Rules and Guidelines
Want to participate in the discussions? Please read our Community Rules and Guidelines. Need some help? Visit Support and Answers.

  • State Not Answered
  • Locked Locked
  • Replies 70 replies
  • Subscribers 32 subscribers
  • Views 4741 views
  • Users 0 members are here
Options
You may also be interested in
This discussion has been locked.
You can no longer post new replies to this discussion. If you have a question you can start a new discussion

Details of BS7671:2018 Amendment 1 are here.

Alan Capon
Details of Amendment 1 of BS7671:2018 is available here: https://electrical.theiet.org/bs-7671/updates/


Regards,


Alan.
Parents
  • 0

    AJJewsbury:




    Paul Judd:

    Is the formula for calculating the maximum neutral current (Im) in Annex A722; A722.1 Neutral current of a three-phase installation, actually correct?


    There's an L missing (IL3) and only half of the final multiplication is shown. 


    Probably!

     




    Good question - it's also nothing like the formula in BS 7671:2018 yet doesn't have any change bars...


      - Andy.


     




    The correct expression is:

    bea1b3f366016bc756977985ec71ea38-huge-a722.1.jpg


    Mathematically, it is identical to the expression in BS 7671:2018 ... if you consider that 0.866 = SQRT(3)/2 and do a bit of algebra.


    The replacement is more likely to have been encountered by those who have come across three-phase calculations in text books.

Reply
  • 0

    AJJewsbury:




    Paul Judd:

    Is the formula for calculating the maximum neutral current (Im) in Annex A722; A722.1 Neutral current of a three-phase installation, actually correct?


    There's an L missing (IL3) and only half of the final multiplication is shown. 


    Probably!

     




    Good question - it's also nothing like the formula in BS 7671:2018 yet doesn't have any change bars...


      - Andy.


     




    The correct expression is:

    bea1b3f366016bc756977985ec71ea38-huge-a722.1.jpg


    Mathematically, it is identical to the expression in BS 7671:2018 ... if you consider that 0.866 = SQRT(3)/2 and do a bit of algebra.


    The replacement is more likely to have been encountered by those who have come across three-phase calculations in text books.

Children
No Data

Community Rules & Guidelines