Auto changeover relay for inverter

Discussion in 'Tech/Mech General' started by Techno, Oct 5, 2012.

  1. Techno

    Techno Funster Life Member

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    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
    [​IMG]
    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
    [​IMG][​IMG]
    Power IN flex lugged up to go on the N/O contacts and the 230volt relay coil
    [​IMG]
    Power out connected to the common pair of terminals and inverter feed connected to the N/C terminals
    [​IMG][​IMG]
    [​IMG][​IMG]
    All that remains is to customise the flexes 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 carefull 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.
    http://www.ebay.co.uk/itm/230-VOLT-...l_Electrical_Fittings_MJ&hash=item4d0458b589#
    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"
     
    Last edited: Oct 5, 2012
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  2. scotjimland

    scotjimland Funster Life Member

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    neat installation .. :thumb:

    a schematic diagram would handy for those who are less knowledgeable .
     
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  3. Techno

    Techno Funster Life Member

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    Thanks
    There is enough information there for anyone competent to undertake the task if they find it useful. The pictures of the relay have a contact schematic :thumb:
    No have a go hero/heroines please :Doh:

    The 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
     
    Last edited: Oct 5, 2012
  4. scotjimland

    scotjimland Funster Life Member

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    fair comment..
    but it wasn't for my benefit, with over 45 years electrical and instrumentation experience, I'm more than capable.
     
  5. Techno

    Techno Funster Life Member

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    Good lets keep it that way :thumb:
     
  6. Techno

    Techno Funster Life Member

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    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
     
  7. pappajohn

    pappajohn Funster Life Member

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    what's an INERTER please :Laughing:
     
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  8. vwalan

    vwalan Funster

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    sshh .you werent supposed to notice that . sonly a smelling pistake .ha ha ,.
     
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  9. Techno

    Techno Funster Life Member

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  10. Wildman

    Wildman Read Only Funster

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    Its a non working (Inert) inverter
     
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  11. Techno

    Techno Funster Life Member

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    Absolutely as I've not bought it yet :Cool:
     
  12. hilldweller

    hilldweller Funster Life Member

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    It has the potential to go pear shaped if your inverter cannot supply the same current as the mains hook-up.

    How is it for reverse polarity ?
     
  13. Techno

    Techno Funster Life Member

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    :Rofl1:
    It's double pole so no different whether it's fitted or not

    If you read my guide it is limited to 10 amps by the fuse you fit in the plug top.
    Inverters also have their own protection against overload and undervoltage.
    Personally I'm not looking to supply 10 amps just my microwave occasionally and 1000watt hairdrier whether she like it or not
     
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  14. Techno

    Techno Funster Life Member

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    [​IMG]:Doh:
     
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  15. vwalan

    vwalan Funster

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    hi techno those other inverters may take a remote .certainly the ring one can . one of my mates put one on his . just plugs in .
     
  16. Techno

    Techno Funster Life Member

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    Cheers Al
    My 350 watt inverter has no remote but I installed it next to the batteries under the lounge seat and drilled a 25mm hole in line with the switch. I just give it a poke when we want power to the away from home entertainment devices :BigGrin:

    [​IMG]
     
  17. vwalan

    vwalan Funster

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    i mounted mine on the upright of a seat unit then i can sort of monitor the lights . plus its got a chance of more air passing over it . my mate hid his away and contacted ring and got the plug in remote bit .
    i keep saying i will get a smaller one but never do.
    its handy if you cam switch it off if it starts squealing in the night in darkest winter.
     
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  18. hilldweller

    hilldweller Funster Life Member

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    Probably faster than your fuse.

    But the point is, if you have 3kW load and 1.8kW inverter, you are boiling your kettle, mains goes off followed by "clack", whine, nothing. It's a good plan but with a built in gotcha.

    Even if you did it properly, 3kW inverter there is still a gotcha, kettle is boiling mains fails, kettle keeps boiling but not for much longer and all the lights go out.

    This business of 240V in a motor home is one big can of worms. One sure solution is no 240V inside.

    I'm just rambling on, frame of mind of someone designing this into a new MH, because someone is bound to say "They should build that into all of them".
     
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  19. Techno

    Techno Funster Life Member

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    You simply have to know your limitations? we never have a 3kw load even on hook up even in winter.
    Kettle is always gas
    Yes I have Gaslow but no gas microwave yet lol.

    Yes it is feasible to fit at source but vans are complicated enough for dealers already to cope with what everyone expects.
    I've designed this to be transferable as we're changing vans before long but it will be our final van and I'll do a more permanent job in the Rapido
     
    Last edited: Oct 5, 2012
  20. vwalan

    vwalan Funster

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    yes it would be nice .when i first did my trailer it was built not to use alot of leccy . but as solar came down plus i realised a gas fridge didnt work in the hot climates i changed to 240v . still cant put up with the 12v ones . my inverter etc really just runs the fridge . ,food mixers ,washing machine and the computer.
    but will power drills etc if need be .
    i still say gas lights use less leccy than led,s .
    i did fit a ehu .but have never used it except for during the build . never use sites so indepancy is the way
     
    Last edited: Oct 5, 2012
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