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Double wound safety transformer for EV supply.

SL1
Hi everyone, I have only posted once before so thanks to anyone who replies!


I am following on from the earlier "70 volt PEN conductor not allowed to exceed post", and looking into supplying a client with an electric vehicle power supply from a three phase isolating transformer BS 7671 722.413 (1.2): " The circuit shall be supplied through a fixed isolating transformer.."


The general consensus seems to be that an external IP box with an RCD (Type B) and a tethered lead is the standard to follow, and this may be the only option with a 230 volt domestic supply, but why not use a 3 phase 400 volt step down or tapped, safety double wound isolation transformer in a standard 100 -200 ampere or above industrial units/sheds?

( Subject to load and diversity).


The answer often stated when I have asked sparks/engineers is that in-rush current are too high but a type D CB BS 60898 will 'let through' the in-rush ( the transformer manufacturer agrees), and will still give at 5 seconds- (final circuit exceeding 32 A) 0.44 ohm EL ( 10oC) , so is achievable in many situations local to Birmingham.


I was then going to run a fused cable out to an external isolated IP 65 box with a Type 2 socket to IP44 or above ( 722.55.101).


Isn't it better to engineer a solution to the upcoming electric charger deluge, rather than buying (insert well known manufacturer name here), and lots of single phase loads usually dumped onto L1?


I would be interested in any thoughts or problems you may consider....





Parents
  • 0

    SL1:

    Thanks Andy,


    What you say is true, most sparks/engineers have seen damaged sockets where kettles or heaters have been used at close to full load. The results are usually just damaged sockets but house fires kill as well as electrocution, and overloaded extension leads could lead to both.

    We are after all dealing with unskilled persons, and as Zoomup's newspaper articles show, accident are already happening.

    Surely it should be the case that "charging from a 13 A mains socket in your home" should be just outright stated as not possible/safe to the domestic consumer.


    I can just see the extension leads across the footpath of the rows of terraced houses now.....



    Thanks


    Simon.

     




     

    As EVs become more popular, there are going to be more occasions when people want to charge off a "granny lead" when visiting other people (that's where the nickname comes from).


    These leads usually limit the charging current to 10A, so the heating should not be excessive.  If we say that people shouldn't be plugging appliances into 13A sockets, where will it end?  No kettles, no lawnmowers?  The whole point of a 13A socket on an RCD protected ring circuit is that unskilled people can plug things into them.
Reply
  • 0

    SL1:

    Thanks Andy,


    What you say is true, most sparks/engineers have seen damaged sockets where kettles or heaters have been used at close to full load. The results are usually just damaged sockets but house fires kill as well as electrocution, and overloaded extension leads could lead to both.

    We are after all dealing with unskilled persons, and as Zoomup's newspaper articles show, accident are already happening.

    Surely it should be the case that "charging from a 13 A mains socket in your home" should be just outright stated as not possible/safe to the domestic consumer.


    I can just see the extension leads across the footpath of the rows of terraced houses now.....



    Thanks


    Simon.

     




     

    As EVs become more popular, there are going to be more occasions when people want to charge off a "granny lead" when visiting other people (that's where the nickname comes from).


    These leads usually limit the charging current to 10A, so the heating should not be excessive.  If we say that people shouldn't be plugging appliances into 13A sockets, where will it end?  No kettles, no lawnmowers?  The whole point of a 13A socket on an RCD protected ring circuit is that unskilled people can plug things into them.
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