I run a three-phase system consisting of 3 MultiPlus-II 5000s and an MPPT 450/200.
The main distribution board contains a Kraus & Naimer KA63B.T904.F437 changeover switch (mains/backup supply). I’ve wired its two auxiliary contacts in parallel to the 3 MultiPlus remote inputs to prevent switching under load. There is also an emergency stop switch connected to the AUX2 input of the MultiPlus master, which can also switch the system via the “Safety switch” assistant.
Question: In case 2, i.e. when the emergency stop switch is activated, I’d also like to switch off the MPPT. Should I do this with an additional normally closed contact in the emergency stop switch and the MPPT’s remote input, or is there a better way?
Ideally, I’d always like to switch off the MPPT whenever the MultiPlus units aren’t running or fail, whether due to a manually switched situation (see above) or a fault. That would require an additional scenario — but what would that be?
I wouldn’t simply connect the three remote inputs on the Multis in parallel. They have a control voltage on them. It should actually be enough to control just one of the Multis.
I simply used several normally closed contacts on the emergency stop switch to isolate the potentials.
I got the idea of using 3 parallel remote contacts from Jörg (meintechblog.de), during the discussion about the neutral contact on the 4-pole Hager changeover switch not switching ahead of or behind the other contacts. I’ve been running it this way for 2 years, and it’s been tested. I’m happy to try using only the master’s contact as well.
Why should the MPPT be switched off if there’s a problem with the MultiPlus?
I also don’t think it’s necessary to switch off the MultiPlus using the bypass switch.
When do you actually switch that off? Usually when there’s a problem with the Victron system, and in that case it’s already off anyway.
Or for a FW update, but the Multis have to be switched on for that, so you’d always have to switch the bypass for the bypass as well.
An EMERGENCY STOP might make sense, but even then I always wonder what kind of emergency would be helped by switching off the MultiPlus/MPPTs…
Perhaps I really do think about the system too theoretically to come up with ideas like that. My systems are packed quite compactly into a 19" rack (including the door and so on), which makes it almost impossible for me to reach the built-in on/off switches. Hence the thought of moving this function somewhere more accessible on the outside. As for the MPPT, it’s only just occurred to me what would actually happen if the MP II cluster shut down, the batteries were—as they almost always are—at 100% SOC, and the MPPT still had 11 kW to deliver at that moment. Obviously, if the GX units are working, the DVCC limit should (hopefully) kick in quickly, but I haven’t actually tried this out yet. On the other hand, I don’t know of any large electrical installation that doesn’t offer several ways to shut it down, both in software and in hardware. I’m not keen on relying solely on parameter tweaks—especially when things are already crackling quite loudly.
I have an emergency stop with two normally closed contacts. One trips the PV isolators in the attic, and the other switches the “Safety Switch” assistant on the Multi L1. I also wanted to have a switch somewhere away from the system.
The auxiliary contact on the changeover switch doesn’t make sense to me.
Without using the auxiliary contacts, the Victron cluster would be switched onto AC Out under load. There’s a break in supply during the switchover anyway, so I can switch off the Victron system beforehand and switch it back on in the ‘Emergency Power’ position — and vice versa. Saves the relay contacts and my nerves.
My emergency button has a contract for inverter like you did.
Another contact to break the enable pin of my mppt.
I also have a shunt trip breaker on the pv side of mppt that trips as well.
Shunt trip breaker is probably more then enough but I built it in steps.
I see this as an easy-to-implement feature that would provide a central off switch that anyone can find. Sure, you can do it with the three existing microswitches, but try finding those in a hurry. And the bypass switch is solely there to provide a second way to activate the MP’s when they’re switched off (for example, during the occasional work on the de-energised HV, so you can still use the inspection lamp or …). Please don’t bring up the battery-powered lamp as a counterargument — chances are its battery will be flat anyway!
