Ground loop and ground-loop interference are a frequent and serious source of problems in many electronic measurement systems. In the earlier discussions on various type of external interference, we noted that ground loop often contribute to the strengthening of noise signals that arise from other forms of interference. It was also emphasized that the effects of ground loop must be considered when methods to suppress capacitively, inductively, and conductively coupled interference are employed. Ground loops can also cause interference difficulties on their own. Since they are often subtle and little-understood entities, ground loop are also frequently blamed for unexplained interference signals. This, a through discussion that explores the origins and effects of ground loop currents, as well as methods used to eliminate them, will be very useful.
ground loop are closed electrical paths in which the sections of the path consist of the ground wires of a system and the ground plane. Ground loop are created whenever the ground conductor of an electrical system is connected to the ground plane at different point (fig . 16.6). Since the ground wires of most system and the found plane are usually low-impedance conducting paths, ground loops as a whole are conducting paths of low impedance.Thus if even small volyage differences exist between any points along the loop, large currents will flow in them