Dry type emag pollution

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sceepe

Senior Member
I have been asked to look into a problem where a Computer Lab was located adjacent to an elctrical room where dry type xformers are located. Owner complains of computer problems due to proximity to xformers (Or so they think). Sorry I don't yet know the xformer size, distance b/n pc's and xformer, or wall materials. My question is has anybody seen similar problem? Is there a product to shield the elec room to contain the field? Any other solution?? (other than insreasing the distance between xformer and PC's)...
 

brian john

Senior Member
Location
Leesburg, VA
Re: Dry type emag pollution

The primary issue related to electric rooms and distribution transformers, is screen shake. This is due to EMF, the easiest fix is distance, then there is shielding. There are other issues related to EMF?s such as health risk, that I will leave to others.

Are they having problems at this time?

[ March 11, 2004, 04:33 PM: Message edited by: brian john ]
 

karl riley

Senior Member
Re: Dry type emag pollution

Mr Jordan,
I have dealt with this situation a number of times. It is essential to determine the exact source/es of the field.
It can be mainly from the Tformers or switching cabinets.
It can be mainly from the busses.
It can be mainly from miswired circuits.

Tformers can be shielded effectively.

If busses or circuits are the cause, it will usually be because a misconnection of the neutral conductor somewhere in the building is setting up a net current magnetic field. This is remedied by tracing and corre4cting the neutral/ground or wrong neutral/neutral connection. Shielding is ineffective for net currents.

Net current fields are very potent because they weaken directly with distance. Tformer fields weaken with the cube of the distance (very fast).

The only way to show clearly the shape of the field and hence to identify the basic sources is to take measurements with a gaussmeter in a grid pattern throughout the room, say on an eight-foot grid each way, at waist level for convenience. I use three paces as a spacing measurement, which goes very fast. I enter the results in a graphics program and come out with a contour map of the field. This is not necessary, but makes it very clear what the type and location of the source/es is/are.

The next steps make use of clamp-on ammeters.

I will stop here.

Karl
 
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