A Real Slide Rule:

[rattus]

Stiff's problem with the uneven load currents can be solved in a number of ways. One is the graphical approach:

Consider L-L loads of 60A and 30A, what are the line currents?

First, draw two lines intersecting at 120 degrees. Now draw tic marks one centimeter apart on each line, and number the tics.

Now SLIDE your metric RULER over the diagram and measure the distance between the 3 on one line and 6 on the other as in the attachment. The distance, 7.85cm, represents a current of 78.5A which is close enough for most purposes. The other two currents are obvious.

Yeah, I know this has been beaten to death, but I thought this was cute!

 

[Pierre C Belarge]

Rattus
When I was in high school, there were no calculators. We used slide rules...you have brought back some old memories...

 

[rattus]

Rattus
When I was in high school, there were no calculators. We used slide rules...you have brought back some old memories...

Pierre, I had the good fortune to play a small part in the development of the hp-35 scientific calculator in 1971. In a few years, the slide rule was obsolete, but it is still a fine piece of work.

Never thought though that we could ever buy a scientific calculator in the grocery store!

 

[petersonra]

I still have my circular slide rule.

 

[rattus]

I still have my circular slide rule.

Hold on to it. It doesn't use batteries, and it doesn't take up much space.