Second Term Flashcards
A power plant that changes energy from moving water into electrical energy.
Hydroelectric-power generation plant
A power plant that uses steam to produce electricity.
Combustion-power generation plant
The energy produced from the flow of electrons through a conductor.
Electricity
A material with low resistance that permits electrons to flow through it easily.
Conductor
A material that resists the flow of electrons.
Insulator
The amount of electrons flowing through a conductor.
Current
The amount of electrical pressure in a conductor.
Voltage
The amount of opposition a material has to the flow of electrons.
Resistance
Ohm’s law
E = I x R ( voltage = current x resistance)
A current that flows in one direction only.
Direct current (DC)
A current that reverses direction at regular intervals.
Alternating current (AC)
A circuit that has two or more components connect so that there is one path for current to flow.
Series circuit
A circuit that has two or more components connected so that there is more than one path for current flow.
Parallel circuit
How does resistance affect a load voltage drop in a series circuit?
High resistance will cause a higher voltage drop then a lower resistance.
The production of current flow due to a magnetic failed on a coil.
Inductance
An alternating current device that steps up our steps down voltage.
Transformer
AN AC phase voltage that contains one alternating voltage waveform.
Single-phase
This AC phase voltage is a combination of three alternating voltage waveforms.
Three-phase
Five common residential and light commercial building power quality problems.
Voltage interruptions, voltage fluctuation, transient voltages, harmonics, and noise.
A temporary, unwanted voltage that ranges from a few volts to several thousand volts and lasts from a few microseconds to a few milliseconds.
Transient voltage
A power frequencies that are whole integer multiples of the base frequency (60 Hz).
Harmonics
A sine wave distortion from motors and electrical devices that enters a power distribution system directly on the wires/grounds or through the magnetic coupling of adjacent wires.
Noise
The stationary part of a motor
that produces a rotating magnetic field.
The stator
The moving part of a motor that spins in response to current flow.
The rotor
What are common motor voltage ratings?
24v, 120v, 208v, and 230/460v
What does FLA or RLA mean?
They both represent the amperage draw when a motor is at full load, aka full load amperage.
What is the meaning of LRA?
This represents the amount of the current drawn of a rotor is unable to turn, is locked, or startup amperage, aka locked-rotor amperage.
What is service factor(SF)?
A number that represents the amount of extra load that can be placed temporarily on a motor without causing damage.
What size of motor is selected if a horsepower requirement falls between two standard horsepower ratings?
The larger of the two.
What are insulation class ratings?
A rating that describes how hot a motor can safely operate in a specific ambient environment.
The formula for finding synchronous speed of a motor?
Rpm= (120xf)/(Np)
The two most common motor mounts.
The rigid mount and resilient mount.
The purpose of a motor enclosure.
To promote safety, reduce maintenance, and to protect internal motor components from the external environment.
An inflexible coupling that is used to join two precisely aligned shafts.
A rigid coupling.
What are the two general categories of flexible couplings?
Flange and sleeve.
What is the purpose of a V-belt?
To drive fans and compressors.
How do shaded-pole motors operate?
They operate using single phase voltage, they develop low starting torque.
Describe the operation of split-phase motors.
A single phase motor that has separate start windings and run windings.
A split-phase motor that has increased starting torque due to a capacitor connected to the start windings.
Capacitor-start motor
A split-phase motor that has increased running torque due to a capacitor connected at all times,
Capacitor-run motor
A split-phase motor with two capacitors to allow greater torque during startup and running.
Capacitor start-and-run motor
How do induction motors operate?
3 phase motors that create a rotating magnetic field in the stator windings, which induces opposite polarity magnetic fields in the rotor bars.
