Iso-phase bus capacitance
Iso-phase bus capacitance
(OP)
I now there are many different geometries and sizes to iso phase bus installations, but I wondered if there is any kind of guide to the capacitance of commonly used iso bus in the US, typically used at generation plants. A pF or uF rating per 100' or some kind of rule of thumb would be great. New installs have the data but not old installations. It would be nice to have some idea of the AC hipot kVA size needed when quoting a job.
Thank all
Thank all






RE: Iso-phase bus capacitance
RE: Iso-phase bus capacitance
RE: Iso-phase bus capacitance
Thinking about this a bit more, you might need to have do two sets of calcs and sum the capacitances because on machines with unit aux transformers and/or exciter transformers tee'd off the main bus it is quite common to have a reduced size IPB serving the auxiliaries which will have a different capacitance per unit length. I wouldn't be surprised to find that the auxiliary bus has a greater capacitance p.u. than the main bus given the different geometry.
RE: Iso-phase bus capacitance
RE: Iso-phase bus capacitance
First link from google - see last page:
http://faculty.polytechnic.org/physics/3%20A.P.%20...'s/capac_of_coax_cable.pdf
C/L = 2*pi*Epsilon0 / ln(Router/Rinner)
Epsilon0 = 8.854E-12 F/m, which provides the expected units for C/L
If you can estimate length,Router, Rinner, you're in business
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(2B)+(2B)' ?