Electromagnetic Interference (Emi) - Heartway Medical Products PF7S User Manual

ELECTROMAGNETIC INTERFERENCE (EMI)

The rapid development of electronics, especially in the area of communications, has saturated our
environment with electromagnetic (EM) radio waves that are emitted by television, radio and
communication signals. These EM wave are invisible and their strength increases as one approach the
source. All electrical conductors act as antennas to the EM signals and, to varying degrees, all power
wheelchairs and scooters are susceptible to electromagnetic interference (EMI). The interference
could result in abnormal, unintentional movement and/or erratic control of the vehicle. The United
States Food and drug Administration (FDA) suggests that the following statement be incorporated to
the user's manual for all power scooter like the PF7S. Power scooters may as susceptible to
electromagnetic interference (EMI), which is interfering electromagnetic energy emitted from sources
such as radio stations, TV stations, amateur radio (HAN) transmitter, two-way radios, cellular phones
and alarm systems of shops. The interference (from radio wave sources) can cause the power scooter
to release its brakes, move by itself or move in unintended directions. It can also permanently damage
the powered scooter's control system. The intensity of the EM energy can be measured in volts per
meter (V/m).Each powered scooter can resist EMI up to a certain intensity. This is called "immunity
level". The higher the immunity level the greater the protection. At this time, current technology is
capable of providing at least 20 V/m of immunity level, which would provide useful protection against
common sources of radiated EMI.
Following the warnings listed below should reduce the chance of unintended brake release or powered
scooter movement that could result in serious injury:
1. Do not turn on hand-held personal communication devices such as citizens band (CB) radios and
cellular phones while the powered scooter is turned on.
2. Be aware of nearby transmitters such as radio or TV stations and try to avoid coming close to
them.
3. If unintended movement or brake release occurs, turn the powered scooter off as soon as it is
safe.
4. Be aware that adding accessories or components, or modifying the powered scooter, may make it
more susceptible to interference from radio wave sources (Note: It is difficult to evaluate the
effect on the overall immunity of the powered scooter).
5. Report all incidents of unintended movement or brake release to the powered scooter
manufacturer, and note whether there is a radio wave source nearby.
6