ABSTRACT
Placing medical electronic equipment in a hospital or clinical environment often gives rise to equipment anomalies. Sensitive equipment is assaulted by external interference, or perhaps the interference source and other equipment is affected. Electromagnetic interference (EMI) may occur over a wide frequency range, from 60 Hertz (Hz) on up into the Gigahertz (GHz) range, and currents may be amps or microamps. The interference may be transient or it may be quasi-continuous. The most likely sources of Radio Frequency interference (RFI) are communications transmitters. While Electro Static Discharge (ESD) is a very fast and high current pulse, there is very little energy, so filter sizes can be quite small. The cutoff frequency to several Megahertz (MHz), and still provide ample filtering for ESD. Power line monitors will detect most power line disturbances, including transients; however, they are limited to about 2 MHz bandwidth. Pigtails are a common low frequency technique.
