Re: CE means "Can't Enforce."

From: John Woodgate (jmw_at_jmwa.demon.contraspam.yuk)
Date: 07/25/04 

Date: Sun, 25 Jul 2004 21:51:24 +0100

I read in sci.electronics.design that ddwyer <dd@ddwyer.demon.co.uk>
wrote (in <fs93DgA6BBBBFwGy@ddwyer.demon.co.uk>) about 'CE means "Can't
Enforce."', on Sun, 25 Jul 2004:
>In article <ygZZulFytTABFwq+@jmwa.demon.co.uk>, John Woodgate <jmw@jmwa.
>demon.contraspam.yuk> writes
>>
>>Naturally, when the EMC Directive was being discussed, the inclusion of
>>immunity requirements was strongly advocated by the spectrum management
>>authorities, because it would save them a lot of money by not having to
>>deal with complaints caused by poor immunity.

>My lighting employs switched mode transformers, they generate broad band
>interference through the medium and long wave bands rendering these
>bands useless for broadcast reception. They could have been in screened
>boxes with low pass filters on the outputs , clearly their CE marking is
>meaningless.
>I should complain to the trading standards office, but wont get round to
>it because I doubt their ability to respond and force the manufacturer
>to replace with technically acceptable devices.
>Note its not the radio that is at fault, though a radio was all that was
>needed to demonstrate compliance for my application.
>
This may not be an immunity issue, agreed, but your radio may have
rather poor immunity to conducted disturbances on the mains. Is it any
better if working from batteries?

The relevant product standard is CISPR 15/EN 55015, and it has been
amended several times over the past few years. At present, switch-mode
converters have to meet conducted emission limits, and if the converter-
to-luminaire cable length is fixed, additional radiated emission limits,
measured as the magnetic component because LF/MF radios have magnetic
antennas. Converters installed many years ago may not meet current
requirements.

The limits have been accepted by spectrum management authorities in
Europe and elsewhere as realistic for the protection of radio services.
This involves an assumption of a separation between converter and radio
of 3 m minimum. Complaining about products that meet the limits is
inappropriate and, of course, ineffective. But there have been a number
of cases documented where the installation instructions for the
converter were not followed, leading to excessive emissions. A long
cable between the converter and the luminaire is bad news.

The combined effect of the radiated emissions from the converters is
likely to be strongly directional. Does rotating your radio reduce the
interference? 

-- 
Regards, John Woodgate, OOO - Own Opinions Only. 
The good news is that nothing is compulsory.
The bad news is that everything is prohibited.
http://www.jmwa.demon.co.uk Also see http://www.isce.org.uk

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