Hi Sebi,
Thanks for the info.
I am surprised that you say that a 500 W transformer can
draw up to half an ampere with no load!
I would be using the older type construction with removable
laminations, and i would be packing them tightly with minimum
air gaps, as i understand these reduce the overall efficiency.
But i did not know that the lamination shapes had any effect.
Do you mean that the 'E' & 'I' type would be more efficient
than the 'T' & 'U' type, i have seen closed types that have
the middle section made like a tongue, and you sort of slot
them over and in, when in there are no joins around the edges.
What about toroidal types, are they much better ?
I can't see me wanting to leave a half an ampere running
continually on my house mains.
I did not realise the idle current would be that much.
As for the capacitor correction,
i actually thought that the inclusion of a cap
would improve the current/voltage angle, and reduce the peak
current demand.
You say the KWH meter does not cover this ?
I suppose their costing is on current only?
Maybe their profits are more if they charge for 'out of phase'
or unused current.
Regards John