1. Limited time only! Sign up for a free 30min personal 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!

Zero Point Switching with transformer

  1. Jul 17, 2012 #1

    Femme_physics

    User Avatar
    Gold Member

    So with my final test tomorrow I thought to sneak in another question...

    1. The problem statement, all variables and given/known data

    The following circuit applies switch at the load RL via Zero Point Switching. The ratio of the coil windings at the transformer is N1:N2 = 4:1. The introductory voltage is a sinusoidal type and its RMS value is 100 volts RMS at a frequency of f=40hz. The switch circuit activates switch S the following way:

    Every full uneven cycle (from 0 degrees to 360 degrees) the switch is used as a shortcircuit.
    Every full even cycle (from 0 degrees to 360 degrees) the switch is used as a disconnection.

    http://img42.imageshack.us/img42/2498/zpszps.jpg [Broken]



    1) Based on the data above, draw the voltage on the load at 4 cycles of Vin. In your drawing mark the max voltages positive and negative as well as significant times.

    2) Calculate
    A) VRL(RMS), IRL (RMS)
    B) VRL (AVG), IRL (AVG)
    C) PRL (RMS)
    D) Vptp


    3. The attempt at a solution

    http://img849.imageshack.us/img849/7163/wavewavy.jpg [Broken]

    http://img404.imageshack.us/img404/1545/theanswertothequestion.jpg [Broken]
     
    Last edited by a moderator: May 6, 2017
  2. jcsd
  3. Jul 17, 2012 #2

    I like Serena

    User Avatar
    Homework Helper

    Hey Fp.

    1) You graph looks good. :S

    2a) Your formula for Vrl(rms) does not look right.
    There should be a square root in it...

    2b) Good.

    2c) Same problem
    Actually here you should take the average of the powers in each cycle.

    2d) Vptp is the peak-to-peak voltage.
    What is the highest voltage you have (look at your graph)?
    And what is the lowest voltage you have?
     
  4. Jul 18, 2012 #3

    Femme_physics

    User Avatar
    Gold Member

    30 mins before I need to take the test :)

    Vptp is 25 volts


    Are you sure?

    Hmm...we are told that if we're asked for the power with an AC current, we should always take it as RMS power.
     
  5. Jul 18, 2012 #4

    I like Serena

    User Avatar
    Homework Helper

    Then I'm probably too late. ;)
    Good luck!

    Better.
    But peak-to-peak is -25 to +25, which is 50 V.


    Yes.
    It should be 25/√2 volt.

    Actually, RMS power and average power are the same.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook




Similar Discussions: Zero Point Switching with transformer
  1. Transistor as a switch (Replies: 60)

Loading...