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  • Users: cosfi
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  1. cosfi

    Total current vs Symmetrical current method

    This may help you for improtance of x/r ratio. First graph is asymmetrical current which is total of second and third graphs, second one is only exponential component and third one is only symmetrical current.Explanations are in Turkish but you can understand equations.There is a also matlab...
  2. cosfi

    Motor Starting Current and Transformer Voltage Drop

    I have to start motors Direct on line.How can i keep the starting motor MVA lower than the Transformer s.c MVA. Because of DOL i think, i must change transformer ratings.
  3. cosfi

    Main Distribution Board

    Thank you davidbeach, For 160 kW motors , i calculated 185 mm2 cable for 50 meters. And short circuit current at the end of cable (at the load) is 20 kA. But , for 3 kW MOV i selected 2,5 mm2 cable for 50 meters and short circuit current at the end of the cable is approximately 5 kA. I...
  4. cosfi

    Motor Start Voltage Drop-Transformer Selection

    Dear Friends, Suppose that we have 400 V LV switchgear.And 2000 kVA transformer supplies it.while starting a motor which is supplied from this switchgear , a voltage drop occurs. Can we select transformer LV side 420 V at NO LOAD ? To prevent the voltage drop. But transformer power is the same...
  5. cosfi

    Main Distribution Board

    Dear Friends, We're designing a switchgear for a power plant. But we don't use subdistribution panels at this project. Customer want from us to supply all loads from Main D. B. directly. There are no local or another panels. So i want to ask a question , We supply small loads like motor operated...
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