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Topic: Arduino Yùn and power meter: measure Watt with ACS712 5V (Read 243 times) previous topic - next topic

alfred_17

Jul 27, 2014, 06:40 pm Last Edit: Jul 27, 2014, 06:50 pm by alfred_17 Reason: 1
Hi guys!
i'm trying to build a energy meter with this tutorial:

http://www.openhomeautomation.net/arduino-wifi-switch/

I use a simple relay, acs712 5v sensor and arduino yun. I have already connect all components (see tutorial).

But i'm not able to see how many watt are used. When i'm measuring watt without a load i see value = 3 (analogRead from acs712 5V sensor). It should be 0??
So when i plug a load in my socket, i see different and instable values, sometimes above 3 sometimes under 3.

The formula are:
// Convert to current
 amplitude_current = (float)(sensor_value-zero_sensor)/1024*5/185*1000000;
 effective_value = amplitude_current/1.414;
 effective_power = abs(effective_value*effective_voltage/1000);
 power = (int)effective_power;

where am I wrong?

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