DC generator equations

Replies

• 

  narayana murthy

  #-Link-Snipped-#
  i think this may help you
• 

  freak16

  DC genarator are of various connections:
  1) Separately exicted
  2) DC shunt excitation
  3) DC series excitation
  4) DC componund excitation
  DC permagnet is considered as equivalent to dc separately excited motor
  considering the magnetism of magnet does not deteriorate with passage of time ( but it do go down with time) you can apply the equations for separately excited.
  As NM mentioned..
• 

  Arp

  freak is right
• 

  mibawad

  Many thanks for your reply. I would to know if I know the generator speed and the resistance and inductance values for the generator, and the back emf constant. Could I calculate the current and output voltage. I can't find this relation because I found that I have two unknown (I and V) in one equation. Is there two equations to calculate them.
• 

  narayana murthy

  generator speed can be known from name plate details as i know
  resistance and inductance can be calculated from v and I equations
  I can be known from ammeter which is connected at output side
• 

  freak16

  DC machine does not have inductance as far as i know.
  We use the equation for generator
  E (induced emf) = Vt(terminal voltage) + Ia * ra
  Where E is directly proportional to speed
  E = K w
  W= speed of rotor
  K can be found out from no of conductors parallel path and other parameters
  Let me know if problem persists
• 

  narayana murthy

  @freak: thanks freak iam forgotten as iam seeping about DC machines so i mentioned that
  @mibawad: yes freak is right there is no concept of inductance in DC machines
  inductance and capacitance only appears in AC machines because there is no alternating current in DC machines
  inductance only appears at only there is a existence of alternating current
• 

  mibawad

  @freak
  What I want to say that for DC motor or generator:
  Emf=V+Ia*Ra+La(di/dt)
  Emf=K*w
  
  If I know K, w, Ra and La, and I want to calculate V and I according to the speed w. I couldn't from this equation because the number of unknown is more than the number of equations.
• 

  freak16

  Will dce machine is having inductance i strongly doubt..
  And you need to know amout the load somehow..
  you cant absolutely..
• 

  narayana murthy

  freak is right we have no inductance in DC machines
  E=V+(I*R)
  there is no inductance
• 

  mibawad

  @freak
  Therefore, I couldn't calculate the current and voltage generated from the DC generator without knowing the load as well. Is that what do you want to say?
• 

  freak16

  @mibawad
  Yes buddy.. i am saying the same thing..
  And without knowing supply voltage as well as load no engineer of world can do it..
  Kidding😎
• 

  mibawad

  But, there is no supply voltage for generator. It is only in case of DC motor
• 

  IES

  @freak: Yes there is inductance associated with the coils present in parallel paths,
  which produces Reactance Voltage.
• 

  lal

  What about this eqn : E = (fi)*Z*N*P/(60*A)
  
  Fi - flux
  Z - no. Of conductors
  P - parallel paths
  A - its value depends on winding. Eg: 2 for a simplex winding
  
  This is the induced EMF. To get the terminal voltage the armature copper loss is subtracted. (Assuming its seperately excited)
• 

  ganeshbalasti

  
  
  #-Link-Snipped-#
• 

  Akshay Singh

  I am thinking to build a generator with both rotor and stator rotating in this way relative speed between rotor and stator I.e N increase hence more electrical power
• 

  Akshay Singh

  Anyone online please help
• 

  Akshay Singh

  What no one answer here