Effective voltage

Discussion in 'General Electronics Chat' started by kvi037, May 17, 2013.

  1. kvi037

    Thread Starter New Member

    May 17, 2013
    17
    0
    Can somebody please help me with this task?

    Assumption:

    - Emf = 100sin(2pi*ft) +30 sin(6pi*ft)

    Whats the effective voltage?
     
  2. Jony130

    AAC Fanatic!

    Feb 17, 2009
    3,957
    1,097
  3. kvi037

    Thread Starter New Member

    May 17, 2013
    17
    0
    Thanks for reply. Yes, that's the aswer I'm looking for:)

    If you should do it by hand do you have to integrate from 0 to T ?
     
  4. kubeek

    AAC Fanatic!

    Sep 20, 2005
    4,669
    804
    You can simply do it with the two amplitudes, square them, then do the mean, then root and you get the same number as wolfram.

    Side note, how does that work with a single sine wave? Mean of 10000 is still 10000, so the rms would be 100, but wolfram says 70.7 so it obviously halved the square before doing the root, why? Is it like mean of 10000 + 0? That doesn´t really make sense as it could also be 10000 + 0 + 0 which would give a different value..?
     
    Last edited: May 17, 2013
    kvi037 likes this.
  5. Jony130

    AAC Fanatic!

    Feb 17, 2009
    3,957
    1,097
    OR simply solve this

    \sqrt{\frac{1}{2\pi}  \int_0^{2\pi} ( 100 Sin(2t) + 30 Sin(6t) )^2 \mathrm{d}t}
     
    screen1988 and kvi037 like this.
  6. t_n_k

    AAC Fanatic!

    Mar 6, 2009
    5,448
    782
    I would simply use the relationship that for a composite signal comprising N simple sinusoids each having RMS values V1, V2, ......VN then the equivalent RMS value is given by

    V_{RMS}=\sqr{(V_1^2+V_2^2+......+V_N^2)}

    The RMS value of a simple sinusoid of peak value Vp is (as we know) Vp/√2
     
    Jony130 likes this.
Loading...