50A_Current_Sensor(SKU_SEN0098) - jimaobian/DFRobotWiki GitHub Wiki

50A Current Sensor

Introduction

This is a breakout board for the fully integrated Hall Effect based linear ACS758 current sensor. The sensor gives precise current measurement for both AC and DC signals.The thickness of the copper conductor allows survival of the device at high overcurrent conditions. The ACS758 outputs an analog voltage output signal that varies linearly with sensed current. This current sensor enables you to monitor currents in your project every second for energy saving or circuit protecting purposes.

Specifications

Operating Voltage(analog): 5V
Peak Measuring Voltage:3000V(AC),500V(DC)
Current Measuring Rang:-50~50A
Sensitivity:40 mV/A
Operating Temperature: -40~150°C
Dimension:34x34mm

PinOut

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Tutorial

This tutorial is going to test DC and AC current. The result of AC current is its effective value, i.e. the same as an Ammeter reading.

Connection Diagram

                                                    |                                                                                                                                                                                                                                                                |
                                                    |----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
                                                    | **DANGER**: This diagram can also be applied to AC current connection. But notice that the module should be **cascaded** on **one** electric wire ( +/- ). But if you connect it to two electric wires in parallel, you will short circuit and lead to danger. |  |

DC load


#### Sketch

/*
50A Current Sensor(DC)(SKU:SEN0098) Sample Code
This code shows you how to get raw datas from the sensor through Arduino and
convert the raw datas to the value of the current according to the datasheet;

Smoothing algorithm (http://www.arduino.cc/en/Tutorial/Smoothing) is used to
make the outputting current value more reliable;

Created 27 December 2011 @Barry Machine @www.dfrobot.com
*/

const int numReadings = 30;
float readings[numReadings];      // the readings from the analog input
int index = 0;                  // the index of the current reading
float total = 0;                  // the running total
float average = 0;                // the average

float currentValue = 0;

void setup()
{
  Serial.begin(115200);
  for (int thisReading = 0; thisReading < numReadings; thisReading++)
    readings[thisReading] = 0;
}
void loop()
{
    total= total - readings[index];
    readings[index] = analogRead(0); //Raw data reading
//Data processing:510-raw data from analogRead when the input is 0;
// 5-5v; the first 0.04-0.04V/A(sensitivity); the second 0.04-offset val;
    readings[index] = (readings[index]-512)*5/1024/0.04-0.04;

    total= total + readings[index];
    index = index + 1;
    if (index >= numReadings)
      index = 0;
    average = total/numReadings;   //Smoothing algorithm (http://www.arduino.cc/en/Tutorial/Smoothing)
    currentValue= average;
    Serial.println(currentValue);
    delay(10);
}


#### Result

After uploading the sample sketch, open the serial monitor, when the current is 0A, you may found the reading is not 0A, then if you need amore ccurate readings, you have to revise the code with the reading when the input current is 0A.These are the steps:

1 Check the initial current value when the input is 0A;

Initial current value we need is about 0.30A

2 Caculate the initial current value:

-0.34 = -0.04 - ( +0.30 );

3 Revise the sample sketch:

    readings[index] = (readings[index]-510)*5/1024/0.04-0.34;//

revise the code

4 Upload your new sketch again, then you will found the readinga are around 0A, if not, please do the steps above several times to make it.

Initial current value drops down to 0A 5 As shown above, it can be applied to detect the current value accurately, and output analog voltage signals.

AC Load

Sketch

float reading = 0;
float currentValue = 0;

void setup(){
  Serial.begin(115200);
}
void loop() {
  reading = analogRead(*); //Raw data reading
  currentValue = (reading - 510) * 5 / 1024 / 0.04 - 0.34;
  Serial.println(currentValue);
  delay(2);
}

Result of AC current

I tested with a lamp @220V~, and got the result shown below: Read more about the experiment.

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Look at the data, it's a Sine wave data described the effective AC current, and you can read the extreme data which are the maxmum value 0.27 and the minimum value -0.34, use the maxmum absolute one as the ( Effective) AC current.