hello,i am a new entry user;i buoght 2 AC transformer corrent to control two way corrent,first one measure photovoltaic inverter and the other load circuit. 2 devices declaring measuring up to 5 amps, I compared the values measured with an ammeter AC and it seems that the measure is not accurate .in particular when the current and 'less than 1 amp, for example 0.3 / 0.5 amp arduino returns more' high values,f.e.1 amp.viceversa if load is about 3.5 amperes reading and 'much more' precise.
Even changing the analog inputs, the situation does not change.
I ordered 2 pzem-004t in the hope that the accuracy is greater, particularly because 'conversion' performed directly from the module and the reading is interfaced via serial cable with Arduino.
which 'your experience for AC measures ?
Thanks in advance
You need to review alternating current a bit. The current reverses direction 50 or 60 times per second, depending on where you live. The AC ammeter reads and average current over several cycles. Are your tests taking into account the need to average the current and the fact is changes direction?
DIMITRO1036 and PAUL_KD7HB,thanks for your reply;i try to esplain my application.circuit is monophase with neutral not 3 or 4 phase;in italian domestic electricity distribution circuits value is AC 230 VOLTS 50Hz.
In this way to measure current it is not 'difficult, and' Simply connect a current transformer on a cable (for example, phase, but the neutral and 'the same),see photo attach on my first post.
transformer is passive component, is not electronic.
it is a electric winding with an output directly connected on board to a load resistance of 200 ohms,see attach file.
2 output conductors are connected to Arduino, one to the analog input terminal, the other to ground.
in doing so, we have an alternating voltage generator to 50Hz.
the voltage value corresponds to 1 volt when the current flowing in the conductor is 5 amp. AC (checking during tests).
the current reading takes immediately after loading the sketch given by the manufacturer, which I enclose:
#define ELECTRICITY_SENSOR A0 //
float amplitude_current; //
float effective_value; //
void setup()
{
Serial.begin(9600);
pins_init();
}
void loop()
{
int sensor_max;
sensor_max = getMaxValue();
Serial.print("sensor_max = ");
Serial.println(sensor_max);
//the VCC on the Grove interface of the sensor is 5v
amplitude_current=(float)sensor_max/10245/2001000000;
effective_value=amplitude_current/1.414;
//Minimum current value can be detected=1/10245/2001000000/1.414=24.4(mA)
//Only for sinusoidal alternating current
Serial.println("The amplitude of the current is(in mA)");
Serial.println(amplitude_current,1);//Only one number after the decimal point
Serial.println("The effective value of the current is(in mA)");
Serial.println(effective_value,1);
}
void pins_init()
{
pinMode(ELECTRICITY_SENSOR, INPUT);
}
/Function: Sample for 1000ms and get the maximum value from the SIG pin/
int getMaxValue()
{
int sensorValue; //value read from the sensor
int sensorMax = 0;
uint32_t start_time = millis();
while((millis()-start_time) < 1000)//sample for 1000ms
{
sensorValue = analogRead(ELECTRICITY_SENSOR);
if (sensorValue > sensorMax)
{
/record the maximum sensor value/
sensorMax = sensorValue;
}
}
return sensorMax;
}
as already 'written my problem and' accuracy of the current reading.
thanks
max
I found sketch of site of the supplier, but it is identical to others found on the net,like iteaduino.
arduino in theory should only consider the positive side of the half-wave, eliminating the negative part that never exceeds the power value of 5 volts.
if you advise me what to do I'm grateful.
for example, and 'sufficient to put a diode 1n4148 or similar in parallel to analog input?
and filter what you mean? Condenser more 'resistance? 22nF and 2,7kohm?
max
