Measuring resistor - definition
Measuring resistor - definition
Measuring resistor (shunt) is a resistive element with a precisely selected, low resistance value, used to measure electric current in DC and AC circuits. Its primary function is to convert the flowing current into a proportional voltage, which can then be measured using a voltmeter or analogue-to-digital converter, according to Ohm's law. The high accuracy and stability of the resistance characteristics make the shunt an indispensable tool in measurement and control applications.
In technical practice, measurement resistors are designed to have minimal impact on the overall circuit, which means very low resistance - typically from a few microohms to hundreds of milliohms. It is also crucial that their performance does not change significantly under temperature or long-term loading, so materials with a low temperature coefficient of resistance, such as manganese or constantan, are used. For high-precision applications, the measurement resistors have calibration certificates and are subjected to rigorous testing procedures.
Shunt resistors are used in current monitoring systems in Power Supplies, Batteries, inverters, power electronics, energy meters and protection and control systems. They often work in conjunction with Operational amplifiers, analogue-to-digital converters or specialised measurement systems to convert the drop voltage into a current value. In high-current applications, mechanical design is also important, allowing efficient heat dissipation and maintaining low impedance in the connections.
The selection of a measurement resistor must take into account not only the current range and accuracy, but also the loss power and resistance to electromagnetic interference, which determines the reliability and precision of the entire measurement system.
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