Transformer voltage

Discussion in 'General Electronics Chat' started by wes, Feb 7, 2010.

  1. wes

    Thread Starter Active Member

    Aug 24, 2007
    Hi, I have been wondering what would happen if you had a transformer with a super Permalloy for the core, Would the super Permalloy core cause a higher voltage induced on the secondary even if it had the same number of coils as the primary? if it wouldn't then what is the reason for it?

    The magnetic field is still crossing just as many coils as it would in a normal core but now it is increased in strength, so wouldn't this cause more voltage induced on the secondary?

    It's weird because when a secondary pulls a increased current, the primary has to pull more current to overcome this increased magnetic field from the secondary and so it's increased current produces a stronger field but so that when the back-emf is produced from the collapsing field it induces a voltage equal to the primary voltage so no more current is pulled. but why is it that as it creates a stronger field it doesn't induce a higher voltage on the secondary?

    so basically why is it that a stronger magnetic field doesn't produce a higher voltage?

    any help would be great.
  2. t_n_k

    AAC Fanatic!

    Mar 6, 2009
    Go a whole lot better and assume you have an ideal transformer with a perfect magnetic core of infinite permeability.

    The flux produced in the perfect core by the primary voltage is determined entirely by Faraday's Law of induction - which if you think about it has no dependence on the core properties. [It's pretty much the case even if the transformer isn't ideal - with finite permeability, imperfect magnetic coupling, and core and copper losses.]

    In the ideal case the same magnetising flux links both primary and secondary windings so the output voltage is determined only by the primary voltage and the turns ratio.
  3. thingmaker3

    Retired Moderator

    May 16, 2005
    Although most of the input energy of a transformer can be taken from the output, there are always losses in a transformer. There are some losses to heat, some to vibrations, and some to electromagnetics. A better core material can reduce these losses, but does not eliminate them.

    Energy output divided by energy input is called the "efficiency." Efficiency is always less than one, but is closer to 1 with permalloy than with pure iron.