Shunt Resistance Calculator

Shunt Resistance

"Are you looking to extend the range of your ampere meter? A shunt resistor can help you bypass the maximum amount of current with precision. Shunt resistors are low resistance components that are connected in parallel with an ampere meter, enabling its rating to be extended. It's crucial to choose a shunt resistor with a low resistance value to ensure accurate current measurement. Additionally, the power rating of the shunt should be sufficiently large to dissipate the generated power effectively. Shunt resistors find applications in both DC and AC meters, including analog or permanent magnetic moving coil meters as well as digital meters.

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Schematic Diagram, Formula and Precautions

The shunt resistance must be connected in parallel, and its resistance must be lower than the meter resistance so that the maximum amount of current will be bypassed through this external resistance. If shunt resistance is disconnected or loosed accidentally, then a larger amount of current will be bypassed through the meter, which causes the meter's internal coil to burn and the meter will be useless.

The formula is based on Ohm's law, where the resistance is calculated based on voltage divided by current. In this formula, we have two currents: one is the internal full-scale current of the meter, and another is the required current which is always higher than the internal full scale current.

It is essential to understand the schematic diagram, follow the formula, and take necessary precautions to prevent damage to the meter. By implementing these measures, you can effectively utilize shunt resistance while safeguarding the integrity of your meter.


Shunt Resistance Calculator


  • Im: Full scale Deflection current of Meter

  • Rm: Internal Resistance of Meter

  • Ireq: Required Current; must be higher than Full scale current of Meter

Insert the value of Im,Rm & Ireq:

Im (mA) Rm (Ω):  Ireq (mA)  

RShunt:(Ω) PShunt:(W)

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