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

wrote:
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" .
--
Snag
Learning keeps
you young !

Snag wrote:
wrote:
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

On Tue, 12 Jul 2011 23:27:58 +0000 (UTC), wrote:

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

The table is correct.

The legend reads "Current lead or lag on applied voltage"

+ 90 deg under inductance is a lagging current

- 90 deg under capacitance is a leading current

Glad you found the books useful.

Jim

On Jul 12, 10:24*pm, Rich Grise wrote:
Snag wrote:
wrote:

*ELI the ICE man . E leads I , the L standing for an inductor , I leads E

Another memory trick:
An inductor opposes a change in current; a capacitor opposes a change in
voltage.
Rich-

More useful if harder to memorize:
V = L dI/dt, I = C dV/dt

jsw

On Wed, 13 Jul 2011 11:33:39 +0100, wrote:

On Tue, 12 Jul 2011 23:27:58 +0000 (UTC), wrote:

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

The table is correct.

The legend reads "Current lead or lag on applied voltage"

+ 90 deg under inductance is a lagging current

- 90 deg under capacitance is a leading current

Glad you found the books useful.

Jim
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