Multi 01 | Grid lost alarm Node

[Logic28 (Mauro Andreini)]

In the Multiplus II-5000kva, is the Multi 01 |Grid lost alarm node supposed to emit the “lost grid alarm” (2) when the AC1in is not detected?

If so, does it respond to the actual ACin connector or does it take the reading after the AC1-in ignore point?

In other words, does the Ac1in ignore affect the output of this node in any way?

And does it take into consideration the second inverter in parallel?

I seem to get the “0” reading (ACin connected) at all times, even when I physically interrupt the gid.

[nickdb (Nick)]

Yes AC ignore and grid lost are related.

Grid loss will only be triggered when the multi is set to “on” and grid disappears.

If you set the system to invert only, it will always show ok whether grid is on or not.

You can instead try monitor for AC voltage.

[Logic28 (Mauro Andreini)]

@nickdb

If you set the system to invert only, it will always show ok whether the grid is on or not.

That is exactly what I did to create a log. I’ve had several instances of the grid RCD tripping inexplicably during nighttime charging. During the day, I run the system off-grid by activating the “ignore AC in”.
So I added a monitoring log in the Node-Red dashboard to keep an eye on it.

Thanks for confirming my findings, although I would love to know the philosophy behind the Multi 01| Grid Lost Alarm actions as you described them.

[nickdb (Nick)]

I can only suspect the logic is the way it is so that AC ignore/invert-only doesn’t trigger grid loss warnings.

It has been this way as long as I remember, so the use case must be for systems that are permanently grid-tied and don’t use AC ignore.

[Logic28 (Mauro Andreini)]

>>I can only suspect the logic is the way it is so that AC ignore/invert-only doesn’t trigger grid loss warnings.<<

That makes sense.

It is not clear if the Multi’s ACin double-stage relay is only intended for redundancy purposes or if one of the two is also used for the “ignore ACin” function

[nickdb (Nick)]

Purely redundant, they switch concurrently.

If one fails to switch the unit will fault and shutdown.

[Logic28 (Mauro Andreini)]

So the “Ignore AC in” acts on that main relay? But it can’t do. As can be seen by my dashboard, the presence of AC in shows even wen the ignore flag is on

[nickdb (Nick)]

Yes. Check the logic diagram of the inverter. You can see where the meter is located. There is nowhere else to disconnect AC. Same reason you hear the same relay tests on reconnect.

[Logic28 (Mauro Andreini)]

@nickdb

Check the logic diagram of the inverter.

I am familiar with this diagram, and that is exactly my point. I read AC in even when it is in the AC ignore state, so either there is a sensor before both relays (that would be the simplest way) or one of the two relay coils closes in the presence of AC in, and the other only when the AC ignore clears the flag ( but both can open if so commanded by the system for redundancy). After all, they are two independent contactors with their independent coils, following Victron’s diagram.

[nickdb (Nick)]

I don’t understand your issue.

Victron’s current sensor is before the relays, so will always read/display voltage even if the relays are open, this is how it can determine to reject grid or not.

The alarm is designed not to trigger if the relays have first been manually opened for AC ignore, but you can still write your own that triggers based on voltage present at AC in.

The grid alarm on the GX will only trigger if relays are closed and AC is lost. The alarm will also not clear if after grid loss you open the relays with AC ignore and grid subsequently returns.

Bottom line, you cannot rely on the grid loss alarm if you are using AC ignore or manually setting the system to invert only.

That is how it works and always has.

[Logic28 (Mauro Andreini)]

@nickdb

I don’t understand your issue.

Thanks, but let me explain.

Mine is not an issue, as I said before, I resolved that by using the Voltage IN (VAC) just like you were suggesting. It has always been in my mind though, to understand the mechanics of the double relay, nothing more.

Now that you confirm that the ACin sensor is before the relays, which also confirms my theory, that is over.

The grid Alarm I’m referring to is stated in the Victron VE.bus node as one of the data detection choices.

I cannot work happily with equipment that does not give me a full picture of its internal layout, and Victron does not seem to be too explicit about it, so I have to ask.

There are other concerns by the way, one of them is that, even though the Ground relay does exactly what it is supposed to do in terms of Neutral bonding on/off, what is not stated, and in my opinion should be, is that as far as I can see and measure, all PEs, grid an Inverter, are always in common regardless.

What I mean by that is that both the grid and the microgrid share the same ground and ground electrodes, which is a big no-no in the industry (unless solidly bonded, normally underground). Alternatively, in the event of a neighbour’s dwelling neutral supply failure, unintended alternative pathways like metal gas on water pipes would result in my PE becoming live.
I had to implement other ways of separating the two, according to which one is in use.

Again, thanks for your time in listening to my queries.