They are available in various sizes – including versions that are much larger than standard chip resistors – and TCR below 100 ppm/K. Full-metal resistors can operate with an output of up to 36W at maximum temperatures of 155°C. They can have resistive values up to the low single-digit milliohm range.
The optimum resistive value can be determined quite easily: The lowest measuring voltage that still gives sufficiently accurate results is divided by the lowest current value of the measuring range.
There is a trend toward smaller shunts with higher outputs; also in wider use are customer-specific versions with special connection geometries and sizes. As shunt resistors are relatively expensive compared to other resistor technologies, they are available in small batch sizes and test samples.
Some shunts have four wires. Here, the current flows through two connections and the voltage is measured at the other two. The voltage drop at the resistors can be determined using the internal Kelvin connections, so the resulting measuring errors can be eliminated.
Four-wire shunts are used in two scenarios: First, when the line and contact resistance are relatively high and, in contrast to the measured resistance, not negligible. Second, when the resistive value is below 10 mΩ. Because the resistive values of the conductors are also in the milliohm range, they must thus be accounted for.
Microhm Electronics Ltd. is a professional full-metal shunt resistor manufacture with decades of experience. Welcome to contact us for regular or custom shunt resistors for your specific applications.
