Hello George,
An "Inherently Limited" power source is one in which the impedance of the
source, typically a transformers' primary or secondary, is such that the
available output is limited within the constraints of low energy as
defined by a standard. UL 1585, for example, describes the
limits/requisites for such a trafo design and the means for determining
the power available. There is also an IEC standard for such transformers,
but it's number does not come to mind at this instant. I'm certain someone
else on this listserver can provide that bit of info.
I also believe that if a non-accessible, non-replaceable current limiting
device (film-resistor, fuse or ptc, for example) is housed within the
transformer, the output can also be determined to be Inherently Limited.
Also, if considering an Inherently Limited power source, other than a
transformer, the same principles apply.
Regards, Art Michael
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On Fri, 9 Jul 1999 sparaci...@andovercontrols.com wrote:
>
> Hello all,
>
> The standard that I'm working with states under Power Limited Circuits that:
> an "Inherently Limited" power source does not require overcurrent
> protection, while a "Not Inherently Limited" power source does require it.
>
> Could someone give me an explanation of what makes a power source
> "Inherently Limited"..
>
>
> Thank You,
> George
>
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