The Line resistance is the electrical resistance of a test lead or connecting lead. Since every lead has a finite resistance, a voltage drop occurs along the lead. This voltage drop can affect the measurement result and lead to measurement errors, particularly in precise voltage, resistance, or temperature measurements.
The line resistance depends, among other things, on the Cable length, the Conductor cross-sectional area, the Conductor material as well as the Ambient temperature from.
The Importance of Line Resistance in Measurement Technology
In industrial measurement technology, line resistance that is not taken into account can significantly impair the accuracy of a measurement. Voltage drops occur—particularly with small measurement signals or long cable runs—which distort the actual measurement result.
For this reason, wire resistance is often compensated for in demanding measurement tasks. This is done, for example, by:
- Four-wire circuits (Kelvin measurement)
- Three-Wire Circuits for Resistance Temperature Detectors (RTDs)
- Electronic Line Impedance Compensation
- Calibration and Correction Procedures
These methods make it possible to achieve highly accurate measurement results even over longer cable runs.
Line Resistance in Measurement Data Acquisition
When acquiring analog measurement signals, accounting for line resistance is a key factor in achieving high measurement accuracy. This is particularly true for temperature measurements using Pt100 or Pt1000 sensors, resistance measurements, and precise voltage measurements.
The Measurement data acquisition systems Solutions from Delphin Technology support various measurement methods to minimize cable errors and enable high-precision acquisition of a wide variety of sensor signals. When used in combination with the measurement software, measurement data can be reliably acquired, visualized, analyzed, and documented—even for complex measurement tasks involving long cable runs.
Why Line Resistance Must Be Taken Into Account
Taking line resistance into account offers significant advantages:
- Greater Process Reliability in Industry and the Laboratory
- Greater measurement accuracy
- Avoiding Measurement Errors Caused by Voltage Drops
- Precise Temperature and Resistance Measurements
- Reliable measurement results even with long cables
- Improved Quality of Test and Process Measurements