motor controls

Question 1

What are the two main parts of a solenoid?

Answer 1

The coil and the plunger (armature).

Question 2

Multiple stop buttons used to control a magnetic motor starter are connected in

Answer 2

series

Question 3

Multiple start buttons used to control a magnetic motor starter are connected in

Answer 3

parallel

Question 4

What is the difference between a 3Ø magnetic motor starter and a 3Ø contactor?

Answer 4

The mag. motor starter will have an overload relay/block

Question 5

The contacts used to maintain a circuit after the momentary N/O start button has been released
are called

Answer 5

holding contacts

Question 6

another name for holding contacts

Answer 6

maintain, memory,

Question 7

The contacts that will open and de-energize a motor control circuit after prolonged over
currents are called

Answer 7

overload contacts

Question 8

two wire control provides

Answer 8

low voltage release

Question 9

3 wire control provides

Answer 9

low voltage protection

Question 10

The contacts of a motor starter that carry the full load current of the motor are called

Answer 10

pole line or load

Question 11

The contacts of a magnetic motor starter that do not carry motor currents are called

Answer 11

auxillry contacs

Question 12

The contacts on an overload relay that are used to de-energize a magnetic motor starter are

Answer 12

normally open held closed

Question 13

Normally open pilot devices such as a limit sw., floats sw., pressure sw. or temperature sw.
are drawn with the movable contact

Answer 13

below and not touching the stationary contacts

Question 14

Normally closed pilot devices such as a limit sw., floats sw., pressure sw. or temperature sw.
are drawn with the movable contact

Answer 14

above and touching

Question 15

Contacts and control devices are generally shown in their

Answer 15

de- energized state with no outside force cting upon them

Question 16

When installing/replacing plug-in relays, the electrician should pay close attention to the

Answer 16

coil voltage of the relay

Question 17

A method of preventing the coils of a reversing starter from energizing simultaneously is
known as

Answer 17

interlocking

Question 18

A link installed between the forward and reverse contactors of a reversing starter to prevent
their contacts from closing simultaneously is called

Answer 18

mechanical interlock

Question 19

How is the rotation of a three phase motor reversed?

Answer 19

interchange any 2 leads

Question 20

A float switch that is used to control a motor directly must be rated to carry the

Answer 20

full load current

Question 21

The leads of a three phase motor are connected to the terminals a magnetic motor starter
labelled

Answer 21

T1 T2 T3

Question 22

Overload protection does not protect a motor from short circuits; motors are protected from
short circuits b

Answer 22

fuses and breakers

Question 23

The two basic types of overload relays are

Answer 23

thermal and magnetic

Question 24

A control circuit requires that motor “A” or motor “B” is running before motor “C” can be
started. Auxiliary contacts from motor starters “A” and “B” would be placed in

Answer 24

parallel with
each other and in series with the coil of motor starter “C”

Question 25

A control circuit requires that motor “A” and motor “B” are running before motor “C” can be
started. Auxiliary contacts from motor starters “A” and “B” would be placed in

Answer 25

series with
each other and in series with the coil of motor starter “C

Question 26

A motor starter that provides overcurrent protection, overload protection and a disconnecting
means is called a

Answer 26

combination starter

Question 27

Overload relays contain two sections, what are they?

Answer 27

current sensing section and contact sensing

Question 28

To reverse the rotation for a single phase motor, you must interchange either the

Answer 28

start or run winding but not both, usually start

Question 29

The contacts of a 120 volt toggle switch would be described as

Answer 29

single ole single throw

Question 30

A type of control device that is used to detect flow within a pipe or duct is known as a

Answer 30

flow switch

Question 31

A type of control device that is used to monitor the flow rate within a pipe or duct is known as

Answer 31

flow sensor

Question 32

When a motor is being “Jogged”, the motor will be connected to

Answer 32

full load

Question 33

When a motor is being “Inched”, the motor will be connected to a

Answer 33

reduced voltage