final motors and generators

60

Frequency is measured in Hertz. The standard frequency used throughout the United States and Canada is ____ Hz.

phase rotation meter

It is possible to determine the direction of rotation of a motor before power is connected to it with the use of a ____ meter.

hydrogen

Large-capacity alternators are often enclosed and operate in a(n) ____ atmosphere.

120 or 240 volt

Many split-phase motors are designed for operation on ____.

field loss relay

Most large compound direct current motors have a protective device connected in series with the shunt field called the ____ relay.

TENV

Motors have different types of enclosures depending on the application. ____ indicates motors that are generally used in harsh environments such as chemical plants.

centrifugal

Motors that are not hermetically sealed use a ____ switch to disconnect the start windings from the circuit.

two to five

Multispeed fan motors have been used for many years and are generally wound for ____ steps of speed and operate fans and squirrel-cage blowers.

BTU per second,Calorie per second,ft-lb per second

Once horsepower has been converted to a basic unit of power, it can be converted to other power units, such as in the following: ____.

1

Selecting motors with a service factor greater than ____ allows for cooler winding temperatures at rated load, protects against intermittent heat rises, and helps to offset low or unbalanced line voltages.

self-synchronous

Selsyn motors are used to provide position control and angular feedback information in industrial applications. The word selsyn is a contraction derived from ____.

450

Series motors have the ability to develop extremely high starting torques. An average of about ____% of full torque is common.

output

Since the number of stator poles is constant for a particular machine, the ____ frequency is controlled by adjusting the speed of the rotor.

synchronous

Single-phase ____ motors operate on the principle of a rotating magnetic field developed by a shaded-pole stator. Although they will operate at synchronous speed, they do not require DC excitation current.

servomotors

Small permanent magnet motors are used as ____.

trapezoidal

Some converters that supply power to brushless motors produce sine waves, but most produce a ____ waveform.

electrical impulses

Stepping motors are devices that convert ____ into mechanical movement.

iron

Such factors as the amount of ____ used in the stator, the wire size, the number of turns of wire, and the rotor design all play a part in the operating characteristics of a motor.

differential

The ____ selsyn is used to produce the algebraic sum of the rotation of two other selsyn units.

first started

The direction of rotation for a split-phase motor is determined by the direction of rotation of the magnetic field created by the run and start windings when the motor ____.

blv

The following formula can be used to compute the amount of voltage induced in the stator winding: E = ____/108.

S=(120xf/p)

The following formula can be used to determine the speed of the rotating magnetic field when the frequency and number of stator poles per phase are known: S = ______

c

The letter ____ designates a flange mounted motor. This is the most popular style for flange mounted motors, which have a specific bolt pattern on the shaft end of the motor that permits mounting to the driven device.

1.732

The line current supplying a squirrel-cage motor can be computed using the formula: I(LINE) = VA / (E(LINE) x ____)

150% -200%

The pull-out torque for most synchronous motors will range from ____ of rated full-load torque.

stationary

The revolving field type alternator uses a ____ armature called the stator and a rotating magnetic field.

amortisseur

The rotor of a synchronous motor contains a set of squirrel-cage bars similar to those found in a type A rotor. This set of squirrel-cage bars is used to start the motor and is known as the ____ winding.

120

The rotor of a wound rotor motor is constructed by winding three separate coils on the rotor ___ degrees apart

frequency

The speed of a shaded-pole induction motor is determined by the same factors that determine the synchronous speed of other induction motors—____ and number of stator poles.

induced

The squirrel-cage motor is an induction motor, which means that the current flow in the rotor is produced by ____ voltage from the rotating magnetic field of the stator.

run

The stator of a split-phase motor contains two separate windings, the start winding and the ____ winding.

A,B,F,H

The thermal capacity of different insulations is rated as ____. The letters indicate the amount of temperature each is designed to handle over a 20,000 hour period operating at full load.

induction-run

There are three basic repulsion motors: repulsion motor, repulsion-start ____ motor, and repulsion-induction motor.

shunt

There are three basic types of direct current generators: the series, ____, and compound.

strength

Three factors determine the amount of output voltage of an alternator: length of the armature or stator conductors (number of turns), ____ of the magnetic field of the rotor, and speed of rotation of the rotor.

strength of the magnetic field of the armature

Two factors that determine the amount of torque produced by a direct current motor are the strength of the magnetic field of the pole pieces and the ____.

50

What is the output frequency of an alternator that contains six poles per phase and is turning at a speed of 1000 RPM?

1500

What is the synchronous speed of a four-pole motor connected to 50 Hz?

fleming's

____ left-hand generator rule can be used to determine the relationship of the motion of the conductor in a magnetic field to the direction of the induced current.

shunt

____ motors are often referred to as constant speed motors.

9

Most dual voltage motors contain ____ leads in the terminal connection box.

brushes

Most large alternators use an exciter that contains no ____.

the output voltage of the two machines should be the same, the phase rotation of the machines must be the same, output voltages of the two machines must be in phase.

Several conditions must be met before parallel alternators can be used, including the following: ____.

746 watts or 33,000 ft-lb/min

The formula for horsepower is 1 hp = ____.

equal

Armature reaction can be corrected by rotating the brushes an amount ____ the shift of the neutral plane.

50hp

Assume that a motor produces an output torque of 152.23 foot pounds at a speed of 1725 RPM. What is the horsepower output of the motor?

two

Consequent pole motors that are intended to operate with three speeds contain ____ separate stator windings.

excitation

Field ____ current is the DC current that flows through the shunt field winding.

synchronous speed

Full load motor speed is determined by several factors. The main factor is the ____.

7.65

How much horsepower is being produced by a motor turning a load of 350 lb-in. at a speed of 1375 RPM?

direction of aramature rotation

In the right-hand motor rule, thumb = thrust or the ____.

compounding

______is characterized by the fact that the output voltage at full load will be greater than the output voltage at no load.

mechanical

a generator is a device that converts ______ energy into electrical energy

current indueced into the armature

the left-hand rule, the center finger shows the direction of the ____.

high voltage and low current

wave wound armatures are used in machines designed for_______?

ripple

when more than one loop is used, the average output voltage is higher and there is less pulsation of the rectified voltage. this pulsation is called___________?

75

A brush-lifting motor uses a radial commutator, and weights are mounted at the front of the armature. When the motor reaches about ____% of full speed, these weights swing outward due to centrifugal force and cause two push rods to act against a spring barrel and short-circuiting necklace.

magnetism

A rotor provides the ____ needed to induce voltage into the stator windings.

360

A synchroscope measures the difference in voltage and frequency of two alternators. The pointer of the synchroscope is free to rotate in a ____-degree arc.

differential

A(n) ____ compound generator has its fields connected in such a manner that they oppose each other in the production of magnetism