Busbar Design


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  • Hi i am working in a Switchgear Panel Manufacturing company and i am interested to learn more about Busbar sizing and all other related topics. It would be great if anybody can help me to find a training courses in Dubai or Online training is also fine for me.
    My Email ID is : raoofbbisd@gmail.com
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  • I am an electrical engineer and working for panel board manufacturing company , so I have found it most useful document, but some how I cant download it , I think it is much useful for me.I would be grateful If you send me such kinds of useful documents .

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  • Welcome to this LE webcast. It discusses the design of busbar systems, including the choice of material, how to size busbars for a particular current rating and how to optimise the lifetime costs.
  • Busbar Design

    1. 1. Busbar Design Basics
    2. 2. <ul><li>High electrical conductivity </li></ul><ul><ul><li>only silver is better than copper </li></ul></ul><ul><li>Good thermal conductor </li></ul><ul><ul><li>heat reaches surface quickly </li></ul></ul><ul><li>Strong (at working temperature) </li></ul><ul><ul><li>to withstand short circuit stresses </li></ul></ul><ul><ul><li>low creep </li></ul></ul><ul><li>Easy to joint </li></ul><ul><ul><li>resistant to corrosion </li></ul></ul>Materials for Busbar Systems
    3. 3. Busbar System Current Ratings Busbar ratings are determined only by the maximum desired working temperature At working temperature: heat generated = heat lost
    4. 4. Busbar System Current Ratings <ul><li>Busbar ratings depend on: </li></ul><ul><ul><li>Working and ambient temperatures </li></ul></ul><ul><ul><li>Heat lost from the busbar </li></ul></ul><ul><ul><ul><li>by convection </li></ul></ul></ul><ul><ul><ul><li>by radiation </li></ul></ul></ul><ul><ul><li>Heat generated in the busbar </li></ul></ul>
    5. 5. Power dissipated by convection is given by: <ul><li>where </li></ul><ul><ul><li> is the temperature rise above ambient </li></ul></ul><ul><ul><li>v is the vertical height of the surface </li></ul></ul>Busbar System Current Ratings P cv1 P cv2 v
    6. 6. Convection (for 80 C temperature rise) Busbar System Current Ratings
    7. 7. Power dissipated by radiation is given by : <ul><li>where </li></ul><ul><ul><li>P r is the power dissipated per square metre </li></ul></ul><ul><ul><li>T 2 is the working temperature, K </li></ul></ul><ul><ul><li>T 1 is the ambient temperature, K </li></ul></ul><ul><ul><li> is the emissivity </li></ul></ul>Busbar System Current Ratings P r P r
    8. 8. The emissivity,  , describes how effectively the surface radiates heat For a perfectly polished surface, the value is close to zero - a very poor radiator For a matt black surface, the value is close to 1 - a very good radiator Busbar System Current Ratings
    9. 9. Bright copper has an emissivity of about 0.1 During use, the emissivity of the copper surface increases - and the current rating increases - as the copper darkens to reach an emissivity value of about 0.7 Tin plated copper has an emissivity of about 0.3 to 0.5 But painting bars reduces the current rating! Busbar System Current Ratings
    10. 10. Busbar System Current Ratings No radiation heat loss from internal surfaces P r P r P r P r P r P r
    11. 11. Radiation (for 30 C ambient) Busbar System Current Ratings
    12. 12. for 100 mm vertical height, 30 C ambient Busbar System Current Ratings
    13. 13. The power generated by current in the busbar is: <ul><li>where </li></ul><ul><ul><li> is the resistivity of the material </li></ul></ul><ul><ul><li>a is the cross sectional area </li></ul></ul><ul><ul><li>l is the length </li></ul></ul>Busbar System Current Ratings
    14. 14. At some temperature, the heat generated in the busbar is equal to the total heat lost by convection and radiation. Busbar System Current Ratings
    15. 15. Calculation method: 1 Select working and ambient temperatures 2 Assume initial current density of 8 amps/mm 2 3 Find appropriate size in standard range 4 Calculate heat generated due to current 5 Calculate heat loss at working temperature 6 If 4>5, increase size and return to 4 When 4=<5, this is smallest possible size Minimum size calculation
    16. 16. <ul><li>The most economic size gives the lowest lifetime cost . It is the minimum total cost of </li></ul><ul><ul><li>material </li></ul></ul><ul><ul><li>installation and </li></ul></ul><ul><ul><li>energy costs </li></ul></ul><ul><li>over the circuit lifetime. </li></ul><ul><li>Higher purchase cost - lower running costs </li></ul>Best economic sizing
    17. 17. Best economic sizing
    18. 18. Best economic sizing
    19. 19. Economic Sizing of Busbars
    20. 20. Busbar calculation software
    21. 21. Busbar calculation software
    22. 22. Busbar calculation software
    23. 23. Further considerations <ul><li>Having calculated the size of the bar, there are three further considerations: </li></ul><ul><ul><li>voltage drop </li></ul></ul><ul><ul><li>skin effect </li></ul></ul><ul><ul><ul><li>increases apparent resistance by reducing effective area - important for: </li></ul></ul></ul><ul><ul><ul><ul><li>thick busbars </li></ul></ul></ul></ul><ul><ul><ul><ul><li>high frequencies </li></ul></ul></ul></ul><ul><ul><ul><ul><li>harmonics generated by non-linear loads </li></ul></ul></ul></ul><ul><ul><li>short circuit current </li></ul></ul>
    24. 24. Summary of Busbar Material Characteristics <ul><li>High Conductivity </li></ul><ul><ul><li>low loss, low voltage drop </li></ul></ul><ul><ul><li>>101.5 % IACS </li></ul></ul><ul><li>Easy Formability </li></ul><ul><ul><li>due to small grain size and advanced production technology </li></ul></ul><ul><ul><li>easy to bend without surface deformation </li></ul></ul><ul><li>Good Flatness </li></ul><ul><ul><li>simple reliable jointing </li></ul></ul><ul><li>Good Straightness </li></ul><ul><ul><li>easy installation, lower joint stress </li></ul></ul>