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Induction Motor Interview Questions with Answers | Part-1

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Types Of DC Generator


  • There are two types of DC Generator
  1. Separately exited
  2. Self exited

  1. Separately exited DC Generator 
  • In these types of generator, Energisation of field magnets is done by separate dc supply.
  • Circuit Diagram

Here, Ia  = IL
           Eg = V +IaRa+ brush contact drop
           Po = V Ia 

    2. Self exited DC Generator
  • In these types of dc generator, Energisation of field magnets is done by their own field current, so I it's called self exited dc generator.
  • There is small flux present initially due to residual magnetism. So when armature starts the rotate, it produced small emf and small amount of current, which is use for field magnets.
  • According to field winding and armature winding connection dc generator are three types
  1. Shunt wound
  2. Series wound
  3. Compound wound 
    1. Shunt wound

  • In this type of generator the field winding and armature winding are connected in parallel.

  • Since field winding connected in parallel with the armature and load, if it's independent to the load current.
  • It has many turns of thin wire so it's resistance is very high.
  • Here,     
  • Ia = IL + Ish
  •  Eg= V + Ia Ra + brush contact drop
    2. Series wound

  • In this type of generator the field winding is connected in series with armature.

  • When this both winding connected in series also series with load, it carries full load current.
  • It has few turns of thick wire, so it's resistance is very low.
  • Here, 
  • Ia = Ise = IL
  • Eg= V + Ia Ra + Ise Rse
 This generator is exited only on loading condition.

    3. Compound wound

  • Here both types of field winding such as shunt field and series field winding consists, so it's called compound wound generator.
  • Here, flux is provided partially by series field.
  • There are two types of compound wound generator .
(a) Short shunt compound
(b) Long shunt compound  
   (a) Short shunt compound 
  • In this type of generator only shunt field winding is connected in parallel with the armature.

  • Here,
  • Ise= IL 
  • Ia = IL +Ish 
  • Ish = (V + Ise Rse ) / Rah
  • Eg = V + Ia Ra + Ise Rse + brush contact drop
  • P = V IL
     (b) Long shunt compound

  • In this type of generator the shunt field winding is connected in parallel with armature and series winding.

  • Here,
  • Ish = V / Rsh
  • Ia = IL + Ish 
  • Ia = Ise
  • Eg = V+ Ia Ra + Ise Rse + brush contact drop
  • P = V IL 
 Compound wound generator are further classified as

  1. Cumulatively compound generator
  2. Differential compound generator
    1. Cumulatively compound generator
  • When series field attract the shunt field, the generator called cumulatively compound generator.
    2. Differentially compound generator
  • When series field oppose the shunt field, the generator is called differentially compound generator.














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