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Technical Articles
Remote Sense
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Remote Sense |
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| Remote sense or, more correctly, remote sensing
of excitation voltage, is commonly recommended for
use with precision, commercial transducers to prevent
leadwire resistance changes (due to changes in either
temperature or length) from affecting transducer
span, or sensitivity. This feature is less frequently
used with "homemade" transducers, and is
seldom used in strain gage test applications.
Transducer Applications Leadwire attenuation presents a potentially significant error source in transducers utilizing a Wheatstone bridge circuit. The leadwires represent a parasitic resistance, and a portion of the excitation voltage intended for the bridge circuit is dropped in the leadwire system, reducing the voltage actually present at the transducer, and effectively reducing the transducer sensitivity. If the temperature remains constant during the setup and measurement process, then correctly applying shunt calibration, or a physical calibration of the transducer, is all that is necessary to correct for the effects of leadwire attenuation. 
However, if the temperature of the leadwire system changes during the measurement process, the resistance will change correspondingly, changing the amount of attenuation, and again resulting in a calibration error. The resulting error is typically a fraction of one percent, but with commercial transducers, which demand the highest possible accuracy, or when attempting to obtain the best possible performance from a homemade transducer, even that small error may not be acceptable. In those instances, if the measuring instrument is provided with remote sense capability, the error can be effectively eliminated. |