3-phase power is not the universal blessing that you believe it to be.
The overwhelming bulk of the power delivered to today's homes is to
electronic loads, which draw highly distorted current, resulting in very
high harmonic content. That, in turn, results in high neutral currents
that consist of "triplen" harmonics of the fundamental rate (50 or 60
Hz). Triplen harmonics are those whose order is a multiple of 3, and
they add in the neutral rather than cancel, even with loads that are
perfectly balanced. Those harmonics also add in the "green wire,"
producing the characteristic "ground buzz" (180 Hz, 360 Hz, 540 Hz, 720
Hz, . . . ), as opposed to hum (50/60 Hz).
Neutral currents in 3-phase systems can easily exceed the current in a
phase conductor. Neutral current is what started the very real "Towering
Inferno" and burning insulation running up cable risers carried the flames.
73, Jim K9YC
On Sat,8/27/2016 1:37 AM, Gary J FollettDukes HiFi wrote:
Only politics, and the relentless battle that power companies wage every day to
avoid capital investment in new power delivery apparatus.
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