductor in the circuit. **[Specialty Switches]** - In addition to the standard switches, there are many types of switches that perform special functions: - **[Automatic switches]** - deactivate a circuit after a preset time period has lapsed. - **[dimmer switch]** - is a device in the electrical circuit for varying power to a circuit. - **[Time clocks]** - can be used to control the time period that a piece of equipment or a lighting installation operates. - **[Photocell controls]** - sense light and open or close a circuit with the presence of light. **18.5 CONDUCTORS** **[Wire]** - wire is a common electrical conductor. - Most conductors used in building applications are classified according to a wire gauge standard and on the cross-sectional area of the wire in units called **[circular mils]**. - An **[electrical conductor]** is any material that conducts electrical current. - A **[circular mil]** is a unit of circular cross-sectional area, equal to the area of a circle with a diameter of one mil. A mil is one thousandth of an inch. **[Buses]** - A bus, sometimes called a bus bar, is an electrical conductor (usually copper or aluminum) that serves as a common connection for two or more electrical circuits. **[Conductor Material]** - **[silver]** is the best electrical conductor material (other than a superconductor material) because it has the least resistance of common materials. - **[copper and aluminum]** conductors are used in building conductor (wiring) installations as a compromise between good conductivity and economy. - As a **[conductor material]**, aluminum has significant weight and cost advantages over copper. **[Conductor Insulation]** - Conductors are covered with insulation that provides electrical isolation and some physical protection of the conductor material. **[Cable ]** - A cable contains more than one conductor bundled together in a factory assembly of wires. - An outer **[sheathing]** encases and protects the conductors, simplifying installation of multiple wiring. **[Nonmetallic-Sheathed Cable]** - Nonmetallic-sheathed cable is classified as type NM or NMC and is commonly called by its trade name, Romex. **[Underground Feeder Cable]** - Underground feeder (UF) cables are flame retardant and moisture, fungus, and corrosion resistant. UF cable is available in No. 14 AWG copper and No. 12 aluminum AWG through No. 4/0 AWG. **[Service Entrance Cable]** - Service entrance (SE) cable is suitable for exposed above-grade conditions. Underground service entrance (USE) cable is used in underground service applications. **[Armored Cable ]** - Armored cable, classified as either AC or ACT, is sometimes referred to by the trade name, BX cable. **[Metal-Clad Cable]** - Metal-clad (MC) cable is similar to armored cable except it is not limited to the number sizes (from 18 AWG to 2000 kcmil) of conductors it can carry. **[Flat Conductor Cable]** - Flat conductor cable (FCC) is a wiring system composed of very thin cable with three or more conductors and special connectors and terminals. **[Thermostat Cable]** - Thermostat cable is used in applications with voltages less than 30 V, such as wiring to doorbells, chimes, and thermostats. **[Cords]** - Cords are made of stranded conductors within a flexible insulated sheathing material. **[Concealed knob-and-tube wiring]** - Concealed knob-and-tube (K&T) wiring consists of an old-style wiring technique using insulated conductors strung between glass or porcelain knobs and tubes. **[Conductor Power Loss]** - Heat generated by current flow through a conductor result in a loss of power. This lost power is referred to as power loss or line loss. **[Conductor Ampacity]** - A conductor's ampacity is the maximum current (in amperes) it can carry continuously without exceeding the temperature limitations of the insulation and sheathing material. **[Voltage Drops in Conductors]** - Voltage drop is directly proportional to power loss. This is true because current flow (I) through a conductor will not change. And, with the power equation P = EI, because power is lost (wattage available is less), the voltage (E) must drop. **18.6 ENCLOSURE AND RACEWAYS** **[Enclosure]** - Enclosures are electrical boxes and cabinets made of metal (e.g., steel, galvanized steel, aluminum, and so on) or nonmetallic (plastic) materials that provide protection for conductors, connections, controls, and other electrical equipment. **[Electrical Boxes]** - Electrical boxes are metal and non-metallic (plastic) enclosures that hold devices such as switches or outlets and safely permit wiring connections. **[Conduit and Other Raceways]** - A raceway is as an enclosed channel such as a conduit, tube, or gutter designed for holding wires, cables, or busbars. Examples of raceway materials or systems follow: **[Rigid metal conduit ]** - is a heavy galvanized steel or aluminum tube that looks like the galvanized steel pipe used for plumbing applications except it is much smoother and is labeled with a UL Listed stamp or label. **[Intermediate metal conduit (IMC) ]** - is a galvanized steel or aluminum tube that has a thinner wall than rigid metal conduit. **[Electrical metallic tubing (EMT)]** - is a thin-walled galvanized steel or aluminum tube in nominal diameters up to 4 in. Unlike conduit, EMT cannot be threaded. **[Electrical nonmetallic tubing (ENT) ]** - is a flame-retardant corrugated plastic tube that is semiflexible such that it can be bent by hand. **[Rigid nonmetallic conduit ]** - is a thin-walled pipe of PVC. It is joined with fittings that are solvent welded. **[Flexible metal conduit ]** - is similar to armored cable, but it is installed without cables or wiring in it; wiring must be pulled. **[Liquid tight flexible metal conduit ]** - is similar to flexible metal conduit, but it is covered with a plastic, watertight jacket that is sunlight resistant. **[Liquid tight flexible nonmetallic conduit ]** - is a flexible plastic conduit used in a manner similar to flexible metal conduit. It cannot be used over 6 ft in length. **[Cellular concrete floor raceways ]** - are hollow voids in floors made of precast concrete slabs (core slabs) found in certain precast concrete buildings. **[Busways]** - A busway is of a standardized, factory-assembled enclosure consists of outer duct-like housing, bus bars, and insulators. Busway systems are typically used in service equipment or as feeders because these systems are designed to carry large amounts of current. **[Wireways]** - Wire gutters or wireways are sheet metal or nonmetallic, flame-resistant plastic troughs that serve as a housing that encloses and protects conductors. **18.7 ELECTRIC MOTORS** **[Electric Motors ]** - are found in refrigerators, freezers, dishwashers, kitchen sink waste disposal, portable kitchen appliances, exhaust and ventilation fans, clothes washers and dryers, furnaces, air conditioners, and paddle fans. In commercial and industrial buildings, electric motors drive exhaust/ventilation fans, air-handling unit blowers, refrigeration equipment, air and fluid compressors and pumps, heating system circulators, and manufacturing equipment and machinery. The **[electric motor]** serves us well beyond the limits of what one human being can produce. **[Motor Ratings]** - Electric motors are rated in horsepower (hp). One horsepower is equivalent to 33 000 foot-pounds (ft-lb) of work per minute (550 ft-lb/s). **[TYPES OF MOTORS]** - [**Universal** **Motor**] - The universal motor is a fractional horsepower (less than one horsepower) motor designed to operate on both AC and DC power. - **[Split-Phase Motor]** - This type of motor starts slowly with low torque so it is not capable of starting heavy loads. The split-phase motor is available in sizes up to 1 ⁄3 horsepower. - **[Capacitor Motor]** - Capacitor-start motors have a capacitor that stores and discharges energy to help start the motor rotor. - **[Induction Motors]** - These motors use electromagnetic induction to cause the motor rotor to turn. - **[Three-Phase Motors]** - Three-phase motors also vibrate less than single-phase motors, so they are lighter and less costly. - **[Dual-Voltage Motors]** - Motors above 1 ⁄4 hp are designed to operate on one of two different line voltages such as 115 V or 230 V. **[Motor Controllers]** - A motor controller is a switching device designed to start, stop, and protect the motor. **18.8** **[Need for Occupant Protection]** - In the United States, hundreds of people are accidentally electrocuted each year. Electrocution occurs when a small amount of electrical current flows through the heart for 1 to 3 s. **[Tamper -- Resistant Receptacles]** - Tamper-resistant receptacles have built-in shutter systems that prevent foreign objects from touching electrically live components when these are inserted into the slots. **[GROUND FAULT PROTECTION]** - A ground fault is the unintentional flow of electrical current between a power source, such as an ungrounded (hot) wire, and a grounded surface. Receptacle Outlet Type - This type is generally used in place of standard duplex convenience outlets that are commonly found throughout the house. Circuit Breaker Type - A GFCI circuit breaker can be installed in the panelboard in buildings equipped with circuit breakers. Portable Type - It can be plugged into a convenience outlet so an electrical appliance plugged into the GFCI is protected. ARC FAULT PROTECTION - An arc fault is an unintentional electrical discharge (an electrical arc) characterized by low and erratic current. Circuit Breaker Type - A branch/feeder AFCI breaker with protection provided to branch-circuit wiring in the form of a circuit breaker. Convenience Outlet Type - An outlet AFCI for protecting connected cord sets and powersupply cords in the form of an outlet receptacle. Portable Type - A portable AFCI for protecting connected cord sets and powersupply cords that can be moved from outlet to outlet. Cord-Mounted type - cord-mounted AFCI for protecting the power-supply cord connected to it (in the form of an attachment plug on a power-supply cord). NUISANCE TRIPPING - Because GFCIs and AFCIs are extremely sensitive, they have a tendency to trip frequently. This repeated tripping is referred to as nuisance tripping, as the general public sees it only as a nuisance. **[Extremely low-frequency electromagnetic fields]** - Extremely low-frequency electromagnetic fields (EMF) are silent, invisible magnetic fields produced any time electricity runs through a wire, an appliance, or piece of equipment. **18.9 EQUIPMENT PROTECTION** **[Ground fault protection]** - Ground fault protection (GFP) is designed to detect and rapidly interrupt low-level equipment ground faults. **[SURGE PROTECTION]** - A power surge is a sudden increase in electrical current or voltage that is very short in duration. - A **[surge protection device (SPD)]** is an electrical device that prevents power surges from reaching electric and electronic equipment or another device. Types of SPD include the following: **[Metal Oxide Varistor (MOV) ]** - A semiconductor device used mainly on AC power applications that has surge ratings ranging from a few hundred to many thousands of amps. **[Gas Discharge Tubes (GDT) ]** - A primary surge protection component with a surge rating of several thousand amps that is comprised of a sealed tube containing a special gas that breaks down at a given voltage rise time. **[Zener Diode ]** - A secondary surge protection component used for accurate clamping of surge voltages. It has a quicker response time than the GDTs and provides a more accurate clamping voltage than MOVs. **[Hybrid Circuit ]** - A circuit comprising different types of surge protection component, taking advantage of each component's strengths. **[Inrush current Protection]** - Inrush current or input surge current refers to the peak instantaneous current, measured in amperes (A), drawn by an electrical appliance or piece of equipment (e.g., power supplies, AC motors, lamps, and lighting ballasts) when it is first turned on. **[Lightning Protection]** - More than 100 lightning flashes occur every second in the atmosphere, which equates to about 8.6 million per day and over 3 billion annually. About 20% of these flashes actually strike the ground. **[EQUIPMENT FOR HAZARDOUS LOCATIONS]** - A hazardous location is a location in which fire or explosion hazards may exist because of the presence of flammable gases or vapors, flammable liquids, combustible dust, or easily ignited fibers under normal operation or abnormal operating conditions.