voltage drop

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  • #11004
    yudhi
    Participant

    Hi I am yudhi

    I have problem with voltage drop ,
    When the load at 3400 amp the voltage drop until 360 volt
    I use 4000 kva step down transformer from 20 kv to 400 volt.
    The cable is NYY 1x400mm , 8 cable for each phase at 400 volt
    And 1x120mm at 20 kv, cos q is 0.9
    Distance grom transformer to switchboard around 60 mtr

    I dont know where the problem
    I hope you guys can help me to solve this problem

    Regards
    Yudhi

    #13121
    admin
    Keymaster

    Hi yudhi,

    Your posted has been moved to the right section of the forum, “General discussion”. Now the community will see your topic and probably help you.

    #13078
    Spir Georges GHALI
    Participant

    @yudhi said:
    Hi I am yudhi

    I have problem with voltage drop ,
    When the load at 3400 amp the voltage drop until 360 volt
    I use 4000 kva step down transformer from 20 kv to 400 volt.
    The cable is NYY 1x400mm , 8 cable for each phase at 400 volt
    And 1x120mm at 20 kv, cos q is 0.9
    Distance grom transformer to switchboard around 60 mtr

    I dont know where the problem
    I hope you guys can help me to solve this problem

    Regards
    Yudhi

     

    Dear ;

    First, by calculating the voltage drop of cables between the transformer and switchboard, I found that should be around “ 1% ”, noting that I assumed the arrangement of these cables is “ Trefoil ”, but let me know if the mentioned voltage drop “ ≈5% ” is only for this distance ? Or in a another place of network ?

    If it’s only of this distance, you should do the following :

    – Measure the output voltage of the secondary’s transformer at no-load.

    – if it’s “ 400V ”, we should know the specifications of the transformer and the length of MV line to be able to calculate if this phenomena is caused by MV line.

    – if the output voltage is smaller than “ 400V ”, the reasons are either the MV voltage is less “ 20kV ” (you should know this value), or the position of the “ Tap-off changer ” is not correct, in all cases, try to change this position to have around “ 400V ” or even just a little more.

    – if this voltage drop is in another place of network, please let me the type, section, length, and arrangement ( if it’s Single Core ) of that cables to be able to calculate the voltage drop at that point.

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