[TenTec] Slightly OT: Sunspots for propagation? Who needs 'em?

[Gary J FollettDukes HiFi]

3-phase power is not the universal blessing that you believe it to be. Well, I don’t really think I said it was the universal blessing. I just said that there is a reason why 3 phase power is used in heavy power consumption settings with efficiency in mind. There is no room for argument that a 3 phase RF power generator, operating without transformers, without filter capacitors is more efficient and less costly than its single phase counterpart. In addition, the elimination of filter capacitors reduces heat loss and eliminates the single most failure prone component in power supplies, the electrolytic capacitors.

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.

Does this apply to Delta 3 phase systems that have no neutral?

I am not trying to be confrontational here. As we all should be doing, I am just trying to learn more as we discuss radio related topics. I am not right about everything, which is why I am always trying to learn more.

For example, I am still trying to understand how the power companies pulled off that scheme of promoting “money saving efficient appliances”, a multi-year pitch followed by the whining plea to the PUC for higher per KWh rate to make up for lost sales caused by massive implementation of more efficient (and often less reliable) appliances. 

This is relevant to radio hobbits because the expenditure of some capital to make three phase available more widely available would reduce cost of linear amplifiers and other power equipment.

Gary


> On Aug 27, 2016, at 12:30 PM, Jim Brown <k9yc at audiosystemsgroup.com> wrote:
> 
> 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.