Ground Loop Noise
February 12, 2020
Back to: System Noise and Ground Loops
In electrical and electronic systems, the word “ground” has two meanings depending on the context.
- In power electricity, ground is a physical connection to the earth (“earth ground”)
- In electronics, ground is not a connection to the physical earth but a reference point to 0 volts (0V)
Electrical Grounds
Electrical grounds keep humans safe, protect electrical circuitry from damage, and provide a baseline for voltage measurements.
In power electricity, the earth ground is a third wire. It minimizes the possibility of electrocution by shorting any potentially hazardous electricity—such as a high voltage surge—to the physical ground.
In electronics, grounding is applied throughout the circuitry and is critical to the device’s proper function.
Grounding and Ground Loops
Vibration Control Systems
Each component of a vibration testing system has a ground reference in the control circuitry. It may also have an electrical ground connection to the earth for safety. The combination of these grounds can potentially cause ground loops.
What is a Ground Loop?
A ground loop occurs when multiple devices with an individual ground to the electrical power system are connected via a signal or communications cable that also carries a reference ground connection. Multiple paths to ground through multiple devices can form a loop or loops. The loop(s) pick up interference currents and create electrical noise.
Figure 1.2. A simple ground loop.
In a vibration testing system, this electrical noise can cause physical motion on the shaker. In other cases, it only affects the measurements. Ground loops are common, but their effects can be minimized or eliminated using the appropriate steps.
The following lessons will explore how ground loops can occur in a vibration testing system and the steps you can take to eliminate them.