Hello,
I tried to build a measuring tool with an Arduino Uno board and this CT: SCT-013-030.
Here is my electronic schematic:
The "Stromsensor" is my CT. Now I have problems, that I don't get a good measurement...
How to connect the 2,5V voltage to the CT? The CT is with an audiojack, on which port on the jack I have to connect the 2,5 voltage?
Re: Build EmonTH with SCT-013-030 -- Problems
If you use the plug, the connections are Tip and Sleeve. There is no connection to the Ring. If you take the plug off, connect the red and white wires. There is no connection to the screen of the cable.
You can connect either way round.
[The picture is the wiring for a temperature sensor, but the names of the parts of the plug are the same.]
Re: Build EmonTH with SCT-013-030 -- Problems
Ok thanks for your information.
I connected the 2.5 V to the tip and put a wire from the sleeve to the Arduino analog input.
I made a test and it works. The really current of the coffee machine was 6.080 ampere, my measure was 6.15888 ampere for example.
How I calibrate this now or what can be the difference? I edited the SUPPLYVOLTAGE in the EmonLib.cpp to 5000, because the Arduino works with 5.0 V. My sketch works with "emon1.current(0, 30);", because A0 and the SCT-013-030.
Re: Build EmonTH with SCT-013-030 -- Problems
Your value is wrong by 1.3%, that is easily within the tolerance of the current transformer alone, and possibly within the accuracy of your meter that you used to measure the 6.080 A. You can read about the things that affect the accuracy here. It is permissible to alter the calibration constant 30 in "emon1.current(0, 30);" to get exactly the same reading as your meter.