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
