Electric Motor Control Final Exam 2023 Q&A
motor connections factors ✔️ horsepower, service factor,marked
temperature rise, voltage, full load current rating and nema code letter
Synchronous motor advantage ✔️ they can provide power factor
correction for themselves
Squirrel cage induction motors are used ✔️ to power most of the
machines throughout industry
motor starters can be divided into two classes ✔️ IEC and NEMA
NEMA starters range ✔️ 00-8
NEMA size 00 ✔️ is rated to control a 2-horsepower motor connected to a
460 volt, three phase power supply
NEMA size 8 ✔️ Will control a 900 horsepower motor connected to a 460
volt, three phase power supply
semiautomatic controls ✔️ characterized by the use of push buttons, limit
switches, pressure switches and other sensing devices to control
manual controls ✔️ simple devices that are hooked onto the line of a
motor
Automatic controls ✔️ similar to semiautomatic controls but operator
does not have to initiate control
across the line starting ✔️ accomplished by connecting the motors
directly to the power line
ramping ✔️ requires a motor to start at a low speed and accelerates to full
speed over time
Simplest method of stopping ✔️ disconnect power line
, Normally open push button ✔️
Normally closed push button ✔️
When components are shown connected by a dashed line in a schematic
diagram ✔️ it indicates that the components are mechanically connected
together
Normally open liquid flow switch ✔️
float switch ✔️
temperature switch ✔️
disconnect switch ✔️
circuit breaker ✔️
on delay timer ✔️
Current transformer ✔️
air core transformer ✔️
Dual voltage transformer ✔️
Auto transformer ✔️
First step of trouble shooting ✔️ determine whether the motor is
overloaded
Shorted windings in the motor ✔️ can cause the motor to draw excessive
current
Current flow in a 3 phase motor should ✔️ all be the same
manual starters that are installed in a switch box ✔️ more susceptible to
ambient temperature problems
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