Consumer Product Safety

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June 17, 1997

Ministry of International Trade and Industry informs on a test performed in the National Institute of Technology and Evaluation for elucidating the possibility that the electromagnetic wave existing in an everyday life environment causes functional trouble of an electric wheelchair and the contents are as follows.
If you want to know more details, please refer to the following contact number.

1.Outlines of Test

1.Time of the test
May 1997
2.Tested device
Electric wheelchair MC - 13 made by SUZUKI Motor Corporation
3.Test contents
  1. 1.Frequency bands causing the malfunction by the electromagnetic wave were surveyed using an anechoic chamber.
  2. 2.a.as for the frequency bands confirmed to cause the malfunction in a., whether the malfunction was actually generated or not and the behavior when the malfunction actually occurred were surveyed by approaching the situations in the anechoic chamber to the practically using states of the wheelchair.
  3. 3.b.based on the results of b., the behavior of the malfunction generated when a radio on the market was used near the electric wheelchair was surveyed in the open air.

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2.Test Results

  1. 1.The results of the test performed in conformity to the ISO draft (international standards draft on requirements of electromagnetic compatibility of a wheelchair with a motive power and a motor scooter) showed that, when the electromagnetic wave was irradiated with the wheelchair set to the speed 50% (3 km/h) of the advance maximum speed (6 km/h), the wheelchair was decelerated or accelerated 20% or more under some frequency bands including 50 MHz and 144 MHz used by the radio amateur.
  2. 2.The electric wheelchair with 45kg of load applied thereto by assuming the practical using state, was put in the anechoic chamber in a stop state and when the electromagnetic wave of the strength exceeding the provisions of the ISO draft was irradiated thereto under the frequency bands including 50 MHz and 144 MHz, which are used by the radio amateur, the brake was released and the wheelchair moved by approximately 1m in the front/rear when the frequency was 53.5 MHz and the field intensity was25 V/m, and also moved by approximately several cm, when the frequency was 145 MHz and the field intensity was 85 V/m, however no malfunction was observed in the other frequency bands.
  3. 3.The appropriate electric wheelchair was put in the open air, or a practical using environment, in a stop state under conditions operated by a person (45 kg) and, when the electromagnetic wave was irradiated with the radio for the amateur brought in contact with the operation part (joystick) or approaching thereto of 5cm in the distance, the malfunctions such that the brake was released under the frequency band of 59 MHz, the motor was driven, and the wheelchair advanced by several cm were confirmed.
    In the frequency 144 MHz band, the confirmed were the brake release, a slight speed change (deceleration) in running, and going-down in a slope, however, no such phenomena occurred in other radios for the amateur, portable telephones, and personal radios except those.

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3.Others

Responding to the test results, the manufacturer of the appropriate electric wheelchair has already spontaneously taken actions such as calling attention to the users to avoid using a radio communicator, etc. in using the electric wheelchair.

Contact us

 Risk Analysis and Public Relations Division  Product Safety Technology Center  National Institute of Technology and Evaluation
Phone number:+81-6-6612-2066
Fax number:+81-6-6612-1617
Address:1-22-16, Nankokita, Suminoe-ku, Osaka-shi, Osaka 559-0034 Japan MAP