Electric motors test 1 nameplates Flashcards
Since a nameplate has limited space to convey the ratings, most information is abbrieveated or coded to save space
T
The actual voltage applied to a motor should be withing 15% of the motor’s nameplate rated voltage
F
AC motors will typically use levels of 24V, 48V, 90V, or 180V
F
The list of motor nameplate locked-rotor indicating code letters begins with the letter “A” and ends with “Z”
F
Directly applying any frequency to a motor other than the nameplate rated frequency will change the motor;s operating characteristics and can damage the motor
T
Electric motors typically require either direct current, single-phase AC or three phase AC
T
When the nameplate of a motor does not list a service factor rating, a service factor rating of 1.00 is assumed and there is no built in safety margin for the motor
T
Motor manufacturers produce only energy efficient motors
F
Insulation breakdown is the most common cause of motor failure
T
For fractional-HP frame sizes, the frame number represents the distance from the bottom of the base to the center of the shaft in 8ths of an inch.
F
Typically operating environments for totally enclosed motor enclosures include the following: wet locations, dirty locations, oily locations, corrosive locations, extremely low and high temp locations gas and other hazardous locations and combustible dust locations
T
Most motors include light-duty or medium-duty rated bearings
T
The voltage applied to a motor must always exactly match the nameplate voltage rating
F
For every 1% of voltage unbalance there can be up to a 6% current unbalance
T
Design B motors are the most common type of industrial motors in use today.
T
A __________ is a metal tag permanently attached to an electric motor frame that gives the required electrical ratings, operating ratings, and mechanical-design codes of the motor
nameplate
Electrical ratings included on motor nameplates include a ____ rating and phase
current, voltage, frequench (alltheabove)
The_________ rating is the amount of current a motor draws when delivering full rated power output.
current
__________ current or starting current, or irush current is the amount of current a motor draws on startup
locked rotor current
The _______ rating is a description of the expected or allowed application of a motor
usage
The ________ is the difference between the winding temp of a running motor and the ambient temp
temp rise
______ motors are used in applications such as compressors, waste-disposal systems, electric hoists, gate-opening motors, and other applications in which the motor need only be turned on for short time periods to meet application requirements
Intermittent-rated
The NEMA_______ letter isa code letter representing a National Electric Manufacturers Association motor classification for the torque and current curves of a motor
design
A design__________ motor is an integral-horsepower 3phase induction motor design made for full voltage starting nad high locked rotor torque, with locked rotor current not exceeding a specified value
B
A_______ is a machine component used to reduce friction and maintain clearance between stationary and moving parts.
motor bearing
The ____ is a code letter signifying the maximum operating temp of the insulation used in a motor
insulation class
A design ________ motor is an integral-horsepower single phase motor design made for full voltage starting and locked rotor torque higher than for design M, N and O motors.
L
The ________ , or duty cycle, is the amount of time a motor can be operated without being turned OFF to allow for cooling
operating time rating
________ type is the type of protection given to a motor to shield the motor from the outside environment as well as to protect individuals form the electrical and rotating parts of the motor
Enclosuure
A motor’s nameplate rating is the optimal voltage that should be connected to the
motor for best operating performance.
voltage
__ ___ratings include the power rating, usage rating, service factor rating, speed
rating, operating time rating, motor efficiency rating, ambient temperature rating, and insulation
class.
operation
The rating_______ is the amount of power a motor can deliver to a load
power
The ____________rating of a motor is the approximate speed at which the rotor of a motor
rotates when delivering rated power to a load.
speed
The __________is a number designating standard dimensions of a motor housing, shaft,
and mounting holes.
frame size
____________motors have three- or four-digit frame numbers
integral-horsepower
__________is a measure of the effectiveness with which a motor converts electrical
energy to mechanical energy.
motor-efficiency
A design motor is a fractional-horsepower single-phase motor design made for fullvoltage starting and locked-rotor current not exceeding specified values.
N
A(n) ___________motor enclosure is a motor enclosure that prevents air from entering
the motor
totally closed
The____________ is a multiplier that represents the amount of load, beyond the rated
load, that can be placed on a motor without causing damage.
service factor
Motors that are rated for ___________________ usage are used in a wide range of applications and
for mechanical loads such as conveyors, machine tools, and belt-driven equipment.
general purpose
______________motor enclosures include general, drip-proof, splashproof, guarded,
semiguarded, and drip-proof fully guarded types.
open
