Chapter 2.1, 2.2, 2.3 Flashcards
Chapter 2 title
Building ELECTRICAL MATERIALS and EQUIPMENT
Chapter 2.1 title
Power Generation and Transmission
Nearly all of the electrical energy consumed is __________, _________, and ________ by large public or privately owned utility companies.
generated, transmitted and distributed
Consumers purchase electricity from these ________ companies, either ________ or through a _________________.
utility, directly, cooperative association
Electricity is usually produced at a _____________ and is conveyed through a transmission system of overhead metal cables supported on high towers. At the ______________, electricity is usually generated in the range of
________________.
power station, 2.4 to 13.2 kV.
- it is an industrial facility that house equipment to generate electricity from _____________.
POWER STATION, primary energy
Most power plants use _____________ that convert____________ into ___________ in order to supply power to the electrical _____ for society’s electrical needs.
one or more generators, mechanical energy, electrical energy, grid
EFFICACY RATE OF CONVERTING HEAT ENERGY TO MECHANICAL ENERGY for Fossil fuel plant
40%
EFFICACY RATE OF CONVERTING HEAT ENERGY TO MECHANICAL ENERGY for Nuclear Plant
30%
A mechanical device that converts mechanical energy into electrical energy.
Generators
- rotated by the generator, is a ____ with ________________ wrapped around an iron core
through stationary magnetic field, toproduce current flow.
ARMATURE, shaft, conductor windings, produce current flow.
- a rotary engine, is connected to the _____________ and drives the rotation of the __________.
TURBINE, generator, armature shaft
- High pressure _____ moves through turbine thus rotating the _____ attached to _________.
STEAM TURBINE, steam, discs, turbine shaft
- the ________ is produced by heating water through burning of _______, ________, ________, or ________________.
STEAM TURBINE, steam, burning of coals, oil, natural gas, or heat coming from nuclear reaction.
The most ______________________ typically generate power continuously, unless off line for maintenance or repairs.
economical power stations
During periods of ___________, ____________ power stations are brought on-line.
heavy demand, less economical
For ___________________, a ____________ steps up the voltage to above ______, usually between ______________.
economical transmission, step-up transformer, 39 kV, 115 kV to 765 kV
___________________ is now being explored for equipment and lines rated for _______.
Ultra-high voltage transmission, 1100 kV
Distribution line voltages are generally _______, _______, ________ or _________, although higher voltages can be made available if loads are large enough.
4160 V, 4800 V, 6900 V or 13,200 V
______________ at ________ requires ____________, and subsequently, there are _______ power losses in the transmission lines.
Power transmission, high voltages, less amperage, lower
________________ are small facilities in fenced yards that contain ____________, __________, _______________.
Power substations, transformers, switches and other electrical equipment
It is created to avoid danger of high-voltage power transmission in populated areas.
Power substations
- used to __________ down the transmission voltages to safer distribution levels.
POWER SUBSTATIONS, reduce or step down
- generally ________, _______, and _________ _________________. _______________ is obtained from one phase of a set of three phase line.
POWER UTILITIES, generate, transmit, and distribute, three-phase AC power.
Single-phase AC power
- use highest transmission and distribution voltages consistent with _______ and ____________.
UTILITIES, safe and economical use
It is very economical to carry power at high voltage because it requires larger conductors. (T or F)
F (smaller)
High voltages introduce safety
clearance hazards, so high voltages are reserved for use in unpopulated areas or special applications. (T or F)
T
________________ MEANS ___________ ( AND __________________) FOR A SPECIFIC LOAD. IT IS MORE __________, BUT MORE ___________, TO TRANSMIT POWER AT ______________.
HIGHER VOLTAGE. LOWER AMPERAGE, SMALLER CONDUCTOR SIZE, ECONOMICAL, DANGEROUS, HIGH VOLTAGE.
Chapter 2.2 title
Building Electrical Service Equipment
- passageway where wires are connected to the load side of the meter enters the house or building.
Service Entrance
- commonly used to supply power to your home- carrying power from the ____________ through a __________ to the building’s service disconnects
SERVICE ENTRANCE, transformer, metering device
- comprises three cables ( two hot and one neutral} that run from the ___________ to the point of attachment at the _________, then down an entrance cable or conduit to the ___________. In this type of system, the utility company’s equipment ends at the ______________ to the house.
SERVICE ENTRANCE, utility lines, weatherhead, meter socket, point of attachment
- extend from a pole mounted distribution transformer to the building’s service entrance
Overhead Service Entrance Conductors (Service Drop)
- the penetration is sealed with a __________ to keep from leaking.
Overhead Service Entrance Conductors (Service Drop), roof boot
- connections at the __________ is extended at least _________ above the roofline and at least _________ the ground.
Overhead Service Entrance Conductors (Service Drop), weatherhead, 2 to 3 feet above, 10 feet above
- are two hot wires and usually has three conductors: ____________ and a ________.
UNDERGROUND SERVICE ENTRANCE CONDUCTORS (SERVICE LATERAL), two hot wires and a neutral.
- the ____________ is attached to the ________ and is fed through a ____________ attached to the utility company’s __________.
UNDERGROUND SERVICE ENTRANCE CONDUCTORS (SERVICE LATERAL), feeder wire, transformer, PVC conduit sleeve, power pole
- it should be trenched at least ________________ so to avoid damage.
UNDERGROUND SERVICE ENTRANCE CONDUCTORS (SERVICE LATERAL), 4 feet underground
- receives the service entrance conductors.
SERVICE ENTRANCE EQUIPMENT
- the service equipment includes measuring _______ through an _____________, a method of cutting off power, and overcurrent protection devices (circuit breakers or fuses) that protect the service entrance conductors.
SERVICE ENTRANCE EQUIPMENT, power,electric meter
- an instrument that is used by the utility company to ________ and ________ electrical energy consumed.
ELECTRIC METER, measure, record
-as the current flow, the _________, and ____________ revolve to record the amount of power used in ______________ (kWh).
ELECTRIC METER, disc rotates, pointers on dials, kilowatt-hours
- used in building services rated up to about ________.
FEED-THROUGH METER, 400 A
- this meter is a small electric motor
FEED-THROUGH METER
- with a speed that is proportional to the power consumed
FEED-THROUGH METER
- used in building services rated above about ______.
CURRENT-TRANSFORMER (C/T), 400A
- measure ________ through each ungrounded (hot) conductor.
CURRENT-TRANSFORMER (C/T), amperage
- housed in an enclosure called a _____________ that is part of the service entrance equipment.
CURRENT-TRANSFORMER (C/T),
CIT cabinet
- a required part of the service entrance equipment allows electrical service from the utility company to be _________ so that power is disconnected to the building installation. It is a __________ or a _________ that protects the service entrance conductors
SERVICE DISCONNECT switched off, set of fuses, circuit breaker.
-a large cabinet or assembly of metal cabinets with electrical switches and devices connect/ disconnects electric
circuits, either manual or automatic.
SWITCH BOARD
-generally distributes _______ to transformers. panelboards, control equipment, and ultimately to individual system loads.
SWITCH BOARD, power, transformers. panelboards, control equipment, individual system loads
- contains _________________ (fuses or circuit breakers) and instruments designed to neutralize/divide a large amount of ____________ into suitable levels for other electrical equipment.
SWITCH BOARD, overcurrent protection devices, electrical power
- floor mounted, rated for current levels of ____________, and voltages _____________.
SWITCH BOARD, 1200 to 6000 amperes (A), below 600 volts (V)
- wall mounted, single unit of one or more metal cabinets, including buses, automatic overcurrent protection devices(fuses or circuit breakers).
PANELBOARD
- equipped with or without _____________ for light, heat, and power circuits
PANELBOARD, controlling switches
- it consists of a sheet of a metal box, a cabinet cover, and an interior section that encloses and protects the vertical buses containing vertical buses used to distribute power.
PANELBOARD
- it may be referred to as a ___________ or _________ typically used in residential applications.
PANELBOARD, power panel, load center
- usually, it works as a _________ to change the volatge, current and phase of electrical power transmitted and distributed from the ________source to a _____________.
TRANSFORMERS, regulator, voltage, current, and phase of electrical power, primary power, specific substation.
A building transformer is rated in kvA. (T or F)
T
Every Transformer comes with a nameplate that typically identifies:
kVA
Primary and Secondary Voltage
Impedance (if 25kVA or larger)
Required clearances (if it has ventilating openings)
- has a ____________ that is less than its primary voltage
STEP- DOWN TRANSFORMER, secondary voltage
- typically used in buildings to reduce building system ________ touseable levels.
STEP- DOWN TRANFORMER, voltages
- one with a ____________ that is greater than its ________.
STEP- UP TRANSFORMER, secondary voltage, greater, primary voltage.
- _________ build up prematurely deteriorates a _________. The transformer’s desirable operation level is at only ____________; above this rate will _____ the transformer’s life by _______.
TRANSFORMERS HEAT HAZARD, Heat, transformer, 20°F(11°C), cut, half
- it is caused by internal losses from _______, __________, and _________ in exterior locations
TRANSFORMERS HEAT HAZARD, internal losses, loading, high ambient air temperature, and solar radiation
- small transformers use ________ by ventilation while larger ones are __________.
VARIOUS HEAT REDUCTION FEATURES, air cooling, liquid cooled
- ________________ transformer has its _____ and ____ in a _______or ___________.
VARIOUS HEAT REDUCTION FEATURES, ventilated dry-type, coils, core, gaseous, dry compound
- _____________ transformer has its core and coils immersed in an ____________.
VARIOUS HEAT REDUCTION FEATURES, Liquid-immersed, insulating liquid
- has a single primary winding, single secondary winding
SINGLE- PHASE TRANSFORMER
- a 7200/240/120 V AC is a __________ transformer commonly used in most _________ and __________ applications.
SINGLE- PHASE TRANSFORMER single-phase, residential, small commercial
- a 7200 V, two-wire power is transformed and stepped down to a 120/240 V AC, three-wire system.
SINGLE- PHASE TRANSFORMER
- a three-phase transformer has three primary and three secondary windings.
THREE-PHASE TRANSFORMERS
- it has two main types
THREE-PHASE TRANSFORMERS, delta and wye system.
- windings are connected in series, forming a triangle, thus resembling the Greek letter Delta.
DELTA- CONNECTED TRANSFORMER
Only a single voltage level is available: the phase to phase voltages. (T or F)
T
- obtaining other voltages can only be done using ______ or __________.
DELTA- CONNECTED TRANSFORMER, step- up and step- down transformers
- it has _____________ windings connected at a common point, called a ______ or _________.
WYE CONNECTED TRANSFORMER (Y), three independent transformer, neutral or star point.
- the angular displacement of each winding is at __________, resembling a ________ physical arrangement of the winding.
WYE CONNECTED TRANSFORMER (Y), 120 degree, Y shaped
- an ectrical device that converts three-phase electric power without a neutral into three phase power with a neutral wire.
DELTA- WYE (6-Y) TRANSFORMER
- additional transformer combinations such as _______________________ are available.
DELTA- WYE (Y-Y) TRANSFORMER, wye- wye (Y-Y), delta- delta, and wye- delta)
Historically, standardized
system voltages related to _____ transformers’ use were based on multiples of 120V ( ex. 120 V, 240 V, 480 V, 7200 V). Voltages that have the 1.732 as a multiplier are ___________ (e.g., 208 V, 4160 V 12.47 kV).
delta, wye connections
New distribution transformers are very efficient, with losses of less than _______ in large units. Most large facility distribution transformers convert at least ______ of input power into useable output power. Smaller closet transformers have efficiencies of _____ or above.
0.25%, 95%, 98%
Chapter 2.3 title
Overcurrent Protection
- safeguards the circuit components from _________ when the current flowing through the circuit reaches an _________ that will cause an excessive or dangerous temperature rise in conductors.
OVERCURRENT PROTECTION (OCP) DEVICE, overheating, amperage
- ________ and __________ serve as automatic overcurrent protection devices that are designed to ______ a circuit if the amount of current, in amps, that flows through the circuit exceeds the OCP device rating.
OVERCURRENT PROTECTION (OCP) DEVICE, fuses and circuit breakers, open.
- an OCP that acts as a switch that can be _____ and _______ manually, and it automatically “_________” which _____ the circuit when the current flowing through it _______ the circuit rating.
CIRCUIT BREAKER, switch, opened, closed, trips off opens, exceeds, circuit rating.
- a voltage rating classifies it in amperage (A) and current-carrying capacity in volts (V). (T or F)
CIRCUIT BREAKER, F (volts, amperage)
- the __________ is the __________ voltage the circuit breaker can carry.
CIRCUIT BREAKER, voltage rating, maximum
The voltage of the electrical circuit or system being protected by the circuit breaker must exceed the circuit breaker voltage rating. (T or F)
F (must not)
- most popular type of circuit breaker
THERMAL MAGNETIC TYPE
- it consists of the ____________that bends when heated by power loss
THERMAL MAGNETIC TYPE, bimetallic strip
- when current flow is excessive, the ____________ _ heats up, bends and , trips a release that opens contacts and interrupts the current flow.
THERMAL MAGNETIC TYPE, circuit breaker
- when tested in the open air, it can carry a load of about ____ above its rating and hold _____ above its rating for a minute.
THERMAL MAGNETIC TYPE, l0%, 50%
- other characteristics include the current limiting feature that instantly trips at its rating and the ____rated part limiting the load to ______ when the load is continuous for over __ hours.
THERMAL MAGNETIC TYPE, l00%, 80%, 3
THE UL (UNDERWRITERS LABORATORIES, INC.) STANDARD CIRCUIT BREAKER RATINGS FOR ELECTRICAL CURRENT:
FOR AC: 120 V, 120/240 V, 277 V, 277/480 V, 480 V, and 600 V
FOR DC: 125 V, 250 V, and 600 V
CIRCUIT BREAKERS THAT PROTECT THE UNGROUNDED (HOT) CONDUCTORS IN A CIRCUIT:
SINGLE POLE (SP), TWO POLE (2P), THREE POLE (3P)
- protecting a single ungrounded conductor
SINGLE POLE (SP)
- when protecting two ungrounded conductors such as on a 240 V circuit.
TWO POLE (2P)
- used when protecting three ungrounded conductors on a three phase circuit.
THREE POLE (3P)
- an overcurrent protective device with a _________ fusible part that is heated and severed by the passage of overcurrent through it.
FUSES, circuit-opening
- a reliable and simple OCPD made in various configurations fundamentally comprised of “_______” links encapsulated in a tube or housing connected to terminals. The _______________ is so low that it acts as a conductor until it encounters current levels above its amp rating. Then it _____and ______ the circuit to protect conductors, components and loads
FUSES, fusible, link’s electrical resistance, melts, opens
- act as “______________” by providing a _____ link in the circuit path that, when properly applied, will melt and open the circuit to _____ or ________ any damage that can be caused by an excessive flow of current.
electricity’s safety valve, weak, minimize, eliminate
- it comes in a ___________ with a sight glass that shows if the fuse is blown or not
PLUG FUSES, screw-type configuration
- the older type fuses have a __________ on the side and a central contact point. The more contemporary style, __________, has a plastic line with a _________ contact and a _______ contact
PLUG FUSES, brass screw thread, Edison-based, spring-type, centre
- it is used to protect electrical appliances such as _____, _________, ________, ________ etc., where high ______ ratings and _________ are required
CARTRIDGE FUSES, electrical appliances, motors, air-condition, refrigerators, pumps, voltage, currents
- they are available up to ______ and ________ and widely used in industries, commercial, and home distribution panels
CARTRIDGE FUSES, 600A 600V AC
- a special kind of fuse that allows electrical surge for a short time before it blows. Its unique design can bear electricity overload in a
________ cycle for a short period
without blowing (Andrew, 2010).
TIME DELAY FUSE, electrical surge, repeated
- they are desirable on circuits serving electric motors such as___________ and __________because motors draw much more current at a ________ than during ___________.
TIME DELAY FUSE, air conditioners, machinery, startup, regular operation
An OCP device’s overcurrent rating is the _____________ it can carry continuously without exceeding a specific _______________.
highest amperage, temperature limit
The __________ of an OCP is listed in _______ such as 15A, 20A or 30A.
overcurrent rating, amperes
If the ____________ flowing through the protection device exceeds the device setting for a significant period, the _____ device will ______.
current (amperage), OCP, open
The ______ carried by the ________ or system protected by an OCP device must not exceed the ____________ maximum current rating.
amperage, electrical circuit, circuit breaker’s
- the highest current at rated voltage that a device is intended to interrupt under standard test conditions
INTERRUPTING RATING
- an ________ must be able to interrupt destructive fault current energy safely. If a fault current ________ a level beyond the OCPD’s capability, it may rupture, causing damage and posing a safety hazard
OCPD, exceeds
-The _______________________________ for circuit breakers is ______ and _____for fuses. ________ and ______ typically have an AIC rating of ___________.
amperes interruption current (AIC) rating, 5000 A and 1000A, Circuit breakers, fuses, 10000A
