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3 phase supply size

Discussion in 'Electrical Forum' started by James sparks, Apr 13, 2014.

Discuss 3 phase supply size in the Electrical Forum area at ElectrciansForums.co.uk.

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  1. James sparks
    Offline

    James sparks Active EF Member

    Hi all,

    I need to put in a 3 phase supply for a piece of equipment in a commercial unit. They've sent the spec sheet for the item over and all it says is

    Current type (Ph/V/Hz): 3/420/50
    Power rating (kW): 7.8


    I just want to clarify if it's 7.8kW per phase or 7.8kW total over all 3 phases.

    Thanks!!
     
    James sparks, Apr 13, 2014
    #1
  3. uksparks
    Offline

    uksparks Electrician's Arms

    Location:
    Market Harborough
    I would imagine it's in total not per phase.
     
    uksparks, Apr 13, 2014
    #2
  4. darkwood
    Offline

    darkwood Super Moderator Staff Member Super Moderator

    Location:
    West Yorkshire
    usually if you use a kw rating in the same spec as 3ph its per phase ...
     
    darkwood, Apr 13, 2014
    #3
  5. uksparks
    Offline

    uksparks Electrician's Arms

    Location:
    Market Harborough
    I suppose the best thing would be to get more data from the device
     
    uksparks, Apr 13, 2014
    #4
  7. micknew
    Offline

    micknew Electrician's Arms

    Location:
    Kent
    I agree with you.
    If not it should have said 'per phase.
     
    micknew, Apr 13, 2014
    #5
  8. James sparks
    Offline

    James sparks Active EF Member

    [TABLE="width: 100%"]
    [TR="class: tecdata_title"]
    [TD][h=3]Technical data[/h][/TD]
    [TD] [/TD]
    [TD] [/TD]
    [/TR]
    [TR="class: tecdata_row"]
    [TD="class: bodysmall lineundertd"][TABLE]
    [TR]
    [TD]Current type Ph/V/Hz[/TD]
    [/TR]
    [/TABLE]
    [/TD]
    [TD="class: bodysmall lineundertd"] [/TD]
    [TD="class: bodysmall lineundertd"][TABLE]
    [TR]
    [TD="class: tecdataval"]3[/TD]
    [TD]/[/TD]
    [TD="class: tecdataval"]420[/TD]
    [TD]/[/TD]
    [TD="class: tecdataval"]50[/TD]
    [/TR]
    [/TABLE]
    [/TD]
    [/TR]
    [TR="class: tecdata_row"]
    [TD="class: bodysmall lineundertd"][TABLE]
    [TR]
    [TD]Flow rate (l/h)[/TD]
    [/TR]
    [/TABLE]
    [/TD]
    [TD="class: bodysmall lineundertd"] [/TD]
    [TD="class: bodysmall lineundertd"][TABLE]
    [TR]
    [TD="class: tecdataval"]500[/TD]
    [TD="class: tecdataval"]-[/TD]
    [TD="class: tecdataval"]1000[/TD]
    [/TR]
    [/TABLE]
    [/TD]
    [/TR]
    [TR="class: tecdata_row"]
    [TD="class: bodysmall lineundertd"][TABLE]
    [TR]
    [TD]Pressure (bar/MPa)[/TD]
    [/TR]
    [/TABLE]
    [/TD]
    [TD="class: bodysmall lineundertd"] [/TD]
    [TD="class: bodysmall lineundertd"][TABLE]
    [TR]
    [TD="class: tecdataval"]30[/TD]
    [TD="class: tecdataval"]-[/TD]
    [TD="class: tecdataval"]200[/TD]
    [TD]/[/TD]
    [TD="class: tecdataval"]3[/TD]
    [TD="class: tecdataval"]-[/TD]
    [TD="class: tecdataval"]20[/TD]
    [/TR]
    [/TABLE]
    [/TD]
    [/TR]
    [TR="class: tecdata_row"]
    [TD="class: bodysmall lineundertd"][TABLE]
    [TR]
    [TD]Max. temperature (°C)[/TD]
    [/TR]
    [/TABLE]
    [/TD]
    [TD="class: bodysmall lineundertd"] [/TD]
    [TD="class: bodysmall lineundertd"][TABLE]
    [TR]
    [TD="class: tecdataval"]155[/TD]
    [TD="class: tecdataval"]-[/TD]
    [TD="class: tecdataval"]80[/TD]
    [/TR]
    [/TABLE]
    [/TD]
    [/TR]
    [TR="class: tecdata_row"]
    [TD="class: bodysmall lineundertd"][TABLE]
    [TR]
    [TD]Power rating (kW)[/TD]
    [/TR]
    [/TABLE]
    [/TD]
    [TD="class: bodysmall lineundertd"] [/TD]
    [TD="class: bodysmall lineundertd"][TABLE]
    [TR]
    [TD="class: tecdataval"]7.8[/TD]
    [/TR]
    [/TABLE]
    [/TD]
    [/TR]
    [TR="class: tecdata_row"]
    [TD="class: bodysmall lineundertd"][TABLE]
    [TR]
    [TD]Consumption fuel oil (kg/h)[/TD]
    [/TR]
    [/TABLE]
    [/TD]
    [TD="class: bodysmall lineundertd"] [/TD]
    [TD="class: bodysmall lineundertd"][TABLE]
    [TR]
    [TD="class: tecdataval"]6.4[/TD]
    [/TR]
    [/TABLE]
    [/TD]
    [/TR]
    [TR="class: tecdata_row"]
    [TD="class: bodysmall lineundertd"][TABLE]
    [TR]
    [TD]Fuel tank (l)[/TD]
    [/TR]
    [/TABLE]
    [/TD]
    [TD="class: bodysmall lineundertd"] [/TD]
    [TD="class: bodysmall lineundertd"][TABLE]
    [TR]
    [TD="class: tecdataval"]25[/TD]
    [/TR]
    [/TABLE]
    [/TD]
    [/TR]
    [TR="class: tecdata_row"]
    [TD="class: bodysmall lineundertd"][TABLE]
    [TR]
    [TD]Fuel tank (cc³)[/TD]
    [/TR]
    [/TABLE]
    [/TD]
    [TD="class: bodysmall lineundertd"] [/TD]
    [TD="class: bodysmall lineundertd"][TABLE]
    [TR]
    [TD]-[/TD]
    [/TR]
    [/TABLE]
    [/TD]
    [/TR]
    [TR="class: tecdata_row"]
    [TD="class: bodysmall lineundertd"][TABLE]
    [TR]
    [TD]Weight (kg)[/TD]
    [/TR]
    [/TABLE]
    [/TD]
    [TD="class: bodysmall lineundertd"] [/TD]
    [TD="class: bodysmall lineundertd"][TABLE]
    [TR]
    [TD="class: tecdataval"]171[/TD]
    [/TR]
    [/TABLE]
    [/TD]
    [/TR]
    [TR="class: tecdata_row"]
    [TD="class: bodysmall lineundertd"][TABLE]
    [TR]
    [TD]Dimensions (L x W x H) (mm)[/TD]
    [/TR]
    [/TABLE]
    [/TD]
    [TD="class: bodysmall lineundertd"] [/TD]
    [TD="class: bodysmall lineundertd"][TABLE]
    [TR]
    [TD="class: tecdataval"]1330[/TD]
    [TD="class: tecdataval"]x[/TD]
    [TD="class: tecdataval"]750[/TD]
    [TD="class: tecdataval"]x[/TD]
    [TD="class: tecdataval"]1060[/TD]
    [/TR]
    [/TABLE]
    [/TD]
    [/TR]
    [TR="class: tecdata_row"]
    [TD="class: bodysmall lineundertd"][TABLE]
    [TR]
    [TD]Detergent tank (l)[/TD]
    [/TR]
    [/TABLE]
    [/TD]
    [TD="class: bodysmall lineundertd"] [/TD]
    [TD="class: bodysmall lineundertd"][TABLE]
    [TR]
    [TD="class: tecdataval"]20[/TD]
    [/TR]
    [/TABLE]
    [/TD]
    [/TR]
    [/TABLE]
     
    James sparks, Apr 13, 2014
    #6
  9. micknew
    Offline

    micknew Electrician's Arms

    Location:
    Kent
    That is telling you that the total load of the machine is 7.8KW.
     
    Last edited: Apr 13, 2014
    micknew, Apr 13, 2014
    #7
  10. uksparks
    Offline

    uksparks Electrician's Arms

    Location:
    Market Harborough
    So it's 7.8kW split across phases, so not much then, what is it you say? A pump?
     
    uksparks, Apr 13, 2014
    #8
  11. darkwood
    Offline

    darkwood Super Moderator Staff Member Super Moderator

    Location:
    West Yorkshire
    its per phase 7.8kw per phase otherwise it would have stated single
     
    darkwood, Apr 13, 2014
    #9
  12. micknew
    Offline

    micknew Electrician's Arms

    Location:
    Kent
    No it wouldn't.
     
    • Like Like x 2
    micknew, Apr 13, 2014
    #10
  13. darkwood
    Offline

    darkwood Super Moderator Staff Member Super Moderator

    Location:
    West Yorkshire
    If you have a spec asking fot 3ph and a Kw rating its Kw per phase .. . no disrespect to other posters but your guessing and not experienced in 3ph so express this in your post or you may mislead the OP ... I assume a 3ph device is part of the setup like a motor; motors are specd per phase not devided by 3..
     
    • Like Like x 1
    darkwood, Apr 13, 2014
    #11
  14. NickD
    Offline

    NickD Regular EF Member

    Location:
    Vulcan
    panto.jpg

    I would ask the question of the supplier/manufacturer/whoever. Assumption is the mother of all cock ups.
     
    • Like Like x 1
    NickD, Apr 13, 2014
    #12
  15. micknew
    Offline

    micknew Electrician's Arms

    Location:
    Kent
    You are wrong and most of my work is industrial 3 phase.
     
    micknew, Apr 13, 2014
    #13
  16. darkwood
    Offline

    darkwood Super Moderator Staff Member Super Moderator

    Location:
    West Yorkshire
    If you request a supply from DNO in Kw then its per phase.
    If you get a motor and it says 4kw 400v then its per phase.
    If you have a machine that asks for a 3ph supply 10kw then thats per phase.


    25yrs of industrial intalls design and machine panel building plus several requests to DNO for supplies or upgrades im sure im not wrong....

    Only exception is the occasional machine usually from china and 2nd hand that does go over 3ph and checking the wiring plan or load characteristics can usually identify this but other than that ill say your wrong.

    Its always good to cross check these values Ive seen architects mess up if a reading is in KVA on a machine or supply then its likely to be a total demand across the phases as dave points out below but the OP spec'd a Kw value.
     
    Last edited: Apr 14, 2014
    darkwood, Apr 14, 2014
    #14
  17. davesparks
    Offline

    davesparks Forum Mentor

    Location:
    guildford
    Consider a 32A three phase mcb, that's 32A per phase. Same goes for KW rating.

    Only fly in the ointment I can think of is from UKPN's paperwork where a 100A 3ph supply is described as being a 69KVA 3ph supply.
     
    davesparks, Apr 14, 2014
    #15
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