Grounding and Shielding Force Sensors

Proper grounding and shielding can be critical to the successful application of load cells generating low level signals. There is no best way to set up all systems and the specifics of the installation and associated instrumentation must be considered in arriving at a system configuration that is satisfactory.

The basic rule that should not be violated is that continuous ground loops should be avoided, i.e., a system should not be grounded at multiple points. This could occur, for example, if the shield of the load cell cable were grounded at both ends.

Interface load cell cables are supplied with a braided shield which provides protection from electrostatic interference when properly grounded. This shield is floating (not connected) at the load cell end so that a ground loop will not be inadvertently created.

A basic system layout that is easily achieved and usually is satisfactory is as follows:

The load cell case is grounded by mechanical attachment to the structure to which it is mounted.
This structure should be properly grounded to the electrical circuits which drive the excitation for the load cell.
The braided shield enclosing the load cell leads is grounded at the instrument and the instrument is grounded through the power cord.

Grounding Diagram

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