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Inverter/mains switching circuit

Discussion in 'General Electronics Discussion' started by Stevies205, Mar 21, 2017.

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  1. Stevies205

    Stevies205

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    Mar 21, 2017
    Hi all,

    New to this forum and very much a novice when it comes to electronics. I have designed a circuit for a camper van but am having issues somewhere. The aim was to provide the sockets in the van with 240v ac with a single switch to swap from the mains hookup 240, to the 12v powered inverter 240. I tested the circuit last night and the mains supply worked fine but on switching over to the inverter supply the inverter didn't initially power up, after a couple of seconds there was a reasonably loud pop and shortly after that the fuse supplying the 12v to the inverter blew too. Has anybody any suggestions as to what I have wrong? It is possible the inverter (a cheap Chinese thing apparently) has failed but it had been working for a short time previously as it has been tested seperately. I have attached a quick sketch of the diagram below.
    Thanks in advance
    Steve
     

    Attached Files:

  2. Bluejets

    Bluejets

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    957
    Oct 5, 2014
    Quite a few errors actually, some which could see your pushing up daisies. First is playing with mains supply. Second is the use of non-approved c/o relays. These must be seperate units AND mechanically and electrically interlocked. This is without even seeing how you have physically connected everything. You are very lucky if you don't get a visit from a local supply authority for connecting equipment to mains that could endanger one or more of their workers let alone one or more of your family or neighbours downstream. Totally irresponsible.
     
  3. Stevies205

    Stevies205

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    Mar 21, 2017
    Thanks for that. When I say mains supply I'm talking about a 16a supply from my workshop. What do I need to do to put this right then?
     
  4. Tha fios agaibh

    Tha fios agaibh

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    Aug 11, 2014
    Bluejets is right. You really need to be extremely careful here. This is not a project for a novice. Best advice is to consult an electrician that can calculate the load you need, properly size the inverter and battery bank, select the proper equipment such as a transfer switch, RCDs, fusing and conductors.

    I'd hate to see your camper van go up in smoke or have someone get electrocuted by one silly mistake.
     
    Bluejets likes this.
  5. Bluejets

    Bluejets

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    Oct 5, 2014
    An approved UPS would be a good investment.
     
  6. Stevies205

    Stevies205

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    Mar 21, 2017
    Yes smoke is always bad!!

    The inverter, consumer unit, rcd and breakers have all been given the ok by an electrician and a camper van specialist. The battery is just a standard 12v leisure battery as its only going to be running equipment such as phone and iPad chargers etc. the electrician also suggested the dpdt relay as the neutrals would have to be switched with the lives to enable the rcd to work properly.

    A ups looks like exactly the thing I need but I had a look around and couldn't seem to find anything suitable. Any pointers greatfully received!
     
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