Chapter 9 Flashcards
A device that supplies alternating current
AC power source
Electric current that reverses direction periodically usually 60 times per second
Alternating current
AC
Device used to measure the electrical current in a circuit
Ammeter
A unit of measure of the electrical current flow in an electrical circuit; similar to gallons of water flow in a pipe
Ampere (amp)
A machine component that rotates, slides, or oscillates. Bearings reduce friction between the motor’s rotating and stationary parts
Bearing
A system of one or many electrical components that accomplish a specific purpose.
Circuit
An electrical component that opens a circuit and stops the flow of electricity when the current reaches unsafe levels.
Circuit breaker
Materials that have electrons that can break free from the flow more easily than the electrons of other materials.
Conductor
Electrical current that flows in a single direction through a conductor.
Direct current
DC
A large electrical switch used for isolation during system repairs and maintenance.
Disconnect
The flow of electrons from one point to another along a pathway called a conductor.
Electricity
Magnetism produced by an electric current.
Electromagnetism
Negatively charged particles that orbit the nucleus of an atom.
Electrons
A rotating blade inside a motor housing or casing that cools the motor by pulling air in through the shroud.
Fan
A structure that holds the internal components of a motor and motor mounts.
Frame
A device used to protect equipment and electrical wiring from overcurrent.
Fuse
A device that converts mechanical energy into electrical energy.
Generator
A motor that turns slightly slower than the supplied frequency and can vary in speed based on the amount of load.
Induction motor
Any substance that prevents the passage of heat, light, electricity, or sound from one medium to another. Insulators do not conduct electricity.
Insulator
The amount of torque necessary for a motor to overcome the resistance of the driven machine.
Load
An enclosure that houses the equipment for motor control, including isolation power switches, lockouts, fuses, overload protection devices, ground fault protection, and sometimes meters for current amps and voltage.
Motor control center
MCC
A measurement of resistance in electrical circuits.
Ohm
A device that converts AC voltage to DC voltage.
Rectifier
A material that is neither a conductor nor an insulator.
Semiconductor
A casing over the motor that allows air to flow into an around the motor.
Shroud
Electricity that occurs when a number of electrons build up on the surface of a material but have no positive charge nearby to attract them and cause them to flow.
Static electricity
A stationary part of the motor where the alternating current supplied to the motor flows, creating a magnetic field using magnets and coiled wire.
Stator
And electrical device used to start, stop, or otherwise reconfigure the flow of electricity in a circuit.
Switch
A motor that runs at a fixed speed that is synchronized with the supply of electricity.
Synchronous u
And electrical device that takes electricity of one voltage and changes it into another voltage.
Transformer
A motor that can be driven by either AC or DC power.
Universal motor
The electromotive force or a measure of current that establishes a current of one amp through a resistance of one ohm.
Volt
A measurement of the potential energy required to push electrons from one point to another.
Voltage
A device that can be connected to a circuit to determine the amount of voltage present.
Voltmeter
Unit of measure of electric power; the power consumed by a current of one amp using an electromotive force of one volt.
Watt
The formula for ohms law is: V=IR
V =volts
I=current flow in amps
R=resistance to flow in ohms
When working with Ohm’s law, if you know the value of two units, you can always figure out the third using one of the following calculations:
I=V/R(current=volts/resistance)
R=V/I (resistance=volts/current)
Ohm’s law
named after James Watt, who invented the steam engine.
Watt
Named after Andre Ampere, the first person to explain the electrodynamic theory.
Ampere
Named after George Ohm, a German mathematician and physicist.
Ohm
Process of connecting an object to the earth using copper wire and grounding rod to provide a path for the electricity to dissipate harmlessly into the ground. Typically accomplished by a separate conductor specifically designed for this purpose. With this conductor in place, if the equipment case becomes energized, a low resistance path for the flow of ground current back to the source is already in place, and it reduces or eliminates the shock hazard to the operator.
Grounding
An inventor who invented the phonograph and improved the printing telegraph. Also he built the first practical direct current generator.
Thomas Edison
The most common type of motor used in the process industries, primarily because of the simplicity of its construction.
Alternating current (AC)
Most commonly used in situations where variable speed or high torque applications are needed.
Direct current (DC)
Motors that run at a single rotator speed; generally AC motors.
Single speed
Allows for the rotation speed of the motor to be adjusted; maybe either in AC or a DC motor.
Variable speed
Motor composed of a frame, shroud, stator, rotor, fan, and bearings.
AC motors
Rotating member of a motor or turbine that is connected to the shaft; is usually consists of an iron core with copper bars attached to it. When the stator creates an electric current in the rotor, this creates a second magnetic field in the rotor to turn. The magnetic fields from the stator and rotor interact, causing the rotor to turn.
Rotor
Metal rotating component (spindle) that holds the rotor and all rotating equipment in place.
Shaft
Two types of loads are:
Full loads and no loads.
When the motor is using the full amount of torque to which it is rated.
Full load
Occurs when the motor is not using torque.
No load
The first level of electrical hazard classifications is the class ___________. Yea
designation
Class designations are grouped by:
Explosive/ignitable materials
Gases, vapors, and liquids that can be present and explosive or ignitable mixtures.
Class I
Dust, combustible dust that can be present in the amounts that could produce potentially explosive mixtures.
Class II
Fibers that are easily ignitable.
Class III
(True or false) AC motors are the most common type of motor used in the process industries due to their simplicity.
True
(True or false) DC motors have the ability to adjust the rotor speed of the motor.
True
(True or false) synchronous motors are the most common type of AC motor.
False
A ____________ is the amount of torque necessary for a motor to overcome the resistance of the machine it drives.
load
Which of the following is not a factor that affects motors?
Rotation
A coupling failure is often dangerous because of _________________.
Flying shrapnel
What is not a potential hazard associated with motors?
Corrosion
Where can a list of additional restrictions be found for hazards?
National electric code information
What three things must process technicians do as they perform routine tasks on electrical motors?
Look, listen, and feel
A casing over the motor that allows air to flow into and around the motor
Shroud
A structure that holds the internal components of a motor and motor mounts
Frame
The stationary part of the motor where alternating current supplied to the motor flows, creating a magnetic field using magnets and coiled wire
Stator
A rotating member of a motor or turbine that is connected to the shaft
Rotor
A rotating blade inside a motor casing that cools the motor by pulling air in through the shroud
Fan
