Chapter 12

Question 1

One of the avantages of using a double-break contact instead of a single break contact is that a double-break contact _______.

Answer 1

has a higher contact rating in a smaller space.

Question 2

________ power line(s) must be broken when using a contactor to control a 3 phase load.

Answer 2

three

Question 3

_______ are uses to help confine, divide, and extinguish arcs for each set of contacts.

Answer 3

Arc chutes

Question 4

The power rating of a contactor or motor starter_____as the NEMA number (size 1,2 etc..) of the contactor or motor starter increases.

Answer 4

increase

Question 5

As ambient temperature increase, _____ current is needed to trip overload devices.

Answer 5

less

Question 6

______ contactor assemblies are made of laminated steel.

Answer 6

AC

Question 7

The current rating of a contactor or motor starter is the rating for ______.

Answer 7

each individual contact

Question 8

Copper contact have been replace with _____ alloy contacts because of the problems of using copper with knife switches.

Answer 8

silver

Question 9

A _____ diagram shows the connection and placement of an installation or its component devices or parts.

Answer 9

wiring

Question 10

____________ interlock contactors are two contactors that are connected in such a way that both sets of contacts cannot be close at the same time

Answer 10

Mechanical

Question 11

Manual starters are selected based on phasing, number of poles, voltage, starter size, and _________

Answer 11

enclosure type

Question 12

A(n) _________ is a condition that occurs what a motor is loaded so heavily that cannot turn.

Answer 12

locked rotor

Question 13

The three stages that a motor must go through in normal operation are resting, starting, and ___________.

Answer 13

operating under load

Question 14

Fuses or________ are used to protect a motor against very high current, short circuit and, or a ground fault.

Answer 14

circuit breaker

Question 15

A 120 V, 1 phase source has one hot wire and _______ natural wire(s)

Answer 15

one

Question 16

A 230 V, 1 phase power source has two hot wires and _____ neutral wire(s)

Answer 16

no

Question 17

A 3 phase power source has _____ hot wire(s) and zero neutral wires.

Answer 17

three

Question 18

A _________ is a device that is used only periodically to remove electrical circuits from their supply source.

Answer 18

disconnect

Question 19

Manual contactors are normally used with _____ circuit and resistance loads.

Answer 19

lighting

Question 20

The main device in an overload relay is the _____.

Answer 20

eutectic alloy tube

Question 21

A manual starter is a ___________ with an added overload protection divice.

Answer 21

contactor

Question 22

Overload protection devices are required by the _________.

Answer 22

NEC - National Electrical Code

Question 23

_________ temperature is the temperature of the air surrounding a motor.

Answer 23

Ambient

Question 24

A _______ alloy is a metal that has a fixed temperature at which it changes directly from a solid to a liquid state.

Answer 24

eutectic

Question 25

A starter may be reset after a _____ is removed.

Answer 25

overload

Question 26

Enclosures provide _______and electrical protection for the operator and the starter

Answer 26

mechanical

Question 27

An ___________is a control device that uses pushbuttons to energize the load connected to it.

Answer 27

manual contactor

Question 28

________ contact are contact that brake electrical circuit in two places

Answer 28

double-banker

Question 29

A(n) ____________ is a sensing device used to monitor the heat generated by excessive current and the heat created though ambient temperature rise.

Answer 29

heater coil

Question 30

NEMA Type ___________ enclosures are intendant for indoor use primarily to provide a degree of protection from human contact with the enclosed equipment in locations where unusual service condition do not exist.

Answer 30

one

Question 31

Manual motor starters are used in applications such as air compressors, conveyor systems, and _________.

Answer 31

drill presses

Question 32

Manual contactors directly control _________circuits.

Answer 32

power

Question 33

A(n) _____________ overload measures the strength of the the magnetic field around the wire instead of converting the current into heat.

Answer 33

electronic

Question 34

__________ arcs are the most difficult arcs to extinguish on a set of contacts.

Answer 34

DC

Question 35

The main difference between a contactor and a motor starter is the addition of ______ to the motor starter.

Answer 35

overload

Question 36

Two overload relays used to protect motors are thermal and _______ overload relays.

Answer 36

magnetic

Question 37

Ambient temperature, full-load current rating, and _________ must be know when selecting the overloads for a motor starter.

Answer 37

service factor

Question 38

An inherent motor protector is designed to protect a motor from _______

Answer 38

overloading

Question 39

__________ contactor assemblies may have several sets of contacts.

Answer 39

AC

Question 40

A(n)________ is a device that dissipates the energy present across opening contacts.

Answer 40

arc suppressor

Question 41

A(n) ___________ relay is an overload relay which resets automatically.

Answer 41

bimetallic

Question 42

A(n) ___________ is built into an overload device to indicate to the operator that an overload has taken place within the device.

Answer 42

trip indicators

Question 43

________ are used on large motor starter to reduce the current flowing to the overloads relay.

Answer 43

current transformer

Question 44

_________ are overload devices located directly on or in a motor to provide overload protection.

Answer 44

Inherent motor protector

Question 45

A(n) ____________ performs the same function as a motor starter, but can also vary motor speed, reverse the motor, and display operating information.

Answer 45

motor drive

Question 46

A(n) ________ is an electronic device that changes AC into DC

Answer 46

converter

Question 47

A(n) ________ is an electronic device that changes DC into AC

Answer 47

inverter

Question 48

Article _________ of the NEC covers the design and installation of electronic system that contain motors, motor circuits,and motor controllers.

Answer 48

430

Question 49

When motor was first introduced, they were started and stop by______.

Answer 49

knife switches

Question 50

______ are used to provide a magnetic field that helps move contacts apart as quickly as possible.

Answer 50

Blow-out coils