Views:30 Author:Site Editor Publish Time: 2020-04-30 Origin:Site
How a Load Cell Works
The conversion is achieved by the physical deformation of strain gauges, which are bonded onto the load cell structure. The strain gauges are connected into a Wheatstone Bridge circuit with four strain gauges (full bridge), two gauges (half bridge) or one gauge (quarter bridge). With half and quarter bridges, the bridge is completed using precision monitors.
Additional bondable resistors are configured within the bridge circuit to compensate for the effects of temperature on the zero or no-load signal and the sensitivity (output due to the applied load, plus a further resistor to enable the bridge to be nulled at no load).
The completed Wheatstone Bridge requires a stable DC supply to excite the circuit. This is usually 5Vdc or 10Vdc but can be any value from 1Vdc up to 18Vdc.
As stress is applied to the bonded strain gauges, a resistive change takes place which unbalances the Wheatstone Bridge. This provides an output signal that is linearly proportional to the stress value. The value of this signal, which is also proportional to the excitation voltage, is typically a few millivolts.