Transformer-less "All in One"- Inverters, Back-door Voltages, Grounding mistakes
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- Опубліковано 22 лют 2023
- Hi. This video is about answering some questions which came up after Will Prowse was showing about some dangerous Back-door Voltages on unused terminals of "All-in-one" Inverters. It's again a talk about "Transformer-less" Inverters.
In this video I am showing the usage of a Voltage -Continuity Meter. The meter that I am using is the UNIT-T UT18B.
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I love your clip
This is immensely helpful! Thank you very much for your videos. I learned a lot watching them!
Thank you very much for this important information ! Your demonstrations and explanations are very good and clear!
Great video, thank you.
The issue of transformerless charger/inverters is a growing issue. I have had various Voltronics inverter chargers and am currently using the the A11 Max as my needs have increased. There is a vast difference in price between the Voltronics units and, for example the equivalent Victron units.
The market is pretty well dominated by Chinese items in the UK. What I am wondering is if the risks could be eliminated by the inclusion of a 1:1 autotransformer between the inverter output and the downstream AC circuits?
Just a matter of finding an autotransformer that will cope with the 50A output of the inverter and whether the surge on startup will shut the inverter down!
Hi, yeah. Isolation Transformers at the output would of course get you that barrier, but as you said, they are not easy to get and then the required power level would make them expensive.
But it shouldn't be much of a problem just to use the High frequency inverters. They usually do have leakage monitoring and should shut down when something strange is going on between the Busses. And the other thing is, to use Type-B RCDs at the output to look for DC leakage if the inverter doesn't catch it.
Unfortunately Cost is King nowadays and even the cheapest HFI have all the best UI/System settings so they are very attractive. If I needed to build a 100% Off-Grid system, I would go for a Chinese Low Frequ. Inverter. Cheaper then a Victron and having the advantage of internal isolation.
I think another interesting area is the PV array itself. There is DC power from the panels, and probably a metal frame(s), and possibly AC power from micro-inverters.
I'm building a larger PV array and purchased a combiner box with a "lightning arrestor". It called for a grounding rod. Luckily I'm not using micro-inverters so don't have to worry about both DC and AC, but am wondering if it is worth it to tie-in all the frames to that.
Frames should not be tied into a grounding system via a Lightning Arrestor=Surge protection device. It should always be directly grounded either by a rod at the array or connected to your house grounding if the array is part of your house. SPDs would allow a buildup of voltage before they counteract. Thats not what we want with structural grounding.
Thanks ,great topic , as usual
Keep going
Danke, ich habe wieder was gelernt. Der Hersteller Longi empfiehlt übrigens den minus-Pol eines String zu erden, weil dann der Ertrag höher sei. Ich konnte mir nicht vorstellen, dass das stimmt. Fahre deshalb meine Panels isoliert.
Höheren Ertrag kann ich mir erlich gesagt auch nicht vorstellen. Da ist mir der Sicherheitsaspeckt eines isolierten Systems wichtiger. LG
Hi Roland. I was with a friend yesterday who has a new Mr.Pow Hybrid inverter, with the orange stripe on a grey background color scheme.
He reported getting shocked on the neutral line when working on a sub-circuit when he had isolated the live fuse in the local fuse board. When we checked the voltage he has 230v across L+N, 110v ish between L+ incoming earth and problematically we record again around 110v from the Neutral conductor to the earth. We measured this at a socket in the house and at the outgoing cables leaving the inverters. Questions are why is he getting 110v to earth on the L and not 230v ? Also would bonding the neutral and the chassis to earth put the Neutral to zero potential?
Thanks
Hi, yes. His Neutral and PE line must be physically grounded and bonded. Then the problem should disappear.
The 110V from PE to L and N is quite typical for most inverters today if they do not get ground reference. Cheers
I have the same situation on my 24v 1000va Souer FPC 1000 B Standard non hybrid inverter of not having 230v L to earth. so if i bond neutral output to earth i won't blow the inverter up ? @@RolandW_DIYEnergyandMore
@@Steveuploads no, as long you do not bond both N and L to ground :))
Hello sir
I want to ask you a question I have inverter PIP 5048 Mkx Mpp solar company my only issue us that when I have fully battery charged and low load home and high pv power. I see Mppt is up and down the power and that makes fluctuations in waveform output of inverter and i see that in bulbs.
So, if you shut down the PV input at that situation the AC output would stabilize? My Must inverter is actually just doing that in the SOL mode. Once my battery is full, the PV input would be shut down for 90 minutes and power would then come from batteries only.
@@RolandW_DIYEnergyandMore yes PV up and down effect on output should pv working with battery to make output stable like some Mppt I used before.
Sir, thank you for the video. The casing of my All-in-One Voltronic Apex-11 inverter is shocking. There is a ground connection between the inverter and the grounding wire of the main electrical panel. When I checked the voltage between the casing and the ground, it read between 210 and 250 volts. However, when I disconnected the PV via the MC4 connectors, the voltage dropped to 104 volts. What could be the cause?
hi. check the voltage from the PV plus and minus to ground when the wires are disconnected from the inverter. is one showing steady high voltage, while the other is steady at around zero? if yes, then there is a DC leakage in your PV array. maybe a broken panel, broken cable, etc
Thank you for the response. I will check that and get back to you.@@RolandW_DIYEnergyandMore
Hello. I have done as you suggested. Both the positive and negative PV array terminals did not record a sustained high voltage relative to the ground. The voltage was under 20 volt. However, I noticed that when I turn off the input breakers of the panel and the AC input into the inverter and run the inverter only from the battery, the shocking ceases and the voltage drops to practically zero. It increases to about 60 volt AC when I turn on the AC input and rises to 125 volt AC when I turn on the panel breakers.@@RolandW_DIYEnergyandMore
@@1982757 is your inverter chassis or the ground wires physically grounded by an earthing rod? where do you live? what is your grid type? Is this shocking experience something new or was it there from the beginning. Is any of your battery poles bonded to ground?
The inverter chassis is grounded and connected to the earth wire of the main panel, which leads to the earthing rod. I live in Nigeria, and our grid is 230v 50Hz. I use flooded lead-acid batteries, and I don't think any poles are grounded. I noticed the shock after connecting a second 4.8kw PV array to the second MPPT input of the dual MPPT AIO inverter.@@RolandW_DIYEnergyandMore
Because there is no iron core, copper wound output transformer to provide galvanic isolation between the DC boost stage and the high frequency inverter's AC output, all it would take is for the AC output monitoring circuitry to fail and one of the MOSFETs in the inverter's H-Bridge circuit to short to ground, and a high frequency inverters can send dangerous, high voltage, high amperage DC current straight to your AC appliances which can not only damage your appliances, but can also set your appliances on fire. Never buy a Chinese made high frequency, transformerless inverter.