AC/DC Machinery & Controls 1 Units 29-33
differential-compound
A compound generator has both series and shunt field windings. When those windings are connected so their fields oppose each other in the production of magnetism, the connection is called ____.
cumulative-compound
A compound generator has both series and shunt field windings. When those windings are connected so they aid each other in the production of magnetism, that connection is called ____.
1.75 hp
A motor is operating at 3450 RPM and is producing a torque of 32 lb-in. What is the output horsepower of the motor?
4.17%
A squirrel-cage rotor induction motor has a synchronous speed of 3600 RPM and an actual rotor speed of 3450 RPM. What is the percent slip?
synchronous condenser
A synchronous motor operated with no load and used for power factor correction is sometimes called a ____.
50 Hz
A three-phase alternator containing six poles is turning at 1000 RPM. What is the output frequency?
90 degrees
A two-phase power system has two voltages that are ____ out of phase.
synchronoscope
A(n) ____ is used to measure the difference in voltage and frequency between two alternators.
repulsion
A(n) ____ motor operates on the principle that like magnetic poles repel.
air
Alternators of small kilovolt-ampere rating are generally _____-cooled.
lap-wound
Armatures are wound to provide high voltage, high current or some specific combination of voltage and current. Which type of winding provides low voltage and high current?
wave-wound
Armatures are wound to provide high voltage, high current, or some specific combination of voltage and current. Which type of winding provides high voltage and low current?
frogleg-wound
Armatures are wound to provide high voltage, high current, or some specific combination of voltage and current. Which type of winding provides moderate voltage and moderate current?
series
Conductive compensation is accomplished by connecting the compensation winding in ____ with the armature.
True
Counter-electromotive force (CEMF) and back-EMF are names for the voltage induced into the armature of a DC motor.
two to five
For most squirrel-cage induction motors the typical percent slip is about ____ percent.
parallel
If one alternator does not produce sufficient power to supply a load, another alternator can be connected to the circuit. The second alternator is connected in ____.
armature; shunt field
In a compound DC motor control circuit, the field loss relay will disconnect the ____ if power is lost to the ____.
AC only.
In a universal motor, inductive compensation can be used when the motor is connected to ____.
hydrogen
In order to increase the efficiency of the cooling, some alternators operate in a(n) ____ atmosphere.
centrifugal switch
In single-phase motors such as the resistance start induction-run motor, the start winding is disconnected by the ____.
higher
Permanent magnet motors have ____ efficiency than conventional field-wound motors.
sliprings
Power is carried to the outside circuit of a revolving armature type alternator via brushes riding against the ____.
single-phase
Selsyn motors operate on ____ voltage.
few; large
Series field windings are connected in series with the armature. They are wound with ____ turns of fairly ____ wire.
many; small
Shunt field windings are connected in parallel with the armature. They are wound with ____ turns of fairly ____ wire.
parallel
Shunt generators contain only a shunt field winding connected in _____ with the armature.
servomotors
Small permanent magnet motors that have lightweight rotors are often used as _____.
rotating
Split-phase motors operate on the principle of a ____ magnetic field.
compounding
The relationship of the strengths of the two fields in a generator determines the amount of ____.
less; less
The revolving armature type alternator is capable of ____ power output and is, therefore, ____ often used than the revolving field type.
a generator
What is a device that converts mechanical energy into DC electrical energy?
shunt
When the field winding of a DC motor is connected in parallel with the armature, the motor is called a _____ motor.
shunt
The DC motor, known as a "constant speed motor", is the ____ motor.
Series and shunt
A compound motor has ____ field windings.
motor
A device that converts electrical energy into mechanical energy is called a(n) ____.
compound
A generator containing both series and shunt fields is called a ____ generator.
9 V
A square wave voltage varies between 0 V and 12 V. The positive pulses are 75 microseconds wide and there is a 25 microsecond gap between them. What is the DC average of the waveform?
100 Hz
An alternator containing eight poles per phase is turning 1500 RPM. What is the output frequency?
cut in half
In the consequent pole motor, if the number of poles is doubled, the motor speed will be ____.
1200
The Holtz motor operated at ____ RPM.
printed-circuit
The ServoDisc motor is also often called a ____ motor.
3600
The Warren motor operates at ____ RPM.
universal
The ____ motor can operate on either AC or DC voltage.
amortisseur winding
The set of squirrel-cage bars on the rotor of a synchronous motor is used to start the motor and is known as the ____.
armature resistance
The speed regulation of a DC motor is proportional to the ___.
output voltage
By increasing or decreasing the strength of the magnetic field of the rotor, the ____ of an alternator is controlled.
synchronous
In a three-phase motor, the speed of rotation of the magnetic field is called the ____ speed.
series
Some motors are constructed so that they will operate on either of two voltages. When they are connected to operate on the higher of the two voltages, the windings are connected in ____.
parallel
Some motors are constructed so that they will operate on either of two voltages. When they are connected to operate on the lower of the two voltages, the windings are connected in ____.
high
The consequent-pole motor is used where ____ running torque must be maintained at different speeds.
excitation
The direct current that is an input to the alternator's rotor is the ____ current.
phase
The direction of magnetic field rotation is known as ____ rotation.
run
The ____ winding is made of a few turns of large wire and is located at the bottom of the stator core of a split-phase motor
start
The ____ winding is made of many turns of small wire and is located at the top of the stator core of a split-phase motor.
False
A series motor may be operated with no load connected.
60 Hz
An alternator containing eight poles per phase is turning at 900 RPM. What is the output frequency?
phase rotation meter
If a piece of machinery needs a replacement motor and will be damaged if the new motor rotates the wrong way. The test equipment needed to test the rotation direction of the new motor is a ____.
bars; rings
The squirrel-cage rotor is constructed of ____ and end ____ embedded is steel laminations.
single-phasing
Three lines supply power to a three-phase motor. If one of these lines should open, the motor will be connected to a single-phase power. This condition is known as ____.
Armature reaction
____ is the twisting or bending of the magnetic lines of flux of the pole pieces.
hysteresis
A single-phase synchronous motor is sometimes referred to as a(n) ____ motor.
3 V
A square wave voltage varies between 0 V and 12 V. The positive pulses are 25 microseconds wide and there is a 75 microsecond gap between them. What is the DC average of the waveform?
6 V
A square wave voltage varies between 0 V and 12 V. The positive pulses are 50 microseconds wide and there is a 50 microsecond gap between them. What is the DC average of the waveform?
brushless exciter
An alternator that has a separate small alternator mounted on the shaft of its rotor is equipped with a(n) ____.
series field shunt rheostat
In a generator, the ____ permits part of the current that normally flows through the series field to flow through the resistor.
synchronous speed
In a motor that has a rotating magnetic field, the speed of that magnetic field is referred to as the ____.
magnetic field strength
In the shaded-pole induction motor, the direction of rotation of the magnetic field is determined by the ____.
shorted
In the shaded-pole induction motor, the shading coil acts like a transformer with a(n) ____ secondary winding.
Inductance
Multi-speed fan motors achieve multiple speeds by inserting additional ____ in series with the run winding.
brushes
The ____ ride against the commutator segments and are used to connect the armature to the external circuit of the DC machine.
differential
The compound motor connection that should generally be avoided is the ____.
decreases
The frequency of the current in a squirrel-cage rotor ____ as the rotor approaches synchronous speed.
field
The higher power output alternators use a revolving ____.
brushless DC
The motor that does not contain a wound armature, commutator, or brushes is the ____ motor.
stator
The non-rotating part of a revolving-field-type alternator is called the ____.
moves through a specific angle for each input pulse.
The output shaft of a stepping motor ____.
field excitation current
The output voltage of a generator is usually controlled by the amount of ____.
torque
The pushing or turning force created by the magnetic field of the pole pieces and the magnetic field of the loop or armature is called ____.
armature
The rotating part of a generator is called the ____.
rotor
The rotating part of a revolving-armature-type alternator is called the ____.
series
The series generator has only a series field, which is connected in ____ with the armature.
ServoDisc
The servomotor featuring a fiberglass and copper rotor is the ____ motor.
pulse-width modulation
The speed of the disc servomotor can be varied by changing the amoung of voltage supplied to the armature. The voltage is generally varied using ____.
starting torque
The squirrel-cage rotor code letters indicate the shape (type) of rotor bars. Different types of bars have a large effect on the ____ of a motor.
False
The synchronous motor is an induction motor.
0 degrees
The torque of a squirrel-cage induction motor will be maximum when the phase angle between the stator and rotor fields is ____.
compensating winding
The universal motor has a wound armature and brushes like an AC motor, as well as an added component, the ____.
high; low
The wound-rotor induction motor is popular in industry because it has ____ starting torque and ____ starting current.
any two leads
To revers the direction of rotation of a three-phase motor, reverse ____.
field discharge resistor
Using a(n) ____ is one method of preventing induced voltage from becoming excessive.
torque motor
What is a special type of motor designed to operate with the rotor stalled without damage to the motor?
number of stator poles and rotor rotation speed
What is one factor that controls the output frequency of an alternator?
commutator
What is the component of a DC generator that converts the armature AC into DC?
alternators
What machines operate on the same principle of electromagnetic induction as DC generators, but they have no commutator?
pole pieces
What provide(s) the magnetic field necessary for the operation of a DC machine?
shunt field
When a motor is connected differential compound, the _____ determines the direction of rotation of the motor at no load or light load.
several times the running current
When a squirrel-cage motor is first started, the value of the current draw is ____.
air-cooled
____ alternators have a fan attached to one end of the shaft.
countertorque
____ is the measure of the useful electric energy produced by the generator.
