sci.electronics.basics

"interuser"

> Hi
> I live in Europe and have a network router that operates powered by a
> power supply (transformer of 240VAC->5VDC)
>
> I bought the exact same router from US and plugged its power supply
> (transformer of 120VAC->5VDC) on a 240VAC->120VAC transformer.
>
> I notice that the US transformer heats up more than the european one.
> It is more hot that the 240VAC->120VAC transformer.
>
> Can anyone explain as to why this is happening?
> Does it have anything to do with the frequency in the US being 60HZ as
> opposed to here being 50HZ?
>


** It is solely due to that fact.

120 volt primary transformers made for the US domestic market are simply not
designed to operate at 50 Hz. Making them do so by using a 230/120 step-down
transformer causes them to run hotter - sometimes MUCH hotter and this
can lead to failure of the transformer's insulation or the activation of an
internal thermal fuse.

Other problems include buzzing or humming noises emanating form the
transformer or nearby metal panels.

Toroidal transformers intended for 120 volt@ 60 Hz are most likely to be in
serious overload if ever operated at 50 Hz - even with no load applied to
the secondary.




...... Phil