Precision DC Current Shunts

Riedon™ products by Bourns RS series of off-the-shelf, base-mounted, and bus-bar precision current shunts offer current ratings from 1 A to 6,000 A and several mounting configurations to meet various installation requirements. The RS, RSH, RSI, RSJ, RSK, RSN, and RSW series combine low cost and short lead times, while custom design capability caters to unique requirements. These devices target applications in the renewable energy market, high-capacity battery monitoring, and heavy industry.

The principle of current measurement using a shunt resistor depends on measuring the small voltage dropped across a precision resistor placed in series with the load. Riedon products by Bourns offer standard parts that provide 50 mV and 100 mV outputs but can also provide custom output voltages. The very low-resistance values required for shunt resistors, 50 mΩ at 1 A and just 0.0083 mΩ at 6000 A, are provided by Manganin® resistive elements. These are precision-etched to a standard tolerance of ±0.25%, while the RSN series features a tolerance of ±0.1%.

The RS range is divided into different families depending on the current rating and mounting style. All feature a 4-terminal design, which separates the heavy-duty load-carrying connections from the voltage-sensing terminals. Terminal blocks are brass or copper, depending on the series and current rating. Operation is specified over a temperature range of -40°C to +100°C with a temperature coefficient of resistance (TCR) of ±15 ppm/°C or better and a dielectric strength for base-mounted models of 750 V_DC (terminal block to base).