Student "edition" found at {csi dot journalspace dot com}.

Maybe I shouldn't have started this blog now, not with everything that's been going on.

In my energy conversion lecture class, during our most recent session, we discussed three-phase motors/generators with unbalanced loads.

That is, the impedances are not all the same for each branch or phase of the load, which was our initial assumption for the previous topic which made a lot of our equations simpler at the start.

After discussing how the three expressions for the voltage were taken (asking the students to get the references such as Kirchhoff's node rule, the voltage rule and Ohm's Law, and the definition of potential difference) we moved on to how to get the values of the currents in each of the branches.

For this one, we had to use systems of equations in two variables.

Choosing either determinants (relatively easy for two equations) or substitution, they would come up with the same fraction for any of the three currents involved. Now, the derivation for this one I made into an optional assignment for them.

From their reactions though, I doubt if anyone would submit it.

I emphasized for them that the values of the impedance and the voltages used in the equations, as well as for the final answer, are all in phasor or vector form (which means having a magnitude and an angle in the answer), making the operations not so easy to simplify as the students may have guessed.

And because at this point there were already some students miming winding an alarm clock and going to sleep for the remainder of the period, I made our first example into a seat work, to be submitted by pairs, which I said could be finished in twenty minutes, but which actually took them the rest of the period.

That is, including all the verifications they made with their classmates of their computations. At least they tried to solve it.

Now I'm also thinking that with all the topics we've discussed since their last exam, maybe it's time for another exam before the set schedule of the twelfth week, just to lighten their load, and not have so many topics to cover for week #12.

Session 1751 likes being given options by the teacher, and choosing what seems to be the easier. Class dismissed.