# Damaged inverters - how to prove a 208V system has been connected to a 480V source?

Hi.

We are having an issue with a customer. he rented a 208V-3ph unit from us and when the onsite technician hooked up the generator, he said the inverters blew up instantaneously and there was been some spoke going out of the unit from what they have told us. This is a unit with 6x Quattro 5kVA 120V inverters

The technician on site insist that the generator was switched to 240V 3Ph but I really suspect the generator was set up to 480V and that is why the inverters blew instantaneously. We do not want to start a fight with the client as it is potentially a big customer for us but we need to be able to prove that the fault is on their side. there is no alarm on the VRM unfortunately. My questions are:

- If a 208V unit is hooked to a 240V generator, can the inverters blow up?

- In case that doesn’t and the generator was switched to 480V, Is there any specific component that will only blow up at 480V that can prove this?

I will really appreciate some help on this. We have got 6 inverters damaged and this is an important client that we do not want a fight with but we want to prove them that this was due to a negligence

Thanks

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Justin Cook - Bay Marine Supply USA answered ·

There isn't any such thing as a 208v Quattro... it's either a 230v Quattro or a 120v Quattro, with both having a range of v acceptance - thus, a 230v Quattro can take 240v without issue, that sort of thing. But from what you say, it seems like you have 120v Quattros that are wired in parallel-split for 3 legs of 120v input and 3-phase output... is that correct? If so, and if they're wired properly, then 240 on the input wouldn't fry them by any means, because the input legs are being separated to 120v legs. Of course, if they're wired for parallel-single phase (ie, supposed to input 120v) then 240v input would almost certainly let out the smoke, though I will immediately argue that 1. the AC input breaker that you (I certainly hope) have installed at the main AC input should have blown, and 2. The surge arrestor that you (I certainly hope) have installed in the system should have blown.

Can you provide more detail as to how exactly these systems are assembled and wired, and for what input/output?

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Thanks Justin for your reply, I might not have been too clear explaining the issue, let me try again,. My system comprises 6x 5kva 120V Quattros connected in 208V three phase configuration, so two in parallel per phase in three legs.

If the generator would have been set up to 240V-3Ph (as the technician is saying), 240V Line-Line should be about 140V Line-Neutral. Then, I really doubt 140V or something slighly higher can damage a 120V inverter, but this is what he states. Bear in mind that I have not been in front of this when happened.

Regarding your comments about the breaker, as far as I understand breakers act because of overcurrent or overtermperature but not overvoltage, how can they prevent this from happening?. And, this system does not have surge arresters, this system is offgrid and for temporary power and never felt that I should install them. Do you think that installing surge arresters would save me from having this issue again if someone doesn´t select the right voltage on the generator? I would appreciate if you can expand on that.

A surge arrestor once saved me from blowing up a unit because of incorrect wiring (feeding 400 VAC instead of 230 VAC), they're not cheap..but can safe a lot of money.

Daniël Boekel (Victron Energy Staff) ♦♦

Sounds like a really good idea. I don´t know too much about SPDs, what Type do you think it is suitable for this application?

Daniël Boekel (Victron Energy Staff) ♦♦

Also, another question if you dont mind. In the case that for negligence, the technician has the generator switched to 480V and it keeps it power on, my understanding is that the surge arrester will end up blowing and the generator is going to keep working at 480V and damage the inverters because the SPD is connected in parallel right? are they not designed just for momentary surges such us lightning strikes? I am not sure if the spd will protect in this situation

SPD's are (AFAIK) -always- used behind a fuse or breaker that blow / trips when the SPD conducts.

please check local suppliers for suitable makes / models.