Re: Over Saturation?

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: Finn Hammer <f-h-at-c.dk> 

Randy,

In my book, the term "over saturation" is bordering on being bogus.
The right term to use is "saturation", plain and simple.
(Though, being related to magnetism, _really simple_ it never gets)

In a transformer, the current passing trough the windings create a magnetic 
flux in the core. The density of this flux is measured in Tesla.

Iron without much carbon in it is capable of supporting about 2.1 Tesla, a 
mix of 50% iron and 50% cobalt, called permendure, will allow 2.4 Tesla to 
pass. Typical silicon laced iron transformer laminations will start to 
saturate at 1.7 Tesla .

Try to go any higher, and the permeability of the iron material gradually, 
but rapidly decreases to near that of air. Permeability drops => Inductance 
drops, Current skyrockets.

The way to provoke saturation is to apply more volts per turn than the 
transformer is able to handle. The amount of volts per turn tolerated, is 
largely determined by the size of the core cross section.

Stick to "saturation", and you`l be all right.

Cheers, Finn Hammer

Tesla list wrote:
>Original poster: "Randy & Lori" <rburney6-at-comcast-dot-net>
>I knew there had to be some math in there somewhere.  So, as I
>understand it, in most cases where I have read the term "Over Saturate",
>they really mean that they are bringing the core out of Saturation?  If
>voltage is increased, then current will obviously follow, and with
>increased current comes increased magnetism, but saturation goes down?
>I kept thing of "Saturation" as a term pertaining to magnetism; do I
>have it backwards?  I really do appreciate the response, but until I get
>the "Visualization", the math doesn't help.  You mentioned volt-second??
>Randy
>Savannah, GA
>-----Original Message-----
>From: Tesla list [mailto:tesla-at-pupman-dot-com]
>Sent: Wednesday, January 28, 2004 10:11 AM
>To: tesla-at-pupman-dot-com
>Subject: Re: Over Saturation?
>Original poster: "gtyler" <gtyler-at-drummond-dot-org.za>
>Not too much of a reflection on you, any people involved in electronic
>design don't understand this one either! Often people ask "how much can
>I load it before it will will saturate?" or something similar, but
>increasing the load actually moves a transformer further from
>saturation. Increasing the supply voltage or reducing the frequency
>causes saturation as it is the volt-second product that is the critical
>issue.
>The formula n/v =1/ 4.44BFA tells you what the flux density is.(B)
>F= frequecy
>a= Area of the core in Metres
>n/v = turns per volt
>George Tyler
>
>----- Original Message -----
>From: "Tesla list" <tesla-at-pupman-dot-com>
>To: <tesla-at-pupman-dot-com>
>Sent: Wednesday, January 28, 2004 1:52 AM
>Subject: Re: Over Saturation?
>
>  > Original poster: "Hydrogen18" <hydrogen18-at-hydrogen18-dot-com>
>  >
>  > simplest way I can think of over saturation is as excess magnetising
>of the
>  > core. Air cores will not saturate no matter how hard you try. Ferrous
>ones
>  > do.
>  > ----- Original Message -----
>  > From: "Tesla list" <tesla-at-pupman-dot-com>
>  > To: <tesla-at-pupman-dot-com>
>  > Sent: Tuesday, January 27, 2004 8:52 AM
>  > Subject: Over Saturation?
>  >
>  >
>  >  > Original poster: "Randy & Lori" <rburney6-at-comcast-dot-net>
>  >  >
>  >  > Can someone explain Saturation and Over Saturation as it pertains
>to
>  >  > Transformers and Inductors?  I know the term and I have a clue,
>but
>how do
>  >  > you know?  Why does my Variac (powered up) give me 0 volts
>difference of
>  >  > potential when an ohm meter tells me 0 ohms?  I don't need a
>lesson
>on how
>  >  > my meter reads in DC, I know it's the AC but how?  I even taught
>Basic
>  >  > electronics for three years in the military, but this one has
>always
>  > eluded me.
>  >  >
>  >  > Randy
>  >  > Savannah, GA
>  >  >
>  >  >
>  >
>  >
>  >
>