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Electrical Motor Control Midterm Review Q&A
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Electrical Motor Control MidtermReview Q&A
Chapter 1 ✔️General Principles of Motor Control
When a machine is installed, the motor, machine, and controls are all
interrelated and must be considered as a unit. ✔️True
The most complicated method of starting a motor is across-the-line starting.
✔️False
The conductor size, fuse or circuit breaker size, and overload size are
generally determined using the ____. ✔️National Electrical Code
Fuses and circuit breakers are generally employed for circuit protection, and
____ are used to protect the motor. ✔️overload relays
Motor control systems can be divided into three major types:
____________________, semiautomatic, and automatic. ✔️manual
Diodes are used to suppress the voltage spikes produced by coils that operate
on ____________________. ✔️direct-current or DC
Chapter 2 ✔️Symbols and Schematic Diagrams
Push buttons are always shown as normally open. ✔️False
Limit switches are drawn by adding a wedge to one of the four basic switches.
✔️True
Push buttons that contain multiple contacts are often called ____ push buttons.
✔️stacked
The symbol for a float switch illustrates a ball float. It is drawn by adding a ____
to a line. ✔️circle
, Schematics are always drawn to show components in their de-energized, or
____________________, state. ✔️off
The most common coil symbol used in schematic diagrams is the
____________________. ✔️circle
Chapter 3 ✔️Manual Starters
Manual starters are characterized by the fact that the operator must go to the
location of the starter to initiate any change of action. ✔️True
Integral horsepower manual starters with low voltage release automatically
restart after a power failure and don't have to be manually reset. ✔️True
Starters that are intended to protect motors that operate on 240 volts should
contain ____ load contacts. ✔️two
Anytime a motor has tripped on overload, the electrician should check the
motor and circuit to determine why the overload tripped. The first step is
generally to ____. ✔️determine if the motor is actually overloaded
When using a sensing pilot device to directly control the operation of a motor,
you must make sure that the type of pilot device is equipped with contacts
that can handle the rated current of the motor. These devices are generally
referred to as "____________________" devices ✔️line voltage
Manual starters that are installed in a(n) ____________________ inside a wall are
especially susceptible to ambient temperature problems. ✔️switch box
Chapter 4 ✔️Overload Relays
Overloads are designed to protect the circuit from a short-circuit condition.
✔️False
Three-phase motors must have an overload sensor (heaters or magnetic coils)
in two of the three-phase lines. ✔️False
There are two major types of overload relays: thermal and ____.
✔️magnetic
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