Hi,
i just built my shield and wanted to test it. On all ct-inputs i get values like:
6204
66
55
74
127
58
64
98
92
60
64
98
55
62
56
59
56
55
57
59
104
62
63
60
The CT-sensor measures the 230V-AC-input of a 12V power supply with no load on it. So it should show only very small values...
I tested all (3) ct-sensors on all ct-inputs on the board. always the same readings
How can i track the error? Or did i understand something wrong?
I used the sketch with the name "Shield_CT1234"
Greetings
Andreas
Re: Help - EmonTxShield V3 - measuring unexplained values?
Firstly, there was no need for a title to your post that uses language that might be taken by some to be offensive.
If you search this site, you will find very many reports of a similar problem, with roughly the same explanation each time. You may well be misunderstanding something, but you have given no details of the current transformer that you are using, nor any other significant details - not even what the column of numbers refers to, so it is hard to judge whether the readings you see are reasonable for an Arduino board, or not. If I assume you have not changed the sketch and you have a 100 A c.t, then you are seeing readings that represent about 0.4% of the maximum reading of apparent power.
Re: Help - EmonTxShield V3 - measuring unexplained values?
This is the serial output of one ct-sensor (100A). i am wondering, what the values want to tell me?
Apparent power is watts? This cannot be correct, because the power supply has no load and the values are in one second 55, some seconds later its more then the double.
I made another test some minutes ago: ct sensor connected, but the wire in the sensor is not plugged in - absolutely no power on the one line going through the sensor!! This should produce a lot of zero values, shouldn't it?
But i get again many different values:
76
92
122
103
112
133
117
92
132
136
88
137
134
I get these values on every ct-sensor input and with every ct-sensor i connect (i have 3x 100A).
What significant details do you need? I am new to this...
Re: Help - EmonTxShield V3 - measuring unexplained values?
Have you tried searching? Try reading Measurement implications of ADC resolution at low current values, http://openenergymonitor.org/emon/node/4822, http://openenergymonitor.org/emon/node/5303.
What you are reading is almost certainly noise from the digital part of the microprocessor being picked up by the analogue to digital converter and being measured. The emonTx V3 was carefully designed to include as much filtering and shielding as possible to reduce this. As far as I know, the Arduino boards have very little filtering and shielding, if any.
Re: Help - EmonTxShield V3 - measuring unexplained values?
Hi,
thanks for the links. it is sometimes quite difficult to search with the correct words without beeing a native speaker english.
i will read this carefully.
greetings
Andreas