1. Not finding help here? Sign up for a free 30min tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

DC Machines

  1. Aug 24, 2008 #1
    1. The problem statement, all variables and given/known data
    A dc machine(6W, 120V,1500rpm) is separately excited and delivers rated current at rated terminal voltage.Field winding is connected to 120V supply. Rfw=100[tex]\Omega[/tex].
    a) Determine the value of field current
    b) Determine the value of Rfc required.

    2. Relevant equations
    Vf= IfRf

    3. The attempt at a solution
    In the question the value of Vf is given, while both If and Rf are variables. So I need another relation to find out both the values. Is there another relation that I'm missing?
  2. jcsd
  3. Aug 24, 2008 #2
    Unless I misunderstand the problem, you can get everything you need from the power equations P=IE and P=I^2*R.
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?

Similar Discussions: DC Machines
  1. The law of the machine (Replies: 4)

  2. Electrical machines (Replies: 0)

  3. Induction Machine (Replies: 3)