Kelvinkoppling

Kelvinkoppling, also known as Kelvin coupling or Kelvin connection, is a technique used in electrical measurements to reduce the effects of lead resistance and improve the accuracy of voltage measurements. The method is named after Lord Kelvin, who developed it in the late 19th century.

In a Kelvin connection, four wires are used to connect the measuring instrument to the device under test. Two of these wires carry the current to be measured, while the other two measure the voltage drop across the device. This arrangement ensures that the current-carrying wires do not contribute to the voltage measurement, as they would in a two-wire connection.

The Kelvin connection is particularly useful in applications where the resistance of the leads is significant compared to the resistance of the device being measured. It is commonly used in high-precision measurements, such as those required in metrology and semiconductor testing.

The technique can be applied to both DC and AC measurements, although the implementation may vary slightly between the two. In DC measurements, the Kelvin connection is straightforward, while in AC measurements, additional considerations must be made to account for the phase shift between the current and voltage signals.

Despite its advantages, the Kelvin connection requires more wires and connections than a simple two-wire setup, which can increase the complexity and cost of the measurement system. However, for applications where high accuracy is critical, the benefits of the Kelvin connection often outweigh these drawbacks.