Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

PDD/PPD > SYSTEMS - ELECTRICAL > Flashcards

SYSTEMS - ELECTRICAL Flashcards

1
Q

Ampere

A

electrical current

ampere = I

flow of electrons in a conductor

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Impedance

A

Impedance - Z - resistance in alternating current AC circuit measured in ohms

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Ohm

A

unit of resistance in electrical circuit

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Watt

A

W- electrical power = P

• Watt: the standard measurement of power,

equivalent to 1 joule per second

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Energy CALC

A

E = P*T

Energy = Power * time

measured in watt hours or kilo watt hours

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Series circuit

A

Rtotal = R1 + R2 + R3

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Parallel circuit

A

1/ Rtotal = 1/R1 + 1/R2 + 1/R3

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q
A

Two-way

SPST - Single pole, single throw

A simple on-off switch: The two terminals are either connected together or disconnected from each other. An example is a light switch.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q
A

Three-way

SPDT - Single pole, double throw

A simple break-before-make changeover switch: C (COM, Common) is connected either to L1 or to L2.

needed to control 1 light from 2 locations

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q
A

Four-way switch

Double pole

DPST -Double pole, single throw

Equivalent to two SPST switches controlled by a single mechanism.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q
A

Four-way switch

DPCO - Double pole changeover
or Double pole, centre off

Schematically equivalent to DPDT. Some suppliers use DPCO for switches with a stable center position and DPDTfor those without. A DPDT/DPCO switch with a center position can be “off” in the center, not connected to either L1 or L2, or “on”, connected to both L1 and L2 at the same time. The positions of such switches are commonly referenced as “on-off-on” and “on-on-on” respectively.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Delta connected transformers

A

have their windings arranged in a triangular shape, which connects all three hot wires together and does not include a neutral wire. This type of source is almost exclusively used by power companies and you will not be able to run most equipment directly off this arrangement.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Wye connected transformers

A

have their windings arranged in a Y shape, which connects each of the three hot wires to a neutral wire. Wye connected sources give users a choice of voltages and can be used to run most equipment in buildings.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Ground rod

A

connects electrical system’s ground and neutral to the earth.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Monocrystalline photovoltaics

A

are more efficient than Amorphous or Polycrystalline photovoltaics.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

The number of poles in a switch

A

The number of poles in a switch refers to the number of separate circuits that the switch controls.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

throw count of a switch

A

The throw count of a switch refers to how many positions (other than off) each switch has.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Underfloor raceWays

A

Underfloor raceWays

underfloor ducts - proprietary steel raceways cast into concrete floor

Cellular metal floors - part of structural floor, same concept. Cells are closer together

Under carpet cable/wiring - thin, flat, protected wire that can be laid on the carpet without protruding through the carpet.

punch through recepticals

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Q. Transformers are used for which of the following purposes?

Provide load control

Distribute power

Change alternating currents

Serve as a switchgear

A

Transformers are used to change alternating currents.

They are not used for load control or to distribute power.

They are part of switchgear.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Horsepower

A

• Horsepower: A measure of power equal to 746 watts

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

• Load Factor

A

• Load Factor: the ratio between the average and maximum power demands of a building

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Motor vs Generator

A
  • Motor: a machine that converts electrical energy into mechanical energy
  • Generator: a machine that converts mechanical energy into electrical energy
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

Transformer, kva

A

• Transformer: device that transfers energy from one circuit to another by magnetic coupling with no moving parts. It changes the voltage (or force) of an AC circuit to a higher or lower value

Transformers change voltage in a circuit but not the total power

Separate wires are wound around an iron core. The wire with a greater number of winds has a higher voltage, The wire with less winds has a lower voltage

• KVA: is simply 1,000 volt-amps

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

• Demand factor:

A

• Demand factor: ratio of maximum demand or expected power usage to the total connected load

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
watt examples • Examples: * • A lightbulb * • A medium size car * • A small gas generator
* Examples: * A **lightbulb** might consume about **60** watts * A medium size **car** might consume about **100,000** watts • A small **gas generator** puts out about **2,000** watt
26
Voltage 120/240
120/240 1 Phase 3 Wires 3 wire Connection • Residential, small buildings, or where actual load is less than 80A or 3 Phase 4 Wires Delta Connection **• High Leg Delta typically only found in older buildings**
27
240
240 1 Phase 3 Wires Delta Connection • Commercial
28
480
480 3 Phase 3 Wires Delta or Wye Connection • Commercial
29
120/208
120/208 3 Phase 3 Wires Wye Connection • Larger buildings with greater variety of loads
30
277/480
277/480 3 Phase 4 Wires Wye Connection * Larger buildings, smaller feeders, conduit sizes, switch gears that lower voltage * large, multistory building that principally uses fluorescent or HID lamp
31
2400/4160
2400/4160 3 Phase 4 Wires Wye Connection • Huge commercial buildings and factories
32
• A circuit of plugs in your home has two floor lamps (300 watts each), a home entertainment center (750 watts), a computer work station (900 watts), and the occasional vacuum (600 watts). What is the current expected from this circuit? What size should the breaker be?
Figure out the load: • 2 (300 watts) + 750 watts + 900 watts + 600 watts = 2,850 watts Convert to amps to find the current: • 2,850 watts **/ 120 volts** = 23.76 amps Size the breaker: • Breakers come in 10A, 15A, 20A, and 30A so you’ll need a 30A for the circuit
33
Conductor
• Conductor: means by which a current is conducted, typically cable and wire Basic material of electrical system Sizes are based on **American wire gauge (AWG**) and **thousand circular mil (MCM)** designations
34
Conduit
• Conduit: **tubes that house, protect, support, and provide grounding for wiring.**
35
American Wire Gauge System:
A standardized wire gauge system for the diameter of **round, solid, nonferrous**, electricity conducting wire **Cross-Sectional Area** of each gauge is an important factor for determining its **current-carrying capacity** **Increasing gauge numbers** give **decreasing wire diameters** No. 36 AWG = 0.005 inches No. 0000 AWG = 0.46 inches **Larger than 4/0 is MCM cable sizes of 250, 400, and 500.**
36
Circular Mil
Circular Mil: the area of a wire having a diameter of one mil or 0.001 of an inch, used in specifying wire size Current carrying capacity of a conductor depends on the size, type of insulation around it, and surrounding temperature Use 14 gauge minimum in buildings
37
Aluminum Wire (No. 8 AGW or smaller)
* Requires a special installer * Oxide can form when joints loosen and/or overheats * Must be larger than copper to carry amperage * Limited to primary circuits because of overheating **Commercial**
38
Copper Wire (No. 8 AGW or smaller)
**• Same carrying capacity as aluminum but smaller and cheaper** • Most cost effective for small and medium sized wire and cable **Residential/ Small Construction**
39
Romex
**Nonmetallic sheathed cables** 2+ plastic insulated conductors and ground surrounded **by a moisture resistant sleeve** **No conduit required**, it’s an alternative **Must be protected from damage within walls, etc.** **Residential, Wood Framed less than 3 stories**
40
Flex Metal Clad Cable (BX)
Flexible metal clad cable **2+ plastic insulation conductors encased in spiral wound** strip of steel tape **No conduit is required** **Can be easily pulled** **Remodel/ Residential**
41
Busbar
**Busbar** * Rectangular bars of copper that carry high voltage * Used in place of very large cables and high currents
42
• Conduit Types:
Supports and protects wiring and serves as ground and protects surrounding construction from fire in case of overheating Used for large residential and commercial projects **Rigid Steel** * The safest type * After pipe is installed (indoor/outdoor) wires are pulled through • Connections are rigid and threaded like pluming pipes * Connect to J-boxes and devices **Intermediate Metallic** * Steel conduit with thinner walls but same outside diameter as Rigid • More economical * Use with threaded fittings **Flex (Flexible Metal)** * Used everywhere except underground * Reduces vibration transmission from equipment where not possible to install rigid **Electric Metallic Tubing** * Thinnest metal conduit * Too thin to thread, connections are made with clamps • Easy/fast install * Not allowed in hazardous areas
43
Raceways
Channels for holing electrical wires
44
Under Carpet Wiring:
Under Carpet Wiring: thin, flat wiring that can be laid under carpet without protruding • Must be used with carpet tile
45
Cellular Metal Floors:
Cellular Metal Floors: part of the structural floor, essentially metal decking used for cable raceways * Cells are closer than underfloor ducts * Preset inserts are placed for tapping
46
Underfloor Ducts
Underfloor Ducts: proprietary steel raceways cast into concrete floor at regular spacing (4’, 5’, or 6’) • Feeder ducts run perpendicular to distribution ducts carrying power and wiring from the electrical closet • Preset inserts are placed along distribution for tapping
47
Options for protecting a building from lightning
• Lightning Rods and conductors **• A conductive rod** is attached to upper points of a roof structure and electrically bonded by bonding conductors called downleads. • **Downleads** are connected by the most direct route to one or more grounding or gathering terminals * *• Overhead grid of wire conductors** extended to the ground * *• Lighting rods** connected to the building’s steel frame and then to the ground **• Steel framed structures** can bond the structural members to earth to provide lightning protection. **• A metal flagpole** with its foundation in the earth is its own extremely simple lightning protection system. However, the flag(s) flying from the pole during a lightning strike may be completely incinerated.
48
• Load Factor vs • Load Control
**• Load Factor**: the ratio of average power used to the maximum power demand **• Load Control**: a building’s electrical system is designed to **avoid peak** electricity use.
49
Feeder
• Feeder: set of electrical conductors which extend from the source of energy to a distribution center
50
Switchgear
• Switchgear: central electrical distribution center that consist of an assembly of switches, circuit breakers and cables or bus-ducts that distribute power to the building
51
• Panelboard (Breaker Box):
• Panelboard (Breaker Box): a component of an electrical supply system tha**t divides an electrical power feed into subsidiary circuits** while providing a protective fuse or circuit breaker for each circuit, in a common enclosure
52
Branch Circuit:
Branch Circuit: the insulated wires that run between the outlet and the panel board
53
• Uninterruptible Power Supply (UPS):
• Uninterruptible Power Supply (UPS): an electrical apparatus that provides emergency power to a load when the input source fails. Typically used to protect computers, data centers, telecom equipment, or wherever power outage can disrupt business
54
• Primary Distribution:
**A central electrical distribution center that consists of an assembly of switches, circuits breakers and cables** that **distribute** **power** to the **building** is called **switchgear** A load center pad-mounted unit substation would typically have a primary voltage range of 2.5-15 kV The most popular form of exterior transformer installation for individual buildings is mounted on a concrete pad In a typical building electrical power system wiring closet, **dry-type transformers** are typically placed between **plug-in busways** and **120V panelboards** **A meter and transformer** are included with it to split power into separate circuits, each with a master switch and circuit breaker for protection **Switchgear** also distributes power to substations for further transforming and distribution as part of a secondary distribution system
55
• Secondary Distribution System:
Power is distributed **from the main switchgear to panelboards** **Panelboards** (or breaker box) divides the electrical feed into subsidiary circuits while providing a protective fuse or circuit breaker for each circuit Typical power voltages of 120V, 240V, and 277V **Distribution** is made with wires in conduit, underfloor raceways, or flex cables Protected by **circuit breakers** typically 15A and 20A, also come in 10A and 30A...with 100A for main disconnects
56
One Switch Location: switch type?
One Switch Location: (1) two way (on/off) switch is used
57
Two Switch Locations:: switch type?
Two Switch Locations: (2) three-way switches (on/off, on/off) are used
58
Three Switch Locations: switch type?
Three or More Switch Locations: (2) three-way switches, and (1 +) four-way switches
59
Low voltage Switching:
Low voltage Switching: operated on 24V circuit and controls relays that provide the 120V switching. Same light can be controlled from several remote positions Central control station can be set up for monitoring and override Less expensive than line-voltage wiring and devices for large installations that need to be flexible.
60
Outlets hight ada, spacing
height min 15" ## Footnote Spacing should be 12’-0” max, or so that no point is further than 6’ from an outlet Floor receptacles must be within 18" of an exterior wall to count as a required power receptacle in a dwelling Circuits are usually 15” and at least 20A for the kitchen, pantry, and dining
61
Joules
Joules are a unit of energy.
62
Newtons
Newtons are a unit of force.
63
Pascals
Pascals are a unit of pressure.
64
• Breakers sizes?
• Breakers come in 10A, 15A, 20A, and 30A
65
Busway
Busway • Multiple busbars in a metal housing
66
**kVA**
The **kVA** unit represents **kilovolt-amperes, or 1,000 volt-amperes**. A transformer with a 1.0 kVA rating is the same as a transformer with a 1,000 VA rating and can handle **100 volts at 10 amps of current**. **multiply** the required **input** **voltage (V)** by the required **current load** in **amperes (l)** and then **divide** that number by **1,000**: **kVA= V \* l / 1,000**
67
ohms law mnemonic
**W**oman **A**re **V**irgins **W**att = **A**mps x **V**olts **V**irgins **A**re **R**are **V**olt = **A**mps x **R**esistance (ohm)

PDD/PPD (20 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions