LAP 8 Reversing Motor Control
NEMA and IEC recommend reversing motor connections T1 and _____ to reverse the direction of rotation for a three-phase motor.
T3
The _________ mode repeatedly cycles a machine.
automatic
The two basic modes of machine operation are manual and _______________.
automatic
When the __________ mode is selected, the motor will not run until certain conditions are met.
automatic
The __________ __________ method of interlocking is the most common method. It uses the normally closed auxiliary contacts of the reversing magnetic motor starter.
auxiliary contact
When the forward starter coil is energized the __________ contacts will close.
forward
A ____-_____-___ circuit provides a continually operating motor mode, off mode, and automatic mode.
hand off auto
3 types of _____________- Auxiliary contact interlock- Most common method. Electrical method that uses the N.C. interlock contacts of the reversing motor starter in series with the starter coils. Pushbutton interlock- Very effective method. Uses two double-pole single-throw pushbuttons to accomplish the interlock. Mechanical interlock- Uses a lever that physically prevents the armature of one coil from moving when the other coil is energized. Stop button must be pressed before the opposite contact can be energized.
interlock
A common application for the H-O-A circuit is an __________ __________ for crops.
irrigation system
In the manual mode, operators often _________ an actuator to position it.
jog
A ____-______-____ circuit provides a jog mode, off mode, and automatic mode.
jogs off run
________ stop is when a stop button is mechanically held open to prevent the start button from interlocking so the machine can be jogged.
lock
A ________-_______ circuit uses a locking pushbutton to switch between manual and automatic modes.
lock-stop
The motor automatically runs continuously in the __________ mode.
manual
The ________________ method of interlock uses a lever to physically prevent the armature of one of the coils from moving.
mechanical
A reversing magnetic motor starter has _______ relay coils and overload protection. Each contactor (forward & reverse) have their own set of contacts.
2
Each relay in a reversing magnetic motor starter has its own set of ____________.
contacts
A _________ ________ is a manual switch used to change the direction of rotation for a motor.
drum switch
________________ interlocking is often used with mechanical interlocking to protect the coils from damage.
electrical
To avoid ____________ both coils of a reversing magnetic motor starter at the same time, interlocks are used.
energizing
The ______________ method of interlocking uses two double-pole single-throw (DPST) pushbuttons to create the interlock.
pushbutton
When the reverse starter coil is energized the __________ contacts will close.
reverse
Two common methods used to reverse a three-phase motor are _________ and drum switches.
reversing magnetic motor starter
A drum switch contains moveable contacts on an insulated __________ ____________.
rotating shaft
A ________________ switch is often used to select modes of operation.
selector
