Bourns, Inc. has introduced the Bourns MSF Series Four-Terminal Shunt Power Resistors, including the MSF-2 and MSF-2L, for accurate current measurement in high-current power systems. The resistors have a 5 W power rating and resistance values from 0.5 mΩ to 5 mΩ. Maximum current is 100 A at 0.5 mΩ, with lower current at higher resistance values to stay within the 5 W rating.
Current measurement in battery management, power conversion, motor control, welding and industrial power equipment can be affected by resistance in leads, conductors and electrical connections. The series uses a four-terminal Kelvin configuration to separate the load-current path from the voltage-measurement path, minimizing errors caused by lead resistance.
A Manganin resistance element is welded to oxygen-free high-conductivity copper terminals, and a flame-resistant, high-temperature silicone coating protects the resistor. The series operates from -55 °C to +275 °C and has a temperature coefficient of resistance (TCR) of ±100 ppm/°C from 0 °C to +85 °C. Standard tolerance ranges from ±0.5 to ±10%, and dielectric strength is 1000 VAC.
Key features of the MSF Series include radial, self-supporting construction that mounts directly on the PC board; a four-terminal Kelvin design that minimizes errors caused by lead resistance; a 5 W power rating; maximum current of 100 A at 0.5 mΩ, with higher resistance values carrying less current; an operating range of -55 °C to +275 °C; ±100 ppm/°C TCR from 0 °C to +85 °C; a flame-resistant coating; and RoHS compliance.
Walter Garcia, product line manager, resistors at Bourns, said: “Accurate current measurement becomes more difficult as system current increases because resistance in the conductors and connections can influence the sensed voltage. The MSF Series uses a four-terminal Kelvin configuration to separate the measurement path from the load-current path, supporting current measurement up to 100 A with resistance values as low as 0.5 mΩ.”
The MSF Series resistors are available now through Bourns authorized distribution partners. Product details, inventory information and sample requests are available at bourns.com/products/resistors/current-sense-resistors.
