I have a Victron Multiplus 2 3000W inverter charger. What overvoltage protection is there on the AC input? Can it handle a phase fault from the grid where the neutral is swapped with a phase, resulting in 400V on the input?
asked
Multiplus 2 AC input overvoltage protection
I cant answer that, and I suspect nobody will commit, just don't do it... What scenario do you think would cause that in the first place?
In general, and I am not saying this is true for a Multiplus specifically, an AC input will have MOV's, and or TVS diodes, often with some form of current limit, which are designed to cause a big enough fault to open the external overcurrent protection, MCB, fuse whatever.
I do know that the Multiplus has a ground relay that can connect the N&E inputs together where TT operation is not the required earthing scheme and the MP will operate with the AC input disconnected, which would remove this external current path. AC is AC, the neutral is only defined / configured when one side of a generators/inverters output is referenced to ground for a none TT system.
I will say again just, DO NOT DO IT or even let it happen by mistake, connect the thing properly, ensure you know what system you are using and make sure that you have adequate final circuit protection in place...
BTW Also be careful of connecting a current limited source to an existing circuit... It is entirely possible that the existing overcurrent protection will fail to operate, or operate way too slowly, because it was designed to have a huge PSC available from the supply.
I am pretty sure you shouldn't be using a small inverter to run any circuits that are not designed as a TT system and also have adequately large cables and fast MCB's fed from an RCD or better yet RCBO's of the correct type!
I cant give you specifics, and wouldn't anyway, without full details and a way better understanding of your skill/knowledge level.
Be very careful, or better yet get an electrician involved.
Your question worries me to be brutally honest! Sorry...
I am supposing the OP wanted to know if it would survive if this situation arose for reasons beyond his control.
As I recall the Multi 5k is fitted with MOV varistor type devices across the incoming supply but they are quite small, about 20mm dia.
I would not rely on them to protect in this situation, if I were worried it might happen I would fit much bigger industrial devices externally so if the worst happened (a) it would be more likely to protect the inverter (b) I wouldn't need to replace them afterwards and (c) it would be easy to do so if necessary. A close-rated circuit breaker would also reduce the let-through I2T, or a quick blow fuse.
HTH. There was a similar thread a few days ago but I can't find it now.
That's a fair point, and not one I considered. For that to occur the DNO would have to pitch up at a transformer, deenergize it, physically swap the cables, fail to test it and then call for it to be reenergized. If the system wasn't TT it would immediately take out the cutout because the N-E link would be between a phase and ground. If it was TT then the outcome is less clear but I suspect a crispy inverter would result without eternal over voltage protection backed up by a very fast disconnect... So crispy! I probably could have been kinder, I just worry when someone who doesn't appear to have grasped the basics asks about a high energy death machine. I am sure if I had engaged with the implausible scenario someone would have suggested that was a poor plan too, and they would have been correct as well.
I don't want to here about someone who crossed a wire because they didn't know how to check first and destroyed an inverter or worse, killed themselves. I genuinely didn't consider the DNO sabotaging the entire sites supply!
I will be more careful, or at least try to be more diplomatic, your opening comment being a good example of that :-)
Agreed, the OP writes from Denmark and does say grid. However other interested readers may be from countries where supplies are less well organised than in Europe, there are many Victron setups in SA for example.
Sometimes supplies are even tapped illicitly off overhead lines where this could easily occur. Or from a mis-wired 3-phase connections to a generator in the field. You might be reliant on others getting it right e.g. at a pop festival.
Have now found this link, at least my own advice is self-consistent <g>. It would be interesting to know if there are any tried and tested solutions out there, but no one has weighed in after 6 days now!
Others have commented here on this forum that double the rated voltage will damage the AC input. I assume that would be the case for the 170% voltage resulting in a floating neutral on a 3-phase system.
Floating neutral is probably one of the most damaging failure modes in 2- and 3-phase systems. You need tosense over voltage on a leg relative to the neutral going into your devices and disconnect the hot leg (or both hot and neutral). The disconnect needs to happen VERY quickly to prevent damaging voltage from reaching the device.
