Motors Lvl 1 Flashcards
INDUCTORS store energy in the form of a(n) ____ field.
Electromagnetic
CAPACITORS store energy in the form of a(n) ____ field.
Electrostatic
____ is a force by which materials exert an attraction or repulsion to other materials.
Magnetism
Magnets are created or magnetized by aligning the ____ within a material.
Domains.
A(n) ____ magnet holds all magnetic domains aligned whether it is conducting current or not, near another magnet or not.
Permanent
A magnet that loses most magnetic properties when current/lines of flux are removed from it would be a(n) ____ magnet.
Temporary
Magnetic lines of flux flow from the ____ pole to the ____ pole.
North to South.
Magnetic lines of flux are strongest at the ____,
Magnetic Poles
Permeability is the ability of a material to ____
Conduct Magnetic Flux
Permanence is the ability of a material to ____.
Hold Residual Magnetism
A ferromagnetic material is easily ____ and has high ____.
Easily Magnetized and has High Permeability
A ____ material weakly aligns in the SAME direction as the applied field.
Paramagnetic
A ____ material weakly aligns in the OPPOSITE direction as the applied field.
Diamagnetic
A ____ is a temporary magnet produced when current flows through a conductor such as a coil.
Electromagnet
A magnetic material has reached ____ when all magnetic domains are aligned and any additional current would no longer affect magnetic properties.
Saturation
____ is the ability of an inductor to induce a voltage into another circuit or conductor.
Mutual Induction
What 3 things are needed to create electricity?
- ) Conductor
- ) Magnetic Field
- ) Relative Motion
The ____ rule explains the relationship between the direction of applied current, direction of magnetic field, and direction of the induced conductor motion, within a motor.
The Right-Hand motor rule.
____ are used to concentrate magnetic lines of flux inside a coil.
Cores.
Commutators are used for ____ current motors.
Direct (DC)
____ are used to reverse direction of current in DC motors.
Commutators.
What are the 4 ELECTRICAL ratings listed on a motor nameplate?
Voltage, Current, Frequency, and Phase
Voltage listed on the nameplate represents the ____ operating voltage of the motor.
Optimal.
1 Horsepower is equal to ___ watts.
746 Watts
What are the two usage ratings for motors?
- ) General Purpose
2. ) Definite Purpose
____ is a multiplier that represents the amount of load beyond the rated load that can be placed on a motor without damaging it. (Is for accommodating starting current)
Service Factor.
How is speed rated for a motor?
Rounds per minute (RPM)
Operating Time Rating is either one of which two ratings?
- ) Continuous Duty
2. ) Intermittent Duty
The measure of how effective a motor is at outputting mechanical energy from the electrical energy it receives.
Motor Efficiency Rating
Insulation Class of a motor signifies the maximum ____ rating of the insulation used in the motor.
Temperature.
Where is the table in the NEC providing information for Locked-Rotor indicating code letters?
430.7(B)
When it comes to fractional hp motors, frame size is given in 1/__ of an inch, but in Integral motors, frame size is given in 1/__ of an inch.
Fractional = 1/16" Integral = 1/4"
In the chart for Integral motor frame sizes, the second set of numbers is your “F” measurement and it gives you the measurement between what two points?
The center to center of the mounting holes.
You would half the value for the distance between one hole and the center of the motor
What two things does the motor enclosure protect?
- ) Protects the motor from the environment and damage
2. ) Protects personnel from coming in contact with the energized and rotating interior parts of the motor.
A(n) ____ is a synchronous machine that produces Alternating Current.
Alternator
The ____ is the fixed part of a generator that includes a core and windings.
Stator
The ____ is the moving/spinning part of a generator.
Rotor.
What are the two types of alternators?
- ) Revolving Field
2. ) Revolving Rotor.
What type of rotor is most common for utility power generation?
Revolving Field
Brushes and slip rings allow you to make electric contact with ____.
Rotating Objects
A small three-phase generator that is sometimes mounted on the shaft that supplies current to the alternator rotor is called a(n) ____.
Exciter
How does an exciter regulate voltage in an alternator?
It changes the strength (or flux density) of the magnetic field on the rotor.
What is the formula for calculating Alternator and Motor Rotor Speed.
RPM = (120xFrequency)/PolesPerPhase
How does the ‘lights out’ method determine if alternators/generators are out-of-phase?
If the voltages are out of phase, there will be a difference in potential, causing the light bulbs to light up. When voltages are in phase, the light bulbs will stay off.
A device that indicates whether two alternators are in a correct phase relationship is called a(n) ____.
Synchroscope
The more poles a motor has, the ____ it will turn.
Slower
T/F: Motors can be single or dual voltage.
True.
In ____-connected motors, all three phase windings are connected at a single point.
Wye
In ____-connected motors, the phase windings are wired end-to-end to create a closed circuit.
Delta
How a motor is to be wired to a specific voltage should be shown on ____.
The motor nameplate.
T/F: The higher voltage option of a dual voltage motor is often selected, because the current draw of the motor is less.
True.
T/F: Current and Voltage are Directly Proportional.
False. They are Inversely Proportional
How is motor torque measured?
Pound-Feet (lb-ft). Which is different from ft-lbs.
How are Squirrel Cage and Wire-Wound motors different?
They both have conductive material (Copper or Aluminum) on the rotor, but Squirrel Cage has a cage like set of bars, while wire wound has wraps of wire around the rotor.
T/F: The stator is different between Squirrel Cage and Wire-Wound Motors.
False.
A(n) ____ is a metal piece on the end of squirrel cage rotor to connect all the bars.
Shorting-Ring
Why are thin insulated laminated sheets of iron used in motor stators instead of a large blocks?
To eliminate Eddy-Currents.
Which NEMA motor design is most common? (Often selected because of its normal starting torque and low-starting current.)
Motor Design B
What gives motors the means to turn? (torque)
Like magnetic poles in the rotor and stator repelling each other.
An Exciter that is mounted on the shaft is called a(n) ____.
Brushless Exciter
What two things must be brought into a correct phase relationship before an alternator can be paralleled with another?
Voltage and Frequency
