Conductivity Standard
Unit scales based on the electrical conductivity of a standardized annealed copper reference at twenty degrees Celsius are used globally to compare the electrical properties of non-magnetic metals. This measurement unit, referred to as the IACS percentage, defines pure copper as one hundred percent, against which all other industrial conductors are evaluated. Low-conductivity alloys can have values below one percent, while high-purity aluminum alloys can exceed sixty percent.
Metrological Accuracy
The electrical resistivity of the sample is measured directly and then converted to the standard scale. This conversion assumes a constant reference temperature during the test.
Calibration Protocol
Instruments are calibrated using dual-standard reference blocks with known values at opposite ends of the measurement range. To verify an unknown sample, the probe is placed on each block to establish the sensor gain and offset in terms of the IACS percentage. These standard blocks must be certified by a national metrology institute.
Temperature Compensation
Because the conductivity of metals is highly temperature-dependent, the test instrument must apply a correction factor. This correction is calculated using the thermal coefficient of resistivity for the specific alloy being tested. Without proper temperature compensation, a five-degree deviation can cause a measurement error of more than one percent.
