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GE M
S
EDICAL
YSTEMS
D
FK091075, R
IRECTION
2-2-6
EMI Limitations
Ultrasound machines are susceptible to Electromagnetic Interference (EMI) from radio frequencies,
magnetic fields, and transients in the air or wiring. They also generate EMI. The Vivid 3N Pro/Expert
ultrasound unit complies with limits as stated on the EMC label. However, there is no guarantee that
interference will not occur in a particular installation.
NOTE:
Possible EMI sources should be identified before the unit is installed, and should not be on the
same line as the ultrasound system. A dedicated line should be used for the ultrasound system.
Electrical and electronic equipment may produce EMI unintentionally as the result of a defect. Sources
of EMI include the following:
•
Medical lasers.
•
Scanners.
•
Cauterizing guns.
•
Computers.
•
Monitors.
•
Fans.
•
Gel warmers.
•
Microwave ovens.
•
Portable phones.
•
Broadcast stations and mobile broadcasting machines.
The following table lists recommendations for preventing EMI:
Table 2-11
EMI RULE
Ground the unit.
Be aware of RF sources.
Replace and/or reassemble all
screws, RF gaskets, covers and
cores.
Replace broken RF gaskets.
Do not place labels where
RF gaskets touch metal.
Use GE specified harnesses
and peripherals.
Take care with cellular phones.
Properly address peripheral
cables.
04
EVISION
EMI Prevention/ Abatement
Poor grounding is the most likely reason an ultrasound unit will have noisy images. Check the grounding of
the power cord and power outlet.
Keep the unit at least 5m (16.4 ft) away from other EMI sources. Special shielding may be required to eliminate
interference problems caused by high frequency, high powered radio or video broadcast signals.
After you finish repairing or updating the system, replace all covers and tighten all screws. Any cable with an
external connection requires a magnet wrap at each end. Install the shield over the front of the card cage.
Loose or missing covers or RF gaskets allow radio frequencies to interfere with the ultrasound signals.
If more than 20% or a pair of the fingers on an RF gasket are broken, replace the gasket. Do not turn ON the
unit until any loose metallic part is removed and replaced, if required.
Never place a label where RF gaskets meet the unit. Otherwise, the gap created will permit RF leakage. In
case a label has been found in such a location, move the label to a different, appropriate location.
The interconnect cables are grounded and require ferrite beads and other shielding. Cable length, material,
and routing are all important; do not make any changes that do not meet all specifications.
Cellular phones may transmit a 5 V/m signal that causes image artifacts.
Do not allow cables to lie across the top of the card cage or hang out of the peripheral bays. Loop any
peripheral cable excess length inside the peripheral bays or hang on the hooks provided below the console.
Attach the monitor cables to the frame.
Chapter 2 Pre-Installation
V
3N P
/E
IVID
RO
DETAILS
S
M
XPERT
ERVICE
ANUAL
2-5
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