- #1
moh abdelsalam
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At M.V. (10.5KV), what is the difference in material between 1250A, 40KA busbar & 1250A, 50KA?
Difference in material between 1250A, 40KA & 1250A, 50KA?
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Discussion Overview
The discussion centers on the differences in materials used for busbars rated at 1250A with fault current ratings of 40KA and 50KA, particularly in the context of high power AC systems at a voltage of 10.5KV. Participants explore various aspects of busbar design, including conductor materials, insulation, and structural considerations.
Discussion Character
- Technical explanation
- Debate/contested
Main Points Raised
- One participant notes the vagueness of the initial question and requests clarification on the specific materials being referred to.
- Another participant provides general information about busbar design, mentioning that high power applications may require specialized engineering and that aluminum alloys are commonly used despite concerns regarding mechanical and electrical connections.
- A participant emphasizes the importance of rigidity in busbar design, particularly under high current fault conditions, suggesting that the busbars must be robust enough to prevent bending and potential faults.
- There is a mention of the relationship between fault current ratings and the required structural support, indicating that higher fault ratings necessitate increased bracing and consequently higher costs for busbars and breakers.
- One participant discusses the use of current limiting inductors in switchgear to manage fault currents, which can allow for the use of less expensive busbars and breakers downstream.
Areas of Agreement / Disagreement
Participants express varying levels of agreement on the importance of material choice and structural integrity in busbar design, but no consensus is reached regarding the specific differences between the materials used for the 40KA and 50KA rated busbars.
Contextual Notes
The discussion lacks specific details about the materials in question, and assumptions regarding the design requirements for high current applications remain unresolved.
- #2
davenn
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hi and welcome to PF 
your question is extremely vague
What material ?
outline more clearly what you are referring to with as much relevant info as possible
your question is extremely vague
What material ?
outline more clearly what you are referring to with as much relevant info as possible
- #3
moh abdelsalam
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I'm sorry, I'm talking about busbar material (the conductor, insulation, supports and etc...).davenn said:hi and welcome to PF
your question is extremely vague
What material ?
outline more clearly what you are referring to with as much relevant info as possible
Last edited:
- #4
Jeff Rosenbury
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Here's some busbar information. This seems to be for more typical busbars and may not be as useful for high power applications. Still, most of the same problems will still need to be solved.
For high power AC systems, lots of engineering work will need to be done. The electrical characteristics will depend on geometry. Typically these will be large hollow roundish metal structures. Aluminum alloys are a popular choice, but has some concerns about mechanical/electrical connections.
After the electrical characteristics are determined, structural problems need to be solved.
This is a specialized field and you may need to hire a power engineer with experience with station/substation design if you need specifics.
For high power AC systems, lots of engineering work will need to be done. The electrical characteristics will depend on geometry. Typically these will be large hollow roundish metal structures. Aluminum alloys are a popular choice, but has some concerns about mechanical/electrical connections.
After the electrical characteristics are determined, structural problems need to be solved.
This is a specialized field and you may need to hire a power engineer with experience with station/substation design if you need specifics.
- #5
jim hardy
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One of the design considerations is rigidity.
Under high current faults the conductors are attracted to one another,
so it is required they be stout enough that a downstream fault will not make them bend and touch between supports which would cause another fault.
So i'll assume your 40 and 50 ka numbers are fault current ratings,beyond the 1.25 ka.
Presumably the busbar is supported as necessary and made more rigid considering the forces produced by fault current. Those forces are in proportion to the product of the currents as indicated in that Hyperphysics image above, http://hyperphysics.phy-astr.gsu.edu/hbase/magnetic/wirfor.html
502/402 = 1.56+,
ie 56% more bracing required.
That of course raises the cost of busbar and breakers.
Sometimes you'll see a current limiting inductor in switchgear.
It limits fault current allowing use of less expensive busbar and breakers downstream . My plant had them in the 4kv switchgear , located between the breakers supplying multi-thousand horsepower motors and those feeding only multi-hundred horsepower motors.
Under high current faults the conductors are attracted to one another,
So i'll assume your 40 and 50 ka numbers are fault current ratings,beyond the 1.25 ka.
Presumably the busbar is supported as necessary and made more rigid considering the forces produced by fault current. Those forces are in proportion to the product of the currents as indicated in that Hyperphysics image above, http://hyperphysics.phy-astr.gsu.edu/hbase/magnetic/wirfor.html
502/402 = 1.56+,
ie 56% more bracing required.
That of course raises the cost of busbar and breakers.
Sometimes you'll see a current limiting inductor in switchgear.
It limits fault current allowing use of less expensive busbar and breakers downstream . My plant had them in the 4kv switchgear , located between the breakers supplying multi-thousand horsepower motors and those feeding only multi-hundred horsepower motors.
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