Shuntresistoreita

Shuntresistoreita, commonly referred to as shunt resistors, are low-value resistors used to measure electrical current by converting a portion of the current into a measurable voltage drop. By Ohm's law, the voltage drop V across the shunt is V = I × R, where I is the current and R is the shunt’s resistance. Because the resistance is small, the voltage drop remains modest, minimizing power loss and disruption to the circuit.

Shunt resistors come in a range of constructions and formats. They include metal foil, thick-film, and thin-film low-ohm resistors, as well as dedicated PCB shunts and high-current metal bars. Variants are available in through-hole and surface-mount packages. High-precision shunts offer tight tolerances (often 0.1% to 1%), low temperature coefficients, and low inductance. Materials used include manganin, constantan, and copper alloys. For improved accuracy at low voltages, four-terminal or Kelvin connections are often used to separate current-carrying paths from the sensing path.

Key specifications include resistance value, nominal tolerance, temperature coefficient (ppm/°C), maximum current, and power rating (P = I²R). Temperature changes can shift resistance, so temperature performance is important in precision applications. Inductance and parasitic inductance may affect dynamic measurements, particularly in switching power supplies. Mechanical and thermal design, including mounting and cooling, influence long-term stability.

Applications of shunt resistors span power electronics, battery management systems, motor controllers, DC-DC converters, and metering equipment. They are typically placed in series with the load or supply, and accurate measurements often employ Kelvin sensing and careful layout to minimize noise, trace resistance, and self-heating effects.