motor controls Flashcards
What are the two main parts of a solenoid?
The coil and the plunger (armature).
Multiple stop buttons used to control a magnetic motor starter are connected in
series
Multiple start buttons used to control a magnetic motor starter are connected in
parallel
What is the difference between a 3Ø magnetic motor starter and a 3Ø contactor?
The mag. motor starter will have an overload relay/block
The contacts used to maintain a circuit after the momentary N/O start button has been released
are called
holding contacts
another name for holding contacts
maintain, memory,
The contacts that will open and de-energize a motor control circuit after prolonged over
currents are called
overload contacts
two wire control provides
low voltage release
3 wire control provides
low voltage protection
The contacts of a motor starter that carry the full load current of the motor are called
pole line or load
The contacts of a magnetic motor starter that do not carry motor currents are called
auxillry contacs
The contacts on an overload relay that are used to de-energize a magnetic motor starter are
normally open held closed
Normally open pilot devices such as a limit sw., floats sw., pressure sw. or temperature sw.
are drawn with the movable contact
below and not touching the stationary contacts
Normally closed pilot devices such as a limit sw., floats sw., pressure sw. or temperature sw.
are drawn with the movable contact
above and touching
Contacts and control devices are generally shown in their
de- energized state with no outside force cting upon them
When installing/replacing plug-in relays, the electrician should pay close attention to the
coil voltage of the relay
A method of preventing the coils of a reversing starter from energizing simultaneously is
known as
interlocking
A link installed between the forward and reverse contactors of a reversing starter to prevent
their contacts from closing simultaneously is called
mechanical interlock
How is the rotation of a three phase motor reversed?
interchange any 2 leads
A float switch that is used to control a motor directly must be rated to carry the
full load current
The leads of a three phase motor are connected to the terminals a magnetic motor starter
labelled
T1 T2 T3
Overload protection does not protect a motor from short circuits; motors are protected from
short circuits b
fuses and breakers
The two basic types of overload relays are
thermal and magnetic
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
parallel with
each other and in series with the coil of motor starter “C”
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
series with
each other and in series with the coil of motor starter “C
A motor starter that provides overcurrent protection, overload protection and a disconnecting
means is called a
combination starter
Overload relays contain two sections, what are they?
current sensing section and contact sensing
To reverse the rotation for a single phase motor, you must interchange either the
start or run winding but not both, usually start
The contacts of a 120 volt toggle switch would be described as
single ole single throw
A type of control device that is used to detect flow within a pipe or duct is known as a
flow switch
A type of control device that is used to monitor the flow rate within a pipe or duct is known as
flow sensor
When a motor is being “Jogged”, the motor will be connected to
full load
When a motor is being “Inched”, the motor will be connected to a
reduced voltage
