How to Calculate a Shunt

By Nachiket Deshmukh

A shunt is a high precision resistor that you can use to measure the current flowing through a circuit. According to Ohm's law, you can calculate the resistance of a shunt resistor by dividing the voltage drop across the shunt by current flowing through it. Shunt resistors are marked with power rating. Overheating of shunt resistors can result from a higher current flowing through them. Therefore, shunt resistance calculation is important in circuit design.

Step 1

Write down the Ohm's law expression of "V = I * R" where "V" is the voltage drop across shunt resistor, "I" is the current flowing through shunt and "R" is the shunt resistance.

Step 2

Substitute value of voltage "V" and current "I" in the Ohm's law expression. For example, if voltage across shunt is 10 volts and current flowing through it is 1 ampere, then the expression is 10 = 100 * R.

Step 3

Divide the expression throughout by 100 to calculate the "R" value. Using a calculator, find the value of "R." From the example, the value of "R" will be 0.1 ohm, which is the value of shunt resistor.