Electromagnetic interference with electronic medical equipment induced by automatic conveyance systems.

Electromagnetic interference (EMI) with electronic medical equipment induced by automatic conveyance systems is estimated. We measured the electric intensities of electromagnetic waves transmitted by three self-controlled electric truck systems. We also observed EMI with an infusion pump and a syringe pump set 1 m from the rail. The maximum electric field intensity was observed at the supplied current frequency in two systems with non-contact power supply mechanisms. The highest value, 137.0 dB microV/m, was measured just beside the rail. This is higher than the international electromagnetic immunity standard limit for electronic medical equipment. EMI may occur if electronic medical equipment is used within 2 m of the rail when the system contains an inductive power supply mechanism. With a contact power supply mechanism, the electric field intensity was much lower than that of the immunity standard. EMI should not occur even when electronic medical equipment is used just beside the rail.