When strain gage transducers are used outdoors with extended cables, measurement errors occur because of cable conductor resistance, ambient temperature changes, and other factors. By using 6-wire, this error factor can be eliminated, and the bridge voltage stabilized. For example, if a 0.5mm2 multi-core cable is extended 100m, conductor resistance = 0.4Ω, resulting in a round-trip resistance of 8.0Ω in the input circuit in Figure 1. If the input/output resistance of the transducer is 350Ω, the voltage at both ends of the bridge will be e=(E?Ks?ε)/4, resulting in a decrease in sensitivity of about 2.2%. Furthermore, if the ambient temperature changes by 10°C during measurement, the voltage at both ends of the transducer will fluctuate by 0.1%, so even a load cell with an accuracy of 0.02% will lose significant accuracy.
As shown in Figure 2, when two ”sense lines" are added to the bridge power supply, the Error amplifier and Control Circuit makes the bridge input voltage is constant regardless of the cable resistance r.???????????????????????????????????????????????????????????????????????????????????????????
This feature enables highly accurate and stable measurements.