Hi to all,
Sorry for my poor English. I'm a new spanish member of the forum...
The first thing I would say is that I appreciate all the work done in this forum.
This is my first post after read about the MK2 PV router and other tips in the forum for about one week.
Well, now that I have a little idea about the system works, I've begun with some probes before get to build the final prototype. I'm waiting for some components (Pcb's), but meantime I 'm here: http://openenergymonitor.org/emon/mk2/build
In the step that reads -> "- run the MinAndMaxValues tool to check that the ADC’s output values are scaled appropriately for the values of voltage..."
I made my first voltage sensor circuit with a 230v/9v Ariston transformer and a LM358.
The results I receive are like this:
22 9 23
21 9 23
23 9 23
22 9 23
21 9 23
20 9 23
19 9 23
20 9 23
17 9 23
17 9 23
16 9 23
16 9 23
12 9 23
This means that the code is reading from analogRead function "raw values" between 9 and 23 volts?.
There are correct? Or are units that must be convert to volts?
I test too the "simple voltage and current" sketch, but in order to receive a good Vrms value I need to set VCAL to 115.5.
The second step is test the CT sensor too, but I want to have clear in my mind the electronic "maths" involved in the measurements before I engage the whole project.
************************************************************
Edited to update and final boards completed.
(I use the old thread to post my results with the final PCB's. )
I have mounted the Richard's kit and I've made some tests with it. Values measured are aleatory and I suppose that something is wrong but I don't know what is this...
-The AC transformer 230v-9v reads 10,7 volts.
-The CT sensor is SCT-013-30. (No burden resistor in PCB)
-In the resistors of the voltage divisor: 2,66v (R150K - 1 Pin 9V), 1,24v (resistors junction) and 3,26v (2 Pin 9V - R15K).
-Reads from LM358: Pin1-> 1,20v; Pin2-> 1,28v; Pin3->2,50v; Pin4-> 5v
Any ideas what's happening?
Here is he rawsamplesTool_4ss test:
millis() now = 0
recordingMayStartAt 5000
4
3
2
1
0
No of cycles recorded = 3
cycleCount 254, samplesRecorded 229
| v . c |
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minVoltage 0, maxVoltage 1023, minCurrent 0, maxCurrent 1023
Re: Mk2 first test and voltage results - (update with new PCB)
There is something wrong there. The numbers you read are "counts" directly from the analogue to digital converter. The first number is the value that was read this time, the second number is the minimum value and the third number is the maximum value. So you should read a minimum of about 75 and a maximum of about 950.
What is the voltage of your electricity supply - 230 V?
Are you using this circuit diagram: http://openenergymonitor.org/emon/sites/default/files/Mk2_PV_Router.ino_...
What d.c. voltage do you read on the output of the LM358? and the input pin (with the transformer connected but with a.c. switched off)? Both should be close to 2.5 V.
The sketch reads Analogue Input 1 unless you change it, is that the pin which your transformer is connected to? The circuit diagram shows Analogue In 2 is the voltage input and Analogue In 1 is the current input.
Re: Mk2 first test and voltage results - (update with new PCB)
Hi Robert,
I know that something is wrong but all the electronics seems ok...
Here are the answers to your questions:
What is the voltage of your electricity supply - 230 V? --> 226-228v says my tester
Are you using this circuit diagram --> Well I'm not using yet this skech for arduino or Robin diagram, because I did'nt have the diodes. I'm testing now the AC_buffered bias diagram with a LM358AN instead of LMV321.
Umm the voltage is 0,75v+-
Now, looking at the Robin's diagram again I notice different pins in the LM358. This could be the cause.
I believe that I "goofed" (metí la pata)...
Well, this morning I've received the diodes and I can try with the correct diagram...
Thank you for the advice, and I'll tell something in the following test.
regards
victorv
Re: Mk2 first test and voltage results - (update with new PCB)
Ok, I "remade" the circuit and now the numbers are between 37-552...
(edited for new data)
Re: Mk2 first test and voltage results - (update with new PCB)
Getting better....
The numbers should be roughly equal distances each side of 512 ( = 2.5 V ). Those numbers say to me the LM358 output is approximately 1.4 V So I think your bias buffer is still too low. It should be 2.5 V, if your Arduino is using a 5 V supply (or 1.65 V for a 3.3 V supply).
Re: Mk2 first test and voltage results - (update with new PCB)
Umm (I don't understand arduino electronics). I''ve checked again all the connections and now I have 504-532, for about 5 minutes. This could be right?
The measures for LM358 PIN's 1, 2 and 3 are 2,52v.
Now I must fight with the CT. Yesterday probes were not very good, because a was using a 30w lamp. I'll try with a hair dryer when I can.
Thank You again
Re: Mk2 first test and voltage results - (update with new PCB)
Umm (I don't understand arduino electronics)
Have you read these in Building Blocks: http://openenergymonitor.org/emon/buildingblocks/measuring-voltage-with-... and http://openenergymonitor.org/emon/buildingblocks/ct-sensors-interface
OK, you have a LM358 buffering the voltage from the two resistors (R3 & R4 in the voltage diagram), but the principle is the same and so are the voltages.
Those numbers look much better - provided your transformer is not powered up! If it was, I would expect the range to much bigger.
(Remember when you try your c.t. to only pass either the line conductor or the neutral through the c.t., not both. You can make your lamp look much bigger by winding the wire many times through the c.t. - 4 times = 120 W and so on.)
Re: Mk2 first test and voltage results - (update with new PCB)
Please do not post new material by editing your first post. I nearly did not see it as there was nothing new at the end of the thread.
-The AC transformer 230v-9v reads 10,7 volts. That is OK
-The CT sensor is SCT-013-30. (No burden resistor in PCB) That is OK.
The voltages on your LM358 / LMV358 are wrong:
Pin 4 is the ground, Pin 8 is the positive supply voltage. You should have 0 V on the ground (pin 4) and 5 V on Vcc+ (pin 8). You must correct that fault first.
The amplifier is a voltage follower, so the inverting input ( IN-, pin 2) is connected to the output (OUT, pin 1), and the non-inverting input (IN+, pin 3) is connected to the voltage divider. If the amplifier is working correctly, all three voltages should be the same, half the supply voltage = 2.5 V. You should measure those voltages with the ac adapter/transformer switched off and the c.t. unplugged.
The rawsamples results tell me that both the voltage input and the current input a.c. voltages are far too big, so I think you have used the wrong value resistors. I have done a new diagram here, that might help you.
With the ac adapter/transformer switched on:
You should read across both 150 K and 15 k resistors in series: the transformer voltage 10.7 V a.c.
You should read across the 15 k resistor: one eleventh of the transformer voltage 0.97 V a.c.
With the c.t. connected and on a wire carrying current:
You should read across the c.t. secondary winding 1 V a.c. with 30 A flowing, proportionately less at smaller primary currents.
Re: Mk2 first test and voltage results - (update with new PCB)
Sorry, but I would not start a new thread...
Without CT and AC connected I read (relative to arduino Vcc 5v)
Pin1->4,98v
Pin2-> 0,10v
Pin3->2,48v
Pin4 de ground relative reads 5v
Pin1 and Pin2 are receiving wrong voltage. I'll review again the PCB and look for any part damaged...
Thank You Robert
Re: Mk2 first test and voltage results - (update with new PCB)
Ok, I found the PIN1 in the PCB "orphan"and is not jointed to PIN2. This could be the problem...
Re: Mk2 first test and voltage results - (update with new PCB)
Ok I've done a few test's on the new boards but I couldn't calibrate the system with a good accuracy.
A test with CT connected and AC connected (226v)
No of cycles recorded = 3
cycleCount 18604, samplesRecorded 226
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minVoltage 202, maxVoltage 810, minCurrent 501, maxCurrent 518
When I disconnect the CT from the circuit:
No of cycles recorded = 3
cycleCount 18304, samplesRecorded 227
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minVoltage 205, maxVoltage 815, minCurrent 205, maxCurrent 807
With a 180W load (a 60W bulb with 3 cable turns around CT
No of cycles recorded = 3
cycleCount 18904, samplesRecorded 227
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minVoltage 206, maxVoltage 810, minCurrent 489, maxCurrent 527
I've test the latest sketches Mk2a and Mk2i in order to calibrate the system but I have a 20% more deviation of power.
I've change PowerCal and voltageCal but something escapes to my kwnoledge...
voltageCal is computed based in 240v -> 649 units divide by the difference of the units in the wave.
For my rig is 226V -->640 units and 810-206=614. This means 640/614 ¿? I set up with this value the sckech, and runned some tests with it:
180W; powerCal = 0.063; voltageCal = (float)640 / 610
Tallymode setup:
Time to run (secs)? 10
Min value (Watts)? 0
Max value (Watts)? 200
167, 0
165, 1
163, 8
161, 29
159, 86
157, 117
155, 153
153, 66
151, 31
149, 8
147, 1
145, 0
120W; powerCal = 0.063; voltageCal = (float)640 / 610
Tallymode setup:
Time to run (secs)? 10
Min value (Watts)? 0
Max value (Watts)? 150
128.25, 0
126.75, 1
125.25, 4
123.75, 3
122.25, 25
120.75, 59
119.25, 80
117.75, 97
116.25, 101
114.75, 73
113.25, 39
111.75, 13
110.25, 5
108.75, 0
60W ; powerCal = 0.063; voltageCal = (float)640 / 610
Tallymode setup:
Time to run (secs)? 10
Min value (Watts)? 0
Max value (Watts)? 100
91.50, 1
90.50, 0
89.50, 0
88.50, 6
87.50, 9
86.50, 10
85.50, 23
84.50, 39
83.50, 60
82.50, 57
81.50, 68
80.50, 53
79.50, 60
78.50, 45
77.50, 26
76.50, 27
75.50, 12
74.50, 3
73.50, 0
72.50, 1
71.50, 0
With no load connected I received about 40watts
44.75, 26
44.25, 32
43.75, 35
43.25, 40
42.75, 32
42.25, 35
41.75, 44
41.25, 27
40.75, 30
40.25, 21
39.75, 27
If I change PowerCal to get accuracy in great values, the "zero" power is impossible to read. I was playing with differents values for PowerCal and voltageCal without success...
What's happens here?
regards
victorV
Re: Mk2 first test and voltage results - (update with new PCB)
You have a signal from the voltage leaking into the current input. Have you assembled the circuit boards exactly according to the instructions?
What alternating voltage do you measure on the output of the op.amp? Unless you have put a component in completely the wrong place, that is the only place where the voltage and current signals come together. The d.c voltage there should be 2.5 V and the alternating voltage should be zero - always, whatever voltage or current is present.
If you short-circuit the current transformer (that is OK, it is a current source), what do you see when you run the RawSamplesTool? You should see zero current even though you have a voltage.
Re: Mk2 first test and voltage results - (update with new PCB)
Have you assembled the circuit boards exactly according to the instructions?
I think so...I check all the components before soldering...
What alternating voltage do you measure on the output of the op.amp?
PIN1 DC->2.5V
PIN1 AC->4.2V with and without AC plugged <---(wrong)
I read from PIN4 10VAC ¿? this is possible?
I'm newbie in electronics, what's cause the AC voltage?
regards
Re: Mk2 first test and voltage results - (update with new PCB)
I changed the LM358, the old one could be damaged, and now I receive better "performance".
** 0W **
2.10, 0
1.50, 16
0.90, 61
0.30, 213
-0.30, 114
-0.90, 59
-1.50, 35
-2.10, 2
-2.70, 0
** 60W **
65.50, 0
64.50, 1
63.50, 4
62.50, 36
61.50, 104
60.50, 163
59.50, 123
58.50, 61
57.50, 6
56.50, 1
55.50, 1
54.50, 0
Theresults with a 100w bulb, 200w (2 turns in CT) and 300w (3 turns in CT)
show an average of 95w. I will try with a hairdryer or similar of 1000wats.
Today is sunny, (no clouds at sight) I'll begin testing the power diverted part .
regards
Re: Mk2 first test and voltage results - (update with new PCB)
I read from PIN4 10VAC ¿? this is possible?
I'm newbie in electronics, what's cause the AC voltage?
If you read any voltage on that pin, there is a big problem: