Lågimpedansmätare

A lågimpedansmätare, which translates to low-impedance meter or low resistance meter in English, is a specialized instrument used for accurately measuring very low electrical resistances. These resistances are typically in the milliohm or microohm range, far too small to be measured reliably with standard multimeters.

The primary challenge in measuring low resistances is the influence of contact and lead resistances. A lågimpedansmätare employs specific techniques to overcome this. The most common method is the four-wire measurement, also known as Kelvin sensing. In this setup, separate pairs of wires are used for the current injection and voltage measurement. A constant current is passed through the component being tested using one pair of leads, while a separate pair of highly sensitive leads measures the voltage drop across the same component. By applying Ohm's law (R = V/I), the resistance can be calculated with high precision, as the voltage measurement is unaffected by the resistance of the current-carrying leads.

Lågimpedansmätare are crucial in various industrial and scientific applications. They are used for quality control of electrical components such as connectors, switches, fuses, and busbars, where even small deviations in resistance can significantly impact performance or safety. In research and development, they are employed to characterize materials with very low resistivity, like superconductors or conductive polymers. They are also utilized in the maintenance and testing of power systems, including transformers, generators, and grounding systems, to ensure efficient operation and prevent potential failures. The precision offered by these instruments is vital for ensuring the reliability and safety of electrical circuits and equipment.