FvA

Keith from Sunsynk said in one video that although the SunSynk is rated for 500V Open Circuit Voltage, one should not go above 450V. To High Volts over electronics components is a big no no.

Report back on the Issue I emailed a copy of the issue I posted here to SunSynk Support. They came back to me today, that I was spot on with the reason and that they implemented a quicker disconnect of the ATS240V signal in later firmware. My Unit firmware is MCU3374. I will upgrade the MCU and COM firmware when I am back late June. So all should be good

Are the temperature rise in synch with each other? What happen if you switch one OFF? Run without loads, maybe there is something that draw current.

I did bypassed the RCD for now🙄. I am committed to get it sorted

Did not change that as I think that is the time it will take before it will change over. To make sure the Grid is stable. The actual changeover happened when I tested 10 seconds after that. The problem lies in my view the instance when the Earth-Neutral bond breaks (ATS signal) vs when the Inverter switch back the Load to the GRID.

Hi Nexus, thanks for your feedback. I uploaded the complete wiring diagram. I know it is not a requirement for the RCD in front of the Inverter, but I will not go without. You will note that I have a RCD just for the Non Essentials, one for the Essentials and another for the AUX feed. Yes, I saw the Video where Keith from SunSynk mentioned the slight delay. But that might be when the Grid fails. One certainly do not need a delay when the Inverter switch back to the Grid. Rather a fraction before Changeover. I tested that by manually disconnecting the ATS Signal to the Earth Neutral Bond Relay around 60 seconds after switching ON the Grid. About 10 seconds later the Inverter changed back to Grid. During that 10seconds there was no Earth-Neutral bridge. The RCD did not trip as there was no Earth-Neutral bond. And that brings me to another option I had in mind: a Delay ON adjustable Timer that can do that that one can set as close to the point that the Inverter Change back to Grid. The problem is I do not know how much the time will vary. I suspect the Inverter is synching it's frequency and Voltage to the Grid before changeover. On top of that is it a gradual feed in of Power or a sudden changeover? For my next visit I will take 2 small Isolation Transformers with and hook it up to my Oscilloscope to see what is happening when.

Agree with you. My 1st option is to wire it as SunSynk propose, if they sorted the timing. On top of that it it ads to the costs. Yes, thanks for pointing that out to me. I actually have a changeover mechanically interlocking contactor with NC's contacts (but only 25A). I looked at the Hager 63A ESC263U for Option 2a. Changeover time 20ms open and 25ms close.

Good day BritishRacingGreen Thanks for your reply, I appreciate it. I uploaded the layout as I installed it to clarify some issues. The Inverter is not configured to push power back to the grid. I have a value of 100W from the grid.

Just added the full diagram of the Installation. No PV panels yet so the AUX out is for future use. No load on it. KLF3.pdf

Trying to get to grips with the RCD tripping issue and get a solution. Background: I recently installed a 5kW SunSynk Inverter with a Hubble AM2 5.5kW Lithium battery for a friend. All are working except that the RCD feeding the Inverter trips when the Inverter switches back to the Grid. I did some test and I recon I know what the issue is. Below is my take on the problem and some options to work around it. I will appreciate any input as I can't test until July as I am out of Country. I am not an Electrician but electronics is my bread and butter. ------------------------- Disclaimer: My understanding of the fault maybe wrong and the suggestions listed here is not tested at all. The diagrams are just for illustration purposes with just the basic elements. No Surge Protection devises, etc are shown. -------------------------- Note: There should always be an Earth - Neutral bond on the Grid Feed. When the Inverter is in "Island Mode" it will not draw power from the Grid and therefore the Inverter Feed RCD can’t trip when the Inverter is running in Island Mode. Figure: SunSynk Inverter ATS240V output controlling the Earth-Neutral-Bond-Relay switching as recommended by SunSynk. 1: GRID Power is UP: When the Grid is UP (live) the Earth-Neutral bridge will be at the Grid. The Inverter's ATS240V signal will be off and the Earth-Neutral-Bond-Relay de-energized. . All OK 2: GRID goes down: When the GRID power goes down, the Inverter will energized the Earth-Neutral-Bond-Relay. The Earth-Neutral bond will now be at the Output of the Inverter that will also supply power to the Essential Loads. . All OK 3: GRID restored: When the Grid comes back ON the Inverter will take 1-2 minutes before it will switch back to the GRID. a: During this time the Inverter will still generate power for the Essential Loads with the Earth-Neutral Bond at the Output of the Inverter. b: When the Inverter switch back to the GRID it will also disconnect the Earth-Neutral Bond at the Inverter Output (ATS 240V signal goes OFF). All should be OK provided the Earth- Neutral bridge and Power transfer happen at the same instance. With my Installation the Inverter Feed RCD trip every time at this point. This is with SunSynk Firmware version; MCU:3374 I manually cut the Earth-Neutral bridge just before the Inverter reverted back to the Grid as a test. That will prevent the RCD from tripping. That proves to me that the ATS240V signal is a fraction too late (for my install and many others it seems). According to this video by Keith https://www.youtube.com/watch?v=QtDblj7MMjY (at 2m15sec) he mentioned a delay is programmed in. I am not sure if that delay is when the Grid goes down or come back on, or both. In my opinion SunSynk should add another setting in the Software where one can adjust/optimize the ATS signal timing vs Changeover time. It seems these are the main solutions that the installers go for No RCD that feeds the Inverter Use the Grid Feed to control the Earth Neutral Bridge Box supplied. Notes on the above: No RCD: Simple solution and not a requirement because of downstream RCD's? BUT, the Sunsynk Operators Manual recommends a Type A, 30mA instantaneous, 2 pole RCD feeding the inverter. Keith from SunSynk also mentioned that an RCD should be fitted. As I am familiar with most of the electronic components that are involved within an Inverter I understand why SunSynk insist on one. Your choice, I would not go without an RCD. I could not find a Type A anywhere, nether mind a sales person that know that there are different types. However I don’t think that not using a Type A is the problem. The Earth-Neutral Bridge Box: When the Grid comes back ON the Earth-Neutral bridge is immediately broken while the Inverter still provides current to the Load until it switch back to the Grid. During that 1 - 2 minutes there will be no Neutral bridge (floating Neutral) until the Inverter switch back to the Grid! Workarounds: Figure: Workaround 1 Workaround 1: GRID Feed controlling the Earth-Neutral-Bond-Relay switching The GRID voltage controls the Earth-Neutral-Bond-Relay. The moment the Grid goes down the N/C contacts closes bridging the Earth and Neutral at the LOAD output of the Inverter. . All fine. But, when the Grid comes back ON this bond is immediately broken while the Inverter still generates the current until switchover time (1 - 2 minutes). That will result in a floating Neutral until the Inverter switch back to the Grid! (not OK) Fig: Workaround 2a Using a Changeover Contactor switched by the Inverter's ATS240V signal When the Grid is UP there will be no output from the ATS240V, so the Earth-Neutral-Bond-Timing-Contactor will be de-energized. The Grid Power will then flow through the N/C contacts to the Essential Loads bypassing the Inverter. The Earth-Neutral Bond will be at the Grid Feed. When the Grid goes down the ATS240V signal will energize the E-N-B-T-Contactor transferring the Essential Loads to the Inverter. The Earth-Neutral bridge is then at the LOAD output of the Inverter. If the Grid comes back ON, for the 1st minute or 2 the Inverter will keep on providing power before the ATS240V signal will fall away. The E-N-B-T-Contactor will then change back to the Grid. Workaround 2b Similar to 2a, except if 2 Contactors is used. KLF_NBR_Trip1.pdf KLF_NBR_Trip2.pdf