Calculate Size of Transformer and Voltage drop due to starting of large size motor

ScreenHunter_01 May. 07 20.13

  • Calculate voltage drop in transformer due starting of Single/Multiple motor
  • Calculate Full Load Current of Transformer.
  • Calculate Short Circuit Current at Transformer Secondary.
  • Calculate Max KVA of Transformer at Short Circuit Current.
  • Calculate Motor In Rush KVA At Starting.
  • Calculate Voltage Drop at Transformer Secondary Due to Motor in Rush
  • Calculate Transformer Secondary Voltage


About Jignesh.Parmar
Jignesh Parmar has completed M.Tech (Power System Control), B.E(Electrical). He is member of Institution of Engineers (MIE) and CEng,India. Membership No:M-1473586.He has more than 16 years experience in Transmission -Distribution-Electrical Energy theft detection-Electrical Maintenance-Electrical Projects (Planning-Designing-Technical Review-coordination -Execution). He is Presently associate with one of the leading business group as a Deputy Manager at Ahmedabad,India. He has published numbers of Technical Articles in “Electrical Mirror”, “Electrical India”, “Lighting India”,”Smart Energy”, “Industrial Electrix”(Australian Power Publications) Magazines. He is Freelancer Programmer of Advance Excel and design useful Excel base Electrical Programs as per IS, NEC, IEC,IEEE codes. He is Technical Blogger and Familiar with English, Hindi, Gujarati, French languages. He wants to Share his experience & Knowledge and help technical enthusiasts to find suitable solutions and updating themselves on various Engineering Topics.

19 Responses to Calculate Size of Transformer and Voltage drop due to starting of large size motor

  1. Latesh says:

    Hi Jignesh, this latest file “Calculate Size of Transformer and Voltage drop due to starting of large size motor” When you try to download it, it comes as an exe file and the antivirus program confirms that it is a virus. Please have a look. Thanks

    • There is No any VIRUS but It is Download manage exe File of File sharing site.
      When You downloading the file please “Unmarked” the Download with accelerator and get recommended offers.
      By default it is marked so when you downloading the file it first download file sharing download manager “Exe” file.
      Whenever you download any file from any file sharing site please be alert to unmark the download manager “exe” file of the site.
      after unmark You will not get Download manager and get xls file. I have Recheck it as your comment.

  2. dear sir i cant down load the file any help?? please

  3. mozes says:

    I can’t download. How do i download?

  4. Paul Lo says:

    I download the file without .exe but it opens with funny things!
    No spreadsheet is found.

  5. Sathya Narayana says:

    Respected Sir,
    can;t download, pl help me in downloading

  6. Janardhan says:

    Dear sir,
    pls advice for below problem

    DG for 400 KW HT MOTOR: We need separate DG Set for running 400KW, 11
    KV MOTOR. The Motor has DOL Starter. We are going to run this motor
    through 2.5 MVA Transformer. The DG Shall be 415V, Three Phase. DG
    output shall be feed to LV Side (415V) of 2.5 MVA Transformer. And the
    Motor shall be connected to secondary side (11kv) of the transformer.
    We request to advice suitable rating of DG Set.

    Moter spectifications as below

    Power – 400kw / 536HP
    Pole – 2
    Voltage / PH / Hz – 11kv / 3ph / 50Hz
    Speed – 2975 RPM
    Type of Motor – SCR
    Service Factor – 1
    Rated PF – 0.88
    Full load Current – 25amp
    Method of Starting – DOL
    Application – Pump

    Thanks and regards

    • Not getting Your Point as per your detail Motor is 11KV and you state that “The DG Shall be 415V, Three Phase. DG
      output shall be feed to LV Side (415V) of 2.5 MVA Transformer. And the Motor shall be connected to secondary side (11kv) of the transformer”

      What is out put of TC 11KV/415 or else..Where you want to connect 11KV Motor..What is Out put of DG 11KV or 415V..
      Use DG Size Calculator of this Blog..

      • Janardhan says:

        Dear sir,

        DG set is having out put voltage of 415V. and 50Hz

        This DG out put will be given to Step-up 2.5MVA Transformer (415v to 11kv ).

        Input supply for the HT Motor of 400kw will be taken from the 11kv transformer.

        Please suggest what shall be the rating of LT DG set.

  7. Padlock01 says:

    Please make available ” Buy Unlocked version
    Thanks Padlock01

  8. Bob says:


  9. Bob says:


  10. sandeep says:

    sir pls tell me the average house kw per month…..
    how many house can be connected to one 100 kva transformer

  11. gani says:

    discharge and head is given
    then we calculate motor capacity in kw ?
    pls help me
    if u calculate give me formula sir

  12. jaspreet says:

    dear sir,
    please suggest me how to select dg size for the following-
    8 nos 150kw,415v motors with soft starter and auxiliary load of 100kw.

  13. i’m new at electrical.
    how many motor in the right side?

  14. manu sibi says:

    sir ,pls give me a notes on electrical Design

  15. Pooja Sankhe says:

    Dear Sir,

    what is the basis for considering motor full load current should be less than or equal to transfomer secondary full load current.


    it is complicated to download and open , better you give us straight forward link, it will be helpful to us.

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