2.2 DC Generators

• Meaning and purpose of a DC generator
• Principle of operation of a DC generator through electromagnetic induction
• Construction and parts of a DC generator
• Function of the commutator in producing a unidirectional output
• The generated e.m.f. equation for a DC generator
• Types of DC generators: separately excited, shunt, series and compound
• Load characteristics of series, shunt and compound generators
• Power output, losses and efficiency of a DC generator
• Reading the data on a DC generator nameplate
• Selecting a DC generator for a given application
• Safe handling and maintenance of DC generators

• explain the principle of operation of a DC generator
• identify the parts of a DC generator in relation to their functions
• describe load characteristics of different types of DC generators
• calculate the generated e.m.f. in a DC generator using appropriate formulae
• select the appropriate generator for a given application
• appreciate the application of DC generators in day-to-day life

“How does a DC generator work?”

“How are DC motors selected for specified applications?”

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1. Principle of operation of a DC generator
   40 min · 1 practice tasks · quiz
   Explain how a DC generator produces an e.m.f. through electromagnetic induction.
2. Parts of a DC generator and their functions
   40 min · 1 practice tasks · quiz
   Identify the parts of a DC generator and state the function of each.
3. The commutator and the output
   40 min · 1 practice tasks · quiz
   Explain how the commutator changes the alternating coil e.m.f. into a unidirectional output.
4. Calculating the generated e.m.f.
   40 min · 1 practice tasks · quiz
   Use the generated e.m.f. equation to calculate the output of a DC generator.
5. Types of DC generators
   40 min · 1 practice tasks · quiz
   Describe and compare the separately excited, shunt, series and compound generators.
6. Load characteristics of DC generators
   40 min · 1 practice tasks · quiz
   Describe how the terminal voltage of each generator type changes with load.
7. Power output, losses and efficiency
   40 min · 1 practice tasks · quiz
   Calculate the output power, losses and efficiency of a DC generator and read its nameplate.
8. Selecting, using and caring for DC generators
   40 min · 1 practice tasks · quiz
   Select a generator for a given application and apply safe handling and maintenance practices.