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Paul last won the day on December 30 2021

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  1. Also if it only has 3 capacitors on the mainboard (like mine did), adding a 4th one in the empty position may help.
  2. 170AH at 24V is very little for sustaining more than 1kW, let alone the startup surge of a large motor. I have 600Ah of gel batteries at 24v for my Upower '8k' at which I sometimes have sustained loads of up to 3.6kW on. Even then, the battery terminal voltage drops slightly below 24v after a few minutes if there is no solar input. I suspect your inverter might be cutting out because the motor startup surge causes the DC voltage to drop below the cut-off threshold momentarily due to the undersized batteries and internal resistance thereof. Also what gauge of cable are you using to connect the batteries to the inverter? I would recommend 70mm2 or thicker.
  3. Thats a good point actually, and you mentioned it before but it escaped from my little brain since! However I would be surprised if they could get enough turns of suitable gauge wire on a ASL2 core to do more than 3kW. There's not a lot of space left in the centre of my ASL3, and as mentioned before that can't do more than 3.5kW continuous without getting hotter than I am comfortable with. If they have used 3mm dia wire on the output that would certainly help reduce heat buildup, but then it's harder to get as many turns of that on a small core so that might become a limiting factor.
  4. ASL2!? Thats even smaller than the one in my 8k 240v unit (ASL3). And my 8k unit can only do 3.5kW continuous. But I notice they've changed the primary voltage from 18v to 16v, which should help reduce the flattened peaks on the sine wave under load.
  5. Ah thanks for the explanation, it makes sense now. I've never quite got my head around the US split-phase system. In the UK and most of Europe domestic supplies are usually single phase 230v, industrial supplies usually 3-phase.
  6. Maybe I'm going a little off topic now, but whilst we are on the subject of wattages I noticed that the casing of your '8000w AMG' inverter looks more like the '6000w 230v' that they used to sell on ebay UK. So I had a look on the ebay US website and sure enough the '8000w split phase': https://www.ebay.com/itm/403247207055 looks like the '6000w single phase' 230v unit I have seen for sale on the UK ebay site before (no listings at present for comparison). The '10000w split phase' unit https://www.ebay.com/itm/403127622433 looks identical in casing size etc. to the 8000w single phase 230v that they sell on ebay UK: https://www.ebay.co.uk/itm/373439121334 (thats the one I have). Is there some reason for this difference or it just some more dodgy chinese maths? I'm not sure whether the 'split phase' thing makes the same size inverter somehow able to miraculously produce more output than a single-phase 230v unit??
  7. Indeed, that is another benefit. When I bought the house it had a single RCD. On damp evenings this would sometimes 'buzz' and very occasionally trip. Yet without an expensive tester I couldn't find which circuit (or combination of circuits) was causing this During the rewiring I found two rodent-chewed wires on different circuits in the void between ground and 1st floor. The damp air circulating here must have occasionally condensed on the wire and the sum of the two was enough to cause a trip. Obviously both lengths of cable were replaced!
  8. Yep earthing and fusing is simply there to protect the installation (wiring etc) from overheating and potentially catching fire in the event of a fault. And as you rightly state, the maximum disconnection time is 5 seconds for most circuits, in UK regs anyway, not sure about other countries. When rewiring the house shortly after buying it in 2013, I opted to fit RCBO's on every circuit rather than the clumsy dual-RCD and a bunch of MCB's which seems to be the uk electricians default choice. Reason being is that although my choice costs a bit more, it allows the use of a smaller consumer unit by saving 4 unnecessary slots, makes any kind of earth leakage fault traceable to a single circuit, and crucially, prevents an earth leakage fault on one circuit from killing other circuits. So for example the washing machine develops an earth leakage fault, it doesn't put out the lights! Regarding the off/on grid switching I utilise a 2PCO switch with centre-off to ensure no risk of grid-inverter connection. I have the inverter neutral tied to the grid earth, which is actually combined with the grid neutral as the supply is what is called PME in the Uk. So my RCBO's will still trip in the event of a >30mA earth leakage on any circuit. The inverter case is also tied to the same earth. I have no earthing on the DC side other than the metal framework on which the PV panels are mounted being about 2ft into the soil.
  9. My v10.3c/ASL3 upower 8k 24-230V does intermittently develop some 12.5Hz (fOut/4) voltage oscillation under light load (<200w). Above that it seems pretty stable. This only causes a noticeable issue with cheap chinese LED bulbs that don't have a proper AC-DC converter inside. All the decent quality LED bulbs that I have bought from uk retailers are fine. The direct-from-china bulbs don't have a proper converter chipset - just a rectifying diode, capacitor (usually undersized so some noticeable 50Hz flicker even on grid, which most people don't even notice but really disturbs me) and a dropper resistor. The really old PJ V1.4 of same specs with 2x AS2 transformers in series doesn't exhibit any oscillation. But Sid said in response to one of my older posts that has a completely different MCU and hence firmware
  10. Looks like a very nicely built unit. I'm suprised at the transformer rating though - only 1650VA (1.65kW max depending on the power factor of the load). I guess thats the continuous rating. But I vaguely remember you saying it could do 4.4kW for 20mins. That seems optimistic for a 1650VA rated transformer, unless I'm getting confused with another thread. How does the size/weight of the transformer compare to the PJ/Upower you had before?
  11. Ah well, at least the outer casing looks pretty compared to the average chinese inverter :) Hopefully the design and components will still be to the same european spec that they were before, and simply produced in China. So in theory it should still be 'better' than the average chinese designed+built inverter. But not a lot of use if the manual is in ChinGerEng, it doesn't support LiFePO4 batteries like you expected (was this mentioned in the spec before you bought it?) and they ignore technical support emails!
  12. Yes it had gone rather off topic, thanks for moving it! Like you say, the formulas used may be ideal for a fixed power transformer where both input and output are expected to be a pure sine wave and the load is usually within a closely controlled range. But this is not the case for a DC-AC inverter, where the primary is driven by an SPWM signal (even if cleaned up a bit by a choke) and the output load can vary from nothing to several kW and we need to maintain reasonable efficiency throughout this entire range. This makes designing an inverter transformer much more complicated than my simple spreadsheet suggests. Somehow I think that Sid's method of testing, experimenting, and calculating from the test results is far better approach. Mine was just a first stab in the dark being new to all this. I've yet to measure it's efficiency across it's entire load range and may find efficiency it is utter pants despite the fact it copes fine with the 3kW load during a 20 minute test run. Also I don't have the full tool set that Sid has (Variac etc), just a simple scope to check the cleanliness of the sine wave, AC/DC current clamp and multimeter to measure voltage and current.
  13. I'm impressed that the prototype 12kVA GS inverter only consumes 0.8A at 48V idle. That's so much better than I expected! Like you say, backyard testing (as I did) can come out with just the same results as expensive test equipment. I just used those formula as a guide for building my little transformer. as thought they might make in interesting read for the less experienced here. I don't pretend to understand it all to the extent the GS guys do. Apologies if I came across as a 'know it all'. I can assure you that was not my intention. It's just a very interesting discussion that I'm enjoying being involved in.
  14. Here's the spreadsheet I've been referring to. The 'max kVA' calculation for any given core dimensions assumes a maximum gauss of 10,000, although the simplified formula doesn't take this as in input parameter. The other parameters you can play with, and I've included links to some reference sources for those who are interested. transformercalculatorv3.xlsx
  15. Going back to my earlier point, we don't actually need to measure flux density (Gauss) as it is already incorporated in the formalue in my spreadsheet. All that matters is that we stay under the maximum gauss of our chosen core, and 10,000 is a good compromise but higher is possible with good quality toroidal cores. @Sid Genetry Solar I got confused in my previous post. You were quite right that the turns/volt is not a fixed constant for a given core. However it varies according to the maximum flux density we want our core to see. This can be seen by altering the 'target gauss' parameter in my spreadsheet. As long as we stay well below 14,000 gauss all should be well. Assuming a fixed pri-sec turns ratio, the more turns we add to both the primary and secondary, the lower the maximum gauss will be at full load, allowing for a smaller core. However then we start to encounter other problems such as wire resistance and difficulty getting enough turns on the undersized core. As the old saying in automotive engineering goes, there's no substitute for cubic inches! The same applies to transformer CSAs. However just like automotive engines, larger transformers use more power (fuel) even under light load! It's going to be a very difficult compromise to make an efficient 12kVA transformer, but I know you will get there in the end. It will never be as efficient at low-load as the 6kVA but I expect people buying the 12kVA unit will have more generating capacity than those buying the 6kVA and so can tolerate the higher low-load consumption.
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