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Transfer Switch for Victron Multiplus 12/3000

Hi all,

I'm currently planning out my wiring for a van conversion and looking at getting a Multiplus 12/3000. As a newbie to wiring and someone who's British tendencies tend to make me quite modest, I'm damn proud at how confident I feel about electrics after the amount of research I've done. (Main thanks to the author of Wiring Unlimited.)

That being said, I can't for the life of me figure out how this transfer switch relates to van conversions. Most of the info I've read online seems to relate to fitting into buildings rather than vans. But even then I'm struggling to understand it as there seems to be a variety of uses.

What's more, after zooming in on other peoples videos and guides I can see there's roughly a 50/50 split between those who use the 50a and those who use the 16a. But frustratingly, they mention all the reasons and specs as to why they purchased the unit, other than talk about the transfer switch rating.


Is anyone able to explain in simple terms what a transfer switch is and what it will do for me in relation to a van conversion? Main things I'm worried about are blowing shore feeds when hooked up at campsites, or over/underpowering my systems.

That being said, my main source of power will be the 525w solar array I plan on installing as well as the Orion DC-DC charger feeding into 2x200ah Victron Lithium Smart Batteries.

Also while I'm here, in Wiring Unlimited it mentions creating a bypass switch for the inverter. (Section 6.6)


I can understand the reasons behind this. But firstly, it looks like a lot of people doing van conversions don't seem to bother with it. Secondly, how do you actually go about wiring this to connect to a comsumer unit?


mattestlea asked
gyzko answered ·

1 Answer

Configuring Multi II Internal Transfer switch

Having several MPII 48 x 5KVA systems, working in DVCC off grid configuration with Generator, when load exceeds Multiplus II 5 KVA Nominal Power, pex 10 KVA, and Power Assist is not able to achieve load demand (when SOC % is too low) is supposed that internal Power Switches should get into action connecting 10 KVA Generator ACIN to serve loads bypassing to ACOut 1 or 2 , disconnecting Inverter (but still allowing charging) , as Multiplus II 5KVA specs allow constant 11 KVA in this bypass mode (220 v @ 50 amps).

Question: is this behaviour description correct? has to be programmed or it is automatic ? How? Is there any link to understand how internal bypass switches work or programmed?

mito asked
derrick thomas answered ·

6 Answers

Filax Switch Hz selection


Just wondering if anyone would be able to help with a quick technical question or point me in the right direction.

I’ve just purchased a Victron Filax 2 automatic transfer switch. In Australia we run at 50Hz, however I’m finding the selection between 50Hz and 60Hz a little confusing in the Filax 2 manual from the website.

I’ve attached the relevant page here - Filax 2 - 50Hz to 60Hz selection.pdf.

The first point appears to make sense, suggesting if the frequency is 50Hz remove the jumper or place it on one pin. Also, that this is the default position from the factory, which all makes sense. The second point then states if the frequency is 60Hz place the jumper on both pins, again this all make sense.

However, the images below then go on to show two images with captions (Jumper placed = 50Hz ……………….. Jumper not placed = 60Hz) which I read as being the opposite to the two initial points above.

I may well have missed something so hoping someone can help me out.

bgk-contech asked
gyzko answered ·

1 Answer

LOM Detection

Some Multiplus advertising claims, that UPS transfer switching gap is below 20mS:


How can I use the internal LOM signal to switch off big optional loads by using external contactors ?

Is there a more detailed description on what the Multiplus Type A and Type B LOM Algorithms exactly do ?


janvi asked
Alexandra answered ·

2 Answers

safety of the VE transfer switch


Victron sells this single-phase automatic transfer switch. If you look at the second photo, the ATS is implemented by using a four-pole 2NO+2NC contactor (labeled K1 in the photo).

Poles 1-2 and 7-8 are NO. Poles R3-R4 and R5-R6 are NC. Victron connects line and neutral from the first power source (L1 and N1) to R3 and R5 and line and neutral from the second power source (L2 and N2) to 1 and 7. Then they obtain the output line and phase by connecting 2 with R4 and 8 with R6, respectively.

As long as K1's coil is powered the connected source is the first one. As soon as the coil loses power the second power source is connected. Pretty straightforward.

However, the most important characteristic of an ATS is that the two sources are NEVER paralleled, not even when the ATS fails. One of the possible failures of a contactor is when the two contacts of a pole meld together and can't open anymore.

What happen if, say, contacts 1 and 2 meld together? Under this kind of failure does K1 guarantee that its two NC contacts (R3-R4 and R5-R6) will stay open? (because otherwise the two sources would be paralleled).

One would think that the moving contacts inside K1 are all mounted on the same structure moved by the coil. This is certainly true when a contactor has all NO poles. However, when a contactor has a mix of NO and NC poles I'm not sure that that is necessarily true and it might depend on the implementation of the NC contacts.

I'm not aware (and maybe it's my lack of knowledge) of any standard prescribing that all the moving contacts have to be on the same moving structure also when there a mix of NO and NC contacts in the contactor.

Is anyone aware of any such standard? Because otherwise the only way this ATS is completely safe is if the contactor maker (Schrack in this case) guarantees the above property for the moving contacts.

jterrag asked

0 Answers

Battery Switch ON/OFF 275A for isolating 48V battery system

Is this switch actually suitable for use in battery systems up to 48V?

I have purchased a 48V 10kVA Quattro, a host of other Victron gear and numerous Victron Battery Switch ON/OFF 275A 48V switches to isolate various parts of the system. Victron datasheets and manuals say that this switch is "suitable for battery systems up to 48V". However, these documents also state that the voltage rating of the switch is 48V whereas a 48V battery system will see voltages approaching 60V.

Can anyone please clarify? If these battery switches are not suitable for a 48V system, are there any that are suitable?

alexs asked
gazza answered ·

1 Answer

Phoenix 12/500 - Countdown/timer switch on remote

Hi everyone !

I have a Phoenix 12/500 inverter and I would like to activate it with a countdown/timer switch like this :


Is it possible to connect it directly to the remote port ? and if yes, would you have a diagram on how to ? (i didnt find much information on the remote port in any manual or datasheet)

Would any of you have a switch of that type to recommand for a 12v system. I would imagine that it should be something with a low ampere usage, or ?

Thanks for you help !

vishnuh asked
vishnuh answered ·

2 Answers

How to automatically switch pv array from MPPT to Grid-tie inverter

First question on the forum so be gentle with me!


Recently due to rising UK energy prices I built an off-grid "Solar Generator" using a 405W panel, MPPT 100/30 charge controller, 24v/500W Phoenix inverter and DIY 7s10p 24V 18650 Li-ion battery... all worlking as intended. The battery is charged during the day, and its used to run appliances and charge things during the night.

I would like to use the same panel with a small G98 certified grid-tie inverter, so that once the battery is charged each day, the panel connections are automatically switched from the MPPT 100/30 charge controller, to the grid-tie inverter.


Can I use the TX port of the MPPT 100/30 to trigger some sort of 2-pole relay, that would allow the switching of the pv + & - from the MPPT CC to the grid-tie inverter once my battery is fully charged? Do I need to use a Smart Battery Connect somehow to make this work?

Any help would be greatly appreciated.

thomasquinn93 asked
raphael answered ·

1 Answer

Feature request: Allow Multiplus to be switched on&off from the VRM Dashboard

Hi there,

I'm using - and loving - the VRM portal, live controlling my installation (the new layout is great).

As I must spare any lost watt, I'm often switching on&off my multiplus C. Somebody knows if, in the future, it would be possible doing it directly on the main page, without opening the console?

That would be awesome !




denis70 asked
denis70 commented ·

8 Answers

Grid Fail Swith Multiplus II


My system is grid tied.

However, when the power fails, the inverter immediately turns itself off

After the grid is restored, it can take up to 4 minutes before the inverter starts again, during which time I have no power.

This is incredibly infuriating, but I am certain it is just a setting

other than that it works well

Any suggestions as to where to start.

Many thanks




dicspicspt asked
jm0278 edited ·

3 Answers

Remote switching on cerbo gx

Is there a way of using the cerbo gx to remotely switch a 12v fridge on so when we get to the boat it’s chilled down.
Or is there another way via the Wi-Fi on the boat.

Simon Coram asked
Alexandra answered ·

1 Answer

Automatic transfer switch

I want to add an AC sensing automatic transfer switch to manage the Main AC IN/Inverter AC OUT of the Multiplus II in order to take full advantage of ESS.

I noticed the VE Transfer Switch is meant for 220/230VAC. I'm using 120V AC in and Out. Can the victron transfer switch be used for 120 50A.

If not, what do people recommend. Preferably, I want to be able to carry 50A on a single 120 leg (wire cross-section appropriate.)

duswami asked
duswami commented ·

0 Answers

Main battery switch before Lynx distribution system?

I notice in the various Victron produced circuit diagrams for the Lynx system, they never put a main system switch before the Lynx distribution system/Lynx Smart BMS, however most actual people building seem to fit a physical switch between the battery and the Lynx.

Is there a reason why I should fit a physical switch?

I’m assuming people don’t like relying on the software controlled contactor In the Lynx Smart BMS?

Is this just aversion to change, or is there a good reason such as a regulatory requirment?


sweyn asked
sweyn answered ·

2 Answers

How to configure victron transfer switch

In the next phase of my victron setup I plan to order a transfer switch. In the preperation I try to finde documentation / configuration video / training video in how to configure the transfer switch.

In my setup I have a multiplus II with a battery and on AC1 OUT I plan to connect my entire electricity board and PV panels.

Whe the battery becomes too low, the transfer switch should switch back to the grid (PV panels should stay on the multiplus AC1 OUT)

I want to understand and know how to set this up.

rns asked
shaneyake commented ·

11 Answers

VE Transfer Switch - Auxilary Contact?

Anybody uses the VE Transfer Switch? I'm wondering if I'm reading correctly that you have an auxilary contact that enables you to switch power sources using another device? It's not automatic, correct?

taapo asked

0 Answers

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