# 0-100A DC current measurement method using shunt resistor

1. ## 0-100A DC current measurement method using shunt resistor

hi there,
please suggest me best DC current measurement circuit using Amplifier .

2. ## Re: 0-100A DC current measurement method using shunt resistor

Different type of shunt resister are available in market like 100A/50ma, 100A 100ma etc. You can chose one from these. Basically your controller cannot measure a precise millivolt (A 10 bit ADC can measure 0.0048v minimum), you will gain the shunt voltage by amplifier for more flexibility. Many of types amplifiers are available also (LM339, LM324 OP07........). For example you chose a 100A/100mv shunt rasister and want to see value in decimal value... if you want to go maximum 5v. You chose a amplifier witch can gain input 50 times.

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3. ## Re: 0-100A DC current measurement method using shunt resistor

Originally Posted by Ranbeer Singh
Different type of shunt resister are available in market like 100A/50ma, 100A 100ma etc. You can chose one from these. Basically your controller cannot measure a precise millivolt (A 10 bit ADC can measure 0.0048v minimum), you will gain the shunt voltage by amplifier for more flexibility. Many of types amplifiers are available also (LM339, LM324 OP07........). For example you chose a 100A/100mv shunt rasister and want to see value in decimal value... if you want to go maximum 5v. You chose a amplifier witch can gain input 50 times.

@Ranbeer Singh .. what type of measurement ll give accuracy whether top load or bottom load shunt resistor?

4. ## Re: 0-100A DC current measurement method using shunt resistor

The current in a DC loop is constant throughout so it makes no difference to the voltage you measure across the shunt if it is 'top' or 'bottom' connected but you may find one is better than the other in terms of the voltage with respect to other things. For example, if your circuit passes 100A from a 100V supply, measuring a few mV drop across a shunt with 100V on it may be more difficult than measuring the same few mV at the 0V side of the circuit.

Brian.

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5. ## Re: 0-100A DC current measurement method using shunt resistor

Here is my a question...What does mean of top and bottom load?

6. ## Re: 0-100A DC current measurement method using shunt resistor

Hi,

Top of load is the more positive side (nearer to V+/positive output), bottom is the more negative side (nearer to V-). Think of the typical images of a "load" resistor, the bottom is connected to V- (0V).

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7. ## Re: 0-100A DC current measurement method using shunt resistor

A PNP transistor can measure current at the high side of the load. Use common base operation.

The .004 ohm shunt resistor can be any desired value.

Readings go down as Amperes go up. This may be remedied by sending the signal through an additional stage.

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