active output single phase ac sensor

Other Hardware Sensors
1

hello,

I am new to Arduino, and have not programmed since high school. I have spent the past week working on how to get this sensor to work. The "active output single phase ac sensor" is pretty common on ebay and removes the need to make your own board to monitor voltage, unfortunately there is little information on this. The only post that pointed me in right direction is here

http://forum.arduino.cc/index.php?topic=357095.0

Unfortunately a little more information would have saved me time, so I am sharing it here.

Starting with Emonlib EmonLib/EmonLib.h at master · openenergymonitor/EmonLib · GitHub

the challenge is finding the information on how to calibrate the system for a sensor that is not made by openenergymonitor.

so here is the sketch that I used to understand the calibration, and timing. I set the potentiometer in the middle because it didn't seem to make much of a difference.

I used a voltmeter to watch the real voltage from the outlet, and increased the calibration number till my computer was reading close to what my voltmeter did.

emon1.voltage(A0, 600, 1.7); // Voltage: input pin, calibration, phase_shift

I found that if I used a multiplier in the loop, ie: x= emon1.Vms * 2; I would get funny results for different voltages. (I need to read from 0 - 400v ac) So use the calibration.

for my project I need speed more than accuracy, I found that when using the settings in the github example my loop would take 200ms,

emon1.calcVI(20,2000); // Calculate all. No.of half wavelengths (crossings), time-out

so I wrote this sketch to see the accuracy between 2 and 20 crossings, found the accuracy to be 3v with 2 crossings, and 2v with 20. The time difference is 180ms. I also found my project hanging when the voltage went to zero... then I noticed the 2000ms timeout.

still working on this, and will update as I learn more

Voltage_sensor.ino (1.34 KB)

2

I finished testing and setting up the system, Here is what I found for the next person who buys these and are looking for answers.

  1. the sensors read different so each one will need to be calibrated separately, one is set at 540, the other at 650 to get similar reading off the same line.

  2. there are two grounds, one needs to go to the board, but I don't know which one, it is easier if you just power it from the board. I learned this because I tried powering it with my relay bank and was getting really weird readings.

  3. one of the 3 that I bought started really high 1000v and dropped down to zero each time I reset the board

hope this helps