On Fri, 16 Apr 2010 01:34:32 +0100, "Q" ..@.. wrote:


"Dr J R Stockton" wrote in message
. invalid...

Now join the three
neutrals into one; the three return currents, being of different phases,
add to nothing, with balanced loads; therefore the neutral, carrying
only off-balance currents, can be comparatively thin. See sig.

Or not... Subject to the type of load it is recommended that you up-rate the
neutral's

Doesn't the cheat for that one involve the use of star-delta
transformers at each end of the circuit (i.e. no neutral at all on the
"trunk" part of the circuit) and controlling the out-of-balance
currents appropriately ?

Capacitive loads, those with a poor crest factor and high THD will
(unchecked) burn your neutral bars/links out in no time at all.

This has been a big problem in I.T installs of ye olden days using current
kit and high density computing.

Then we get into the problems with kVAr...