When the range of an ampere metre is increased, a shunt resistor is utilised so that the greatest amount of current may be bypassed.
It is a resistor of extremely high accuracy and has a very low resistance.
Shunt resistors are the low resistance components that are linked in parallel with ampere meters that need to have their ratings increased.
The resistance of the shunt prevents the greatest amount of current from flowing through it; however, the power rating of the shunt should be sufficient to dissipate the power.
Shunts like this are used in conjunction with DC &Â AC meters.
It is a kind of electrical conductor that is used in analogue and permanent magnetic moving coil meters, in addition to digital meters.
Shunt resistance must be linked in parallel and must have a lower resistance than the meter resistance in order for the greatest amount of current to be bypassed via this external resistance.
If the shunt resistance is accidentally removed or loosed, a greater amount of current will be bypassed through the meter, causing the meter’s internal coil to be burned and rendering the meter ineffective.
Shunt Resistance Calculator
The formulation is based on Ohm’s law, and the resistance is calculated by dividing voltage by current. With this formula, two currents can be calculated.
One is the meter’s internal full scale current, and the other is the required current, which is always greater than the meter’s internal full scale current.
Rshunt = Vm/(Ireq-Im)
Where,
Im – Meter Full scale Deflection current Rm– Meter Internal Resistance Ireq– Required Current (must be greater than the Meter Full scale Deflection current) Rshunt – Shunt Resistance and Pshunt – Power dissipation of the Shunt Resistance
