.


:




:

































 

 

 

 


I. Read and memorise the words and word combinations.




wound rotor ( )

wound stator ( )

permanent magnet stator

field coil

series wound

shunt wound

permanent magnet motor

advantage

performance

horsepower

fractional

application

efficient ,

reliable

industrial

wound field

rotor magnet

retain ,

field strength

high-strength field

high-intensity permanent magnet

high-power motor .

 

II. Read and translate the text.

DC motors are commonly constructed with wound rotors and either wound or permanent magnet stators.

Wound stators. The field coils have traditionally existed in three basic formats: series wound, shunt wound, and a combination of the two.

Permanent Magnet Motors. Permanent magnet types have some performance advantages over wound stator types, and have become predominant in fractional horsepower applications. They can be smaller, lighter, more efficient and reliable.

Originally all large industrial DC motors used wound field or rotor magnets. Permanent magnets have traditionally only been useful on small motors because it was difficult to find a material capable of retaining a high-strength field. Only recently advances in materials technology have allowed the creation of high-intensity permanent magnets, such as neodymium magnets, allowing the development of compact, high-power motors without field coils.

 

III. Answer the questions.

1. How are DC motors commonly constructed?

2. What types of field coils are traditionally used?

3. What are the advantages of a permanent magnet type of DC motors?

4. What type of rotors were used originally in all large industrial motors?

5. What allowed the creation of high-intensity permanent magnets?


Phase AC induction motor

Text A

 

I. Listen to the words and word combinations from the text. Pay attention to their meaning.

AC (alternating current)

motor

induction motor

phase

application

mains

adjustable

frequency

drive

total ,

energy

convert

manufacturing

processing

pump

fan ,

compressor

mixer

agitator

mill

crusher

machine tool

squirrel cage .

 

II. Memorize the words and word combinations and their equivalents.

 

squirrel cage induction motors ,

variable ,

converter

variable voltage variable frequency (VVVF) converter

variable speed drive (VSD)

technique

design , ,

automated

frame , , ,

performance characteristics ()

reliability

DC motor

bearing

slipring

brush

pre-lubricate

single-phase .

 





:


: 2016-11-12; !; : 275 |


:

:

- , , .
==> ...

1562 - | 1368 -


© 2015-2024 lektsii.org - -

: 0.012 .