Chapter 2 huhu Flashcards
Nearly all of the electrical energy consumed is _________, __________ and _______________ by large public or privately owned companies.
generated, transmitted, distributed
_____________ is usually produced at a power station and is conveyed through a ____________ of overheated metal ________ supported on high towers.
Electricity, transmission system, cables
It is an industrial facility that house equipment to generate electricity from ________ energy.
Power station, primary
At a power station, electricity is usually generated in the range of __________ to _________ kV.
2.4 to 13.2
Most power plants use one or more ____________ that convert mechanical energy into electrical energy in order to supply power to the electrical grid for society’s electrical needs
generators
The efficacy rate of converting heat energy to mechanical energy of fossil fuel plant is
40 percent
The efficacy rate of converting heat energy to mechanical energy of nuclear plant is
30 %
a mechanical device that converts mechanical energy into electrical energy
generators
It is rotated by the generator, it is a shaft with conductor windings wrapped around an iron core, through stationary _____________, to produce _______ flow.
Armature, magnetic field, current
Kinsay crush ni Kentoy?
r<3n mwehehehhe
It is a rotary engine, is connected to the generator and drives the rotation of the armature shaft.
Turbine
a high pressure steam moves through a turbine thus rotating the discs attached to turbine shaft
Steam turbine
The steam produced for a steam turbine is produced by heating water through burning of _________, ___________ , __________ or heat coming from _____________.
coals, oil, natural gas, nuclear reaction
The most economical power stations typically generate power ______________.
continuously
For economical transmission, a step-up transformer steps up the voltage to above ____ kV, usually between ____ kV to ____ kV
15, 115, 765
Power transmission at high voltages requires _________, and subsequently, there are lower _______ losses in the transmission lines.
less amperage, power
__________________ are small facilities in fenced yards that contain transformers, switches and other electrical equipment.
power substationS
created to avoid danger of high-voltage power transmission in populated areas.
power substationS
___________________ generally generate, transmit, and distribute three-phase AC power. _______________ is obtained from one phase of a set of three phase line.
power utilitieS, Single-phase AC power
It is very economical to carry power at low voltage because it requires smaller conductors.
FALSE, high man gud
passageway where wires are connected to the load side of the meter enters the house or building.
service entrance
it is the point of attachment of the service entrance
weatherhead
Service entrance commonly used to supply power to your home— carrying power from the ________ through a metering device to the building’s service disconnects
transformer
extend from a pole-mounted distribution transformer to the building’s service entrance
service drop (OVERHEAD SERVICE ENTRANCE CONDUCTORS)
the penetration of service drop is sealed with a ________ to keep from leaking.
roof boot
Connections at the weatherhead is extended at least __ to __ feet above the roofline and at least ___ feet above the ground.
2, 3, 10
______________ are direct burial cables and usually has three conductors: two hot wires and a neutral.
UNDERGROUND SERVICE ENTRANCE CONDUCTORS (SERVICE LATERAL)
Service lateral should be trenched at least __ feet underground so to avoid damage.
4
Receives the service entrance conductors.
service entrance equipment
The service equipment includes
- measuring power through an electric meter
- a method of cutting off power
- overcurrent protection devices
an instrument that is used by the utility company to measure and record electrical energy consumed.
electric meter
As the current flows, the disc rotates, and pointers on dials revolve to record the amount of power used in ________.
electric meter, kilowatt-hours (kWh)
this meter is a small electric motor - with a speed that is proportional to the power consumed
FEED-THROUGH METER
This measure amperage through each ungrounded (hot) conductor.
current-transformer
a REQUIRED part of the service entrance equipment 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
service disconnect
A LARGE CABINET or ASSEMBLY OF METAL CABINETS with electrical switches and devices connects/disconnects electric circuits, either manual or automatic.
switch board
• Generally distributes power to transformers, panelboards, control equipment, and ultimately to individual system loads.
switch board
• Contains overcurrent protection devices (fuses or circuit breakers) and instruments designed to neutralize/divide a large amount of electrical power into suitable levels for other electrical equipment.
switch board
• Floor mounted, rated for current levels of 1200 to 6000 amperes (A), and voltages below 600 volts (V).
switch board
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 controlling switches for light, heat, and power circuits.
panelboard
It consists of a sheet of a metal box, a cabinet, and a cover that encloses and protects the interior section containing vertical buses used to distribute power.
panelboard
It may be referred to as a power panel or ___________ typically used in residential applications.
panelboard, load center
Usually, it works as a regulator to change the voltage, current and phase of electrical power transmitted and distributed from the primary power source to a specific substation.
transformerS
• has a secondary voltage that is less than its primary voltage.
• typically used in buildings to reduce building system voltages to useable levels
STEP – DOWN TRANSFORMER
one with a _____________ that is greater than its primary voltage.
STEP - UP TRANSFORMER, secondary voltage
The transformer’s desirable operation level is at only ___°F(___°C); above this rate will cut the transformer’s life by ____.
20, 11, half
• small transformers use ________ by ventilation while larger ones are _________
air coolining, liquid-cooled
has a single primary winding and single secondary winding
SINGLE-PHASE TRANSFORMER
A 7200/240/120 V AC is a single-phase transformer commonly used in most residential and small commercial applications.
SINGLE-PHASE TRANSFORMER
• A 7200 V, two-wire power is transformed and stepped down to a 120/240 V AC, three-wire system.
SINGLE-PHASE TRANSFORMER
__________________ has three primary and three secondary windings.
THREE-PHASE TRANSFORMERS
Two main types of three-phase transformers
delta and wye
windings are connected in series, forming a triangle, thus resembling the Greek letter Delta (Δ).
DELTA-CONNECTED TRANSFORMER(Δ)
only a single voltage level is available: the phase-to-phase voltages.
DELTA CONNECTED TRANSFORMER(Δ)
Obtaining other voltages can only be done using step-up or step-down transformers.
DELTA CONNECTED TRANSFORMER(Δ)
• has three independent transformer windings connected at a common point, called a neutral or star point.
• the angular displacement of each winding is at ___°, resembling a Y-shaped physical arrangement of the winding.
WYE-CONNECTED TRANSFORMER (Y) , 120
• an electrical device that converts three-phase electric power without a neutral wire into three phase power with a neutral wire.
DELTA-WYE (Δ-Y) TRANSFORMER
Voltages that have the _____ as a multiplier are ____ connections
1.732, WYE
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
