SCT-013-030 Energy Meter

bpair

Thanks for sharing this! I am hoping to create an all-in-one extension cord plus this meter. I hope this way I can detect when a pump fails or maybe just how much power is being used.

I have read that you when using a CT you must be careful to avoid a voltage build up on the CT output. Is that a concern with this current setup? With a battery powered arduino you are not grounded? In my extension cord project I was thinking I could use the ground from the extension cord.

I am not an electrical engineer so I may be way off here, just trying to be safe.

I think this setup could be very useful. In the high school greenhouse where I have my sensor network there are so many pumps, heaters, air stones, that need to be monitored and an alert sent if they stop working.

I may also try this with the sensebender micro.

patrick schaerer

As far as i understand there is a resistor built in the sct013 that prevents this voltage buildup. But i am not an electrician.

patrick schaerer

I optimized my code with the help of Surge.
I added a KWH reading on a restart of the node.
Now it's Version 1.3

m1rk0

Hello Patrick, thank you for sharing your project. I tested it and it works fine but I want to test how acurate it is with low current measurements. Can you please tell me how to change your code to get results below 60W? I'm just beginning to learn arduino-programming so i don't understand everything..

patrick schaerer

@m1rk0
In Line 95 is the following expression:
if (Irms < 0.3) Irms = 0;

Irms is RMS current. The expression sets all current smaller than 0.3 as 0.
You can delete this line for smaller values.
I suggest to use a SCT-013-005 instead of a SCT-013-030.

m1rk0

Thank you patrik, i already ordered an sct-013-005, but i need sometimes higher measurements than 5a. With this second sensor i will be able to compare the results.

? Offline

@m1rk0 said:

Thank you patrik, i already ordered an sct-013-005, but i need sometimes higher measurements than 5a. With this second sensor i will be able to compare the results.

yeah 5A is within its range. I usually sit between 1A-20A

john7845

hello, where is the MySensor.h file??

tbowmo

This is made for an earlier version of the library, things has changed a lot since.

first off, the library header file is now called MySensors.h (note the added "s" to the name). But also how you use / initialize the mysensors project is very different in 2.x, than in 1.x,

have a look at this post to get an idea of what you have to change, to upgrade your arduino sketch to work with MySensors 2.x library

patrick schaerer

I alread updated to MySensors 2.0

This is the update code:

I also edited the first post.

/**
 * The MySensors Arduino library handles the wireless radio link and protocol
 * between your home built sensors/actuators and HA controller of choice.
 * The sensors forms a self healing radio network with optional repeaters. Each
 * repeater and gateway builds a routing tables in EEPROM which keeps track of the
 * network topology allowing messages to be routed to nodes.
 *
 * Created by Henrik Ekblad <henrik.ekblad@mysensors.org>
 * Copyright (C) 2013-2015 Sensnology AB
 * Full contributor list: https://github.com/mysensors/Arduino/graphs/contributors
 *
 * Documentation: http://www.mysensors.org
 * Support Forum: http://forum.mysensors.org
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * version 2 as published by the Free Software Foundation.
 *
 *******************************
 *
 * EnergyMeterSCT by Patrick Schaerer
 * This Sketch is a WattMeter used with a SCT-013-030 non invasive PowerMeter
 * see documentation for schematic
 * 
 * Special thanks to Surge, who optimized my code.
 * 
 * updated to mySensors Library 2.0
 */


#define MY_RADIO_NRF24
#define MY_REPEATER_FEATURE
#define MY_DEBUG


#include <SPI.h>
#include <MySensors.h>  
#include <EmonLib.h> 
 
#define ANALOG_INPUT_SENSOR 1  // The digital input you attached your SCT sensor.  (Only 2 and 3 generates interrupt!)
//#define INTERRUPT DIGITAL_INPUT_SENSOR-2 // Usually the interrupt = pin -2 (on uno/nano anyway)
#define CHILD_ID 1              // Id of the sensor child

EnergyMonitor emon1;

MyMessage wattMsg(CHILD_ID,V_WATT);
MyMessage kwhMsg(CHILD_ID,V_KWH);
MyMessage msgKWH(CHILD_ID,V_VAR1);
unsigned long SLEEP_TIME = 60000 - 3735; // sleep for 60 seconds (-4 seconds to calculate values)

float wattsumme = 0;
float kwh = 0;
float wh = 0;
int minuten = 0;  //vorher 61
boolean KWH_received=false;

//Humidity Sensor Code
#include <DHT.h>  
#define CHILD_ID_HUM 2
#define CHILD_ID_TEMP 3
#define HUMIDITY_SENSOR_DIGITAL_PIN 2
DHT dht;
float lastTemp;
float lastHum;
boolean metric = true; 
MyMessage msgHum(CHILD_ID_HUM, V_HUM);
MyMessage msgTemp(CHILD_ID_TEMP, V_TEMP);

//End of Humidity Sensor Code


void setup()  
{  
  //energy clamp code
  //gw.begin(incomingMessage, AUTO, true,0); 
  
  Serial.begin(115200);
  emon1.current(ANALOG_INPUT_SENSOR, 30);             // Current: input pin, calibration.

  
  double Irms = emon1.calcIrms(1480);  // initial boot to charge up capacitor (no reading is taken) - testing
  request(CHILD_ID,V_VAR1);
  //end of energy clamp code

//Humidity Sensor Code
  dht.setup(HUMIDITY_SENSOR_DIGITAL_PIN);   
  metric = getConfig().isMetric;
  //End of Humidity Sensor Code 
}

void presentation() {
  // Send the sketch version information to the gateway and Controller
  // Register this device as power sensor
sendSketchInfo("Energy Meter SCT013", "2.0");
present(CHILD_ID, S_POWER);
present(CHILD_ID_HUM, S_HUM);
present(CHILD_ID_TEMP, S_TEMP);

}
void loop()     
{ 
  
  //process();

  //KWH reveived check
  if (!KWH_received) request(CHILD_ID,V_VAR1);
  
  // power used each minute
  if (minuten < 60) {
    double Irms = emon1.calcIrms(1480);  // Calculate Irms only
    if (Irms < 0.3) Irms = 0;
    long watt = Irms*240.0; // default was 230 but our local voltage is about 240
    wattsumme = wattsumme+watt;
    minuten++;
    send(wattMsg.set(watt));  // Send watt value to gw
    
    Serial.print(watt);         // Apparent power
    Serial.print("W I= ");
    Serial.println(Irms);          // Irms   
  }
  // end power used each minute
  
  // hours KW reading
  if (minuten >= 60) {
    wh = wh + wattsumme/60;
    kwh = wh/1000;
    send(kwhMsg.set(kwh, 3)); // Send kwh value to gw 
    send(msgKWH.set(kwh, 3)); // Send kwh value to gw
    wattsumme = 0;
    minuten = 0;
  }
// end of hourly KW reading
    
// Humidity Sensor Code
 if (minuten == 15 || minuten == 30 || minuten == 45|| minuten == 60) {
    float temperature = dht.getTemperature();
    if (isnan(temperature)) {
      Serial.println("Failed reading temperature from DHT");
    } else if (temperature != lastTemp) {
      lastTemp = temperature;
    if (!metric) {
      temperature = dht.toFahrenheit(temperature);
    }
    send(msgTemp.set(temperature, 1));
    Serial.print("T: ");
    Serial.println(temperature);
    }
  
  float humidity = dht.getHumidity();
  if (isnan(humidity)) {
      Serial.println("Failed reading humidity from DHT");
  } else if (humidity != lastHum) {
      lastHum = humidity;
      send(msgHum.set(humidity, 1));
      Serial.print("H: ");
      Serial.println(humidity);
  }
 }

 //End of Humidity Sensor Code
 wait(SLEEP_TIME);
}

void receive(const MyMessage &message) {
  if (message.type==V_VAR1) {  
    kwh = message.getFloat();
    wh = kwh*1000;
    Serial.print("Received last KWH from gw:");
    Serial.println(kwh);
    //send(kwhMsg.set(kwh, 3)); // Send kwh value to gw 
    KWH_received = true;
  }
}

Talat Keleş

@patrick-schaerer said:

I alread updated to MySensors 2.0

I just got my sct-013-000 non-burden version and will try it as soon as atmega+nrf packs arrive. Thanks for code update. :thumbsup:
Meanwhile what is "msgKWH" for? What is different than "kwhMsg"? Which controller do you use?

john7845

Hello, now with the new code I get this error:

Arduino: 1.6.9 (Windows 10), Board: "Arduino/Genuino Uno"

WARNING: Spurious .mystools folder in 'MySensors' library
C:\Users\LENOVO\Desktop\arduino_code\Voltage_sensor_5\Voltage_sensor_5.ino:58:19: fatal error: DHT.h: No such file or directory

#include <DHT.h>

compilation terminated.

exit status 1
Error compiling for board Arduino/Genuino Uno.

This report would have more information with
"Show verbose output during compilation"
option enabled in File -> Preferences.

Talat Keleş

@john7845
Error is related to missing library of DHT. If you will use DHT temperature/humidity sensor in your circuit, you should add DHT library to your Sketchbook/libraries folder. If you don't use that sensor, clear or comment out dht related codes in sketch.

john7845

Hello,

I use this code just to see if the current sensor works, but I get 0.0 on the serial! What am I doing wrong?

/*
ReadAnalogVoltage
Reads an analog input on pin 0, converts it to voltage, and prints the result to the serial monitor.
Graphical representation is available using serial plotter (Tools > Serial Plotter menu)
Attach the center pin of a potentiometer to pin A0, and the outside pins to +5V and ground.

This example code is in the public domain.
*/

// the setup routine runs once when you press reset:
void setup()
{
// initialize serial communication at 9600 bits per second:
Serial.begin(9600);
}

// the loop routine runs over and over again forever:
void loop()
{
// read the input on analog pin 0:
int sensorValue = analogRead(A0);
// Convert the analog reading (which goes from 0 - 1023) to a voltage (0 - 5V):
float voltage = sensorValue * (1.0 / 1023.0);
// print out the value you read:
Serial.println(voltage);
}

john7845

Someone??

Yveaux

@john7845 Try printing the value of sensorValue:

Serial.println(sensorValue);

john7845

Again, I take zeros.

meanmrgreen

Sorry for nuub question but can you use a pro mini 3.3 för this?
Or do i need a nano or pro mini 5v?

Talat Keleş

@meanmrgreen
Sure you can use 3.3v for this. If you are using sct-013-000 version, adjust your burden according to

Burden Resistor (ohms) = (AREF * CT TURNS) / (2√2 * max primary current)

where Aref =3.3 (or at worst case, it's lower than 3.3V- if battery powered)
Also don't forget to change calibration which is

Current Calibration Constant = CT TURNS / burden resistor

Bill Thomson

One thing to keep in mind with this configuration: you're not actually measuring true power. Rather by not using a voltage reference, you're calculating apparent power, which is measured in VA (Volt Amps) vice Watts.

For resistive loads, apparent power and real power are the same, or very nearly so. But with reactive loads, e.g. motors, computer power supplies, compact flourescent or LED lamps, etc. they will differ considerably.

SCT-013-030 Energy Meter

7

11.7k

11.2k

113.0k