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Member

Join Date: Dec 2007
Location: Germany
Posts: 8

EMC regulations for low power devices

04/19/2008 1:46 PM

EMC Directive 2004/108 dated 15 december 2004 states in chapter 1. article1 sub 1:

This directive shall not apply .....(if) a: incapable of generating (disturbance) of radio communications

b: will operate in the presence of disturbances...

This means low power devices with high immunity.

Which devices belong to this category? Where have such devices been defined?

Thanks for your assistance

Schoschimi

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Guru
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#1

Re: EMC regulations for low power devices

04/20/2008 3:19 AM

The regulations are pretty daft...these things are not defined.
One must show that they meet those criteria by due dilligence.

Say I make a piece of electronic equipment which has a 1.5v battery and runs effectively at DC..eg no fast clock frquency...no coils or contacs that open suddenly and could spark thus generating RF.
I could show the design to be incapable of generating a disturbance. I should back this up by a brief technical file as part of the design documentation.

Similarly if I have a circuit board with an 8Mhz processor I could take it to a test house and have some tests done...all future products using this board could be assumed to have similar levels of emissions.

Susceptibility is a different and totaly stupid situation...
You can define your own failure criteria...!!

So on a chemical dosing unit you could say....
If the unit stops working this is OK...
It is only a 'failure' if the dosing pump fails in a state where it runs continuously....
Even then if you are pumping a safe chemical from a small contaianer you could decide that this is not a failure...
You could define 'failure' as ..say..the device exploding or catching on fire.

A further complication is that some equipmwnt should only be tested as part of the 'Installation' if it is permanently wired...thus it is virtually impossible to do emission testing.

I hope this helps

Del

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#2

Re: EMC regulations for low power devices

04/27/2008 4:48 PM

I have to say, it is pretty daft (do I hear an echo there?), but it is a regulation, what do you expect?

If I read it correctly, it means a secondary user of a frequency band, in which it is not allowed to disturb the primary users, and cannot complain (successfully) about disturbance from them. Plenty of them around, and you can find frequency utility charts shoving their relations.

mit freundliche gruesse

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