Deck 19: DC Generators

Question 1

With magnetohydrodynamic (MHD) generation, instead of having a stream of electrons and ions moving through a magnetic field, a wire carrying electrons is moved through a magnetic field.

Answer 1

False

Question 2

Planning a generator design to produce a given emf involves a sensible choice of ____ and takes into account any special demands on the generator in use.

A)webers, flux, rpm, and type of winding
B)urns, flux, and type of compounding
C)urns, rpm, and type of magnets
D)urns, flux, rpm, and type of winding

Answer 2

D

Question 3

Kirchhoff's voltage law can be stated like this: Output voltage equals generated emf minus the IR drop in armature and brushes.

Answer 3

True

Question 4

A practical generator requires more than one ____; additional ones reduce the fluctuations of the pulsating DC output and, at the same time, increase the voltage output.

A)coil
B)loop
C)brush
D)commutator

Question 5

Regardless of the type of winding chosen, a coil is always wound so that its opposite sides pass beneath opposite magnetic poles simultaneously.

Question 6

Direct current is generated in rotating coils surrounded by a moving field magnet.

Question 7

The remedies used for field distortion include ____, interpoles, and compensation winding.

A)stabilization
B)fluctuation
C)rotation
D)arcing

Question 8

A generator can be ____ when enough series ampere-turns can be provided to make the output voltage rise above no-load voltage as the output current increases.

A)overcompounded
B)laterally compounded
C)undercompounded
D)gradually compounded

Question 9

The full-load rating of a generator is a statement of conditions that provide efficient operation without exceeding safe limits of ____.

A)speed and temperature
B)speed and current
C)current and temperature
D)speed

Question 10

There are three possible field connections for ____ generators, energized by current generated in the armature of the same machine: series, shunt, and compound.

A)self-excited
B)series
C)separately excited
D)simple

Question 11

____ winding utilizes preformed coils, which are preshaped, insulated, and fitted to be dropped, ready-made, into their assigned armature slots.

A)Armature
B)Frogleg
C)Lap
D)Form

Question 12

The distortion, or bending, of the main magnetic field of the generator, caused by the magnetic field of the current in the armature, is called armature disorganization.

Question 13

One way of providing a magnetic field for a generator is by having joint current sources energizing the field coils of the generator.

Question 14

____ loss is due to molecule friction in the iron of an armature because of continual reversal of magnetization.

A)Mechanical
B)Eddy current
C)Hysteresis
D)Windage

Question 15

A generator without residual ____ will fail to build up the magnetic field that is necessary to develop an output.

A)voltage
B)current
C)output
D)magnetism

Question 16

Permanent-magnet generators are also known as ____ and find applications with the electrical systems of motorcycles, small tractors, lawn mower engines, and the like.

A)field generators
B)shunt generators
C)magnetos
D)coilers

Question 17

A rotating assembly of coils, placed in slots in an iron core and connected to commutator segments, is called the armature of the generator.

Question 18

The ratio between the power output and the power input is described as the efficiency of the machine.

Question 19

The successful starting up of a generator depends on the existence of residual magnetism in the field iron.

Question 20

As a measurable quantity, the term voltage regulation means the percentage change of voltage from rated-load to no-load conditions.