Who does EMI testing?

Status
Not open for further replies.
charlie b

charlie b

Moderator
Staff member
Location
Lockport, IL
Occupation
Semi-Retired Electrical Engineer
My company is being asked to assist in evaluating EMI issues at an IT room. They want measurements taken of the electromagnetic fields present when nearby equipment (e.g., the adjacent elevator) is operating. Who does this sort of thing? Do I look for a specialty testing company, or would any electrical contractor have this ability?
 
EMI - Electromagnetic Interference.
EMF - Electromagnetic Field ??? (Also electromagnetic force, but that is a different context.)
EMC - Electromagnetic Compatibility.
 
Charlie, most EC's don't have the equipment or the know how to use it but testing outfits do. If you can contact Karl Riley he may still travel for this type of work.

Roger
 
Electrical Magnetic Interference -- I have some interesting info gathered over the years as it has been addressed in my area. looks like you could buy a gaussmeter at Walmart to check milligauss levels -
 
Last edited:
from some info I have -- Introduction In large commercial buildings when offices and work areas are located near electrical systems such as transformers, network protectors, secondary feeders, switchgears, busway risers, and electrical panels, the occupants are usually exposed to very high 60-Hz (Hertz) magnetic field levels ranging from 10-1,000 mG (milligauss). Fortunately, magnetic field strength rapidly diminishes as a function of distance from the electrical source. However, approaching the 60-Hz magnetic source, the occupant may be exposed to extremely high 1,000-100,000 mG levels. Occupants are not aware of this potential hazard unless the magnetic source produces electromagnetic interference (EMI) in sensitive electronic equipment (monitors, computers, magnetic media, audio/video equipment, etc.). Once detected, 60-Hz magnetic field management (mitigation) ultimately becomes the responsibility of the building management; otherwise the victims (occupants) may seek legal action. This Guide, which includes a tutorial section on EMF Fundamentals, should be a valuable aid to building managers and engineers who have a challenging 60-Hz magnetic field problem.
 
When I worked at a college, we had a similar problem in a physics nuke lab. Physics professors did the testing.

The lab, with sensitive monitoring equipment, shared a common wall with the electrical room and the elevator stuff was right on the other side.

We ended up buying these special grounding sheets and tape for the seams to reduce the interference.

About 2500.00$ for a 10' x 20' wall.
 
Pretty sure Charlie is referring to EMI and not EMF.

EMF supposedly affects people.
EMI affects electronic and such equipment.

He mentions an elevator and an IT room. 'Puters not people may be what needs to be protected.
 
charlie b said:
EMI - Electromagnetic Interference.
EMF - Electromagnetic Field ??? (Also electromagnetic force, but that is a different context.)
EMC - Electromagnetic Compatibility.
Click to expand...
EMF is ElectroMotive Force.
The forces that can cause an electron to move. Most often the electric field.
Often used loosely as a synonym for voltage difference.

mobile
 
jumper said:
Pretty sure Charlie is referring to EMI and not EMF.

EMF supposedly affects people.
EMI affects electronic and such equipment.

He mentions an elevator and an IT room. 'Puters not people may be what needs to be protected.
Click to expand...
The common denominator is that both are caused by the same thing(s) and many times it is poor wiring however, equipment itself can also be a culprit.

Roger
 
roger said:
The common denominator is that both are caused by the same thing(s) and many times it is poor wiring however, equipment itself can also be a culprit.

Roger
Click to expand...

Yes, I agree.

Our problem was that every time the elevator ran the nuke lab monitoring equipment was saying we had a baby Hiroshima going off in the lab.:eek:hmy: Some new experiment was being done.

Kinda needed to get it fixed since the reports had to be sent to the NRC.
 
mwm1752 said:
from some info I have -- Introduction In large commercial buildings when offices and work areas are located near electrical systems such as transformers, network protectors, secondary feeders, switchgears, busway risers, and electrical panels, the occupants are usually exposed to very high 60-Hz (Hertz) magnetic field levels ranging from 10-1,000 mG (milligauss). Fortunately, magnetic field strength rapidly diminishes as a function of distance from the electrical source. However, approaching the 60-Hz magnetic source, the occupant may be exposed to extremely high 1,000-100,000 mG levels. Occupants are not aware of this potential hazard unless the magnetic source produces electromagnetic interference (EMI) in sensitive electronic equipment (monitors, computers, magnetic media, audio/video equipment, etc.). Once detected, 60-Hz magnetic field management (mitigation) ultimately becomes the responsibility of the building management; otherwise the victims (occupants) may seek legal action. This Guide, which includes a tutorial section on EMF Fundamentals, should be a valuable aid to building managers and engineers who have a challenging 60-Hz magnetic field problem.
Click to expand...

Should the word "Guide" in the last sentence have included a link?
 
charlie b said:
My company is being asked to assist in evaluating EMI issues at an IT room. They want measurements taken of the electromagnetic fields present when nearby equipment (e.g., the adjacent elevator) is operating. Who does this sort of thing? Do I look for a specialty testing company, or would any electrical contractor have this ability?
Click to expand...

What exact issues?
Are they talking about magnetic field or radio frequency noise?

The one Stetzerizer people talk about is the magnetic one. It only takes one of these things too close to cause a shaky image on a CRT monitor, but they're absurdly sensitive. Some CRTs are so sensitive that their orientation affects the image due to earth's magnetic field. The only things you can do to shield magnetic field is iron or distance. Companies that setup MRI suites are experts at this.

An amp or two in an unpaired 3-way runner or a switch loop behind the wall.
Desk fan.
wall wart.
UPS.
sharing a wall with equipment room.

CRTs are not in general use today but electron microscopes and other instruments that use electron beams or very slight magnetic forces are affected like CRTs but modern computer gears shouldn't be affected.

Then the electromagnetic kind causes reception issues with radios and other wireless communication. Running drive related cabling in EMT and proper grounding minimizes this and further reductions can be made with filters. A lot of hard switched power control with a high dv/dt (v/uS) have this issue. Some common offenders are LED ballasts, leading edge wall dimmers and motor drives. Usually they're addressed through shielding and/or increasing the rise time with a choke reactor.
 
A long time ago, we had a consultant come to a site and make EM readings.

The two main issues were the accuracy of the testing equipment and what is an acceptable threshold for the sensitive equipment in question. The later issue had no correct or verifiable answer.
 
I've no relationship with either companies, other than having used them in the past for EM testing. I recall that these guys put antennas up around the area in question and measure EM fields from DC thru hi microwave freqs, so I am confident someone like them could do any EM testing requested, be it 60hz stuff or higher frequencies:

http://www.eucs.com
EUCS EU COMPLIANCE SERVICE
7580 St. Clair Ave.
Mentor, OH 44060
Att: Chuck Janki, President, email: emcjanki@aol.com
Phone: (440) 918-1425
Very competent dudes

and maybe:
https://www.tuv-sud-america.com/us-...U6TLTwe8V3Rj6vVn8n0BL8cmALSfuDS0igaAuj68P8HAQ
Typical UL type people (notice I did not say competent or not competent)
 
Status
Not open for further replies.
Top