Here in the transit industry, we know our PFs for all our loads;
however, I can't convince them that they do not have to increase their
conductor sized to meet this NFPA requirement. Besides, we're not even
subject to the NFPA. Because we're talking hundreds of miles of 750 kcm
Cu conductors here, we're talking about millions of wasted $$.
<rant over>
<><><><><><>
For the record, Michel is right in that the reactive power wants to
return to the load via the transmission system and contributes to
conductor heating.
Our client wants to raise the conductor diameters over the initial
design and cites the NFPA. However, our traction power engineers argue
that a 20% safety factor inherent in the design is more than enough.
The NFPA is very conservative in conductor heating issues.
Turns out the engineers have already proposed adding negative VAR
devices over larger copper (PF correcting capacitors).
Terry
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