I installed my Solar PV a couple of weeks ago and I am unable to see any activity (output) on the Wind Turbine Inverter’s AC Output.
OK, granted, I am not a Linux or mathematical genius but when my Inverter tells me that it should be putting out between 50 and 100+ Watts, Emoncms tells me the output is between -1 and 1.
I initially had the two CTs connected – one on the live wire and one on the neutral wire with arrows pointing in different directions (hoping that magically it would tell me the power I was generating and the also the power consumption of the Inverter when it was not generating) .
After noticing no values of any interest, I unplugged the second CT and concentrated just the one with the arrow pointing towards the utility side (arrow pointing from the Inverter to the Mains).
This made zero difference – suspecting a faulty CT I swapped it around for the other one – no difference.
So, here I sit… watching the Wind Turbine do its thing in really good wind today via a CTV Camera and frequently going to the garage to check the output on the Inverter itself but still zero interesting or usable stuff from emonPi/Emoncms.
Is this because I am not a Linux expert or is it because I have a faulty DOA emonPi?
Yes, all updates are current.
One strange thing I noted was that Emoncms stopped recording data about a day ago and it looked like it just “guessed” a mean average of -1 Watt for that duration – I rebooted it and it seems to be back recording live data between -1 Watt and 1 Watt.
Sadly, that’s a misunderstanding. The same current, which is what a c.t. measures, flows in both wires - in on one and out on the other - so both should have read the same. The direction of power flow depends on the instantaneous direction of the current compared to the voltage (see ‘Learn’ for an explanation). This is why you need the a.c. adapter. Without it, you can only measure the magnitude of the current (like with any multimeter). With it, power will be positive (our convention, flip the c.t. round on its cable if not) when you’re generating and negative when the inverter is consuming.
You appear to have avoided the common mistake of putting the c.t. on a 2-conductor or 3-conductor cable and expecting it to read something. It won’t.
Did you avoid the second trap of plugging in the c.t. after you’d powered up? You need to have the c.t’s plugged in before you power the emonPi (rebooting doesn’t help, because it doesn’t reboot the emon part of the emonPi). The same goes for the a.c. adapter. I’d expect a solid zero if you had, so from what you write, you appear to be OK here.
50 - 100 W is 200 - 400 mA. That’s on or below the point where you can expect reasonable accuracy from a 100 A c.t., but I’d still expect to read something. You can multiply the sensitivity of your c.t. by making a multi-turn primary winding. This you do simply by putting multiple loops of the wire through the centre. For each time the wire goes through, you multiply the current, hence the power. (I use a coil with 20 turns when testing the c.t’s, so 5 A reads as 100 A.)
If you’ve got a multimeter capable of reading a.c. milliamps, you could try measuring current from tip to sleeve of the c.t’s jack plug. You’ll need a sensitive range, the current is 50 mA per 100 A, so you’ll see about 0.2 mA from your turbine, but 6 mA from a 3 kW kettle (you’ll need to split open an extension lead to get at one wire to put the c.t. on).
Have you looked down the FAQs in case there’s something in there that I’ve missed?
Thanx Robert
Using the search function here and FAQ is not easy unless an exact Boolean search request is recognized and, sadly, I was not sure what to search for and just entering “CT” took me to whole new and unknown universe.
Admittedly, after first installing the emonPi and seeing no favourable (or useful) information I began a journey of CT swapping while patiently waiting for the Turbine to do its thing (its a 1000W Turbine - during a hurricane).
Now that I have been scolded - I completely shutdown the emonPi, unplugged both the AC and USB Power Source and left it for about 1-hour before firing it up again (with just one CT connecter connected on just the Live wire coming from the Inverter).
Sorry, no wind at all today or the time to retrofit a cable for the kettle Paul.
I will be tidying up cabling this coming weekend as a 3-Phase brake switch needs to be installed and I need to shutdown the Solar system (5KW) to split wiring for the other CT clamp.
I am keen to compare the Growatt and Muskpower Solar output with what emonPi sees.
The reason I went down this road was to get myself out of this horrible and frustrating dedicated “Cloud” environment (which I hate with a passion) and consolidate my generation into one console.
If measuring the generation of 100W+ source is going to be a problem then I have probably chosen the wrong solution for my setup and will need to look at alternative solutions.
For emonPi, this is my first testing of a promised simple and accurate solution to which I am yet to verify.
Will update soon this coming weekend or if there is sufficient Wind for testing before then.