How to Convert Current to Voltage using Resistor ?

In this article, we discuss about How to Convert Current to Voltage using Resistor with different examples like 0-20 mA to 0-10 VDC Conversion, 4-20 mA to 2-10 VDC Conversion, 0-20 mA to 0-5 VDC Conversion.

Convert Current to Voltage

It is extremely simple to measure 0-20 mA signal with a device that will measure only Voltage inputs. If the Voltage input module available will accept a 0-10 Vdc signal, but may not accept a 0-20ma signal directly.

Basically, Ohms law is used to calculate a resistor value in order to convert the 0-20ma signal to a voltage.

Example : 0-20 mA to 0-10 VDC Conversion

Ohms law states: R = V/I where V is the Voltage, I is the current and R is the resistance

R = 10V/0.020A = 500 Ohms

V = I*R = 0*500 = 0V

V = I*R = 0.020*500 = 10V

Example : 4-20 mA to 2-10 VDC Conversion

Ohms law states: R = V/I where V is the Voltage, I is the current and R is the resistance

R = 10V/0.020A = 500 Ohms

V = I*R = 0.004*500 = 2V

V = I*R = 0.020*500 = 10V

Example : 0-20 mA to 0-5 VDC Conversion

Ohms law states: R = V/I where V is the Voltage, I is the current and R is the resistance

R = 5V/0.020A = 250 Ohms

V = I*R = 0*250 = 0V

V = I*R = 0.020*250 = 5V

Note:-

To avoid damage you must ensure that the external current source has short-circuit protection in all conductor cases.
The external resistor is a source of error because of its dependency on temperature and its inaccuracy.
In order to obtain measuring results that are as precise as possible it is recommended to use resistors with tolerances that are as small as possible.

Credits : myplctechnology blog

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