Positive and negative sequence

[junkhound]

OK, here is a mechanical analogy for discussion since the zero sequence CT discussions were closed.

Capstan raising a sail or anchor.

3 bars (phases) with the same number of guys of the same weight on each capstan bar (pole?).

All positive torque, all even.

But now the capstan was built unevenly, different length bars with different guy (or gal not to offend PC police) on each bar.
The mate does not know how to calculate total torque, so he asks an onboard math guru for how to do it. The math guru comes up with:

-- 3 capstan bars unequally spaced with different number of guys with different strength on each bar.

Mathematically, one can split the capstan torque into a symmetrical capstan with equal sized and number of guys on each bar pushing to rsise the anchor or sail, plus another symetical capstan with 3 euql sized smaller guys pushing the other way.

Net torque.

The question: to complete the analogy, where are the zero sequence guys, ho big are they and what are they pushing to complet the analaogy?
Are any of them playing a Harmonic_a?

 

[mivey]

OK, here is a mechanical analogy for discussion since the zero sequence CT discussions were closed.

Capstan raising a sail or anchor.

3 bars (phases) with the same number of guys of the same weight on each capstan bar (pole?).

All positive torque, all even.

But now the capstan was built unevenly, different length bars with different guy (or gal not to offend PC police) on each bar.
The mate does not know how to calculate total torque, so he asks an onboard math guru for how to do it. The math guru comes up with:

-- 3 capstan bars unequally spaced with different number of guys with different strength on each bar.

Mathematically, one can split the capstan torque into a symmetrical capstan with equal sized and number of guys on each bar pushing to rsise the anchor or sail, plus another symetical capstan with 3 euql sized smaller guys pushing the other way.

Net torque.

The question: to complete the analogy, where are the zero sequence guys, ho big are they and what are they pushing to complet the analaogy?
Are any of them playing a Harmonic_a?

There may not be negative guys. The zero sequence guys are three equal sized guys pushing on one bar.

So you have three equal strength guys pushing on three equal length bars (pos) and three equal strength guys pushing on one bar (zero) and if you want negative then three equal strength pirates pushing on three equal length bars in the opposite direction (negative).

Not sure if the analogy works but something like that.

 

[junkhound]

What direction are the zero guys pushing? Striaght up on vector diagram, just sittin on the capstan in the analogy?

 

[mivey]

What direction are the zero guys pushing? Striaght up on vector diagram, just sittin on the capstan in the analogy?

If we want direction to mean sequence, then the zero guys would be sitting, or maybe pushing up or down on the capstan rather than on bars around the capstan because they have no sequence (hence zero sequence).

In time, they all rotate in the same direction. One group has maybe a man-woman-child order, one group has a man-child-woman order, and the last is a group of three equal strength people having a man, woman, and child pushing one bar.

Not really a good mechanical representation because the sums don't produce the net force.

Suppose you have a blue, red, and yellow team (a,b,c phase). The three blue team members of man, woman, child (+-0) have to have a result that gives the total blue team force (a phase). same for red and yellow teams.

Let the teams shovel dirt, fill ballons, or some kind of work. If the teams produce the same work, the teams are balanced. If some team members shovel the wrong way, the result is less production (shorter vector for the team).

I'm trying the think of some way to represent the sum of pos, neg, zero, equals the phase. Sometimes the other sequences complement each other and produce a long vector and sometimes they are fighting each other and produce a shorter vector.

I'll have to give it more thought.