TABLE OF CONTENTS D.A. Burt and K.D. Baker
Department of Electrical Engineering
Utah State University, Logan, Utah
Even experienced electronics engineers on occasion have been known to say that there is some black art to building and using electronic equipment that does not oscillate or have some unwanted noise signal impressed on it. In many cases, however, this black art is actually a good basic knowledge of how to ground all interconnecting systems properly.
Originally, an electrical ground was a conducting connection between an electric circuit and the earth; however, the word has been rather loosely applied in the electronics industry as a point or points which are used as a zerovoltage reference.
In a measurement system, grounds are conventionally separated into three types:
Power grounds: the return path for electric current that provides the power necessary to operate the instrument.
Signal grounds: the reference point and return path for all signal currents.
Chassis and shield grounds: usually the chassis and outer metal case of instruments and cable shields.
The basic grounding criterion is the requirement that each type of ground have the same potential throughout the system. This requirement, however, is seldom, if ever, met completely in any practical system. For this reason, this chapter is devoted to showing some of the sources of potentials appearing on the grounds and ways to minimize the problems caused by them.
Among the largest sources of electrical interference are ac power-distribution systems. For this reason, it...
