Having problems with your process controls and electrical instrumentation?
The source may be a grounding disturbance known as a ground loop.
Basically, ground loops cause problems by adding or subtracting current or voltage to or from a process signal.
As a result, the receiving device can't tell the difference between the wanted and the unwanted signals. So it can't accurately reflect process conditions.
When signal wires have paths to ground at both ends of the loops, problems are likely to occur.
A ground loop forms when three conditions are present:
1.There are two grounds;
2.The grounds are at different potentials;
There is a galvanic path between the grounds.
To remove the ground loop, any one of these three conditions must be eliminated. However, the first and second conditions are not plausible candidates for elimination, as you cannot always control the numbers of grounds and it’s often impossible to just “lift” a ground.
Use a signal isolator to “break” the galvanic path between the two grounds. When the conductive path between the differential voltages is broken, a current cannot form. So even though there are two grounds and different voltages at each ground, there is no current flow.
The ground loop has to be eliminated.