Hi, I have a Quattro II system already installed, and I want to verify that it correctly disconnects from the grid during an outage and manages the Neutral-Earth connection safely.
System Configuration:
Grid: 3-phase + PEN (TN-C) entering the meter cabinet.
Grounding: A local ground rod is connected to the PEN busbar in the meter cabinet.
PEN-Split: The PEN is split into separate N and PE in the main distribution board before the Quattro II.
Quattro Connection: Fed with L, N, and PE.
Observation: I noticed that AC 2 L-in and AC OUT 2 L-out are bridged with a cable on the inverter.
I need to confirm the following for safety verification:
Back-feed Protection: When the grid fails, does the Quattro II guarantee physical isolation of both Line and Neutral from the grid, ensuring no voltage is back-fed into the PEN conductor?
Island Mode Neutral Reference: Since my PEN-split and ground rod are located upstream (in the meter cabinet), the Quattro loses its Neutral-to-Earth reference when the internal back-feed relay opens. Does the internal “Ground Relay” correctly create a new N-PE link on the AC-out side to ensure RCDs still function during island mode?
Correct Wiring Logic: Is it correct to have the ground rod connected to the PEN at the meter cabinet rather than at the Quattro, or does this prevent the Quattro from safely isolating the system during a grid fault?
I want to ensure that the installer has configured the system correctly.
Thanks for your previous response. I have attached a simplified schematic image of my system (the physical installation).
To clarify one part of my question: You mentioned that the bridge between AC 2 L-in and AC OUT 2 L-out “should not be”.
My main question is: Does this specific bridging (marked in the image) affect the Quattro’s ability to guarantee a complete and safe physical isolation from the grid during a power outage (LOM)?
I am worried about whether it bypasses the internal safety relays intended to prevent backfeeding to the grid.
Your schematic shows completely different points of connection. Which of the two is it?
Besides, both are not correct, ACin and ACout should not be bridged.
Your schematic shows a bridged Neutral, this means whatever the Quattros state is, on-Grid, on-Genset Island, Off, the Grids Neutral is permanently connected to the ACout.
Before removing the bridge and testing the internal earth bond relay, make sure the relay is set to automatic/enabled, switch off all loads and do an isolation and earth resistance test, just to make sure this bridge is not there to patch some other defect/bodge (internal earth bond relay could have failed at some point in the past). If in doubt, let a certified electrician do the testing
Attaching a picture of the bridge. So you can see what I’m trying to illustrate and describe. As I am not the installer but an electronic design engineer, it does not look correct to me. Because it bridges some of the internal relays for the LOM…
This is a new installation… The RCD on the backup generator is tripping when it connects. The installer just instructed to bypass it the genset
I dont see a bridge on the neutrals, theres one wire in each neutral clamp. Or is the viewing angle covering it?
Seems like they did not read, or didnt understand, the manual. The bridges on PE are unnecessary, not safety critical, but shows a lack of knowledge. All PEs are internally bridged already.
However, a potentially safety critical issue would be that your main earth bond seems to be the PE conductor of the grid cable. It doesnt look like theres a second conductor connected to the stud on the right edge of the picture. Thats where a separate earth conductor is supposed to connect to. I would not want my system running on genset, because the grid failed, to still rely on the grid cables PE. But depending on your local regulations it could be allowed.
If there is said neutral bridge between ACin and ACout then that would be the cause of the gensets RCD tripping. Disabling/bridging an RCD because it trips is not a solution, its another bodge. And at this point you should ask your installer what kind of qualifications they have. Clearly nothing electrical
The problem I have is that my installer is not giving me a clear technical answer. That’s why I need some help to get a better understanding.
Is the picture better now? Showing the bond cable between the AC out and the AC in? Only one L goes to the breaker panel and one to the genset. (left port)
This bypasses the relays circled in red and could also influence the operation of the green circled relay, depending on the state of the other two relays.
I need a clearer understanding of whether this is correct and, if it is not, what the correct implementation should be.
I guess thats part of the confusion above. Your saying they used only the L or phase of the ACout wire and bridging the neutral?
Its a very confusing wiring, i dont understand why someone would combine that. ACin 1 needs its own cable and thus its own neutral. ACin 2 needs its own cable and thus its own neutral. ACouts 1+2 you could combine into a single four core cable (L1NPE hooked up to ACout1 and L2 to ACout2 to save on a bit of cabling).
Whatever way you look at it, ACout neutral need to be separate from the ACins.
In my opinion, yes. This bridge bypasses the neutral isolation provided by the Quattro. In the unlikely event of a L/E short in your system, this could cause the incoming neutral to have a brief energy spike on it, which possibly could cause an issue for someone working on the incoming line.
Unlikely I know, but the protection system is designed to prevent this type of issue. Victron don’t put (double) relays in for the fun of it, they are required to meet the standard. These are also (internally) tested for operation during the start up, so bridging this will cause problems.
