# Auto changeover relay for inverter



## Techno100 (Oct 5, 2012)

First picture is a selection of relays from RS components. The one on the right is my choice as it is 10 amp rated through the normally closed contact set which will be used for the inverter when off hook up.
The normally open contact set is 30 amp rated and will be used to power a skt/skts as normal when on hook up





I've mounted the relay in a "really useful box" and fitted a 25mm thread stuffing gland big enough to grip 3x1.5mm flexes all together







Power IN flex lugged up to go on the N/O contacts and the 230volt relay coil




Power out connected to the common pair of terminals and inverter feed connected to the N/C terminals














All that remains is to customise the flex to required lengths 
fit a 13 amp plug top to the inverter feed but with a 10amp fuse!!!
Fit two pairs of 10 amp rated connectors being careful to fit the female halves to the ends that will be live i.e. the flex from the 10 amp breaker that you are going to cut that normally feeds the skt and the power out lead from the changeover.
The male ends go on the feed in to the relay box and the other part of the flex cut earlier that continues on to the socket.
230 VOLT 10 AMP 3 PIN IN LINE COUPLER CONNECTOR PLUG/SOCKET MALE / FEMALE WHITE | eBay
Now I just need an inverter, probably a 1.8K for my needs but I'll see what's on special.

I've already been using this setup with the other relay in the first picture but with a 350watt pure sine inverter for the entertainment and gizmo charging area "lounge"


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## Bigpeetee (Oct 5, 2012)

Here's a circuit of how I did it.


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## Techno100 (Oct 5, 2012)

Lighting is 12 volts already so no point running an inverter unless power is required?
Surely its better to use hook up to power the relay coil no matter how small.

My modus operandus is
The socket radial circuit is now routed through the normally open contacts of the relay, as soon as the hook up is made this makes those contacts close to feed the socket as normal.
Without hook up you just switch the inverter on and the socket is now fed through the normally closed contacts of the relay


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## Techno100 (Oct 5, 2012)

I started out some long time ago by copying Clive Mott's auto changeover system which used a contactor. Unfortunately this has an annoying hum while ever on hook up.
The search for a suitable QUIET relay took some time and I believe I struck gold with this latest offering


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## shortcircuit (Oct 5, 2012)

I have a simple silent but non automatic system.  The output from the inverter is fed to a single socket adjacent to the consumer unit.  I cut the feed to the consumer unit from the hookup input and wired it to a second socket mounted adjacent to the first socket.  A 13A plug is attached to the other side of the hook up cable that feeds the consumer unit.  When on hook up it remains on the mains socket and when on inverter moved to other socket.  Fortunate that the consumer unit is accessible so change over is easy but I can understand using relays if remote.  To be honest I very rarely use the system and should take it away to reduce complications.


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## Techno100 (Oct 5, 2012)

It's all worth it to run this by doing nothing more than turn the inverter on

Panasonic microwave integration project.
Cupboard over sink/drainer selected as most suitable cleared out,door removed,opening increased to unit dimensions and 130x30mm vent fitted through wall.
Trailing lead made up and installed in mintrunk down to extra socket fitted back to back with sink socket in previous project.








timber stringer fitted 87mm off outer wall for microwave support positioned so back legs fit between stringer and wall thus holding it in the cupboard.
strip wood surround made to support and hold front.




Unit fitted and trim fitted with stainless screws and cup washers.












Trim notched for door hinge




Because of the loss of a cupboard I had to scrap the wine & glass cupboard fitments and modify the crockery cupboard to accomodate glasses too.
From this to that


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## ellisboy (Oct 5, 2012)

Nice work Chap ! :banana:


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## Techno100 (Oct 6, 2012)

80p Asda container upgrade


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## Techno100 (Oct 6, 2012)

Ready to go


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## Techno100 (Oct 7, 2012)

I've had some questions so I've elaborated on the installation

Side locker floor removed and there is the flex from the mains board coming up through the floor and on its way to the nearside kitchen sockets




I managed to obtain spare length by re routing the converters choice of cable run.
Fit the 10amp through connector Female to mains side male to socket side




unit plugged in between the open ends




No holes to drill in my case, feed from inverter flex passed through gap into vicinity of batteries.




Plugged into my 350watt inverter just to test




Microwave lights on 




Kitchen sockets live




When my new inverter arrives it has 2 sockets so the 350watt could be redundant.


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## Techno100 (Oct 14, 2012)

My new Sterling 1800watt Quasi fitted and working. Microwave has no problems and drain on batteries is surprisingly low


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## Ggohd (Oct 21, 2012)

*Round in circles*

What occured to me was that if I hard wired my inverter into the van, with relay, changeover switch, or whatever, then I would still have the problem of the battery charger being powered up, which would then try to charge the battery supplying the inverter. I use a separate socket for the inverter and put up with the inevitable trailing lead.
My external power already comes through a convenient socket next to the consumer unit, but the above put me off installing a socket fed from the inverter and changing over the plug from the vans circuits.
One solution would be to get a backup power inverter and disable the existing charger, therefore allowing the clever circuitry in the inverter to cope with the charging and changeover issues. But they cost a lot.


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## Techno100 (Oct 21, 2012)

Mine doesn't do that 
It feeds the sockets not the charger


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