Greetings Jim, I have a couple of your books. Read 'em too. They were good reads. I have a question about a table on page 16 of the second edition of Electric Motors. The table shows that for an inductor the current leads 90 degrees and for capacitance the current lags by 90 degrees. I thought it was just the opposite. Am I wrong again? Thanks, Eric
ELI the ICE man . E leads I , the L standing for an inductor , I leads E , the C standing for capacitance . Larnt thet in my BE&E class NTC San Diego 1971 ... along with other gems like "ex a bell equals 2 pies effell" .
Another memory trick: An inductor opposes a change in current; a capacitor opposes a change in voltage.
Cheers! Rich
The table is correct.
The legend reads "Current lead or lag on applied voltage"
- 90 deg under capacitance is a leading current
Glad you found the books useful.
Jim
More useful if harder to memorize: V =3D L dI/dt, I =3D C dV/dt
jsw
Greetings Jim, So the +90 degrees refers to the voltage leading the current. So I did understand what happens with the current but did not understand the table. This means that whenever I see current lag or lead in reference to voltage the amount of lag or lead refers to voltage how much the voltage leag or leads. Thank you, Eric
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