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Connectors for 200V dc

davidwalker2
I have an installation that uses 200V dc (balanced about earth but not earthed). All the installed equipment is direct wired, but I have an application that needs a plug and socket.  I don't want to use the standard connectors that are also used for ac to avoid ac equipment being plugged in inadvertently.  The equipment in question will draw a current around 8 amps and is metal framed, not double insulated so needs an earth.  I would be grateful for any suggestions/ advice.


I am sure that this has been discussed previously, but I cannot find it on the old forum.


Many thanks,


David
  • 0
    I guess the "correct" answer (according to standards) is a BS EN 60309 2 pole + PE connector with the earth at the 3h position (in white) -  which is specifically for 50-250V d.c. Where you'd source such as beast from I've no idea though (I don't recall ever seeing such a thing even in a catalogue never mind real life).


    Failing that perhaps one of the old-fashioned systems (BS 196 or similar vintage) as long as it's not interchangeable with anything else on site.


       - Andy.
  • 0

    AJJewsbury:

    I guess the "correct" answer (according to standards) is a BS EN 60309 2 pole + PE connector with the earth at the 3h position (in white) -  which is specifically for 50-250V d.c. Where you'd source such as beast from I've no idea though (I don't recall ever seeing such a thing even in a catalogue never mind real life).

     




    Based on your reply, I did a quick internet search and at least found them in a catalogue (page 93)….  http://www.farnell.com/datasheets/1514435.pdf 

  • 0
    Many thanks for your replies, and for the Farnell information - I didn't realise it was so complicated!  So, having identified the "approved" connector, I cannot find anywhere to buy them, they do not seem to be in the (UK) Farnell catalogue.


    An alternative I have had suggested is to use a 16A 3-pole Schuko plug and socket.  It is a controlled, industrial situation, and we do not have any equipment on site that uses continental-style connectors, they are readily available and cheap.  Any thoughts?


    David


  • 0
    Apart from the dedicated DC CEEFORMS that look hard to find, almost any modern socket outlet including schuko or other continental types will be marked "AC only" I might be inclined to look for an old type BS 543 15 amp 3 pin outlet. Preferably a N.O.S. unit with a built in switch rated for DC.


    The matching plugs are still available but  not too readily which will discourage improper use. Mark it clearly, the youth of today tend to think that DC means a very low and harmless voltage as from a small battery and might suffer accident with a mains level DC supply.
  • 0

    davidwalker2:


    An alternative I have had suggested is to use a 16A 3-pole Schuko plug and socket.  It is a controlled, industrial situation, and we do not have any equipment on site that uses continental-style connectors, they are readily available and cheap.  Any thoughts?


    David


     




    Perhaps a little caution using the Shuko plug ... many standards for equipment that we use for mains are specified for AC applications only (some are also not specified for ELV use). This is certainly the case for the BS 1363-series.


    More information on suitability of some of the "usual" accessories standards and their suitability for DC applications can be found in the following FREE publication from the IET: https://www.theiet.org/publishing/iet-standards/built-environment/practical-considerations-for-dc-installations/

  • 0
    I would avoid the Schuko if possible, you may not have anything else on site that fits but a visiting European may find it the perfect place for his/her Europlug wallwart charger. Probably ok if it is a switchmode unit, not ok if it has a transformer.


    A few years ago Conrad, a German Maplin/RS, was offering BS1363 plugs and sockets for 12V caravan use. Ok until you holiday in the UK.


    Best regards


    Roger
  • 0
    Again, many thanks for your replies.  The Guide recommended by Graham is very useful and addresses many things we have needed to resolve over the years.  Unfortunately it rather cops out on the connector issue, stating that “the standards required by this legislation [Plugs and Sockets (Safety) Regulations] restrict the use of general-purpose socket-outlet circuits for currents of 13 A or less operating at LV d.c. in relevant parts of electrical installations.”

    For information, on our site the main dc source is a 200A mercury arc rectifier (see my avatar) backed by a lower power solid state supply (40A).  Fuses are BS88 dc types, disconnectors are heritage (1928) open frame, and a couple of modern dc contactors.  Our major problem has been wire colours, red/black on the oldest heritage cabling, brown/blue on later heritage modifications.  We have chosen not to introduce a third combination, the current standard brown/grey and rely on separation, clear labelling and a competent expert workforce.


    David

  • 0

    davidwalker2:
    Again, many thanks for your replies.  The Guide recommended by Graham is very useful and addresses many things we have needed to resolve over the years.  Unfortunately it rather cops out on the connector issue, stating that “the standards required by this legislation [Plugs and Sockets (Safety) Regulations] restrict the use of general-purpose socket-outlet circuits for currents of 13 A or less operating at LV d.c. in relevant parts of electrical installations.”

    For information, on our site the main dc source is a 200A mercury arc rectifier (see my avatar) backed by a lower power solid state supply (40A).  Fuses are BS88 dc types, disconnectors are heritage (1928) open frame, and a couple of modern dc contactors.  Our major problem has been wire colours, red/black on the oldest heritage cabling, brown/blue on later heritage modifications.  We have chosen not to introduce a third combination, the current standard brown/grey and rely on separation, clear labelling and a competent expert workforce.


    David

     




    The intent of the statement about the Plugs and Sockets (Safety) Regulations is aimed at the use of DC in domestic and similar situations for general purpose use - this would perhaps require a change in legislation if widespread small power LV DC were to be used (as opposed to ELV DC)?


    Wire colours have changed again I'm afraid - and this has nothing to do with the Wiring Regulations (BS 7671). The latest edition of BS EN 60445:2017 (any conflicting standards have to conform by its implementation date in 2019) states that for DC systems:


    • L+ - Red (or Blue if it's on a 2-wire Positive Earth)

    • M - Blue

    • L- White (or Blue if it's on a 2-wire Negative Earth)


    Since the Technical Brief was published, ranges of couplers for DC use in data centres are now available. They are to agreed IEC standards too. I wonder whether these would be of use to you?
  • 0
    I'll look into the data centre couplers.  Do the wire colours apply to non-earthed supplies?  Probably academic as in our environment the white would quickly be grey!


    David
  • 0
    Yes, in an unearthed system
    • 2-wire: L+ RD, L- WH

    • 3-wire: L+ RD, M BU, L- WH


    Someone will post that BS 7671:2018 doesn't have those colours identified in Table 51, so you'll have to wait for Amendment No. 1 (if they are to be included in there ... who knows?) - however, if you look closely at the Corrigendum to BS 7671:2018, there is a Footnote to Table 51 which I think might serve your purposes if you wanted to use the BS EN 60445 colours in the near future. In any case, I guess it's a current British Standard that affords equivalent safety (provided there's no confusion in your installation - perhaps the BS 7671 required label "This installation contains colours to a number of different standards. Great care ..." etc. - or whatever the words are ?)

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