Download VIII. DC Generators - Exercises

ΕΛΛΗΝΙΚΗ ΔΗΜΟΚΡΑΤΙΑ
Ανώτατο Εκπαιδευτικό Ίδρυμα Πειραιά
Τεχνολογικού Τομέα
Ξενόγλωσση Τεχνική Ορολογία
Ενότητα: DC Generators
Παναγιώτης Τσατσαρός
Τμήμα Μηχανολόγων Μηχανικών ΤΕ
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1.
Exercise A: Open questions .............................................................................. 4
2.
Exercise B: Making notes .................................................................................. 5
3.
Exercise C: Identifying functions ........................................................................ 6
4.
Exercise D: Defining technical terms ................................................................. 7
5.
Exercise E: Identifying synonyms and autonyms ............................................... 8
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1. Exercise A: Open questions

Answer the following questions about the reading text.
1. How does a dc generator obtain the mechanical energy it needs?
2. What principle is used to convert mechanical motion into electrical energy in dc
generators?
3. What is the magnetic circuit of a dc generator composed of?
4. How does the armature operate in a dc generator?
5. Why is the core of the armature laminated?
6. Name the parts that form the electric circuits of a dc generator.
7. How are the wave windings joined to the commutator?
8. Why are lap and wave windings referred to as "closed-circuit windings"?
9. How are series field coils different from parallel field coils?
10. Explain why an alternating emf is generated in a coil that is rotated in a magnetic
field
11. What factor determines the amount of emf generated?
12. Why is NO voltage induced in a rotating coil as it passes through the neutral
plane?
13. How does a split-ring commutator act in order to convert the ac induced in the
armature into dc?
14. How does the armature react to commutator action?
15. How do interpoles help to compensate for the main field distortion caused by the
armature reaction?
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2. Exercise B: Making notes

1
2
3
4
5
6
7
8
9
10
In note form, fill in the blanks in the following table using information from the
text and the diagrams provided.
Component
Field yoke
Material
Construction
stell
Pole faces
Air gaps
----------
Armature windings
------------
Field coils
carbon
electomagnets
Location
--------Around circular periphery
Surfaces of pole cores
---------on shaft or cast –steel
spider
on armature core, in
slots
cylinder or ring
interpoles
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3. Exercise C: Identifying functions

Search through the text and find which component performs each of the
functions described below. Note that some components may perform more
than one functions.
1. It serves as a means of connecting the brushes to the armature.
2. It provides the rotating element in a dc generator.
3. It turns rotary mechanical energy into electrical energy.
4. They eliminate the effects of armature reaction.
5. They connect the armature to an external circuit load in order to pick up or use
the induced emf.
6. They provide a means of support for the field coils.
7. It causes a generator to produce dc voltage rather than ac voltage at its output
terminals.
8. It serves as a mechanical support for the pole cores as well as serving as part of
the magnetic circuit.
9. They increase the cross-sectional area and thus reduce the magnetic reluctance
of the air gaps.
10. They provide the magnetic field for producing a voltage.
11. It provides mechanical energy to a dc generator.
12. They form contact with opposite parts of the commutator.
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4. Exercise D: Defining technical terms

Look back in the reading text and find the terms that match the following
definitions.
1. Maximum output or producing ability.
2. Listings indicating effectiveness of an engine in capacity, current, etc.
3. A small flat piece of metal or wood on which the ratings are marked.
4. A piece of magnetic material that connects two or more magnetic cores
permanently.
5. Formed in a mould.
6. Made by assembling parts, manufactured.
7. A supporting rod or bar in a machine that revolves in order to transfer power or
motion.
8. Framework with several leg-like extensions.
9. Narrow openings or holes.
10. Wire-wound spirals or loops of wire used as conducting elements.
11. Material processed with a special substance in order to be protected from
damage or be given special properties.
12. Any of the parts into which a body is separated.
13. Something that is made by cutting across it, usually at right angles to its axis.
14. The speed or degree something is changing in relation to something else.
15. A flash of light caused by an electric discharge, often accompanied by a cracking
sound.
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5. Exercise E: Identifying synonyms and autonyms

1
2
3
4
1
2
3
4
Match each word in column A with its synonym in column B.
Column A
Column B
As to (line 6)
a. Impressed, pressed onto
Stamped (line 39)
b. cancels
Slide (line 69)
c. in relation to
Counteracts (line 125)
d. move slowly over something
 Now match each word in column A with its opposite in column B.
Column A
Declined (line 12)
Assembled (line 36)
bonded (line 45)
Irrespective of (line 67)
Column B
a. In relation to, depending on
b. Detached, separated
c. Dismantled, broken up
d. Risen, increased
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