Discuss Why does my main house consumer unit trip when the inverter switched to AC backup? in the Solar PV Forum | Solar Panels Forum area at ElectriciansForums.net
Is the cabinet earthed back to the main db earth bar? Ie is the earth bar connected the the earth of the ac input c form socket?Hello again Marconi
I followed the instructions and got the AC to charge the batteries with the USB timer set and it was charging for a short while.
I followed the instructions one at a time and then turned on the Solar Consumer unit. I then ran a kettle on the kitchen circuit and the microwave on a separate circuit serving the extension this took the output to 3Kw so I added an induction hob which took the output to 5.1 Kw, the max of this inverter being 5.5Kw I believe.
At this point the MEM rcd has not tripped and until I get another couple of sockets added to the next MCB circuit I can only add to the two I have at present with more items. I am surprised the mem did not trip but this may be as a result of only 2 mcb currently pulling power through the consumer unit.
Let me know your thoughts regarding this test and I look forward to trying some more experiments before I remove the unit to return to the supplier.
I have been testing all of my pv wiring in a last ditch attempt to see what is causing my dc.dc overcurrent issue but with no obvious problems with the wiring I am resigned to returning it to the supplier next week.
regards and thanks as ever for the help
Tonyboy
Dear
Good morning. I wondered if have had time to consider what I sent you? With further research and testing of the Axpert MKS iv 5kW solar inverter fitted in my clients SP5048 off-grid plug and play panel I pretty convinced in my own mind that the tripping of the up-front RCD is because there is an N-E link made inside the Axpert box. Interestingly, I have discovered that for the equivalent (same?) Voltacon or Conversol branded solar inverter there is no internal N-E link. Instead one can buy this unit which makes the N-E link externally whenever the inverter is supplying the output, otherwise ie in bypass mode it is disconnected because the N-E link is made upstream from the supply. Perhaps you could review the links above for me please?
Regards
Good morning Marconi.Is the cabinet earthed back to the main db earth bar? Ie is the earth bar connected the the earth of the ac input c form socket?
Good morning MarconiI think those voltage measurements are unsurprising but to be sure would you draw me a diagram which shows accurately what each earth terminal is connected to and between?
Also show how you made your voltage measurements and the readings. I normally do this by a V in a circle with two leads from it to the two points across which I measure a voltage.
The F12 fault could indeed be due to an pv over voltage measurement. But, I think you said the system functions normally even with F12? This over voltage could be a result of the way the earths are connected and to what hence my first paragraph.
Hello MarconiPlease send me a link to what you have read on earthing on the V Ltd website. The earthing and bonding of your installation is something we need to get right mindful that your supply is PME which has restrictions on using the Main Earth Terminal (MET) outside the 'equipotential zone' generally and simply understood in the domestic setting as anything within the home.
Please send me a link to what you have read on earthing on the V Ltd website. The earthing and bonding of your installation is something we need to get right mindful that your supply is PME which has restrictions on using the Main Earth Terminal (MET) outside the 'equipotential zone' generally and simply understood in the domestic setting as anything within the home.
Hi MarconiPlease send me a link to what you have read on earthing on the V Ltd website. The earthing and bonding of your installation is something we need to get right mindful that your supply is PME which has restrictions on using the Main Earth Terminal (MET) outside the 'equipotential zone' generally and simply understood in the domestic setting as anything within the home.
Hello MarconiHave you reported the state of the inverter on/off correctly for voltages 1 and 2 above? I would expect voltage 2 when the inverter is off to be round about 7 x 50 = 350V and voltage 1 when the inverter is on and MPPT operating to be lower eg your reading of 246V. The open circuit voltage of a panel is about 50V.
The 130-170V reading of the array metalwork to earth rod is to be expected due to the distributed insulation resistance of the panels and cabling to ground. For evenly distributed insulation resistance to earth the voltages would be half the +ve to -ve voltages so 350/2 = 175V and 246/2 = 123V - near enough what you measured.
Hello Marconi and thanks for the replyTo observe a voltage between the PV input terminals when the array is disconnected from them and the inverter is producing an ac output using power form the battery is normal. The solar inverter is transformerless which means there is no air gap between the dc inputs (PV and battery) and the ac output. Due to the way the dc input is converted to a higher voltage and then switched in polarity at the mains frequency and also the earthed output neutral there is an alternating voltage waveform ( square wave shaped ) impressed across the PV+ and PV- inputs. It is usual and nothing to worry about but of course don’t touch live connections!
The 130V dc ( circa half the end to end array voltage) between array metal work and an earth rod is normal when the insulation resistance is uniformly distributed from the plus to minus side of the array and neither the pv+ nor the PV- is connected to earth which they should not be. They are left floating.
You should connect the array metal work to a local earth rod so that the touch potential between the metal work and local ground is small.
I will provide further advice on earthing arrangements for the SP5048 cabinet in a later email.
Regarding the F12 fault code - does it occur in battery only mode, PV only or both battery and PV? Does it occur when the inverter is not supplying the ac output Load ? Does it occur when the battery is fully charged and not supplying any ac output load? Does it occur on switch on of the inverter or some while later? Does it occur when PV only is supplying a small low wattage load? Does it occur battery only supplying small wattage load?
Hello Marconihttps://content.storefront7.co.za/s...56k48v/documents/rct-axpert-mks-iv-manual.pdf
see page 15 Program 2 - Maximum charging current (which is solar and utility currents). What do you have set? Try reducing maximum charging current. If it is set now to the default of 60A then reduce to 30A. If 40A then to 20A. ie whatever the max current set now then halve the current value. Then see if F12 happens when solar pv is charging battery.
Hello MarconiRe: Program 13 page 19 'Setting voltage point back to battery mode when selecting “SBU” (SBU priority)' in program 01' of the manual reference in my #77 - what voltage do you have set as the threshold for point back?
Hello MarconiThank you. I will study what you have said. What do you have set for Program 12 page 18?
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I will find out.Hello Marconi
I Have program 12 set to the default values 46v and 5%, I think in the absence of any information from V ltd I decided to stick to the default values until I got some advice on the impact of any changes. Some are pre-set if you choose Pylontech in menu (5) p17
I have taken a video already on mp4 format but I get a message saying it is too large for the server to process, What is the file size limit for videos please?
Regards
Tonyboy
Hello MarconiThose voltage checks for the two programs were to ensure there is some hysteresis between switching from utility to load in lieu of battery when battery voltage is 'low' and battery to load when its voltage is 'high' in lieu of utility. Without a voltage difference between the switch over thresholds there will be frequent changeovers perhaps at a high rate which would stress the electronics. The same hysteresis idea as employed in a room thermostat which you will be more familiar with.
I look forward to the results of your next trial with a more depleted battery being charged. That it does charge but stops on F12, resets and starts charging again only to be repeated suggests an instability of some sort perhaps of current or voltage. Or a defect which causes an instability in voltage level or current level.
Is there a date on the inverter box saying when it was manufactured? Electrolytic capacitors or which there are a few inside the box do not like being un energised for long periods and can fail or decay in value when they are after a long period dormant.
Quad Plus - https://www.quadplus.com/capacitor-reforming
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