A Dimmer Question

G

Gludy

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www.sailingvideos4us.com
The dimmer switches on my boat controlling the 24 volt lights cause such interference that they stop the intercpm being used and also make the Seafire saftey alarm buzz. They must be emitting a huge electromagnetic field.

Question - are these things controlled to conform to CE standards?

Question - Can anyone help source such dimmers that do not cause such interference?
 
Talk to these folks. I have one of their units to play with from Wiggo who fitted some to his Sealine I believe. They can certainly give you chapter and verse though.

Edit: in their Fact or Fiction bit they have this:

[ QUOTE ]

MYTH3: Switch mode dimmers are inherently noisy and may cause RFI.
FACT: This is some truth in the above however any noise is easily supressed and with an operating frequency of a few hundred hertz, DC dimmers are not generating significant levels of noise anyway unlike switch-mode power supplies which operate at frequencies between 20KHZ and 200KHZ.

[/ QUOTE ]

Perhaps they mean "any noise is easily suppressed in a good design" /forums/images/graemlins/smile.gif

Rick
 
Oh, and the DC dimmers on the Elling don't seem to cause any noticeable interferance. They're 12v dimmers (as all the lights are 12v and fed via DC DC convertors from the 24v system - means the power is stable whether on battery charger or not and so fewer bulb blows).

Rick
 
Paul,

Most dimmers are inherently noisy.
You have to go to quite expensive types to get significant reduction in RFI.

It is a little unusual however to have the extent of interference on an intercom system which is esentially an audio device.
It is almost certain that the intercomm connects are acting as an antenna for the RFI given off by the Dimmers, this then is rectified by a semiconductor device within the intercom amplifier circuit.
Personally my guess is that the intercom leads have been routed very close to the dimmers.
There are solutions however, re-route cabling away from lighting circuits, and use ferrite and/or inductive chokes on the intercom interconnections or even using screened cabling on the intercom circuit.
If it's really bad then isolation transformers on the dimmers.
This would be a job for an RF professional though.
I doubt whether Trader would have the werewithall.
But there is always a cure for all RF interference solutions.

Steve.
 
You disagree with the quote from the CBC website then? Plus the fact that my dimmers aren't noisy at all...

Write-only forums perhaps?

Rick
 
Hi Steve

really very little effort was put into curing this - Trader seemed to have given up with it, without even finding the cause. Paul happened to mention the issue & we had it nailed in two minutes.

There seemed very little interest in solving it however - suggestions about re-routing cables were dismissed as too involved.
 
I think your lightswitches are Gewiss (I base that on pic of your lower helm below - the switch to left of wheel, next to black tank level gauge, looks like a Gewiss). These Gewiss jobs are a bit like lego: you can slot together all sorts of different switches to make up the panels. If you google you will find an online catalogue

I'm assuming your dimmers are gewiss ones, fitted into the lightswitch units, right? Or have Trader fitted some other dimmers, eek?

Gewiss is good stuff, specified by plenty of high end yacht builders as well as the mainstream Fairline/Princess stuff. They are german made so should conform to whatever cE requirements apply. We dont have dimmers on our boat so I can't comment on your buzz problem, but maybe the Gewiss units you have are faulty. Aesthetically it would be loads better to get Gewiss units that work. The UK supplier are the very helpful Hedley and Ellis in Peterborough 01733 551681 - maybe talk to them/get a replacement from them?

08ceb30df268a53c0beb29626de1db70.jpg
 
Gewiss

Fairline fit these i think?

The only slight isue i had with them is that the chrome surrround isn't deperately tarnish-proof. In fact, i saw one boat that had been left with no dehum and they were quite bad. So anyway i wd wipem with wd40. In the md where there is bad condenasattion i pulled off the surround over winter, put them all in palstic bag into which i sprayed a load of wd40 and plonked them back on in the spring.

Sorry dunno about the lecky issue.
 
Havent looked at the CBC website Rick, just going on a lifetime's experience as a radio engineer of dealing with these sort of problems.
Any fast switching device including dimmers will emit a certain amount of interference, that is normal.
The problem here lies almost certainly in the intercom and it's wiring itself.
As I said there are solutions...it just depends on how far you want to go to cure it...but it can be cured as can all RFI problems...eventually.

Steve.
 
Re: Gewiss

Just get some spare chrome surrounds. They click on and off and are cheap as chips. We haven't had any tarnishing on ours over 2 winters anyway.

Hedley and Ellis are happy to take cr card order sfor small quantities over the phone, so long as you get all the part numbers using the online catalog first
 
Paul

If you can, try to replace them with dimmers which conform to IEC 60945:2002. The main implications of this standard are in electromagnetic emmission and immunity, and it is mandatory for any equipment mounted on the bridge of an IMO ship since July 2002

Cheers
Tom
 
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