Electricity II Final

Question 1

What is an electrical device that uses electromagnetism to change voltage from one level to another or to isolate one circuit from another?

Answer 1

Transformer

Question 2

What is an electrical service in which service-entrance conductors are run underground from the utility service to the building?

Answer 2

Lateral Service

Question 3

What is a central location for troubleshooting and servicing motor control circuits?

Answer 3

Motor Control Center

Question 4

What is a graphic representation of a device, component, or object on a print?

Answer 4

Symbol

Question 5

A delta connection is a connection that has each coil connected end to end to form what kind of loop?

Answer 5

Closed Loop

Question 6

What are transformers rated in, which specifies their power output capability?

Answer 6

kVA

Question 7

What is a grounded metal enclosure that contains factory-mounted bare or insulated conductors?

Answer 7

Busway

Question 8

What is an electrical wiring sketch showing actual positions of system devices and wiring?

Answer 8

Wiring Diagram

Question 9

What shows property lines of a building lot, elevation information, compass directions, lengths of property lines, and locations of structures to be built on the lot?

Answer 9

Plot Plan

Question 10

Standard receptacles include what?

Answer 10

Long (N) slot, short (hot) slot, U-shaped ground hole

Question 11

What indicates a high-voltage location and condition that could result in death or serious personal injury from an electrical shock if proper precautions are not taken?

Answer 11

Electrical Warning

Question 12

What kind of current travels a path other than the normal operating path for which a system is designed?

Answer 12

Fault Current

Question 13

What kind of voltage tends to cause continuous muscular contractions that can prolong the individual’s attachment to a circuit and extra care should be taken around?

Answer 13

High-voltage DC

Question 14

What is the process of removing the source of electrical power and installing a lock that prevents the power from being turned on?

Answer 14

Lockout

Question 15

What are the five classes of fires, and what type of extinguisher should be used on electrical fires?

Answer 15

A, B, C, D, and K. Use C on electrical fires

Question 16

Double-insulated electric safety tools have a recommended maximum use of how many volts and are designed to meet NFPA 70E and OSHA requirements for protecting individuals working with electrical equipment?

Answer 16

1000V

Question 17

All electrical circuits include multiple points at which ___ or circuit breakers are located.

Answer 17

Fuses

Question 18

What single word is used to indicate a potentially hazardous situation that, if not avoided, could result in death or serious injury?

Answer 18

Warning

Question 19

What is done to electrical circuits to safeguard personnel and equipment against the hazards of electrical shock?

Answer 19

Grounding

Question 20

According to NFPA 70E, only qualified personnel are allowed to work on energized circuits of how many volts or higher?

Answer 20

50V

Question 21

What is a voltage decrease of more than 10 percent below the normal rated line voltage for a period of longer than 1 minute?

Answer 21

Undervoltage

Question 22

With many modern electronic components derated to save energy and operating costs, the acceptable voltage range is +5% to ___.

Answer 22

-10%

Question 23

What is a short, temporary, undesirable voltage in an electrical circuit?

Answer 23

Transient Voltage

Question 24

Every load, such as a lamp, motor, or heating element, that converts electrical energy into some other form of energy, such as light, rotating motion, or heat, uses ___.

Answer 24

Current

Question 25

What describes the relationship between voltage, current, and resistance in a circuit?

Answer 25

Ohm's Law

Question 26

What is the state where voltage and current in a circuit do not reach their maximum amplitude and zero level simultaneously?

Answer 26

Phase Shift

Question 27

What kind of connection has two or more devices connected so there is only one path for current flow?

Answer 27

Series

Question 28

A series circuit contains 3 resistors. One is 25 ohms, another is 50 ohms, and the last is 10 ohms. What is the total resistance of this circuit?

Answer 28

85 ohms. Series: add. Parallel: 1 / 1/P1 + 1/P2 + etc

Question 29

What is the rate of doing work?

Answer 29

Power

Question 30

What is the amount of electrons passing a predetermined point in a circuit in 1 second?

Answer 30

Ampere

Question 31

What is used to verify only the presense of coltage at receptacles, switches, and fuses or circuit breakers?

Answer 31

Voltage Tester, Voltometer

Question 32

What is an electromechanical device that displays measurements using the mechanical motion of a pointer?

Answer 32

Analog Display

Question 33

Analog scales are divided using what?

Answer 33

Primary divisions, secondary divisions, and subdivisions

Question 34

How should a digital display read when measuring an open circuit?

Answer 34

OL

Question 35

How many jacks does a DMM normally have?

Answer 35

2

Question 36

What is most commonly used to measure current over 1 A and in applications in which current can be measured easily by placing its jaws around one of the conductors?

Answer 36

Clamp-on Ammeter

Question 37

In-line ammeters provide the most accurate current measurements when measuring currents less than ___.

Answer 37

1 Amp

Question 38

Megohmmeters detect what in long wire runs, motor windings, and transformers?

Answer 38

Insulation Failure

Question 39

Conductive leakage current is kept to a minimum by keeping insulation clean and what?

Answer 39

Dry

Question 40

A meter's CAT rating indicates what type of magnitude reading a DMM or other electrical appliance can withstand when used on a power distribution system?

Answer 40

Transient Voltage

Question 41

Standard and isolated-ground receptacles can be tested using a voltage tester or what?

Answer 41

DMM

Question 42

A temperature rise of how many degrees or higher requires immediate attention in an electrical system?

Answer 42

100 degrees, 50 degrees requires investigation

Question 43

When converting energy, electrical loads use what?

Answer 43

Power

Question 44

Although fuse and circuit breaker conductors are rated for a maximum operating current, they should not be operated continuously at more than how many percent of their rating?

Answer 44

80%

Question 45

A temperature rise above ambient temperature is expected on electrical equipment carrying current, and the higher the temperature rise, the greater the possibility of equipment what?

Answer 45

Failure

Question 46

A neutral to ground measured voltage difference of how many volts or higher indicates that the branch circuit is overloaded?

Answer 46

5V

Question 47

Current unbalances should not exceed how many percent?

Answer 47

10%

Question 48

In addition to clamp-on ammeters and DMMs, electrical measurements can be taken at a power or distribution panel with power quality meters and what?

Answer 48

Megohmmeters

Question 49

Fuses and circuit breakers are sized so that they are what type of link in the circuit when the circuit is overloaded or there is a short circuit?

Answer 49

Weakest

Question 50

Voltage on the secondary of a transformer should not drop below how many percent of the transformers rated output?

Answer 50

10%

Question 51

What are the three main types of electric motors?

Answer 51

DC, Single-Phase AV, Three-Phase AC

Question 52

What specifies the operating voltage range in the electrical specifications provided with an HVAC system or motor?

Answer 52

OEM

Question 53

When measuring voltage, a high voltage fluctuation is an indication of what?

Answer 53

The system is overloaded

Question 54

What type of motors are small and inexpensive and normally replaced when they fail?

Answer 54

Shaded-pole

Question 55

What type of switches operate their contacts when a preset temperature is reached?

Answer 55

Thermal Switch

Question 56

What occurs when voltage at the terminals of an electric motor or other three phase load are not equal?

Answer 56

Voltage Unbalance

Question 57

What is a common problem associated with heating elements?

Answer 57

No heat, inadequate heat, electrical shock

Question 58

What is the acceptable voltage percentage range for equipment and receptacles?

Answer 58

Plus 5% to Negative 10%

Question 59

If low voltage is present out of a control circuit transformer but not into it, the problem is that the transformer if ___ or faulty?

Answer 59

Deteriorated

Question 60

Motors used in HVAC systems have been selected and installed by the OEM to operate for how long?

Answer 60

An indefinate period of time

Question 61

When magnetic motor starters are used to control motors, the current and voltage levels have to match what rating on the motor?

Answer 61

Nameplate

Question 62

The high-voltage side of a transformer is marked with an H and the low voltage side is marked with what?

Answer 62

X

Question 63

In a basic AC system, a step-down transformer is normally used to reduce the incoming voltage to ___ VAC for the control circuit components.

Answer 63

24VAC

Question 64

What is an electronic device that controls the direction, speed, torque, and other operating functions of an electric motor, in addition to providing motor protection and monitoring functions?

Answer 64

Motor Drive, VSD, VFD

Question 65

What type of transformer is the interface used to reduce the voltage from the power circuit to the control circuit?

Answer 65

Step-down

Question 66

While troubleshooting motor power circuits, what measurements should be taken when a motor is running?

Answer 66

Voltage and Current

Question 67

What is similar to a clamp-on ammeter in that they both measure the strength of the magnetic field around a conductor?

Answer 67

Current Transformer

Question 68

Most new motor control applications use what?

Answer 68

Fuses

Question 69

Dangerous voltage levels exist when?

Answer 69

A motor drive cover is removed and the drive is energized

Question 70

T/F, Electrical symbols are always shown in their off or de-energized position.

Answer 70

T

Question 71

T/F, Schematic diagrams show components in their electrical sequence without regard for physical location.

Answer 71

T

Question 72

T/F, Components used to provide a function of stop are generally wired normally open and in series.

Answer 72

F

Question 73

T/F, Schematic diagrams are usually harder to read and understand than wiring diagrams.

Answer 73

F

Question 74

T/F, When a relay is energized, all of its contacts change position.

Answer 74

T

Question 75

T/F, Wiring diagrams show components mounted in their general location with connecting wires.

Answer 75

F, Pictorial Diagrams

Question 76

T/F, The way a control symbol is drawn indicates how it is to be connected in a circuit.

Answer 76

T

Question 77

T/F, Schematics are not important to understand when performing troubleshooting.

Answer 77

F, show logic of circuit not location.

Question 78

T/F, Electrical symbols all follow a set standard developed by the industry.

Answer 78

T

Question 79

T/F, Relay contact symbols are laveled in the same manner as the relay coils that control them.

Answer 79

T

Question 80

When testing a circuit or component with an ohm meter, assuming there is an open, what should your meter display?

Answer 80

OL

Question 81

What type of diagram shows components in their electrical sequence?

Answer 81

Line Diagram

Question 82

Dashed lines on a schematic are used to represent which of the following?

Answer 82

Field wiring

Question 83

Referring to schematics, all symbols are usually shown how?

Answer 83

De-energized

Question 84

Referring to schematics, components used to provide a function of stop are shown how?

Answer 84

Wired NC and connected in series