Investigation of Interference with Medical Devices by Power Line Communication to Promote Its Safe Introduction to the Clinical Setting

Power Line Communication ( PLC) is a communication system for transmitting data through power lines instead of using conventional local area network cables. However, signals from a PLC modem superimposed on the alternating current electric power could generate noise to the power system of medical devices and thus induce malfunction. To investigate the effects of PLC use on electronic medical devices, we used six types of PLC modems and 14 kinds of medical devices. The voltages and distribution ranges of the noise superimposed on the electric power voltage by use of PLC and the intensity of the electromagnetic field radiated from each PLC modem were measured. The maximum noise voltage superimposed was 17.68 V, and it appeared every 5.5 msec. The frequency distribution ranged from 2 to 30 MHz for almost all subject modems, but one type modem exceeded 30MHz. The electric field intensity radiated from each PLC modem was less than 1 V/m at 1 m. No interference by the electric field radiated from a PLC modem was observed on any of the subject medical devices, although artifact noise was observed on two pieces of ultrasonic diagnostic equipment when their power was supplied from an outlet between the master and terminal PLC modems and when the operator held the probe. This type of malfunction can be eliminated by dividing power lines for a medical device from the ones for PLC.