[SI-LIST] Re: Transformer Hum
- From: John Wilson <jmwilson@xxxxxxxxxxxx>
- To: si-list@xxxxxxxxxxxxx
- Date: Sun, 18 Apr 2004 13:49:29 -0400
Another reason, which is only an externsion of what Geog outlined below, is that
the transformer in question might be saturating. If the magnetic material
saturates (integ(V*dS)) then the peak current (which will occur each time the
transformer saturates) can be quite large. Take a look at a typical B vs. H
characteristic for a magnetic material and you will see how high the H-field
(proportional to current) can become when the material saturates.
The magneto-striction due to the large currents will make a transformer "hum".
Checke the specs. on the transformer an see if you exceeded its limits.
john
Georg Ramsch wrote:
> Hello, Steve !
>
> There may be 2-3 reasons for the hum, as far as I know:
>
> a) small transformer: the windings may not be wrapped tense enough
> around the iron core. The magnetic field changes cause the
> windings to swing, which is audible.
> b) if the transformer is controlled by a non zero-phase switching
> device, the current transients may cause the effect from a), even
> with tense windings.
> c) larger transformer show magnetostriction, which transfers into
> audible noise( means: the iron core mechanical dimensions swing
> with the magnetic field )
>
> a) and b) may have a solution,
> but c) may be tricky. => what about a torroid core ?
> From my own experience: given a 100 MVA transformer station, you cannot
> enter without a "mickey mouse" ear protection because of the loud "hum"
> of magnetostriction of those big ones.
>
> My 2 cents
>
> Georg
>
> Steve GullWing UK schrieb:
>
> >Dear SI'ers,
> > I have some products recently released to production and
> >the Transformers are exhibiting a Hum. Anybody got any idea how to solve
> >this ?
> >Regards
> >Steve
> >GullWing Ltd
> >
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