Grove : Capteur d'Ã©lectricitÃ©

De Wikidebrouillard.

Sommaire

1 Introduction
2 Features
3 Application Ideas
4 Specification
- 4.1 Key Specification
- 4.2 Electronic Characterstics
5 Usage
6 Resources
7 Support
8 Crédits

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

Features

Grove compatible interface
Maximum 5A input
High accuracy
Small size

Application Ideas

Alternating current measurment
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 Characterstics

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 Frenquency	20	-	20K	HZ
Nonlinear scale	-	-	0.2%	-
Phase Shift	-	-	5'	-
Operating Temperature	-55	-	85	℃
Dielectric strength	-	6	-	KVAC/1min

Usage

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.

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;
}

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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).