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 .