how can i use the sensor SCT-013-030 that outputs 0-1 v dc , it includes a burden resistor,
to measure the current using arduino uno ?
i saw the openenergymonitor project and its amazing but the arduino code is only for sct 013000 so what can i do? >> and what about the accuracy is it more accurate or the 013-000 is much better? and what about the audio jack how can i connect it to the arduino
Welcome to the OEM forum.
To answer: Just ignore any external (to the c.t.) burden resistor. The external burden is the 33 Ω resistor on the diagrams in the ‘Learn’ section here. Leave it out.
The result won’t be optimal - you will only be using a little over half of the available range of the Arduino input (the middle 2.8 V of the 5 V that is the maximum d.c. input voltage it can measure), but otherwise it should work fine. The problem will be that you will have less precision when measuring small currents. Remember your c.t. is only guaranteed down to 3 A, but you should get reasonably accurate readings lower than that.
The SCT-013-000 is more versatile - you can choose the value of burden resistor to suit your needs, but you need to understand current transformers and their limitations to be able to do that successfully. Apart from the burden resistor, there is only a small difference in the number of secondary turns between the two, and I very much doubt that there is any difference in the material the core is made of.
You can either cut it off and connect to your Arduino using the red and white wires you’ll find inside the cable, or you can buy a 3.5 mm jack socket and connect wires to the tip and sleeve contacts on the socket, and then connect those to the Arduino terminals.
The c.t. cable’s screen is not used.
The names of the plug contacts:
I’m not sure what @amerrigan’s post is contributing? I can’t see the relevance to your Arduino Uno.
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thank u sir for this rich information,
i will suffer with this , because i need to measure small currents (0.5A<i<2A)
so what can i do in this case , will i need the 013-000? its max current is 100 A but when calculating the burden res, i should choose the max current that i want to measure so what is the range of current that will give me best accuracy for this and can u tell me the value of the burden res at this case?
another question
in the burden res equation, we use the current as a peak or rms and why ?
and thank u very much sir
That is a good question. I have never tested any SCT c.t. with a burden such as to give the full scale output at 2 A. For that, and using a SCT-013-000, the secondary current will be 1 mA and the burden to give you about 1.6 V will be 1.6 kΩ. I think it will give satisfactory results, but I cannot guarantee it. For any c.t., accuracy gets worse at ‘low’ currents. That is because of the way the magnetic flux behaves inside the c.t, and there is nothing you can do about that, except spend more money.
If you want to use your SCT-013-030, then you can, provided your wire that is the primary winding of the c.t. is small enough, make a multi-turn primary winding. Each time the wire passes through the c.t., it measures the current again. So if you can get 15 turns through, you will measure 15 × 2 A = the full 30 A that your c.t is rated for. If you can do this, it is the best solution for you. If you cannot get 15 turns through, use as many as possible, but do not force the c.t. closed. You will very easily snap the ferrite core and your c.t. will be useless.
Safety warning: Don’t use wire that is too thin, because where 15 wires are bunched together, they will get hot. You should use wire that is normally good to at least 5 A.
The maximum peak-peak value that the input can have is the maximum that the ADC input can accept - in your case, 0 - 5 V.
If you know the peak value of current - and this is especially true if the current wave is not a good sinusoid, then you should use the peak values (= ½ the input range of theADC) . If the shape of the wave is a good sinusoid, then it is safe to assume that the usual relationships (peak-peak = input range of the ADC = 2 × peak = 2.828 × rms). Where you convert between those values does not matter.
But I cheat. I have two numbers that I remember. They are based on the fact that in the real world, no component is exact, and you need to take that into account too and reduce the input accordingly. My numbers for the voltage you require at the ADC input are 1.1 V rms for an emonTx running at 3.3 V, and 1.6 V rms for an Arduino running at 5 V. Those take into account the tolerances of the c.t itself and all the resistors that affect the voltage the ADC receives.
And then I work in rms values, as those are what are customarily used by electrical engineers.