Virtually every electrical device which generates, consumes, or transmits power is a potential source for causing noise in strain gage circuits. And, in general, the higher the voltage or current level, and the closer the strain gage circuit to the electrical device, the greater will be the induced noise. The two types of noise are fundamentally different, and thus require different noise-reduction measures. Unfortunately, most of the common noise sources listed above produce combinations of the two noise types, which can complicate the noise-reduction problem. Electrostatic Noise Electrostatic fields are generated by the presence of voltage with, or without current flow.
Fluorescent lighting is one of the more common sources of electrostatic noise.
501.1 - Electrostatic noise coupling. Magnetic Noise Magnetic fields are ordinarily created either by the flow of electric current or by the presence of permanent magnetism. Motors and transformers are examples of the former, and the earth's magnetic field is an instance of the latter. Electric generators function on this basic principle. Similarly, a conductor moving through the earth's magnetic field has a noise voltage generated in it as it cuts the lines of flux.