User manual

CHAPTER 9 – EMI WARNING

All types of electrically powered vehicles, such as powered

wheelchairs and motorized scooters (in this text all types will be

referred to as “powered vehicles”) may be susceptible to

electromagnetic interference (EMI). This is from sources such as radio

and TV stations, amateur radio (HAM) transmitters, two-way radios and cellular

phones. The interference (from radio wave sources) can cause the powered vehicle

to release its brakes, move by itself, or move in unintended direction. It can also

damage the powered vehicle’s control system. The intensity of the interfering EM

energy can be measured in volts per meter (V/m). Each powered vehicle can resist

EMI interfering electromagnetic energy (EM) emitted up to a certain intensity. This is

called its “immunity level”. The higher the immunity level, the greater the protection.

At this time, current technology is capable of achieving immunity level, which would

provide useful protection from the more common sources of radiated EMI. This

vehicle as shipped, with no further modification, has an immunity level of 20 V/m.

There are a number of sources of relatively intense electromagnetic fields in

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 of EMI will be minimized.

The sources of radiated EMI can be broadly classified into three types:

1. Hand-held portable transceivers (transmitters-receivers) with the antenna

mounted directly on the transmitting unit. Examples include: citizen band (CB) radios,

“walkie talkies”, security, fire and police transceivers, cellular telephones and other

personal communication devices. ** NOTE: some cellular telephones and similar

devices transmit signals while they are ON, even when not being used.

2. Medium-range mobile transceivers Such as those used in police cars, fire trucks,

ambulances and taxis. These usually have the antenna mounted on the outside of

the vehicle .

3. Long-range transmitters and transceivers such as commercial broadcast

transmitters (Radio and TV broadcast antenna towers) and amateur (HAM) radios.

NOTE: Other types of hand held devices, such as cordless phones, laptop

computers, AM/FM radios, TV sets, CD players, cassette players and small

appliances such as electric shavers and hair dryers, as far as we know, are not likely

to cause EMI problems to your powered vehicle.