New ac microammeter for leakage current measurement of biomedical equipment

摘要

A new inexpensive current probe for onhyphen;line leakage current measurement of biomedical devices in hospital environment is described. The prototype is designed to detect and measure leakage currents on the ground wire of the devicersquo;s power cord so that its integrity can be monitored in real time. Realized with a sensing coil specially matched to a lowhyphen;noise op amp, this probe adds only negligible impedance on the monitored ground lines. From this preliminary study about the devicersquo;s metrological performances, a sensitivity of 10 nArmsfor a current range 1ndash;500 mgr;Armshas emerged, together with a mean linearity error of 0.03percnt; and a frequency response flat within 1percnt; of gain from 50 to 2000 Hz.