5. ElectromagneVc Interference (EMI)
This sec2on provides the user with basic informa2on that describes the
problems with electromagne2c interference (EMI), known sources of EMI,
protec2ve measure to either lessen the possibility or exposure or to
minimize the degree of exposure, and suggested ac2on should unexpected
or erra2c movement occur.
AXen2on : It is very important that you read this informa2on regarding the
possible effects of electromagne2c interference on your PW-‐999UL
v
E
lectromagneVc Interference (EMI) from Radio Wave Sources
Powered wheelchair’s may be suscep2ble to electromagne2c
interference (EMI), which is interfering electromagne2c energy (EM)
emiXed from sources such as radio sta2ons, TV sta2ons, amateur
radio (HAM) transmiXers, two-‐way radios, and cellular phones. The
interference (from radio wave sources) can cause the power
wheelchair to release its brakes, move by itself, or move in
unintended direc2ons. It can also permanently damage the power
wheelchair’s control system. The intensity of the interfering EM
energy can be measured in volts per meter (V/m). Each power
wheelchair can resist EMI up to a certain intensity; this is called its
“immunity level”. The higher the immunity level, the greater the
protec2on. At this 2me, current technology is capable of achieving at
least a 20 V/m immunity level, which would provide useful protec2on
from the more common sources of radiated EMI. This power
wheelchair PW-‐999UL has been shipped with no further modifica2on
and with an immunity level of 20 V/m without any accessories.
There are a number of sources of rela2vely intense electromagne2c
fields in the everyday environment. Some of these sources are
obvious and easy to avoid. Others are not apparent and exposure is
unavoidable. However, we believe that by following the warning listed
below, your risk to EMI will be minimized.
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