Managing Electrical Parasitics and Capacitance in Extended Bus Sensor Harnesses
Managing sensor harness parasitics demands fluoropolymer dielectrics, matched line termination, active buffer acceleration, and strict shield grounding topology.
Ground Loop Mitigation
Noise Reduction
Undesired circulating currents in a signal path are eliminated by breaking the conductive path between different grounding points. Ground loop mitigation involves using isolation techniques to prevent the flow of current caused by potential differences between earth connections. This practice is essential for maintaining the accuracy of low voltage sensor measurements.
Isolation Method
Optocouplers and isolation transformers are standard components used for ground loop mitigation in industrial networks. These devices allow the signal to pass via light or magnetic fields while providing a physical break in the electrical connection. Differential amplifiers also help by rejecting the common mode voltage associated with the loop.
Shielding Practice
Proper cable shielding is a component of ground loop mitigation that requires connecting the shield at only one end. If both ends are grounded, the shield itself becomes a path for circulating currents that induce noise into the inner conductors. Some systems use a capacitor at one end to provide a high frequency ground while blocking low frequency currents.
Laboratory testing verifies the effectiveness of these configurations under simulated interference.
System Verification
Field technicians verify ground loop mitigation by measuring the current flowing through the cable shields using a clamp meter.