On Tue, 26 Mar 2002, Bruce Hebbard wrote: > > ... could someone please explain why serious > power equipment often uses VA (kVA, MVA, etc.) as distinct from W ?
VA often implies "reactive power" i.e. p = v.i cos (theta) where theta is the phase angle between potential v and current i of the alternating current in a reactive device. In a pure resistive device v and i are always in phase. i.e. theta = zero and cos (theta) = 1 at all times; ac or dc.
