READING AC 220 V arduino ZMPT101B

https://github.com/openenergymonitor/EmonLib

// EmonLibrary examples openenergymonitor.org, Licence GNU GPL V3

#include "EmonLib.h"             // Include Emon Library
EnergyMonitor emon1;             // Create an instance

int i = 0;
float tenvals = 0.0;
float minval = 1000;
float maxval = 0.0;

void setup()
{
  Serial.begin(115200);
 
  emon1.voltage(2, 109, 1.7);  // Voltage: input pin, calibration, phase_shift
//  emon1.current(1, 111.1);       // Current: input pin, calibration.
}

void loop()
{
  emon1.calcVI(20,2000);         // Calculate all. No.of half wavelengths (crossings), time-out
//  emon1.serialprint();           // Print out all variables (realpower, apparent power, Vrms, Irms, power factor)
 
//  float realPower       = emon1.realPower;        //extract Real Power into variable
//  float apparentPower   = emon1.apparentPower;    //extract Apparent Power into variable
//  float powerFActor     = emon1.powerFactor;      //extract Power Factor into Variable
//  float supplyVoltage   = emon1.Vrms;             //extract Vrms into Variable
//  float Irms            = emon1.Irms;             //extract Irms into Variable

 float Vrms = (emon1.Vrms - 3);
 if (Vrms < 0) { Vrms = 0.0; }

 tenvals += Vrms;
 if (minval > Vrms) { minval = Vrms; }
 if (maxval < Vrms) { maxval = Vrms; }

 i++;

 if (i == 10)
 {
  Serial.print("Avg: ");
  Serial.print(tenvals/10);
  Serial.print(" (");
  Serial.print(Vrms);
  Serial.print(") Min: ");
  Serial.print(minval);
  Serial.print(" Max: ");
  Serial.println(maxval);

  i = 0;
  tenvals = 0.0;
  minval = 1000.0;
  maxval = 0.0;
 }
  delay(100);
}