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Three phase voltage drop

Derek Eccles

For a balanced 3 phase system the supply authority, distributes 400v at the supply transformer.

The supply cables are 150m in length, so care is required to ensure the voltage drop does not become excessive at the customers terminals

Assuming there is a votage drop of 20v, across each cable at a particular balanced load, what voltage would the customer see at his terminals ?

I presume 360v ?

Regards, Derek

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  • 0

    The supply transformer will normally be set at 433V at the terminals to counteract this very problem.

  • 0 in reply to AdrianWint

    The transformer is 200 kVA. I have been told these transformers come with tappings, as you say to counteract this very problem.

    I was also told the tappings are usually set at 10% i.e. 440v.

  • 0 in reply to Derek Eccles

    The tappings are usually on the primary side (HV) so it probably won't be the 10% tap that you are thinking of (and it will a -ve tap - less windings on the primary gives a higher voltage on the secondary). 

  • 0 in reply to AdrianWint

    ok thank you

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