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Apparant PowerPower

Former Community Member
Former Community Member
I have to calculate a cable size for a CHP. The CHP unit is rated at 28.9kVA @ 0.76 PF.


My query is, is the design current taken as 41.7A apparent power, or 31.7A active power? And why is it one and not the other?
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    The full 41.7A - as that's the current actually flowing - the fact that it's not all transferring useful power matters not one jot to the cables. (The poor power factor - a mis-match between the current and voltage waveforms - means that in effect some power is flowing in the wrong direction during a part of the a.c. cycle - overall that power isn't lost but the cables still have to carry it forwards and back nonetheless.)


       - Andy.
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  • 0
    The full 41.7A - as that's the current actually flowing - the fact that it's not all transferring useful power matters not one jot to the cables. (The poor power factor - a mis-match between the current and voltage waveforms - means that in effect some power is flowing in the wrong direction during a part of the a.c. cycle - overall that power isn't lost but the cables still have to carry it forwards and back nonetheless.)


       - Andy.
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