Tag Archives: ammeter

AC Current Measurement using ACS712

The ACS712 measures current in two directions.  It means that if we sample fast enough and long enough, we sure to find the peak in one direction and the peak in another direction as the ACS712 have 5 μs output rise time in response to step input current. We are measuring AC current of 50Hz i.e. 20mSec per cycle and we get around 4000 Samples in one cycle.

With both peaks known, it is a matter of knowing the shape of the waveform to calculate the current.   In the case of line or mains power, we know that waveform to be a SINE wave.   Knowing that allows us to apply a basic electronic formula to yield a decent result.

RMS Current =  root(2) * Peek Current Continue reading AC Current Measurement using ACS712

DC Current Measurement using Shunt Resistor

Designing of Digital Ammeter is basically a process of converting a voltmeter into Ammeter. We know that V=I x R. From this we can say that Voltage drop across resistor (shunt) is directly proportional to the current (V = I). In ammeter this resistance is called Shunt. Shunt resistance have very small value and it will not affect the load voltage. Most commonly 75mV shunts are available in market. Or you can use low value resistance. Continue reading DC Current Measurement using Shunt Resistor