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Shunt Resistors' Main Paramaters

Writer:Microhm Page View:Date:2019-05-20
Shunt resistors is primarily used to measure current.  However, the meaning of the term shunt in electronics is broader than that. A shunt is an element that is used in a circuit to redirect current around another part. The areas of application vary widely. For some applications, electrical devices other than resistors can be used. A few examples are given to illustrate the diversity of shunts.

Several parameters are important to specify a shunt resistor. Shunt resistors have a maximum current rating. The resistance value is given by the voltage drop at the maximum current rating. For example, a shunt resistor rated with 100A and 50mV has a resistance of 50 / 100 = 0.5 mOhm. The voltage drop at maximum current is typically rated 50, 75 or 100 mV.

Other important parameters include the resistance tolerance, the temperature coefficient of resistance and the power rating. The power rating indicates the amount of electric power that the resistor can dissipate at a given ambient temperature without damaging or changing the resistor parameters. The produced power can be calculated with Joules law. Shunt resistors have usually a derating factor of 66 percent for continuous operation. This is defined for a run time longer than two minutes. High temperatures negatively influence the accuracy of the shunt. From 80 degrees Celsius thermal drift starts. This gets worse with rising temperature, and from 140 degrees the resistor will damage and the resistance value be permanently changed.

Keywords:Shunt resist

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