Current shunt resistors are low resistance precision resistors used to measure AC or DC electrical currents by the voltage drop those currents create across the resistance. 

For example. A current shunt whose resistance is 0.001 Ohms having a current of 50 Amps flowing through it will produce a voltage of 0.001 ×50 = 0.05 Volts or 50 mV (milliVolts).

 

 

So by inserting a current shunt into a circuit whose current you want to measure your can find the current by measuring the voltage drop across the shunt. Then knowing the resistance of the current shunt you can calculate the current using Ohm's law arranged as I = V ÷ R.

 

Current shunt resistors are usually specified with a variety of electrical and mechanical specifications. The electrical specifications indicate how close to perfect the shunt is as a current sensor.

A perfect precision current shunt has exactly the resistance claimed. That resistance doesn't change with temperature, age or current. It's inductance (resistance to AC current change) is zero. Precision calibrated current shunts approach those ideals, but are large and very expensive.

Practical current shunts are specified in terms of current Rating, for example 100 Amps, output voltage which indicates the resistance as the voltage produced for the rated current. V = I × R. For example an output rating of 50 mV at 100 Amps which implies 0.0005 Ohms (0.5 mOhms) resistance. Resistance Accuracy, for example their actual resistance is within ± 0.25% of the claimed value. Resistance drift, for example the shunt's resistance changes less than 0.002% (or 20 ppm = parts per million) per °C of temperature change.

 

Microhm Electronics' DC shunt resistor, such as FL-2 series, are popular in ammeters, power supply and other field. Wecome to focus and contact us for now details.