Understanding monophased rectifier

Discussion in 'Homework Help' started by activee, Jun 4, 2014.

  1. activee

    Thread Starter Member

    Jan 16, 2014
    I've a problem understanding this monophased rectifier (I'm not sure it's called a rectifier in english).

    It says Vab = Vam - Vbm. I don't get why it's not Vab = Vam + Vbm and the arrow Vbm should be going upward instead of downward.
    And also why Vam = E.sin.(ωt)?

    I can translate the text if needed but I guessed the picture was self-explanatory.

    Thanks in advance.
  2. Jony130

    AAC Fanatic!

    Feb 17, 2009
  3. vk6zgo

    Active Member

    Jul 21, 2012
    The two voltages Vam & Vbm at any given time are opposite polarity as referred to "M" which is the centre tap.
    Hence one voltage is given a negative sign.(this is completely arbitrary,they could have chosen either one)

    If you subtract a minus,you end up with a positive,so the amplitude of Vab turns out to be exactly what you would expect.(Vam+Vbm)

    They need to emphasise the different signs of Vam & Vbm to help explain how a Fullwave rectifier using a centre-tapped transformer works.