Grove - Electricity Sensor

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Contents

Introduction

The Electricity sensor module is a member of Grove. It is based on the TA12-200 current transformer which can transform the large AC into small amplitude. You can use it to test large alternating current up to 5A.

Model:SEN23931P

Twig-Electricity-Sensor.jpg

Features

  • Grove compatible interface
  • Maximum 5A input
  • High accuracy
  • Small size

Application Ideas

  • Alternating current measurement
  • Device condition monitoring

Specification

Key Specification

Items Min
PCB Size 2.0cm*4.0cm
Interface 2.0mm pitch pin header
IO Structure SIG,NC,NC,GND
ROHS YES

Electronic Characteristics

Items Min Norm Max Unit
Transformation ratio - 2000:1 - -
Input Current 0 - 5 A
Output Current 0 - 2.5 mA
Sampling Resistance - 800 - Ω
Sampling Voltage 0 - 2 V
Working Frequency 20 - 20K HZ
Nonlinear scale - - 0.2% -
Phase Shift - - 5' -
Operating Temperature -55 - 85
Dielectric strength - 6 - KVAC/1min

Usage

With Arduino

The following sketch demonstrates a simple application of measuring the amplitude of the alternating voltage.The SIG pin will output a alternating voltage based on the alternating current being measured. You can measure the value using ADC.

  • Connect the module to the analog A0 of Grove - Base board
  • Put the alternating current wire through the hole of the current transformer.

Grove - Electricity Sensor hardware.jpg


  • Copy and paste code below to a new Arduino sketch.
/****************************************************************************/	
//	Function: Measure the amplitude current of the alternating current and 
//			  the effective current of the sinusoidal alternating current.
//	Hardware: Grove - Electricity Sensor		
//	Date: 	 Jan 19,2013
//	by www.seeedstudio.com
#define ELECTRICITY_SENSOR A0 // Analog input pin that sensor is attached to

float amplitude_current;               //amplitude current
float effective_value;       //effective current 

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/1024*5/800*2000000;
	effective_value=amplitude_current/1.414;//minimum_current=1/1024*5/800*2000000/1.414=8.6(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;
}
  • Upload the code, please click here if you do not know how to upload.

Note: The minimum effective current that can be sensed by the code can be calculated using the equation below. minimum_current=1/1024*5/800*2000000/1.414=8.6(mA).

  • Open the serial monitor, The results is as follows:

Elecricity Sensor.jpg

With Raspberry Pi

1.You should have got a raspberry pi and a grovepi or grovepi+.
2.You should have completed configuring the development enviroment, otherwise follow here.
3.Connection

  • Plug the sensor to grovepi socket A0 by using a grove cable.

4.Navigate to the demos' directory:

   cd yourpath/GrovePi/Software/Python/
  • To see the code
   nano grove_electricity_sensor.py   # "Ctrl+x" to exit #
import time
import grovepi

# Connect the Grove Electricity Sensor to analog port A0
# SIG,NC,NC,GND
sensor = 0

grovepi.pinMode(sensor,"INPUT")

# Vcc of the grove interface is normally 5v
grove_vcc = 5

while True:
    try:
        # Get sensor value
        sensor_value = grovepi.analogRead(sensor)

        # Calculate amplitude current (mA)
        amplitude_current = (float)(sensor_value / 1024 * grove_vcc / 800 * 2000000)

        # Calculate effective value (mA)
        effective_value = amplitude_current / 1.414

        # minimum_current = 1 / 1024 * grove_vcc / 800 * 2000000 / 1.414 = 8.6(mA)
        # Only for sinusoidal alternating current

        print "sensor_value", sensor_value
        print "The amplitude of the current is", amplitude_current, "mA"
        print "The effective value of the current is", effective_value, "mA"
        time.sleep(1)

    except IOError:
        print "Error"

5.Run the demo.

   sudo python grove_electricity_sensor.py

Resources

Support

If you have questions or other better design ideas, you can go to our forum or wish to discuss.

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