Electrical Installation for DC power supply

Discussion in 'General Electronics Chat' started by DumbDummy77, Jul 8, 2010.

  1. DumbDummy77

    Thread Starter Member

    Jan 21, 2010
    43
    0
    Hi

    I am in the process of setting the DC power supply unit for the general use such as connecting the 20 units in parallel (Each draws about 6A) so the total current consumption would be 120A. At the moment my Power supply unit provides 200V @ 200A (40kW) for the output. It needs 3 phase AC input and I have noticed that there are three 100A fuses inside the circuit breaker module. Should it be more than 100A, say about 200A?

    Should I use 200A cable to connect the DC Power supply unit and connect the units in the parallel configuration with MCB?

    DD77
     
  2. timrobbins

    Active Member

    Aug 29, 2009
    318
    16
    I suggest the 3 fuses are for the input AC supply.

    You should indicate if the DC output is regulated (ie. are there controls to vary the DC voltage and current level), and does it have any over-current protection devices (fuse, cb)?

    You should also indicate what you are trying to power (ie. what is a 'unit'), and why you are powering the 'units'.

    Ciao, Tim
     
  3. Jaguarjoe

    Active Member

    Apr 7, 2010
    770
    90
    It sounds like you need a good industrial electrician.
     
  4. alim

    Senior Member

    Dec 27, 2005
    113
    1
    I fully agree with you . This project seems to be one which is beyoind his competence, he certainly needs a competent Industrial Electrician. The OP pursuing this task on his own can be dangerous to himself and surroundings.
     
  5. BMorse

    Senior Member

    Sep 26, 2009
    2,675
    234

    How can you assess someones capabilities by the type of questions he asked?? Does that mean everyone else can assume you have no capabilities either since you could not answered the question and you have to refer him to someone else? (Try using the spell checker also, then we would not get the impression that you have no skills or abilities to pay attention to detail...)
     
  6. BMorse

    Senior Member

    Sep 26, 2009
    2,675
    234
    You do need to supply a little more information on what you are trying to accomplish, and what the "units" are that you are trying to power.... you will get more attention to your project if you can provide this info....

    B. Morse
     
  7. alim

    Senior Member

    Dec 27, 2005
    113
    1
    I think your response is INSULTING. I DO NOT NEED TO USE SPELL CHECK TO SPELL BEYOND. For someone who has made 1631 posts I would ask you if you you have never made a mistype T he letters O and I are next to each other. This is NIT PICKING . You use WE,in your response are you speaking for others or for your self. I have a lot respect for the moderators and members on this site.I want to keep it that way.My sense is the OP is unfamiliar with an electrical system delivering 100- 200amps. You would have seen I endorsed the comments of the previous post, but you did not respond to that post. I have seen many posts with obvious spelling errors, and members just allow them to 'ride' . I am have a sound educational background, and am fully competent to express myself. I do not wish for this to be seen as a tirade, but for the benefit of Mr. BMORSE
     
  8. bertus

    Administrator

    Apr 5, 2008
    15,648
    2,347
    Hello,

    Please stop and wait for what DD77 has to say.
    The information provided is to less to give a good advice.
    Perhaps a schematic of the setup will help a lot.

    Bertus
     
  9. BMorse

    Senior Member

    Sep 26, 2009
    2,675
    234

    Slow your roll there pal.... I apologize if you were insulted by simple sarcasm..... which happens on here quite a bit... did not know you had such a fragile ego.... won't happen again..;)
     
  10. mcgyvr

    AAC Fanatic!

    Oct 15, 2009
    4,770
    970
    The supply wiring should be appropriate for the needs of the dc supply which is probably stated in the manual or on the nameplate. Also just because it is 200VDC @200A output does not mean the input to the supply is also 200A. There is a good chance those 100A fuses on the input side are too large also.. But without the details we don't know. I have a large 1000A (@48vdc) rectifier. The input requirements are 480VAC 3 phase at 41amps. The disconnect feeding that unit has 3 x 60A fuses for each lead of the 480v 3 phase. The input wiring should be rated at 125% of the fuse it is feeding. The fuse is not only for short circuit protection but is intended to protect the input wiring. So assuming your 100A fuses are correct (maybe your supply needs 480V 3 phase 80 amps max but we do not know) , the input wiring should be rated at 125A per leg min.
    The wiring on the output side (200VDC) should also be sized at 125% of your required load current. On my 1000A (@48vdc) recitifer I have a copper bus bar that I can attach multiple loads to. The bus bar is feed by the rectifier. If my load is 100A I typically use 2 AWG (or so) wire to feed the load. It is a good idea to size wire based on the National Electrical Code for the US using table 310.16 75degC column(or equivalent codes for your country). Simply take your max load current and multiply by 125% and find the appropriate wire size in the table that will support that current. The table also has derating for higher ambient temperatures too.
     
  11. alim

    Senior Member

    Dec 27, 2005
    113
    1
    Apology accepted, PEACE AND LOVE.
     
  12. timrobbins

    Active Member

    Aug 29, 2009
    318
    16
    "The wiring on the output side (200VDC) should also be sized at 125% of your required load current. On my 1000A (@48vdc) recitifer I have a copper bus bar that I can attach multiple loads to."

    I beg to disagree here. The wiring on the output should be sized for the overcurrent control or the over-current protection used in the power supply. Without knowing the character of the prospective current of the power supply it is too early in the assessment to advise the type of distribution wiring.

    The distribution may also need to account for other load related requirements, such as voltage drop - which would also come into play when advising on distribution cable sizing.

    Ciao, Tim
     
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