AC DC machine 31,32,33

the out put frequency of an alternator is controlled by the ____________+___________

# of stator poles and speed of rotation

what are the three factors that determine output voltage of an alternator

1.flux density of the magnetic field 2. length of the conducter 3. velocity (rotor speed)

the holtz motor operates at ____rpm

1200

the torque of a squirrell cage induction motor will be maximum when the phase angle between stator and rotor fields is ______

90 degrees

a two phase power system has two voltages that are

90 degrees out of phase

the non rotating part of an alternator is called the

Stator

_________ operate on the same principle of electro magnetic induction as DC generators, bu they have no commutator

alternators

the set of squirrel- cage bars on the rotor of a synchronous motor is used to start the motor is know as the

armortisser winding

in the consequent pole motor, if the number of poles is doubled, the motor speed will be

cut in half

using a ________ ________ ________ is one method of preventing induced voltage from becoming excessive

field discharge resistor

the higher power output alternators use a revolving ________

field type

setting the brushes to neutral plane can be done by connecting voltage to the armature, voltmeter in series, and adjusting the brush positon for _________

null reading

if one alternator does not produce sufficient power to a load, another alternator can be connected to the circiut in _______

parallel

when more than on alternator is used, they are connected in ________ with each other

parallel

conductive compensation is accomplished by connecting the compensating winding in _______ with the armature

series

the _____ winding is made of many turns of small wire and is located at the top of the stator core

start

a synchronous motor operated with no load and used for power factor correction is known as

synchronous condenser

for most squirrel cage motors the the typical percent slip is about _________

2-5 %

the sycnronous motor is an induction motor T/F

False

becuase some of the input energy to the alternator ends up being converted into heat, often cooling is required. the main types of cooling media are _____________

air and hydrogen

the squirrel cage rotor is contructed of ______ and _____ embedded in steel

bars and rings

in single phase motors such as the resistance start induction run motor, the start winding is disconnected using a

centrifugal switch

the universal motor has a wound armature and brushes like an ac motor, as well as an added component, the

compensation winding

frequecny of the current in the rotor _______ as the rotor approaches synchonous speed

decreases

the wound rotor induction motor is popular in industry because it has _____ starting torque an ____ starting current

high; low

in order to increase the efficiency of the cooling, some alternators operate in an atmosphere of ___________

hydrogen

the consequent pole motor is a ______ speed motor

multi

some motors are constructed so that they will operate on either of two voltages. when they are connected to operate on lower voltages the windings are connected in ________

parallel

in a universal motor, setting the brushes to the neutral plane using the compensating winding can be done by connecting voltage to the armature, voltmeter to the compesating winding and adjusting the brushes for a ______ reading on the voltmeter.

peak

three lines supply power to a three phase motor. if on of these lines should open, the motor will be connected to a single phase power. this is know as

single phasing

connection to the armature of an alternator is nomally done by using ______

slip rings

The _____ motor can operate on either dc or ac voltage

stepper

to reverse the direction of rotation of a three phase motor, reverse ________

two of its stator leads

in a universal motor, inductive compensation can be used when the motor is connected to

ac voltage

___________ alternators have a fan attached to one end of the shaft

air cooled

a single phase synchronous motor is sometimes referred to as an __________ motor

hysterisis

multispeed fan motors achieved multiple speeds by inserting additional _____________ in series with the run winding

inductance

the revolving armature type of alternator is capable of ________ power output and is, therefore, _______ often used than the revolving field typw

limited, less

split phase motors operate on the principle of _________ field

rotating magnetic

the rotating part of an alternator is called the

rotor

the ____ winding is made of few turns of large wire and is located at the bottom of the stator core

run

a ___________ is used to measure the difference in voltage an frequency between two alternators

synchroscope

the warren motor operates at ______ rpm

3600

an alternator that has a seperate small alternator mounted on the shaft of its rotor is equipped with a ____________

brushless exciter

in the shaded pole induction motor the shading coil acts like a transformer with ___________________

shorted down secondary winding

selsyn motors operate on __________

single phase ac voltage

the squirrel cage rotor code letters indicate the shape (type) of rotor bars. different types of bars have large effects on the _____ _______of a motor

starting torque

in a motor that has rotating magnetic field, the speed of the magnetic field is reffered to as the _______

synchronous speed

the direct current that is an input to the alternators rotor is the __________ current

DC excitation

the direction of the magnetic field rotation is known as __________

phase rotation

if a piece of machinery needs a replacement motor and will be damaged if the new motor rotates in the wrong direction. the test equipment needed to test the rotation is a __________

phase rotation meter

a ____________ motor operates on the principle that like magnetic poles repel

repulsion

some motors are constructed so that they will operate on either of two voltages. when they are connected to operate on higher voltages the windings are connected in ________

series

when a squirrel cage motor is first started the value of the starting current is

several times higher than the running current

in a three phase motor, the speed or rotation of the magnetic field is called the ___________

synchronous speed