I understand that I would find this info in norms listed in device specification but maybe someone knows it from top of the head ? Thanks.
asked
What overvoltage situations on input (grid) MultiPlusII can handle ?
The inverter has an upper and lower cutoff limit at which point it rejects grid and inverts. You can adjust these. Have a look at Victron connect app demo library. Choose the multi and look at the grid tab in settings. It shows the default limits.
I'm asking about anomalous situations like 1,5kV or 6kV or some insane impulse.
Nothing happened yet I'm just trying to overdesign protection :-)
Goodness, I doubt it would enjoy that very much. Obviously it will do its best to isolate itself but I reckon you would need some external protection for those size problems.
AFAIR devices that connect to grid must fulfill protection requirements. One of them is rejections of overvoltage. For example common Switched power supply should survive (without damage) 1.5kV. I'm simply (not trusting electricians :-) ) trying to protect inverter from grid anomalies. I'm designing circuit for free standing house with full lightning protection installation. Part of it is surge arrester T1/T2 which is mandatory nowadays. Provider's box has B 32A overcurrent and I plan B 25A in front of three MultiPlusII 5 or 8kVA units (three phase setup). I know what needs to go there (norms) but I struggle to verify what's best and what I should worry about. My next question will be what kind of damage I can expect if things go wrong and if I can stock (which) parts to be able to quickly repair it.
The best way to be safe from the grid hard core anomalies is to be OFF-grid and use grid only for charging the battery when needed. When unthinkable happens only charger gets damaged.
Are you trying to prepare your system for the "perfect" polish grid? :)
Usually SPDs on AC are selected based on lightning for the area etc - Electrical Risk assessment tables etc. So check up lightning strike density and local regs if possible for that. The truth is sometimes you can get away with it sometimes nothing will stop it.
I cannot answer for the Mutli 2s but I have seen systems that have had lightning strikes nearby and direct to overhead lines with Quattro and the older multi plus units.
The transformer internally does offer some advantage to slowing current through for transients.
One system the strike was pretty devastating, Quattro destroyed but appliances downstream were fine. (the cable from grid to the house had been totally vaporized) So I don't think much would have helped there.
The second was a strike near my own system. We knew it was going to be an issue so had actually disconnected the main breaker to the house- multi was fine but we did have enough of a transient through the system (must have arced over the open breaker) that made a light switch catch on fire and we had to replace some cabling there (no breakers tripped). Mutli still working 2 years on. The EMP was close enough to cause all electrical equipment to switch off (even tvs an battery BMS) Needless to say we upped the SPD to type 2 added fusing and and have type 2s on A C- then did one better and switch to the Inverter RS so off grid now.
but as has been said - best way to be safe - don't be connected.
Gold standard is fusing and SPD type 1 at main incoming szing based on your incomer breaker among other things. SPD type 2 a little closer to equipment.
There are three components approx 20mm in diameter just next to the AC connection block of the MP II-GX 5k. These look like ZnO varistors connected in delta L-N-E for overvoltage protection. My Steca PV inverters have a similar arrangement.
These would be the first thing to go in a overvoltage situation. It might be worth identifying them and holding spares if you are worried about possible damage.
