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#137647 - 07/19/03 04:50 AM Electronic Gear?
Trumpy Offline


Member
Registered: 07/05/02
Posts: 8211
Loc: SI,New Zealand
In the country where you come from,
What sort of equipment do you use to suppress any harmful interference and other problems caused by things like VSD's, SMPS gear and the odd Electronic device that puts a fair bit of "hash" over the Mains, that supplies the device?.
Things like VSD's cause a real problem, over here, because of the sheer number of them.
AM and FM radio's hate them!.
Any input on this topic, would be cool.
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#137648 - 07/19/03 08:22 AM Re: Electronic Gear?
djk Offline
Member
Registered: 12/26/02
Posts: 1237
Loc: Ireland
Irish/UK socket outlets are available with RF filtering and are used quite a lot in sensitive areas like studios, labs, computer facilities where RF might be a problem

I know Schuko equivilants are easily available in Germany.

In a studio RF emitting gear is often put into a gaussian cage too. Basically a farily fine grounded mesh cage (usually grounded independently to prevent the building's grounding system from producing RF!) Have seen similar arrangements in racks at telephone switches too.
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#137649 - 07/19/03 03:41 PM Re: Electronic Gear?
Belgian Offline
Member
Registered: 10/10/02
Posts: 177
Loc: antwerp
Sorry for my ignorance, but what are VSD's, SMPS ?
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#137650 - 07/19/03 05:22 PM Re: Electronic Gear?
Bjarney Offline
Moderator
Registered: 04/10/02
Posts: 2527
Loc: West-Southern Inner-Northeast ...
Usually, VSD is variable-speed drive, with variable-frequency drives being the most popular type used to power the simple and reliable three-phase motor.

SMPS is switchmode power supply, common in a lot of electronics, that is used as an efficient replacement for heavier, larger line-frequency transformers.

VSDs and SMPSs have the common trait of creating current harmonics which, if not handled correctly, casue AC-waveform distortion that in turn may create additional heating and potential damage in power conductors, switchgear and transformers.
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#137651 - 07/20/03 05:05 AM Re: Electronic Gear?
pauluk Offline
Member
Registered: 08/11/01
Posts: 7520
Loc: Norfolk, England
As Dave said, filtered sockets are widely available here these days. A lot of equipment also has the standard IEC power coupler for a detachable cord, and filtered versions of these are widely employed, both to keep RFI from entering and from exiting the equipment.

Overall design of grounding arrangements can play a big part in reducing noise in these sorts of environments. As the frequencies involved go up, so the grounding becomes more critical. What may be a good ground at 50/60Hz, or even at moderate radio frequencies, can actually become resonant at much higher frequencies and be virtually ineffective.
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#137652 - 07/20/03 08:25 AM Re: Electronic Gear?
C-H Offline
Member
Registered: 09/17/02
Posts: 1497
Loc: Stockholm, Sweden
The EU (through CENELEC) has been bringing out tougher and tougher specifications for how much "noise" an appliance is allowed to generate.

[This message has been edited by C-H (edited 07-20-2003).]
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#137653 - 07/20/03 09:16 AM Re: Electronic Gear?
Bjarney Offline
Moderator
Registered: 04/10/02
Posts: 2527
Loc: West-Southern Inner-Northeast ...
One significant example compares US electromagnetic compatibility allowances versus very different EU requirements.

For VF drives, a EU-mandated line filter to limit exchange of electronic noise is offered as an optional accessory for the US market.
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#137654 - 07/20/03 12:34 PM Re: Electronic Gear?
Belgian Offline
Member
Registered: 10/10/02
Posts: 177
Loc: antwerp
Bjarney, Thanks for the explanation.
Here, too we have special sockets for filtering "noise".

Paul,
"Overall design of grounding arrangements can play a big part in reducing noise in these sorts of environments."

I once heard that that's the reason why we are required (in theory) according to our code to have washing machines on 4mm2 cable.
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#137655 - 07/20/03 03:37 PM Re: Electronic Gear?
djk Offline
Member
Registered: 12/26/02
Posts: 1237
Loc: Ireland
Over here it's normal to keep the heavy appliences like washer/dryer/dishwasher etc on their on their own circuits to prevent any noise/voltage dips etc.

I remember being in a house in the US where plugging in the iron caused the lights to dim!
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#137656 - 07/24/03 11:09 PM Re: Electronic Gear?
Trumpy Offline


Member
Registered: 07/05/02
Posts: 8211
Loc: SI,New Zealand
Guys,
What brought this subject up, was recently, we had to install a new pump at the local meat works, as part of the steriliser water system and it has a VSD driving the pump motor.
But now that it is up and running, the staff working on the slaughter-board, can't use thier Radio-Earmuffs(with AM/FM Radio), because the VSD just splatters the radio recievers with a high pitched squeal across both the AM and FM bands.
Even the radio that feeds the slaughter-board through speakers, is the same, but it and the associated wiring is miles away from the VSD itself.
And believe me, some of the slaughtermen, are not too happy about missing out on thier Horse-races!.
Can anyone give me some advice on where to go to from here?.
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